Browse Topic: Composite materials

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Experimental Investigation on the Failure Behavior of TMC Open-Hole Panels under Tensile Loading2026-99-060211/6/2026
Investigating the load-bearing capacity of Titanium Matrix Composites (TMCs) open-hole panels and their mechanically connected components is of great significance for the application of titanium matrix composites in the aerospace field. This paper investigates the failure behavior of TMC open-hole panels with a [45°/45°/-45°/-45°] laminate configuration under tensile loading. Tensile tests were conducted in conjunction with finite element modeling to analyze the damage evolution process and identify the failure modes of the tensile samples. The results show that the simulation outcomes exhibit good consistency with the experimental results, providing a foundation for the structural optimization and theoretical study of TMC open-hole panels.
Gao, Ximan, Jia, Qiuyue, Liu, Shanshan, Meng, Fanling
Investigation on Dynamic Expansion Response and Structural Safety Assessment of Typical Polygonal Fabric Gasbags2026-99-233710/30/2026
The geometric structure of a gas bag has a profound effect on its effectiveness in transferring energy and reliability of its structure when rapidly expanding. Even though there have been considerable improvements in high-performance composite materials such as Kevlar, the transient dynamic reaction and possible rupture mechanisms associated with particular polygon shapes have been greatly unexplored. In this paper, we focus on conventional polygonal gas bags, and perform extensive inflation tests using high-accuracy transient data recorders to monitor the development of the dynamic pressure. In order to overcome the limitations of physical testing, a highly non-linear dynamic finite element model - based upon the application of the *MAT_FABRIC material model in LS-DYNA - is used. This technique allows the systematic examination of how changes in geometric parameters affect the performance of payload dispersion and membrane stress distribution. The results indicate unique ways of deploying depending on their geometry. The circular gas bags are capable of obtaining a velocity of the payload of 4.23 m/s but have high stress concentrations of up to 426 MPa due to the lack of geometric boundaries which make them prone to tearing failure. Rectangular gas bags with very large aspect ratios will experience a tubular expansion deformation that causes energy transfer efficiency to plummet; the release speed of these types of gas bags falls below 2.77 m/s. Ultimately, the optimal structural design is a regular hexagonal shape that optimally balances work performance and structural safety. It can keep good levels of energy transfer efficiency with a final release velocity of 4.12 m/s. Moreover, it successfully stops the continuous hoop tension and reduces the peak stress by around 46 percent through straight edge boundary constraints. This complete research offers an adequate scientific foundation to the anti-burst design of sophisticated polygonal gas bags.
Wang, Jinwei, Shi, Lv, Hou, Jingjing, Li, Yilong, Li, Dailin, Liu, Zhiyi
Process and Performance Optimization Design of Metal-3D Braided Composite Joint Structures2026-99-234910/30/2026
The sleeve is the key assembly part of the high-speed internal electric spindle support of the high-precision CNC internal and external grinder, and its machining accuracy directly affects the running state of the spindle. The purpose of this study is to adjust the structural process to improve its bearing capacity in all directions. Combined with the refined mechanical simulation of 3D braided composites, the influence mechanism of joint thickness and surface pretreatment on the connection performance is studied from the aspects of stress distribution characteristics and damage failure mechanism. The overall performance analysis and design of the metal-composite sleeve are carried out. Experiments show that the thickness of the joint has a great influence on its bearing performance, and the effectiveness of the proposed pretreatment process is verified, which provides a reliable technical path for the realization of high-performance metal-3D braided composite connection structure.
Wang, Zijun, Chi, Xinfu, Li, Chengen, Li, Dinghua
Synergistic Enhancement of Impact Resistance in SiCw-Polymer Composite2026-99-232510/30/2026
Addressing the performance degradation bottleneck of conventional impact-resistant materials under complex operating conditions, and the limitation of existing research focusing primarily on enhancing single properties while neglecting material equilibrium, this study employs silicon carbide whiskers (SiCw) as the reinforcing phase. Through surface modification techniques, SiCw/celluloid and SiCw/polyimide dual-polymer composite systems were constructed and systematically investigated. Surface modification of SiCw was achieved using titanate and silane coupling agents. Through mechanical testing and X-ray photoelectron spectroscopy (XPS) characterisation, the effects of SiCw loading and modification treatments on composite mechanical properties and interfacial bonding were analysed. Results indicate that SiCw introduction significantly enhances the tensile, flexural, and impact strength of the polymer matrix, with optimal addition ratios identified: 6% for the celluloid system and 1.0% for the polyimide system. Surface modification further optimises toughening effects by reducing surface oxide layers and impurities on SiCw particles while strengthening interfacial bonding. This study provides practical guidance for the system design of high-performance impact-resistant composites. The resulting materials hold broad application prospects in sectors demanding high structural impact resistance, such as aerospace and transportation.
Xue, Kaiming
Research on Dynamic Response and Impact Resistance of Airport Pavement Made of Gradient Carbon Fiber Reinforced Composites2026-99-234610/30/2026
Aiming at the engineering problems of easy cracking and insufficient impact resistance of traditional airport concrete pavement under complex dynamic loads, this paper studies the application of functionally graded carbon fiber reinforced polymer ( FG-CFRP) in airport pavement. Based on the modified Halpin-Tsai model and the first-order shear deformation theory, the dynamic finite element control equation is established. Based on the COMSOL Multiphysics platform, the modal characteristics and transient impact response analysis are carried out, and the dynamic response of the aircraft under moving wheel load is simulated. The static bending test of FG- CFRP plate samples made in the laboratory was carried out, and the numerical model was calibrated. The relative error of test-simulation was controlled within 5 %, which verified the accuracy of predicting static response. The carbon fiber volume fraction gradient curve was parametrically studied to reveal the sensitivity of the gradient to impact and stress reduction. The key engineering factors such as long-term environmental durability and life cycle cost of FG-CFRP pavement are discussed, and targeted improvement and optimization strategies are proposed. The results show that the fundamental frequency of the gradient plate is about 1.93 % lower than that of the homogeneous plate, and the vibration mode characteristics are highly consistent. The peak displacement of transient impact is reduced by 9.4 %. Under the action of moving wheel load, the peak Von Mises stress decreased from 5.32 MPa to 2.15 MPa, with a decrease of 60 %. The gradient design realizes efficient load diffusion and impact hardening through the surface high modulus layer, and the gradual change of interlayer wave impedance promotes the dissipation of stress wave, which significantly improves the safety reserve and dynamic stability of pavement structure. This study verifies the application feasibility of FG-CFRP in high-performance airport pavement engineering, and provides innovative material solutions and theoretical support for the development of a new generation of long-life and high-reliability airport pavement.
Li, Zhenyue
Study on Fatigue Crack Growth of Sandwich Composite Panels with Opening2026-99-232710/30/2026
Owing to their remarkable specific strength and stiffness, coupled with superior impact resistance and thermal/acoustic insulation, sandwich composite panels are extensively utilized in marine, aerospace, and transportation sectors. In contrast to conventional monolithic structures, the multi-layered architecture of sandwich panels introduces complex fatigue failure mechanisms that are not yet fully understood. This study experimentally investigates a U-shaped core sandwich panel featuring a rectangular hatch opening under uniaxial tensile fatigue loading, aiming to characterize its crack initiation and propagation behavior. Subsequently, a custom three- dimensional fatigue crack growth simulation code is developed, grounded in linear elastic fracture mechanics and the extended finite element method (XFEM). A comparison with experimental measurements reveals that the maximum relative error between the predicted and observed fatigue life is 15.7%. The findings offer a theoretical foundation and a technical reference for the fatigue design and life assessment of such sandwich structures.
Chen, Siyu, Xu, Yunze, Liu, Gang
Study on Interface Design and Functional Tolerance of Structured Composites for Zero Thermal Expansion Performance2026-99-232310/30/2026
Structured zero thermal expansion composites demonstrate significant application potential in thermal deformation control for high-end equipment, particularly aerospace precision instruments, due to their unique ultra-low thermal expansion properties. However, during the transition from theoretical design models to manufacturing models, uncertainties at connection interfaces and manufacturing errors alter the thermal deformation coordination between heterogeneous components within the material, leading to significant degradation of its zero thermal expansion performance. To address this issue, this study focuses on lattice-structured zero thermal expansion composites derived from topology optimization. First, the connection interface design between heterogeneous lattice components was completed. Subsequently, two typical manufacturing errors—dimensional errors and assembly tolerances—were incorporated into the manufacturability model. Using Monte Carlo random sampling, a mapping relationship was established between the random and discrete manufacturing errors and the composite's equivalent thermal expansion performance. Building upon this foundation, a yield rate metric based on functional tolerance concepts was introduced. This metric was used to evaluate how different interface configurations affect the stability of zero thermal expansion performance. The results demonstrate that, under identical manufacturing precision conditions, different interface configurations exhibit significantly varying thermal expansion stability in response to manufacturing errors characterized by structural parameter dispersion. This research provides valuable insights for translating theoretical designs of such functional materials into manufacturable solutions that meet thermal expansion performance requirements.
Yan, Shaojie, Yang, Zihao, Zhang, Yongcun
Experimental Investigation on Flame Characteristic for Civil Aircraft Propulsion System Fireproof Test2026-99-231710/30/2026
In order to meet the airworthiness regulations, the civil aircraft propulsion system needs to carry out the necessary fireproof test. The measurement of the flame temperature is very essential for the certification and validation of fire protection thermal simulation models, and also helps to establish the empirical understanding of complex flame behaviors. In order to investigate the influence of the specimen on the flame temperature distribution, the two dimensional flame temperature distribution of the free burning test and several fireproof tests, including titanium panel fireproof tests, stainless steel panel fireproof tests, composite laminated panel fireproof tests, honeycomb sandwich panel fireproof tests, were experimental investigated in this paper. The test results shows that panel specimens significantly alter the temperature distribution of the standard flame and interfere with radiation heat transfer measured by thermocouple, resulting in a significant reduction in the temperature gradient of the flame and a obvious increment in the temperature of the surrounding non-flame-impinging zone. The central flame-impinging zone exhibits minimal temperature variation compared to the baseline flame at 1093 °C, with temperature elevation restricted to approximately 40 °C (within 4% deviation). Both metal panels and composite panels demonstrate consistent trends in affecting flame temperature distribution. However, compared to metal panels, composite materials induce smaller temperature gradients and more uniform temperature fields. Multiple burning tests on same panel progressively intensify the oxidation on the specimen surface, leading to a gradual decrement in flame temperature. Especially, this temperature reduction becomes statistically significant as early as the second time burning test.
Chen, Fang, Guo, Junxian, Peng, Sen
Multi-Objective Robust Optimization Method for CFRP Laminates Based on a Dual Dimensionality Reduction Strategy2026-99-234510/30/2026
This paper presents a robust multi-objective optimization method for a symmetric carbon fiber reinforced polymer laminate under uniaxial tension. The study focuses on the combined design problem of failure strength and failure displacement under material uncertainty. A fast structural response model is built by using classical laminate theory, and the Hashin failure criterion is used to predict the first-failure state of the laminate. The model takes uncertain material properties into account, so it can describe the effect of random changes in stiffness and strength on the structural response. To reduce the computational cost, the method uses a dual reduction strategy. The first step reduces the parameter space. Latin hypercube sampling is used to generate random samples, and Spearman correlation analysis is used to identify the key uncertain parameters. The second step reduces the sample space. K-means clustering is used to group the reduced samples and generate representative scenarios. Based on these scenarios, the study defines robust failure strength and robust failure displacement by combining the mean value and the standard deviation of the responses. A multi-objective genetic algorithm is then used to search for the Pareto solution set. After that, two single-objective optimizations are carried out to obtain the best strength and the best displacement, and these two values are used to form an ideal point. The two objectives are normalized, and the Pareto point with the smallest distance to the ideal point is selected as the final design. The results show that the proposed method can capture the positive relation between failure strength and failure displacement, identify the main uncertain parameters that control the response change, and provide a balanced design with good strength and displacement performance under uncertainty.
Wang, Yaoqiang
A Study on the Tribological Behavior of Silicon Nitride-Based Multiphase Ceramics Under Different Lubrication Systems2026-99-233910/30/2026
To address the urgent need for high-performance self-lubricating ceramic materials for rolling bearings under high-speed operating conditions in the aerospace sector, this study employs Si3N4 as the matrix and incorporates nano lignin and graphene nanoplatelets (GNPs) to develop a self-lubricating composite ceramic system. This paper systematically studies the tribological characteristics and wear mechanisms of the composites. The results indicate that nano lignin undergoes pyrolysis during sintering, forming nitrogen-doped graphene quantum dots (N-GQDs). These structures are uniformly distributed at grain boundaries and participate in the formation of a lubricating film during the friction process, thereby significantly improving the material’s friction and wear properties. Under the special conditions (10 N, 1000 r/min), the composite material exhibited optimal tribological performance when the nano-lignin content was 2 wt.%, The friction coefficient decreased to 0.22 and a significant decrease in wear rate, demonstrating excellent friction- reducing and wear-resistant effects. In contrast, the introduction of GNPs failed to effectively improve friction performance, which may be attributed to their poor dispersion in the matrix and weak interfacial bonding. Mechanistic analysis indicates that during friction, Si N hydrolyzes to form SiO, which, together with the metal transfer layer and N-GQDs, forms a composite lubricating film; under shear stress, the N-GQDs undergo oriented alignment, reducing interfacial shear strength and achieving a synergistic effect of friction reduction and wear resistance. This study gives a new perspective into the application of biomass-derived lubricating phases in high- performance ceramics.
Chen, Wei, Zhao, Wenzhuo, Zhou, Ao, Li, Yetong, Wang, Chao, Yang, Yongqiang, Lou, Rui
Deep Damage Detection of Plain Weave CFRP Using Microwave Rectangular Open-Ended Waveguide2026-99-233410/30/2026
To address the challenge of detecting internal deep damage in plain woven carbon fiber reinforced polymer (CFRP), a microwave nondestructive testing method based on a WR-112 rectangular open-ended waveguide is proposed. Based on the weaving structure characteristics of the material, a discrete electromagnetic model within the 6.57-9.99 GHz frequency band was established. The microwave reflection response characteristics of backside circular damage with different dimensions were investigated through finite element simulation. Simulation results demonstrate that the proposed method can effectively detect backside damage with a minimum detectable diameter of 6 mm and a minimum detectable depth of 0.3 mm on a 2.4 mm thick plate, based on a signal-to-noise ratio (SNR) criterion of 3 dB. Furthermore, the amplitude of the reflection coefficient is sensitive to the variation of damage depth, while the resonant frequency remains stable. A microwave detection experimental platform was set up, and damage specimens were fabricated for verification. The experimental results are in good agreement with the simulations, confirming the effectiveness of the proposed method for damage detection and depth identification.
Chen, Xiaoyuan, He, Yongbo
Research on Multi-Source Navigation Information Fusion Based on Adaptive Weighted Least Squares Algorithm Considering Signal Quality and Geometric Distribution2026-99-296010/19/2026
With the extensive application of satellite navigation technology in intelligent transportation and aerospace fields, the fusion of multi-source navigation information has become a key approach to solving the problem of high-precision positioning in complex environments. To address the issues of single weighting and insufficient robustness in traditional weighted least squares (WLS) algorithms for multi-source navigation information fusion in complex environments, this paper proposes an adaptive weighted least squares (AQG-WLS) algorithm based on signal quality and geometric distribution. This algorithm dynamically adjusts the weights of observations by constructing a composite weight model that integrates the carrier-to-noise ratio and the spherical geometric distribution of satellites. On the one hand, it uses the carrier-to-noise ratio to reflect the level of observation noise corresponding to signal strength. On the other hand, it introduces the area of spherical quadrilaterals to quantify the correlation of satellite geometric configuration, thereby avoiding the deterioration of the geometric dilution of precision (GDOP) caused by satellite clustering. Experimental results show that in scenarios with obstructions such as urban canyons, the AQG-WLS algorithm improves positioning accuracy by approximately 23% compared to the traditional WLS algorithm, and demonstrates stronger robustness against multi path effects and gross errors, providing an effective parameter estimation method for multi-source navigation fusion.
Zhu, Shengling
Carbon Fiber Fabric Repair Prepreg, 120 °C (250 °F) Vacuum Curing, Part 6 - Material Specification: Carbon Fiber Fabric Reinforced Epoxy Prepreg for Repair, Plain Weave Fabric, 193 g/m2, Adhesive Film for Repair and Non-Structural Glass Fiber Fabric Reinforced Epoxy Prepreg, 105 g/m2AMS3970/6A (Current)9/22/2026
AMS3970/6 Material Specification (MS) defines the requirements of carbon fiber plain weave fabric, 193 g/m2, reinforced epoxy structural prepreg for repair, curing under vacuum at 120 °C (250 °F), and a companion non-structural glass fiber fabric reinforced epoxy prepreg, 105 g/m2, used in repair of carbon fiber reinforced epoxy structures and qualified according to AMS3970/1 and AMS3970/2 for aerospace applications. The prepreg system may include an epoxy film adhesive to be applied in a co-curing process with the prepreg for joint and sandwich bonding. The need for a film adhesive shall be established during screening tests. If included, the requirements to be met by the adhesive are also defined in this document.
AMS CACRC Commercial Aircraft Composite Repair Committee
Scene-Level Multi-View Instance Consistency Using Multi-Feature Vision Fusion for Synthetic Ground Vehicle Environments2026-01-75029/22/2026
Maintaining consistent object identities across multiple camera viewpoints is a critical challenge in synthetic perception environments used for autonomous ground vehicle evaluation. This paper presents a scene-level multi-view instance consistency framework that integrates OpenUSD scene composition, Omniverse Replicator synthetic-data generation, and a multi-feature vision fusion pipeline. The proposed approach combines semantic embeddings from CLIP, patch-level descriptors from DINOv2, geometric correspondences from LoFTR, mask-derived shape invariants using Hu moments, and relative-position priors to associate object instances across views, including visually identical objects. A compact composite scoring function fuses these complementary cues to achieve robust cross-view identity assignment while preserving OpenUSD asset modularity through grouped-prim support. Synthetic experiments across 120 multi-camera scenes demonstrate improved Top-1 Match Accuracy and Identity Consistency Rate, with reduced ID-switch occurrences compared to single-cue baselines. The framework supports scalable, repeatable, and traceable digital engineering workflows for defense-oriented perception evaluation.
Bhattacharya, Sambit, Nakamoto, Kyle
AI-Driven Predictive Sonification for Human-on-the-Loop Ground Vehicle Autonomy2026-01-75039/22/2026
Ground vehicle autonomy increasingly depends on human-on-the-loop (HOTL) supervision, yet supervisors are often overloaded by visual interfaces that can obscure emerging risks. This paper presents an AI-driven predictive sonification architecture that converts short-horizon forecasts of platoon behavior into structured auditory cues for supervisory monitoring. A forecasting engine predicts future vehicle interaction states and evaluates predicted and active violations to generate a composite risk indicator. When risk exceeds defined thresholds, a sonification module conveys risk magnitude and trajectory through changes in pitch, loudness, modulation, and spatial panning. The paper describes the system architecture, sonification design, operational use cases, and a planned human-subject evaluation. The proposed framework is intended to improve early awareness of emerging instability and support more timely supervisory intervention.
Plotzke, Zachary R., Mohammadi, Alireza, Cheung, Calvin M.
Powder Metallurgy Hot Isostatic Pressing: Titanium Done Differently for Defence2026-01-75569/22/2026
Powder metallurgy hot isostatic pressing (PM HIP) is a novel manufacturing process extensively utilized in oil & gas and aerospace industries. With the evolution of this advanced manufacturing process, many other industrial sectors including defence are benefiting from the clear strategic advantages of PM HIP compared to conventional manufacturing processes. This paper is intended to give an overview of PM HIP technologies and highlight the potential of this process for the manufacture of components for land based military systems. The study will focus on a brief introduction of PM HIP technology followed by more detailed description of some key benefits of adopting PM HIP in defence sectors. These include easier processability of Ti-alloys, generation of high-performance metal matrix composites (MMCs), manufacturing of complex shape parts and generation of multi-materials structures via HIP diffusion bonding (DB). Finally, the paper will focus on future prospectives of PM HIP.
Clark, Gerry, Sergi, Alessandro
Study on the Friction Characteristics of Disc Brakes with Ceramic Surfaces for High Performance Vehicle2026-01-08279/14/2026
In this study, various methods were reviewed to simultaneously satisfy the high-temperature braking performance required for high-performance vehicles and the brake dust criteria by environmental regulations. Among them, the characteristics of two types of Brake disc with ceramic composite surfaces were evaluated to prevent disc wear even under the condition of using metallic friction materials with excellent fade performance. As a result of the evaluation, carbon ceramic disc without metal-to-metal contact during braking showed superior characteristics compared to hard metal cladding disc.
Kim, Yoon Cheol, Yeongwoo, Cho, Kim, Youngmin
Development and Production of Weight-Reduced Steel Hat Brake Discs: A Contribution to Automotive Lightweighting2026-01-08219/14/2026
The automotive industry's transition towards electrification, particularly in the passenger car (PC) and light commercial vehicle (LCV) segments, has intensified the focus on vehicle lightweighting to maximize battery range and efficiency. Conventional brake systems in electric vehicles (EVs) are subject to minimal mechanical wear due to regenerative braking, making corrosion the primary cause of component failure and replacement. This paper details the development and production of an innovative lightweight brake, which addresses these challenges. The "Cast-In" brake disc combines a traditional gray cast iron friction ring with a pre-finished, deep-drawn steel hat through a specialized composite casting process. This design achieves a significant reduction in unsprung mass—1.6 kg per disc in a 390mm x 36mm example—directly contributing to improved vehicle dynamics and energy efficiency. Key manufacturing challenges, including ensuring a robust material bond, preventing casting defects, and sealing the steel hat during casting, have been overcome through advanced process controls, simulation, and a patented sealing system. Furthermore, a novel, enhanced corrosion protection system has been developed and validated to meet the required service life of over 10 years, addressing the specific demands of e-mobility. With production scheduled to begin in April 2026, this technology is a milestone for modern braking solutions in the era of electrification.
von Reth, Thomas
Study on Rapid Formation Generation Method for Multi-UAV Swarms2026-99-14219/11/2026
This paper presents a generalizable geometric framework for rapid on-demand generation of multi-UAV formations with arbitrary 2D geometries and user-specified scalable scales. First, vertices, edge intersections and edges are extracted from a user-defined formation template to enable parametric description of both simple and composite formation geometries. Second, boundary interpolation, edge expansion and recursive internal expansion are integrated to synthesize hierarchical multi-layer UAV deployment point sets under a controllable expansion ratio. Third, a geometric distortion metric is proposed to optimize UAV node indexing and formation reconstruction while preserving inter-node topological consistency. Algorithmic derivations, complexity analysis and simulation assumptions are further elaborated. Simulation results verify that the proposed method preserves geometric fidelity of target formations while delivering superior scalability and spatial coverage, rendering it well-suited for emergency transport, aerial surveying and low-altitude cooperative missions in dense urban environments.
Fu, Mingyi, Zeng, Guoqi, Gu, XinZhu, Wang, Jia
Experimental Study on Ultrasonic Drilling of CFRP Based on Ultrasonic Tools2026-99-14139/11/2026
To investigate the influence of laws of rotational speed, ultrasonic vibration, and feed speed on burr length, splitting length, and hole roundness of carbon fiber reinforced plastic (CFRP), drilling experiments using ultrasonic tools designed based on the dagger drill principle were carried out on CFRP materials. This study aims to explore methods for improving the hole-making quality of CFRP and further enhancing its hole-making efficiency. The results show that a high rotational speed can effectively reduce the burr length by 60% and the splitting length by 50%. Ultrasonic vibration can reduce the burr length and splitting length by about 70% and increase the hole roundness by about 10%. The higher the feed speed, the lower the hole-making quality, while an excessively low feed speed will impair the hole-making efficiency. In this study, the optimal hole-making quality was achieved when the rotational speed was set at 18500 r/min, ultrasonic vibration was activated, and the feed speed was controlled at 40 mm/min. The research results provide valuable references for the research, popularization, and application of ultrasonic tools and related technologies.
Xiang, Hui, Xiao, Liuwei, Song, Jinhui, Chen, Songlin, Liu, Zhichun, Liu, Yihong, Xiao, Huan, Zhang, Cheng, Ran, Qiuyue, Luo, Jiang
Study on Low-Velocity Impact Damage of Glass Fiber Reinforced Composite Pipeline2026-99-14169/11/2026
Through low-velocity impact testing, the effects of punch shape (conical, hemispherical, and cylindrical) and impact energy (5, 10, and 15 J) on damage characteristics in glass fiber composite pipes were investigated. Ultrasonic A-scan inspection was employed to detect internal delamination damage at the impact points within the composite pipes. Test results indicate that the contact area between the punch and the pipe is a key factor influencing the severity of pipe damage. A smaller contact area results in a higher energy absorption rate, greater punch displacement, larger area under the load-displacement curve, and longer contact time, leading to more severe damage characteristics. When the conical punch delivered 15 J of impact energy, the energy absorption rate of the glass fiber composite pipe reached 91.6%, exhibiting multiple damage characteristics, including pitting, penetration, and cross-shaped cracks. As impact energy increases, the area of internal delamination damage caused by the three punch shapes exhibits near-linear growth. The conical punch induces severe damage characteristics in the thickness direction but results in the smallest delamination area. Blunt-shaped punches (hemispherical and cylindrical) disperse impact energy over a wider region, leading to increased delamination damage area.
Wang, Xuan, Cao, Yanzhen
Study on Water Hammer Effect of an Aircraft Composite Fuel Tank under High-Speed Impact of Multiple Fragments2026-99-14209/11/2026
The investigation examines the damage mechanisms of composite fuel tanks under high-speed impact by multiple fragments utilizing a fluid-solid coupling finite element approach. The Arbitrary Lagrangian Eulerian (ALE) algorithm is used to simulate the single-box composite fuel tank under the impact of different distribution distances of fragments by using the software LS-DYNA. The cavity evolution and the panel deformation of the composite fuel tank are analyzed in detail. The findings indicate that the water hammer effect amplifies the extent of damage to the composite fuel tank structure. During the initial phase following fragment impact, a cavity forms within the tank. The resulting rise in the pressure difference between the interior and exterior of the tank causes the liquid to impinge on the impacted panel, leading to its deformation. In the later stage, due to the large degree of damage to the incident panel, there is a certain degree of pressure relief inside the fuel tank, the degree of water hammer effect is obviously reduced, and the cavity in the fuel tank gradually disappears. The distribution distance of the fragments has a great influence on the damage effect of the fuel tank. As the spacing between fragments diminishes, their effects become more concentrated. This results in increased force from the liquid on the fuel tank panel, leading to greater deformation and more severe damage to the panel.
Wang, Ruiwen, Song, Yahui, Li, Chengwang
Conceptual Design of Steel Shell-UHPC Composite Pylon for Large-Span Suspension Bridges2026-99-15139/11/2026
With the rapid development of the transportation industry, heavy-duty traffic has become extremely common, particularly in some coastal port cities where the presence of container terminals leads to generally high vehicle axle loads. In these regions with an advanced transportation industry, large-scale cross-sea bridges are often required to ensure transport efficiency. However, conventional long-span bridge types, such as cable-stayed bridges and suspension bridges, face challenges in meeting the demands of heavy-duty traffic due to limitations imposed by the self-weight of pylons. In response, this paper proposes a prefabricated steel shell–ultra high performance concrete (SS–UHPC) composite pylon composed of basic SS–UHPC units, aiming to enhance both the load-carrying efficiency and seismic performance of the structure. A conceptual design of the SS–UHPC composite pylon was developed based on a super-long-span suspension bridge with a main span of 2180 m, and a comparative analysis was carried out against a conventional steel shell–normal concrete (SS–NC) composite pylon. The results show that, owing to the higher strength-to-self-weight ratio of UHPC, the SS–UHPC composite pylon achieves a 42.4% reduction in self-weight compared to the SS–NC composite pylon. Under the most unfavorable load condition, the axial force and transverse bending moment at the pylon base are reduced by 13.79% and 6.24%, respectively. Under maximum seismic load, the axial force and transverse bending moment at the base decrease by 14.12% and 28.92%, respectively, demonstrating improved load-carrying efficiency and seismic performance of the pylon. Although the life-cycle cost of the SS–UHPC composite pylon is higher than that of the SS–NC composite pylon, its superior mechanical behavior sufficiently offsets the cost difference. In conclusion, the superior mechanical behavior of the SS-UHPC composite pylon makes it better suited for application in long-span bridges subjected to heavy-duty transportation loads.
Chen, Jing Li, Liu, Yong Jian, Peng, Hong Bo, Sun, Li Peng, Yang, Ze Hong
Simulation and Structural Optimization Design of Thermal-Mechanical Coupling Performance of Supporting Components2026-99-12939/4/2026
This research aims to develop a high-performance composite material support component that meets extreme performance requirements. It is used to solve the problem of protecting critical electronic control units (ECUs) and flight data recorders in aerospace and automotive safety systems under harsh combined conditions of high temperature and high shock. Its internal dimensions are 0.14 m × 0.08 m × 0.08 m. In addition, it is required to withstand a constant temperature of 65°C for 3600 seconds, with the internal core temperature not exceeding 35°C. It can withstand a static load of 1.8 kg and a transient impact acceleration of 1400 G. The dual-layer composite structure based on functional decomposition solves the problems of thermal insulation and load-bearing/impact resistance. The inner layer uses ultra-low thermal conductivity aerogel to form a thermal barrier. The outer layer is a load-bearing frame made of high-strength/high-modulus quartz fiber reinforced epoxy composite material. The study employs a systematic numerical simulation method to verify the optimized design parameters. The results show that the internal temperature remained stable at 34.173°C. The outer layer deforms only at the micrometer level under static load. The inner layer is under zero load and there is no distortion in the internal space. The integrated design method of “material-function-structure-simulation” proposed in this paper provides a research approach for the survivability design of mechanical structures of new-generation aircraft and ground vehicles under complex multiphysics constraints.
Liu, Jiaxin, Wang, Yi, Zhao, Xiaorong, Wu, Chaofu, Zhao, Zhuo, Chen, Long
The Flexibility Coefficient Fitting of Bolt in Metal-Composite Hybrid Joint Structures Based on L-M Method2026-99-12679/4/2026
This study used the L-M (Levenberg-Marquardt) algorithm to analyze the fitting of the flexibility coefficient of fasteners in the mixed connection structure of metal composite materials to address key challenges in aircraft structural design. Through parametric modeling and finite element simulation of single lap joints, the system evaluates eight key factors, including the direction of the composite material layer, the elastic modulus of the metal plate, the plate thickness ratio, the fastener diameter, the elastic modulus of the fastener, the Poisson’s ratio of the fastener, the magnitude of the preload force, and the type of bolt configuration, covering convex and countersunk variants. Advanced material modeling techniques are introduced in the study to accurately capture the anisotropic behavior of the composite material layer and its interaction with metal components under different load conditions. The results show that the higher modulus and thickness of the composite material plate and metal plate significantly reduce the flexibility of fasteners, and larger fastener diameters are associated with reinforcement. The elastic modulus further reduces flexibility. The flexibility of convex head bolts is significantly lower than that of countersunk head bolts, while Poisson’s ratio, preload force, and humidity have little effect. Based on these findings, a new flexible calculation formula containing nine undetermined parameters is proposed. The L-M algorithm is used for nonlinear regression to derive formulas with physical significance. The verification shows that the proposed formula is highly consistent with the finite element results, with a corrected coefficient of determination of 0.956. Among 864 test sample points, 73.61% have an error of less than 5%, and only 0.23% have a deviation of more than 15%. Comparative analysis with twelve existing methods, including the Delft University and Boeing formulas, confirms that the proposed method has better accuracy. This method effectively expands the applicability of traditional flexible formulas, provides solid theoretical support for advanced aircraft connection design, and realizes diverse mixing in aerospace engineering and accurate calculation of connection configuration.
Fan, Zhuotao, Wang, Xu, Wang, Tong, Li, Xianchao
Detection of Pipe Surface Coatings on Ultrasonic Guided Wave Propagation2026-99-12159/4/2026
Coating the surface of pipelines is one of the most crucial and effective methods for inhibiting corrosion and prolonging the operational lifespan of pipelines. The coating acts as a protective shield that isolates the pipeline metal from external corrosive environments. However, once the coating begins to peel off or deteriorate due to aging, mechanical damage, or environmental factors, the exposed metal surface becomes highly susceptible to corrosion. Statistics indicate that over 50% of external corrosion failures in pipelines are directly associated with coating defects. Despite the critical importance of coating integrity, research on the interaction between surface coatings and nondestructive testing methods—particularly ultrasonic guided wave techniques—has remained relatively limited in recent years. In this study, the impact of surface coatings on the propagation behaviors of ultrasonic guided waves in pipeline systems was systematically investigated. Coal tar pitch, a commonly used and cost-effective coating material, was applied to steel pipeline specimens with varying coating lengths. The attenuation rate of the guided wave signal amplitude was measured under different coating conditions to analyze the relationship between coating parameters and acoustic energy loss. The experimental results reveal that the coating significantly affects guided wave propagation, especially in terms of signal attenuation and boundary reflection. Furthermore, the study reveals that ultrasonical guided waves possess strong sensitivity to coating discontinuities and can accurately locate coating boundaries. These findings confirm the potential of guided wave technology for early detection of coating defects and quantitative evaluation of coating adhesion. Moreover, the outcomes provide useful insight for other transportation and aerospace structures that employ multilayer coatings or protective films, such as aircraft pipelines and composite fuselage components, where similar material interfaces and inspection challenges exist. This research provides theoretical and experimental references for improving the reliability of pipeline health status detection.
Xiao, Tianyi, Li, Bing
Dynamic Modeling and Robust Active Control of Graphene-Piezoelectric Composite Missile Wings with Elastic Boundary Constraints2026-99-12819/4/2026
To improve the stability and vibration suppression capability of missile wings under complex aerodynamic conditions, this study develops a dynamic model and explores the active control strategy for a graphene-reinforced piezoelectric composite missile wing subjected to elastic boundary constraints. An electromechanically coupled dynamic model with elastic boundary conditions is constructed by employing CLPT, the geometric nonlinearity following the von Karman assumptions, and piezoelectric coupling theory. The system is discretized and solved numerically using characteristic orthogonal polynomials and the Galerkin method. The influences of graphene distribution configurations, material properties, and boundary flexibility on the linear natural frequencies and nonlinear hardening characteristics are investigated. Results show that the X-type graphene distribution significantly enhances the equivalent stiffness and reduces nonlinearity. Boundary flexibility markedly modulates the vibration characteristics; in particular, increased structural flexibility strengthens geometric nonlinearity, leading to noticeable changes in frequency characteristics and hardening degree. A robust state-feedback controller together with a full-order observer is developed using the Linear Matrix Inequality (LMI) framework, and their performance is verified under different parameter disturbances and uncertainties. The control strategy effectively suppresses vibrations while maintaining good robustness, with the best performance achieved under X-type graphene reinforcement combined with thin piezoelectric layers. This study reveals the coupling mechanisms among material distribution, boundary flexibility, and robust control, providing a theoretical basis for the structural optimization and active control design of smart missile wings.
Qin, Shilong, Chen, Jie
Adaptive-Weighted Coupling-Aware Gaussian Processes for AFP2026-99-12779/4/2026
Composite materials have gained widespread application in the aerospace field due to their advantages, such as high specific strength, high specific modulus, and corrosion resistance. Automated placement technology, as an emerging automated manufacturing method, is gradually replacing traditional manual placement processes and demonstrating significant advantages in composite manufacturing. Currently, the automated placement process for composite materials faces challenges such as insufficient experimental samples and strong coupling relationships between process parameters, leading to low fitting accuracy in process parameter optimization models. To address this, this paper proposes a placement process parameter optimization method based on model weight adaptive allocation. This method integrates three key technologies: a coupling-aware Gaussian process based on combined kernel functions, a weight allocation ensemble model based on leave-one-out cross-validation, and a multi-criteria adaptive sampling mechanism. Experimental validation demonstrates that the integrated model achieves a coefficient of determination R^2 = 0.82, which represents a superior fit compared to the R^2 = 0.65 achieved by a single-kernel Gaussian model and the 0.76 obtained from a single sampling. Furthermore, both the Root Mean Square Error (RMSE=0.92) and Mean Absolute Error (MAE=0.70) are lower than those of traditional baseline models. This framework provides an effective solution for optimizing parameters in the automated placement process for composite materials.
Zuo, Rui, Du, Tingting, Lv, Ruiqiang
Aerospace & Defense Technology: September 202626AERP099/3/2026
The Interconnected Battlefield: Optimizing Systems Beyond Standard D38999 Enhancing Laser Processing Head Service and Quality Assurance: How Advanced Laser Diagnostics Transform Service Operations and Product Development for High-Power Laser Applications The Advantages and Disadvantages of 3U vs. 6U The Quality-Control Backbone of Military Textile Innovation Embedding Physical AI at the RF Edge for Defense Systems Advancing Resilient Long-Range Military Communications for Distributed Operations in the Indo-Pacific DARPA, U.S. Air Force Fly AI-Controlled F-16 Historic VENOM milestone demonstrates scalable AI development capabilities for the operational fleet. DiOXYGEN Research Initiative Launches a New Era for France's Oxide Ceramic Matrix Composites Sector IRT Saint Exupéry and its partners are celebrating the first anniversary of the "DIOXYGEN" project. This program marks the very first structured national initiative dedicated to building a competitive European supply chain for Oxide Ceramic Matrix Composites. A New Research Facility for Robotics and Alloy Discovery in Texas Researchers have received a $24.9 million grant to develop an NSF Materials Innovation Platform where universities, national laboratories and industry members can run alloy-discovery campaigns using robotic systems and artificial intelligence. Can AI Design and Build a Jet Engine? MIT students designed, built, and tested a jet engine with AI copilots, assessing AI's usefulness in developing high-performance aerospace systems. Purdue Engineers Unlock Key to Combining Exceptional Strength with Plasticity for 'Intermetallics' Materials engineers have developed the ability to manipulate structure and matter at the nanoscale for solid-state alloys called intermetallics, making it possible to alter their properties for extra performance characteristics.
DiOXYGEN Research Initiative Launches a New Era for France's Oxide Ceramic Matrix Composites Sector26AERP09_089/1/2026
IRT Saint Exupéry and its partners are celebrating the first anniversary of the “DIOXYGEN” project. This program marks the very first structured national initiative dedicated to building a competitive European supply chain for Oxide Ceramic Matrix Composites. Institute of Research and Technology Saint Exupéry, Bordeaux, France Industrial and academic partners, together with the Institute of Research and Technology Saint Exupéry (IRT Saint Exupéry), are celebrating the first year of the ambitious collaborative project DiOXYGEN, dedicated to the development of oxide ceramic matrix composites (O-CMCs). These next-generation materials, capable of withstanding extreme operating conditions, offer significant opportunities for strategic sectors including aerospace, space, defense, energy, and radioactive waste management. Building on the roadmap outlined in the White Paper “Ceramic Matrix Composites: a French Area of Excellence,” published in March 2024, the project represents the first structured national program dedicated to a strategic industrial sector, with the objective of establishing a coherent, sovereign, and competitive French supply chain. It is also the first time that the entire French oxide ceramic matrix composites community has united around a common initiative.
Navy Flight-Tests 3D-Printed Composite Repairs for F/A-18 Super HornetsTBMG-558259/1/2026
Naval Air Warfare Center Aircraft Division Patuxent River, MD
Synergistic Effect of Matrix Porosity and Grouting Material Type on the Performance of Grouted Composite Pavement2026-99-04058/28/2026
The grouted composite pavement combines the advantages of flexibility and rigidity through the composite structure of organic-inorganic materials, but the optimisation of its performance is affected by the complexity of the matrix asphalt mixture void ratio and grouting material type. This study has revealed the influence of matrix asphalt mixture porosity and grouting material type on the grouting effect and road performance of grouted composite asphalt pavement. The results showed that the increase of matrix porosity could significantly improve the grouting rate and resistance to high-temperature rutting of the mortar, but the high porosity led to a decrease of low temperature cracking resistance of the materials. CA mortar enhanced the flexible deformation capacity by optimising the interfacial bond, and its low-temperature cracking resistance was better than that of ordinary cement mortar, but the grouting efficiency and high-temperature performance were slightly lower. In addition, ordinary cement mortar demonstrated better performance regarding high-temperature stability and resistance to water damage.
He, Mu, Wang, Yan, Ye, Ming, Yu, Chao, Ye, Xiao
Application of Textile Materials in the Design of Safety Protection Products2026-99-04168/28/2026
The research focuses on textile material utilization for safety protection product design to meet rising public safety needs and expanding dangerous operational environments. The research begins by identifying essential performance criteria for safety textiles because these materials serve as core carriers due to their excellent plasticity and functional capabilities and comfort properties. The research examines leading protective materials through a comparative analysis which shows their individual benefits and weaknesses. The study implements an experimental method to evaluate a new aramid fabric composite against flame-resistant cotton fabric through standardized tests which assess protective capabilities and comfort levels and product longevity. The experimental results show that the composite aramid fabric surpasses flame-retardant cotton in all tested parameters including flame resistance and tear strength and durability while providing better thermal comfort. The study establishes a solid quantitative basis for selecting and enhancing textile materials in safety protection product development which enables the industry to create sustainable high-performance protective solutions with multiple functions.
Huang, Jiaqi, Li, He, Peng, Tianxiao
Lightweight Research on CFRP Bumper Impact Beam2026-99-04118/28/2026
As a critical component in vehicular passive safety systems, the automotive bumper beam significantly influences overall crash safety performance and lightweight potential. This study presents a comprehensive investigation into the lightweight design of a carbon fiber reinforced polymer (CFRP) bumper beam, systematically substituting a conventional aluminum alloy component based on the principle of equivalent bending stiffness. The research methodology integrates finite element modeling, design of experiments, and multi-objective decision-making to optimize crashworthiness. Initial design replaced the 3 mm aluminum beam with a 2.4 mm CFRP configuration using a [0°, 45°, 90°, -45°] ply sequence, demonstrating maintained structural integrity with substantial mass reduction potential. Through Latin Hypercube Sampling, 50 design configurations incorporating variations in panel thicknesses (five distinct sections) and ply orientation sequences were generated and evaluated under an 8 km/h frontal impact simulation. Crashworthiness was assessed through four key indicators: mass, specific energy absorption (SEA), maximum intrusion distance (Dm), and peak impact force (Fm). The entropy weight method objectively determined indicator weights, revealing maximum intrusion (49.27%) as the most critical factor, followed by mass (32.75%), peak force (9.75%), and SEA (8.23%). Subsequently, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed to comprehensively evaluate and rank all design alternatives. The optimized CFRP configuration (Scheme #38) achieved remarkable performance: 69.1% mass reduction (from 4.505 kg to 1.392 kg), 379.6% improvement in specific energy absorption, 12.6% reduction in peak impact force, while maintaining intrusion within acceptable design limits. This research establishes a robust framework for CFRP bumper beam optimization, successfully balancing lightweight objectives with enhanced crashworthiness, providing valuable insights for automotive lightweight safety component development.
Wang, Yizhi, Zhong, Rong, Long, Jiangqi
Ceramic Matrix CompositesR-4608/27/2026
The fifth volume of this compendium publishes technical guidelines and properties of ceramic matrix composite material systems. The content includes information on material selection, processing, characterization, testing, data reduction, design, analysis, quality control, application, case histories, and lessons learned of typical ceramic matrix composite materials. Initial Release of Volume 5 superseded Mil-HDBK-17-5 dated June 17, 2002. The Composite Materials Handbook, referred to as CMH-17, is an engineering reference tool that provides comprehensive, practical engineering guidelines that have proven reliable for the design, fabrication, characterization, test, and maintenance of polymer matrix, metal matrix, ceramic matrix, structural sandwich, and non-metallic AM materials. CMH-17 provides information and guidelines necessary to design and fabricate end items from composite materials. The compendium includes reliable data, linked to control of processes and raw materials, to provide material property basis values and design information that promotes the safe use of ceramic matrix composites in aerospace applications. CMH-17 provides information and guidelines necessary to design, fabricate, and maintain components from composite and non-metallic additively manufactured (AM) materials. In support of this purpose, the handbook constitutes an overview of the field of advanced materials technology and engineering. It is used by engineers worldwide in designing and fabricating products made from composite materials.
CMH17, CMH-17
Dynamic Sliding-mode Control with Backstepping for Offshore Boarding Gangway2026-99-03398/14/2026
This paper focuses on the control challenge of the movable ladder section of an offshore boarding ladder. A dynamic sliding mode control (DSMC) method based on the backstepping approach is proposed. To address the disturbance mismatch problem in traditional control strategies, the backstepping approach is adopted for the hierarchical design of the control law, decomposing the complex nonlinear system into low-order subsystems for step-by-step processing. Meanwhile, by integrating the strong anti-disturbance advantage of DSMC, a composite control framework with disturbance compensation capability is constructed, which effectively suppresses the nonlinear disturbances caused by external disturbances and system parameter perturbations during the movement of the movable ladder section. The stability of the proposed control method is strictly proven using the Lyapunov function. Simulation results show that the speed response adjustment time of the movable ladder section is less than 10.3 ms, and the position tracking error is controlled within 1.03 mm. Compared with the traditional PID control, the rise time of DSMC is improved by 89.16%, and the tracking accuracy is improved by 90.98%. Facts fully prove that the effectiveness of the proposed method is solidly established.
Yang, Lixin, Guo, Lidong, Xu, Liang
Carbon Fiber Fabric Repair Prepreg, 120 °C (250 °F) Vacuum Curing, Part 0 - IntroductionAMS3970B (Current)8/10/2026
This document (Technical Specification) gives information about qualification rules and the relation between the different specification parts involved, such as the Technical Specification (TS), Material Specification (MS), and Purchasing Specification (PS). The link to the material qualification and qualified products is presented.
AMS CACRC Commercial Aircraft Composite Repair Committee
Study on Visible-Light-Driven Photocatalytic Degradation of Tetracycline Hydrochloride by g-C 3 N 4 /CoFe 2 O 4 Composite Photocatalysts2026-99-10078/7/2026
g-C₃N₄, a metal-free semiconductor photocatalyst, demonstrates remarkable potential, but its practical application in pollutant degradation is significantly limited by the rapid recombination of photogenerated electron-hole pairs and low photocatalytic efficiency. To address this, a series of magnetic recyclable g-C₃N₄/CoFe₂O₄ composite photocatalysts with different CoFe₂O₄ doping ratios were innovatively designed and prepared via thermal polymerization, sol- gel, and combined with ultrasonic and heat treatment processes. The novelty of this composite design lies in the effective integration of magnetic CoFe₂O₄ with g-C₃N₄ through a heterojunction structure. It substantially boosts the absorption of visible light. Concurrently, it effectively fosters the separation and mobility of photo-induced charge carriers. The composite materials were systematically characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, photoluminescence spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy. Using tetracycline hydrochloride as the target pollutant, the photocatalytic activity of the composites was evaluated under visible light irradiation, and the effects of initial concentration, catalyst dosage, and the influence of solution pH on degradation efficiency were also examined. The results indicated that the composite with a CoFe₂O₄ to g-C₃N₄ mass ratio of 1:3 (denoted as 3-CN/CFO) exhibited the optimal performance: a TCH degradation rate of 80.29 % within 105 minutes and a total organic carbon removal rate of 61.63 %. After five consecutive cycling experiments, the degradation efficiency remained above 70 %, demonstrating good reusability and stability. The performance improvement is attributed to the formation of heterojunctions in the composite, which effectively facilitates charge separation, inhibits carrier recombination, and enhances visible light absorption. Furthermore, the inherent magnetism of the composite permits efficient recovery, streamlining its integration into practical applications. Toward the purification of antibiotic-contaminated water, this research proposes a viable method for fabricating highly effective and recyclable photocatalysts.
Hua, Longjun, Chai, Tian, Wang, Yiming, Zhang, Jing, He, Ting
How Modular Tooling Accelerates Thermoplastic Composite Prototyping for Advanced Air Mobility and Defense26AERP08_048/1/2026
A new prototyping approach leverages thermoplastic composites, swappable cavity inserts and modular tooling to reduce the time required to produce aerospace and defense prototypes by up to 50 percent. Developed by Greene Tweed - the Pennsylvania-based manufacturing and design services provider - the approach is seeing increased demand among advanced air mobility (AAM) and defense companies focused on metal-replacement development projects that require faster testing and validation. Greene Tweed developed its new rapid prototyping process using its Xycomp® DLF™ material, which the company first introduced to commercial aerospace in 2007. Xycomp DLF is a thermoplastic composite that provides a lightweight alternative to complex metallic components for aerospace and defense applications. According to Greene Tweed, Xycomp DLF components can weigh up to 60 percent less than their metal counterparts and are well suited for aircraft, engine and aerostructure applications.
Simulation of Compression and Bending Performance of GFRP Rod of Composite Hollow Post Insulator2026-99-01077/31/2026
Composite hollow core station post insulators utilize fiber-reinforced epoxy resin as the core rod material, offering advantages such as high specific strength, high specific stiffness, and excellent fatigue resistance. This enables them to effectively meet the flexible, variable, and complex operational demands of modern power systems. However, composite materials exhibit anisotropic characteristics, resulting in complex mechanical properties. Additionally, the core rod of hollow pillar composite insulators is typically fabricated through a spiral-plus-circumferential winding process, which significantly complicates structural design and computational analysis. This study establishes a finite element model of the hollow pillar composite insulator core rod in ABAQUS. It analyzes the influence of fiber content on composite material parameters and performs finite element numerical calculations to examine the stress state of core rods with different winding angles under compressive and bending loads. The research findings provide theoretical support for the optimized structural design of hollow pillar composite insulator core rods.
Liu, Jianbiao, Du, Yijun, Quan, Xiaoxi, Zhou, Songsong
Test and Simulation Analysis of Edgewise Compressive Performance of Marine Composite Sandwich Structures with Delamination Defects2026-99-02007/31/2026
In this paper, PTFE membranes were used to preform delamination defects, and VARI technology was employed to prepare marine composite sandwich structures with such defects. The cohesive zone model was used to emulate the interfacial bonding characteristics, thereby establishing a simulation analysis model to assess the edgewise compressive behavior of marine composite sandwich structures with delamination discontinuities. By combining experimental data with simulation results, the edgewise compressive resistance of marine composite sandwich structures was evaluated. Additionally, various parameters including the size, depth, quantity, and geometry of the delamination defects were studied to investigate their effects on the edgewise compressive performance of the marine laminated structures. The research results indicate that as the number of delamination defects increases, the edgewise compressive strength of the sandwich structure gradually decreases. Particularly, when the diameter of the layering defect is less than 30 millimeters, the influence of the defect on the edgewise compressive strength of the sandwich structure can be negligible. Conversely, when the diameter of the defect exceeds 30 millimeters, the rate of decrease in edgewise compressive strength increases significantly with the increase in the diameter of the defect, thereby greatly exacerbating the adverse effects of the delamination defects and ultimately resulting in a 10.77% reduction in the edgewise compressive strength. Furthermore, it was observed that the delamination defects located at the interface between the two panels and the core material on both sides of the sandwich structure do not affect each other, and to a certain extent, improve the compressive stability of the specimen. The degree of edgewise compressive strength reduction caused by elliptical delamination defects with the same area and long axis length is less than that of corresponding circular delamination defects, indicating that using circular delamination defects in the analysis of composite material structures with delamination defects is safer.
Zhang, Yao, Xu, Mingcai, Bian, Tianya, Zhou, Songqiang, Ji, Bing, Cheng, Jiahuan, Zhuang, Ya, Li, Xiang
Tailored Thermo-Mechanical Behaviour of CNT/Epoxy Nanocomposites via Solvent-Assisted Dispersion2026-99-01897/31/2026
Carbon nanotube (CNT) reinforced epoxy nanocomposites were prepared using a solvent-assisted dispersion method and characterized to evaluate their structural, mechanical, and thermal behaviour. X-ray diffraction (XRD) confirmed the presence of CNTs in the polymer matrix through the characteristic (002) reflection, while scanning electron microscopy (SEM) revealed that CNTs were found to be uniformly embedded within the epoxy matrix, showing limited agglomeration and strong interfacial bonding. Fourier-transform infrared spectroscopy (FTIR) supported these observations by revealing absorption bands associated with C=C stretching, C–O–C ether linkages, and O–H vibrations, indicating chemical interactions between CNTs and the epoxy network. Mechanical testing showed that CNT concentrations of 0.25–0.50 wt.% provided the most effective reinforcement, with notable and measurable improvements in tensile and compressive strength as well as modulus. At higher CNT loadings, however, agglomeration led to reduced tensile performance, despite compressive strength remaining comparatively stable. Thermal conductivity increased steadily with CNT addition, from 0.2143 W/m.K for neat epoxy to 0.2435 W/m.K at 0.75–1.00 wt.%, with the most pronounced improvements observed above 0.25 wt.% due to the formation of more efficient conductive pathways. Overall, these findings suggest that low-to-intermediate CNT loadings achieve a practical and useful balance between strength and thermal conductivity while avoiding the drawbacks of excessive filler content. Effective dispersion of nanotubes is a critical factor that governs the mechanical and thermal behaviour of the composites. These results indicate that CNT/epoxy nanocomposites produced under optimized conditions can serve as lightweight, mechanically reliable, and thermally stable materials, making them attractive candidates for advanced applications in aerospace, automotive, and energy-related sectors where both structural performance and efficient thermal management are required.
Gul, Aysenur, Kamali, Ali Reza
In-Situ Alloyed Strong and Ductile Titanium Alloy from Blended Metal Powders2026-99-02427/31/2026
Blended metal powders offer a compelling alternative to pre-alloyed powders in metal additive manufacturing by providing access to a wider range of alloy compositions and avoiding the high costs in producing pre-alloyed powders. In this work, a new and crack-free Ti-5AlMnScZrMgSiFe alloy (in wt.%) was manufactured by laser powder bed fusion (L-PBF) from mixed powders to investigate the microstructures, mechanical performance of printed parts. Ti-5 AlMnScZrMgSiFe alloy contains both alpha (α) and alpha prime (α′) phases. Further microstructural characterizations show that the L-PBF Ti-5 AlMnScZrMgSiFe contain dense dislocations and twins formed in additive manufacturing process. The as-printed Ti-5 AlMnScZrMgSiFe alloy exhibits a tensile fracture strength of ~950 MPa with a fracture elongation of ~12.5%. The eye-catching properties are attributed to the dense dislocations, nano-twins and solid-solution strengthening.
Feng, Shuai, Guan, Shuai, Kong, Haohao, Sun, Yingxiang, Song, Youpeng, Hou, Yaqing, Bi, Zhongnan, Zhang, Shaoming
Structural Design and Simulation Study of Carbon Fiber Electronic Enclosures for Vehicles2026-99-01607/31/2026
Carbon Fiber Reinforced Polymer (CFRP), as an advanced lightweight structural material, exhibits significant application potential in the protection of electronic devices under extreme vehicle-mounted conditions due to its excellent specific strength and specific stiffness, superior energy absorption capacity, and unique damping and vibration reduction properties. This study closely integrates the characteristics of the complex and variable service environment in vehicles and adheres to the principle of equivalent stiffness matching to conduct innovative design explorations for electronic enclosures made of CFRP. To comprehensively evaluate the dynamic strength performance of CFRP vehicle-mounted enclosures under vibration and impact conditions, in-depth and detailed analyses were conducted using ANSYS software to simulate the power spectral density curves of random vibrations and the loading of post-peak sawtooth waveforms. The results indicate that the carbon fiber enclosure not only achieves remarkable weight reduction but also fully meets the requirements of environmental adaptability standards for automotive equipment. This achievement provides theoretical support and technical guidance for the engineering application of CFRP in the field of vehicle-mounted electronic devices and holds significant engineering application value for promoting the lightweight development of transportation equipment.
Zhang, Shuhui, Ma, Qihua
Microstructure and Properties of 316L Stainless Steels Modified with C and Cr Elements2026-99-02177/31/2026
SiC-based power devices are favored for high-voltage and high-power applications due to their superior material properties. However, the demand for higher breakdown voltages and improved channel mobility presents significant challenges to the etching process, especially the micro-trenching effect. In this study, etching results from inductively coupled plasma (ICP) have been presents, which focused on using various SF6/O2/Ar gas ratios to eliminate micro-trenching effect. The profile analysis of micro-trench was taken by cross-sectional scanning electron microscopy (SEM). The results demonstrate that micro-trenches primarily originate from the coupling effect between ion multi-reflection from sidewalls and redeposition of etch byproducts. Based on this mechanism, we propose a quasi-Bosch process: a combined polymerization and etching step in oxygen-fluorine-rich plasma deposits polymer on exposed SiC and the mask, while removing it from the structure bottom via ion bombardment to enable etching and passivation; then alternates with a short fluorine-plasma step, which consumes sidewall polymer through ion incidence and prevents SiFxOy charge accumulation, cycle etching gradually deepens the structure without micro-trenches. Different gas ratios and etching time not only change the plasma energy distribution but also affect the temporal synchronization between etching and passivation steps. This approach reduces the special demands on ICP equipment capabilities while achieving superior trench profiles. The optimal etching conditions produced a micro-trench-free SiC structure with a vertical sidewall angle and a surface roughness of less than 1 nm. This methodology and resulting structures significantly advance the manufacturability of high-performance SiC power devices, enabling next-generation applications in electric vehicles and grid infrastructure where device yield and reliability are paramount.
Zhao, Yingfan, Dong, Shuang, Sun, Xiaoxu, Chang, Xiangpeng, Liang, Yiwei, Tong, Weiping
Surrogate Model Study for Curvilinear Fibre Variable Stiffness Composite Laminates: Based on Dynamic Hybrid Sampling and Adaptive Surrogate Model Hyper-Parameters Co-Optimization Strategy2026-99-02417/31/2026
Variable stiffness composite laminates with curvilinear fibres have demonstrated significant capability in lightweight structural design, particularly regarding buckling resistance and stiffness enhancement. However, directly applying optimization algorithms often faces challenges such as high computational cost and slow convergence during the optimization design process. Consequently, the incorporation of surrogate models prior to employing optimization algorithms is necessary to simplify computations and accelerate convergence. Manual testing is a conventional approach for hyper-parameter (HP) tuning and continues to be widely used in research. However, manual tuning is suboptimal and time-consuming for many problems. Additionally, the effectiveness of these surrogate models largely depends on the training samples. Therefore, a dynamic hybrid sampling and adaptive surrogate model HP co-optimization strategy is proposed for the optimization design of the variable stiffness composite laminate with curvilinear fibre. In the numerical results, the performance of different surrogate models, comprising Support Vector Regression (SVR), Radial Basis Function Neural Networks (RBFNN), and Back Propagation Neural Networks (BPNN), is systematically compared under varying sample set sizes. Neural results show significant differences in accuracy and efficiency among these three models under varying sample set sizes. SVR demonstrates optimal generalization ability in small sample scenarios, RBFNN strikes a balance between accuracy and efficiency with medium sample size, while BPNN exhibits superior overall predictive performance under large sample condition. The proposed cooptimization strategy overcomes the limitations of traditional single strategy through the closed-loop interaction between dynamic sampling and Bayesian hyper-parameter optimization (HPO). This approach not only significantly improves the predictive accuracy of surrogate models but also greatly reduces the computational cost during the optimization process, making it suitable for computational mechanics problems with high nonlinearity and high-dimensional features. This study provides theoretical foundations and practical guidance for the selection and application of surrogate models in composite material structural optimization, contributing to improved design process efficiency and reliability.
Chen, Dengnuo, Zou, Rui, Chen, Binqi
Durability Study of Electronic-grade Glass Fibers in Salt-Alkali Environments2026-99-02197/31/2026
Electronic substrates and copper-clad laminates are widely used in modern life, particularly in electronic products such as coastal communication base stations and ship communication and navigation system. In these environments, salt particles carried by sea fog can adhere to the surface of the substrates along with moisture, leading to salt-alkali corrosion of the products. As a core material in electronic components, electronic-grade glass fiber urgently requires investigation into its durability under salt-alkali conditions. Therefore, this study focuses on a specific type of electronic-grade glass fiber and explores its corrosion behavior in three different environments: 2 mol/L NaOH, 1 mol/L cement solution, and 3.5 % NaCl. Soaking durations of 6, 12, 24 hours and 3, 7, and 14days were selected as key parameters. The mechanical properties and surface morphology of the fibers before and after corrosion were observed and analyzed. Experimental results indicate that the glass fiber exhibits higher durability in saline solutions than in alkaline environments. This study provides theoretical support for evaluating the long-term performance of Electronic grade glass fibers in practical applications. It also contributes to the optimization of raw materials and manufacturing processes, enhancing the performance of such fibers in salt-alkali conditions, and offers valuable reference for future research on glass fiber-reinforced composites.
Pu, Qixin, Sun, Siqi, Fang, Qiang, Dong, Shuo, Li, Peng, Wang, Yu, Zhang, Mengxuan, Zhang, Yubo, Yang, Wenfeng, Guo, Peng
Design and Optimization of Hollow Rotating Traveling Wave Ultrasonic Motor Based on Laser Beam Expander2026-99-01547/31/2026
To meet the critical need for rapid response and miniaturization in laser beam expander drive systems, this study proposes an innovative actuation solution based on a hollow rotary traveling-wave ultrasonic motor. By thoroughly analyzing the optical adjustment mechanism of laser beam expanders and the electromechanical coupling behavior of ultrasonic motors, the motor structure was systematically optimized. Using a multiphysics coupling approach, the performance of stators fabricated from three distinct materials was compared, and parametric optimization was conducted. Experimental verification confirms that the developed ultrasonic motor precisely matches the load characteristics of beam-expanding optics while fulfilling the stringent requirements for both fast response and compact design. This research provides a reference for the miniaturization drive of high-precision optical systems, with promising applications in space optics and precision instrumentation.
Qiu, Haihui, Niu, Chuanhu, Xiao, Zhong, Xu, Zhangfan, Li, Jialiang, Pan, Song
The Protective Mechanism of Polyurea/Aramid Fiber Reinforced Steel Pipes against Implosion-Induced Multi-Physical Field Loads2026-99-01357/31/2026
This paper studies the protective performance of polyurea-coated steel pipes and aramid fiber-wound steel pipes under the multi-physical field load of internal explosion by combining experiments with numerical simulation. The experimental results show that applying aramid fiber winding has a limited effect on improving the anti-explosion performance of steel pipes, while polyurea-coated steel pipes exhibit better anti-explosion performance under the coupled load of shock waves and fragments. Simulation analysis reveals the protective mechanism of composite structures in terms of energy absorption and stress distribution, providing a theoretical basis for the optimal design of blast-resistant vessels.
Tian, Xiangpeng, Wang, Tao, Bian, Xiaobing, Huang, Guangyan
Study on the Properties of Waterborne Polyurethane Laminating Adhesives2026-99-02117/31/2026
This paper designs and synthesizes a series of high-performance waterborne polyurethane (WPU) laminating adhesives using polyester, polyether polyols and isophorone diisocyanate as the main raw materials. It focuses on exploring the effects of polyol types and R value (the ratio of polyol to isocyanate) on the properties of the adhesives, including emulsion viscosity, solid content, water absorption rate of the adhesive film, mechanical properties, and bonding performance on different substrates. The results show that WPU2 with polycarbonate diol (PCDL) as the polyol has the best water resistance and the highest tensile strength; WPU1 with polytetrahydrofuran (PTMG) as the polyol has the optimal elongation at break and exhibits outstanding bonding performance on the polar substrate PET; the regulation of R value can optimize the bonding performance of the adhesive on the non-polar substrate BOPP. This type of WPU laminating adhesive features low VOC emissions, no benzene-based solvents, excellent flexibility, and good resistance to high and low temperatures. It not only meets the environmental protection and safety requirements in packaging fields such as food and medicine, but also shows potential application value in high-end fields like aerospace interior compounding and lightweight transportation structure bonding. Its performance is highly compatible with the strict requirements for materials in the modern aerospace and transportation industries. The adjustable strong adhesiveness, compliance with strict emission standards, and adaptability to various substrates make it an ideal choice for a new generation of composite manufacturing, especially suitable for industrial fields pursuing reliability, sustainability and high performance.
Wang, Chengming, Yu, Jiacheng, Wang, Huixia, Huang, Yiqiang, Ren, Xiue
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