Browse Topic: Composite materials

Items (4,710)

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/m2

AMS3970/6A (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 Environments

2026-01-7502

9/22/2026

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 Autonomy

2026-01-7503

9/22/2026

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 Defence

2026-01-7556

9/22/2026

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 Vehicle

2026-01-0827

9/14/2026

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 Lightweighting

2026-01-0821

9/14/2026

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 Swarms

2026-99-1421

9/11/2026

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 Tools

2026-99-1413

9/11/2026

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 Pipeline

2026-99-1416

9/11/2026

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 Fragments

2026-99-1420

9/11/2026

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 Bridges

2026-99-1513

9/11/2026

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 Components

2026-99-1293

9/4/2026

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 Method

2026-99-1267

9/4/2026

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 Propagation

2026-99-1215

9/4/2026

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 Constraints

2026-99-1281

9/4/2026

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 AFP

2026-99-1277

9/4/2026

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

Navy Flight-Tests 3D-Printed Composite Repairs for F/A-18 Super Hornets

TBMG-55825

9/1/2026

Naval Air Warfare Center Aircraft Division Patuxent River, MD

Synergistic Effect of Matrix Porosity and Grouting Material Type on the Performance of Grouted Composite Pavement

2026-99-0405

8/28/2026

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 Products

2026-99-0416

8/28/2026

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 Beam

2026-99-0411

8/28/2026

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

Composite Materials Handbook Volume 5 - Revision B

R-4608/27/2026

The fifth volume of this six-volume compendium publishes technical guidance and properties on ceramic matrix composite material systems. The selected guidance on technical topics related to this class of composites includes material selection, processing, characterization, testing, data reduction, design, analysis, quality control, application, case histories, and lessons learned of typical ceramic matrix composite materials. Volume 5, which covers ceramic matrix composites, supersedes MIL-HDBK-17-5 of June 17, 2002. The Composite Materials Handbook, referred to by industry groups as CMH-17, is an engineering reference tool that contains over 1,000 records of the latest test data for polymer matrix, metal matrix, ceramic matrix, and structural sandwich composites. CMH-17 provides information and guidance necessary to design and fabricate end items from composite materials. It includes properties of composite materials that meet specific data requirements as well as guidelines for design, analysis, material selection, manufacturing, quality control, and repair. The primary purpose of the handbook is to standardize engineering methodologies related to testing, data reduction, and reporting of property data for current and emerging composite materials. 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 Gangway

2026-99-0339

8/14/2026

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 - Introduction

AMS3970B (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 Photocatalysts

2026-99-1007

8/7/2026

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

Simulation of Compression and Bending Performance of GFRP Rod of Composite Hollow Post Insulator

2026-99-0107

7/31/2026

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 Defects

2026-99-0200

7/31/2026

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 Dispersion

2026-99-0189

7/31/2026

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 Powders

2026-99-0242

7/31/2026

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 Vehicles

2026-99-0160

7/31/2026

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 Elements

2026-99-0217

7/31/2026

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 Strategy

2026-99-0241

7/31/2026

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 Environments

2026-99-0219

7/31/2026

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 Expander

2026-99-0154

7/31/2026

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 Loads

2026-99-0135

7/31/2026

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 Adhesives

2026-99-0211

7/31/2026

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

The Design of an Adaptive Multi-Material Fully Automated Grinding and Polishing Machine

2026-99-0127

7/31/2026

With the increasing demand for material microimaging analysis, there is a growing need for advanced precision grinding and polishing equipment, especially for metals, ceramics, and composites. Existing automated systems struggle with handling complex material challenges. This paper presents a fully automated adaptive grinding and polishing machine based on an STM32 microcontroller that handles multi-material samples. The system includes modules for sample access, cleaning, pad replacement, human-computer interaction, and equipment communication. The STM32 microcontroller executes grinding and polishing tasks based on instructions from the host computer while dynamically adjusting PID control parameters using an improved weighted average optimization algorithm. This approach enhances control accuracy, stability, and overall surface treatment quality compared to traditional PID control methods.

Zhang, Longqing, Kong, Xiangyu, Zhao, Xiuyang, Li, Xingbei

The Cylindrical Component Impacts the Honeycomb Structure

2026-99-0101

7/31/2026

High-performance composite materials are widely used in the main structural components of satellites. Various cylindrical components will hit the satellite at the time. The cartridge is fixed and unchanging. Honeycomb structure and ceramic honeycomb structure are the same, the cylindrical component is lighter and can attack satellites at a greater speed under the same conditions as the propellant. In terms of mass quality, the speed can reach over 1.6 times, and ceramic honeycomb structure can have minimal kinetic energy loss and can face enemies in combat with thicker steel plates, allowing for continuous destruction. Cylindrical component remaining kinetic energy (∆E) is 3.2968e3 J, but ceramic cylindrical component ∆E is 2.082e3 J, and ceramic cylindrical component have more advantages, and there are fewer arbitrary steel balls flying.

Xu, Jian, Yang, Zhen, Chang, Xuefang, Li, Qiang, Zhang, Kun, Qu, Dandan

Surface Modification of SiCw Optimises Impact Resistance of Dual-Polymer Composites

2026-99-0862

7/30/2026

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, Hu, Haobang

Study on Particle Dispersion Mechanism of Ribbon-Type Composite Impeller Based on CFD-DEM

2026-99-0818

7/30/2026

For the solid-liquid mixing of hydroxy-terminated polybutadiene, which is a high-viscosity fluid with a viscosity of 3.5 Pa · s, and micron-sized silicon dioxide particles, this study employs the CFD-DEM numerical simulation method to analyze the solid-liquid mixing process of the ribbon-type composite impeller (RTC impeller). The stirring performance of the RTC impeller is investigated from perspectives including fluid flow field distribution and particle dispersion mechanism. The research results show that the main circulating flow generated by the RTC impeller generally exhibits a roughly symmetric distribution characteristic, and the flow pattern of the main circulating flow on both sides of the central structure is relatively balanced; however, there is a certain difference in the flow trend of the secondary circulating flow pattern on both sides of the central structure. The main circulating flow provides basic flow power for the secondary circulating flow, while the secondary circulating flow adjusts the local energy distribution through vortex motion. These two flows act synergistically to achieve an efficient solid-liquid mixing process.

Li, Ruizheng, Zhang, Yan, Sun, Zhenxing, Wu, Qiong

Research on the Influence of Ultrasonic Vibration on VARTM of CFRP

2026-99-0844

7/30/2026

Due to their high specific modulus and specific strength, carbon fiber reinforced polymer (CFRP) composites have been widely adopted in the aviation field. However, CFRP components produced by conventional vacuum assisted resin transfer molding (VARTM) often exhibit defects such as Pores and dry spots. To address these limitations, this study develops a large-area, highly uniform vibration-assisted VARTM (UAVR) system and conducts ultrasound-assisted experiments. The results demonstrate that ultrasonic treatment at various frequencies consistently improves moulding uniformity. In particular, when the ultrasound frequency is 22 kHz, the tensile strength increases by up to 13.23%, and the compressive strength increases by up to 8.48%. This study has practical significance for improving the performance of CFRP.

Fang, Kaifa, Sun, Ruqian, Song, Gaoke, Zhang, Shuo, Cheng, Liqiang, Ma, Liping, Ruan, Benshuai, Xie1, Jiaqing

Influence of Modified Fly Ash Content on the Properties of Resin-Based Friction Materials

2026-99-1657

7/24/2026

In this study, five resin-based brake pad samples with modified fly ash contents of 0%, 4%, 8%, 12%, and 16% were prepared to investigate the influence of fly ash content on the comprehensive performance of the friction materials. The tribological properties of all samples were evaluated under temperature conditions ranging from 100 °C to 350 °C, and their overall performance was assessed using five evaluation indices. Based on the AHP-MOORA algorithm, sample F12 exhibited the highest comprehensive weighted score of 0.11, followed by samples F0 and F8 with scores of 0.10 and 0.09, respectively, indicating a slight decline. In contrast, the comprehensive weighted scores of F4 and F16 were relatively low, at 0.05 and −0.01, respectively. Among the five composites, F12 demonstrated the best overall performance, with F0 and F8 ranking next, while F4 and F16 performed poorly. These results suggest that, within a certain range, increasing the fly ash content can enhance the comprehensive properties of the material. However, excessive addition of fly ash may lead to the detachment of harder particles during wear, thereby increasing wear thickness and wear rate.

Li, Xiaobiao, He, Kang, Zhao, Zhuanzhe, Wu, Bo, Sun, Fei

Energy-saving and Economic Evaluation of Vacuum Insulation Panels with Glass Wool Core-polyimide Membrane Structure in Hotel Buildings under Different Climatic Conditions

2026-99-1652

7/24/2026

This study prepares high-performance PI/VIP composite thermal insulation materials for buildings by integrating polyimide (PI) composite membranes and vacuum insulation panels (VIPs), and uses EnergyPlus to explore their impacts on building energy conservation, operating costs, and carbon emissions under different climates. Experimental results show the materials have low thermal conductivity, long service life, and excellent thermal insulation and flame-retardant properties due to their internal vacuum structure inhibiting heat transfer. Simulations in Jinan (tropical monsoon), Heilongjiang (cold temperate), and Shenzhen (subtropical humid) climates indicate that compared with traditional XPS and rock wool boards, buildings using PI/VIP composites achieve 21.3%, 34.7%, and 18.9% higher annual energy-saving efficiency respectively, with 27%-41% lower carbon emissions; the most significant effects in Heilongjiang highlight the material’s great promotion potential in severe cold areas.

Bian, Chenqian, Chen, Zhaofeng

Research on the Fabrication of Composite Lattice by the Expandable Mold Method

2026-99-1649

7/24/2026

Advanced composite materials have garnered widespread attention in the aerospace and other fields with stringent weight requirements, owing to their superior properties, such as lightweight, high strength, high modulus, and corrosion resistance. Compared with traditional metal materials, advanced composite materials can reduce structural weight by 30%. Lattice structures possess unique characteristics, including high designability, low cost, and high damage tolerance. As a specialized reinforced structure, they have been identified as one of the key structural configurations for next-generation aircraft. Composite lattice structures, which integrate the advantages of composite materials and lattice architectures, provide an ideal structural material for achieving lightweight and multifunctional aerospace equipment. However, due to the intricate geometries and diverse functional design requirements of lattice structures, the fabrication of these structures presents significant challenges, and there is an increasing amount of research on improving the accuracy and performance of composite lattice structures. The expandable mold process represents an approach for manufacturing composite lattice structures, where pneumatic pressure from rubber expansion enables consolidation of the lattice assembly during elevated-temperature curing to achieve the finished composite part. This study reviews composite lattice structures, verifies the feasibility of using rubber as an expansion mold by investigating the thermal stability and expansion properties, and then prepares composite lattice structures via the expandable mold technique. Additionally, composite lattice structures are prepared using laminated machining, an interlocking process, and a 3D printing process. The advantages and disadvantages of different process methods for forming composite lattice structures are compared, and finally, the future trends in high-performance lattice development are discussed.

Han, Shuhao, Lv, Zhen, Ma, Cheng, Xiu, Zhifeng, Song, Yanhua

Effect of the Rolling Temperature on the Microstructure of the Cu-10Fe Alloys during Warm Rolling

2026-99-1629

7/24/2026

Cu-Fe alloys exhibit excellent performance, and increasing Fe content reduces costs. However, high-Fe Cu-Fe alloys exhibit limited formability at room temperature, while warm rolling improves their processability. This research investigates the effect of rolling temperature on the microstructural transformations and texture development in the Cu-10Fe alloys. The experimental result is that during cold rolling, the morphology of Fe phases is mainly fibrous. With the rolling temperature rising, the microstructural morphology of Fe phases becomes globular / elliptical. The difference is that with the increase in rolling temperature, the average grain size of the Cu-10Fe alloy first decreases and then increases. The matrix microstructure remains dominated by deformed grains, with significant recovery observed at 500 °C. The Fe-phase microstructure primarily consists of substructured grains, and dynamic recovery intensifies with rising temperature. During cold rolling, high dislocation density and localized strain heterogeneity lead to dispersed texture orientations and low strength. In contrast, warm rolling promotes dislocation climb and dynamic recovery, triggering partial recrystallization. This reduces randomly oriented grains, enhances the strength and continuity of specific textures, and establishes a more concentrated texture distribution. This forms a structure with fine recrystallized grains embedded within deformed grains, exhibiting slightly lower strength than cold-rolled samples but better elongation. These findings reveal the crucial role of deformation temperature in controlling microstructure transformation and texture evolution, especially by regulating the recovery and recrystallization behaviors of Cu-10Fe alloys. The above results hope to provide some theoretical and experimental basis for a new approach to improve processing technologies for new Cu-Fe-based composites.

Lin, Baosen, Huang, Su, Wang, Dongxiao, Li, Jianping

Structure Design of the Composite Stabilizer for Civil Aircraft Based on Standards and Airworthiness Requirements

2026-99-1603

7/24/2026

Generally, the allowable strain design is adopted for composite structures, which should ensure that the structure has sufficient strength and stiffness under the service load, and the safety margin should be greater than zero under the design load. The thesis develops a structured design for a stabilizer of civil aircraft based on standards and airworthiness requirements. The main task of this thesis is to compare the results of the all-mental structure and composite material structure of stabilizer on weight reduction at sufficient strength and stiffness.

Pi, Runge, Lv, Baoliang, Zhang, Liang

Evaluation of Structural Service Performance of Low-temperature Modified Asphalt Pavement based on Peavy-Duty traffic Engineering

2026-99-1645

7/24/2026

Relying on the reconstruction project, the low-temperature modified asphalt pavement significantly reduces the construction temperature of the asphalt mixture by 40 °C compared with the traditional asphalt pavement, and improves the road performance of the material. By comparing the two mixture rolling schemes, the compaction effect of scheme 2 is better. For AC-13 mixture, the flexural tensile strength of USP-SBS composite modified asphalt mixture is 0.67 MPa higher than that of SBS modified asphalt mixture, and compared with SBS modified asphalt mixture, the final rut depth of USP-SBS composite modified asphalt mixture is 2.68 mm shallower than that of SBS modified asphalt mixture, and the total deformation rate is 43.8% lower than that of the latter. The post-construction quality evaluation shows that the stability of the low-temperature modified asphalt pavement test section under the bearing capacity and high-temperature-water coupling is better than that of the conventional road section, and the low-temperature stability is comparable to that of the two. This innovative application not only achieves energy saving and emission reduction but also provides a new solution for road construction under heavy traffic conditions.

Liu, Chuanfeng, Xu, Ke, Shi, Zheng, Hao, Jidong, Zhao, Liandi, Xianwei, Wang

Carbon Fiber and Fiberglass Epoxy Prepreg Products with 350 °F (177 °C) Cure for Aerospace Applications

AMS6891B (Current)

7/13/2026

The intent of this specification is for the procurement of carbon fiber and fiberglass epoxy prepreg products with 350 °F (177 °C) cure for aerospace applications; therefore, no qualification or equivalency threshold values are provided. Users that intend to conduct a new material qualification or equivalency program must refer to the production quality assurance section (see 4.3) of this base specification, AMS6891.

AMS P17 Polymer Matrix Composites Committee

Carbon Fiber Fabric Repair Prepreg, 120 °C (250 °F) Vacuum Curing, Part 3 - Purchasing Specification for Carbon Prepreg

AMS3970/3B (Current)

7/13/2026

This Purchasing Specification (PS), AMS3970/3, specifies the batch release and delivery requirements for carbon fiber fabric epoxy prepreg used for repair. This specification is applicable only when the carbon fiber fabric epoxy prepreg is used as part of the repair system defined in AMS3970 and AMS3970/1. This specification also defines the procedure and requirements for storage life extension of materials purchased against this specification. It is only applicable for materials that are qualified against AMS3970 (refer to PRI QPL AMS3970) and shall be carried out within the responsibility of the purchaser and under control of its Quality organization.

AMS CACRC Commercial Aircraft Composite Repair Committee

Carbon Fiber Fabric Repair Prepreg, 120 °C (250 °F) Vacuum Curing, Part 5 - Purchasing Specification for Companion Non-Structural Glass Fiber Fabric Prepreg

AMS3970/5A (Current)

7/13/2026

This Purchase Specification (PS), AMS3970/5, specifies the batch release and delivery requirements for the companion non-structural glass fiber fabric prepreg. This specification also defines the procedure and requirements for storage life extension of materials purchased against this specification. It is only applicable for materials which are qualified and shall be carried out within the responsibility of the purchaser and under control of its Quality organization.

AMS CACRC Commercial Aircraft Composite Repair Committee

Identification and Assessment of Damage to Composite Aircraft Structures Training Document

AIR6825 (Current)

6/10/2026

Individuals who complete the applicable modules aligned with this training document will be able to define the type of damage, define the extent of damage, determine if further inspection is required, evaluate the damage against published allowable damage limits, and provide accurate documentation of the damage. The intended outcome of the training is increased safety such that no aircraft is released with unknown damage and that the aircraft meets continued airworthiness requirements. The goal is to change the culture from damage discovery to damage reporting while also reducing or eliminating flight delays due to incorrect or insufficient information. Teaching levels have been assigned to the curriculum to define the knowledge, skills, and abilities graduates will need. Minimum hours of instruction have been provided to ensure adequate coverage of all subject matter including lecture and practical exercise. These minimums may be exceeded and may include an increase in the total number of training hours and/or increases in the teaching levels. The modules are intended to be a competency-based training approach. Each curriculum is a subpart of this document. Module 1 is the Composite Awareness curriculum, independent of the application. Module 2 is the Initial Inspection and Damage Mapping curriculum. Module 3 is the Special Inspection Tools curriculum. Module 4 is the Reporting, Recording, and Assessment curriculum. NOTE: While the modules in this document are technically interrelated, each module can be trained independently; modules may be selected as applicable to an operator’s or maintenance organization’s needs. The combination of the modules represents the applicable identification and assessment process for damage to composite aircraft structures (see Figure 1). Module 1 is prerequisite for attendance to the other modules. The contents of Module 1 may also be used for composite awareness training of a broader target audience, including line mechanics.

AMS CACRC Commercial Aircraft Composite Repair Committee

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