Browse Topic: Joining

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Reliability Calculation and Analysis of Influencing Factors for Girth Welds in High-Grade Steel Pipelines Based on HMC-SS2026-99-03428/14/2026
Fracture failure of girth welds in high-grade steel pipelines poses a critical threat to pipeline integrity. Leveraging enhanced digitalization in pipeline engineering, a statistical database has been developed to support reliability analysis based on actual operational data. This study utilizes real project data to analyze the failure probability and key influencing factors of girth welds containing crack defects, thereby providing theoretical support for safety design and risk management. To overcome the conservatism of traditional deterministic methods, a probabilistic reliability model was established, incorporating a modified PRCI-CRES ultimate tensile strain criterion. Addressing the inefficiency of standard Monte Carlo (MC) simulation in high-dimensional low-probability contexts, an efficient Hamiltonian Monte Carlo-Subset Simulation (HMC-SS) strategy was introduced. Results show that HMC-SS improves computational efficiency by 99.95% over MC, with only 0.90% relative error. Key findings include: crack depth has the strongest influence – variation from 0.92 mm to 3.68 mm, which increases failure probability by 103 times; the strength matching coefficient is dominant, and higher values reduce failure risk; strain demand exhibits a positive correlation with failure probability and couples with material properties. It is concluded that high- or equal-strength material matching should be emphasized in welding, and reliability-informed design should account for multi-parameter interactions to ensure global safety.
Yang, Kai, Wang, Kaihong, Wang, Bin, Shao, Jia, Yu, Weichao, Zhang, Dong
Research on the Fault Diagnosis Method for Key Components of Inertial Friction Welding Equipment2026-99-03098/14/2026
Inertial Friction Welding (IFW) equipment is essential for the welding process of aircraft engine shaft components. However, the absence of comprehensive fault-handling standards for domestically produced inertial friction welding equipment has hindered its further development. This study focuses on the connecting rod and motor of the 30T-IFW equipment, employing a model-based fault detection method. Through simulation, the deformation of the connecting rod and the frequency response of motor vibration acceleration under different working conditions are obtained. Additionally, a monitoring platform is proposed to collect real-time data on connecting rod deformation and motor vibration from actual welding equipment. By establishing a quantitative correlation model of connecting rod deformation-force and revealing the coupling mechanism between motor eccentricity faults and modal frequency vibrations, a hybrid diagnostic framework that combines simulation of primitive warning and measurement of calibration is proposed. At last, the simulation and experimental results verify the effectiveness of the fault diagnosis method proposed in this paper.
Yang, Haifeng, Yuan, Mingqiang, Sun, Tao, Liang, Wu, Gong, Maolin, An, Xingyi, Wang, Qisong, Liu, Dan
ASSEMBLED COUPLING, THREADLESS-FLEXIBLE, FIXED CAVITY, CURRENT CARRYING, SELF BONDING, ENVELOPE DIMENSIONSAS5831A (Current)8/7/2026
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Multi-Layer, Reconfigurable Batteries That Can Bend, Adapt, and Tune Their Own VoltageTBMG-555508/1/2026
A research team led by Professor Lin Gui at the Institute of Physics and Chemistry, Chinese Academy of Sciences, reports the first fabrication of multi-layer flexible batteries using a combination of liquid metal microfluidic perfusion and plasma-based reversible bonding techniques.
Conventional Friction Stir Extrusion MachineTBMG-555418/1/2026
NASA Marshall Space Flight Center has developed a new small-scale metal extrusion tool, called a conventional friction stir extrusion (C-FSE) machine that may be attached or added-on to a conventional friction stir welding (C-FSW) system. The C-FSE machine uses the heat generation and plastic deformation processes underpinning C-FSW to perform metal extrusion instead of metal joining.
Microstructure and Mechanical Properties of Vacuum Laser Welded Joints in 42CrMo Thick Plate2026-99-01327/31/2026
Vacuum laser welding trials were carried out on 42CrMo steel, a material widely utilized in the defense sector. By employing a 30 kW fiber laser system, complete penetration welds were successfully produced on 20 mm thick 42CrMo steel plates. The resulting joints displayed satisfactory surface quality on both the top and bottom sides, with no evident defects such as cracks or porosity. A comprehensive analysis of the joint microstructure and mechanical properties was conducted. Findings reveal that the weld zone (WZ) is predominantly composed of lath martensite, accompanied by minor quantities of plate martensite, organized as columnar crystals. The joints demonstrated high tensile strength at ambient temperature, with fracture consistently occurring within the base metal (BM). Microhardness measurements indicated higher values within the weld relative to the base metal, and no pronounced softening was detected in the heat-affected zone (HAZ). Additionally, the joints exhibited commendable impact toughness, suggesting overall superior mechanical performance.
Shi, Haicheng, Zhang, Guoyu, Li, Wuhong, Cao, Dongxu, Liu, Tianlei
Weld Formation, Microstructure, and Mechanical Properties of High-Speed Friction Stir-Welded 6061-T6 Aluminum Alloys2026-99-01267/31/2026
In this paper, 6061-T6 aluminum alloys were subjected to high-speed friction stir welding. The associated weld formation, microstructure, and mechanical properties were systematically examined via combined experimental observation and numerical simulation approaches. At a welding speed of 3000 mm/min and a rotation rate of 3800 rpm, the defect-free weld was simply achieved due to the simultaneous intense thermal input and enhanced material flow. Microstructural analysis further demonstrated a fine equiaxed grain structure featuring a predominant simple shear texture with A/A components. The resultant joint exhibited an ultimate tensile strength equivalent to 80% of the base material, accompanied by excellent fracture elongation. This research provides experimental evidence for designing high-efficiency and high-quality bonding processes for aluminum alloys.
Guan, Yuankai, Wang, Ruiyang, Zhang, Kexin, Lin, Zhicheng, Deng, Jun, Liu, Zhe, Ganushchak, Oleg, Voitenko, Oleksandr, Zhao, Yunqiang, Gao, Shiyi
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
Ultrasonic Assisted Room Temperature Welding of Liquid Gallium Indium Alloy Brazing Material and Its Solidification Behavior at the Cu-Cu Interface2026-99-01967/31/2026
Considerable the gallium-based alloys low melting point coupled with easy to synthesize intermetallic compounds with diverse metallic elements, employing liquid gallium-based alloys as the soldering medium and leveraging ultrasonic as assistance are effective to construct pure copper joints under atmosphere condition. The investigation delves into the characterization of the reaction products, interface microstructure, elemental distribution patterns, and evolution of shear strength within the welds. Furthermore, the pivotal role of ultrasonic waves and constituent element diffusion mechanisms during the solidification phase is elucidated. Thus, the initial one-day occurred during solidification showed the 2.6 MPa shear strength but with the time increased to four and a half days, the shear strength raised to 8.4 MPa at room temperature. Thereinto, the results indicate the weld seam has achieved metallurgical connection. This innovative welding technique operates at room temperature provides significant guidance for designing a novel perspective low-temperature joining for applications. It is not only augments the repertoire of material connection methodologies but also presents a viable joining strategy for sensitive elevated temperature materials. Therefore, such process possesses substantial practical significance and promises avenues for future applications.
Guo, Manying, Qu, Yingying, Fang, Qiuyue, Yang, Shen
Force-Balance Analysis of Surface Instability in a Tri-Layer Film/Substrate Structure2026-99-02157/31/2026
Driven by increasing engineering demands, the need for high-performance flexible electronics has surged, accelerating the development of stretchable devices within mechanics. Among multilayer structures, the film/substrate architecture serves as a typical example, and its buckling behavior remains a longstanding focus of mechanical investigation. This work examines how an elastic film bonded to a soft tri-layer substrate loses stability, producing wrinkled surface patterns under compression. We first construct a mechanical model, then derive an analytical expression for the wrinkle amplitude using a force-balance approach, and finally employ finite-element simulations and theoretical comparisons, we systematically explore how the middle layer’s stiffness and thickness jointly govern the onset, wavelength and amplitude of surface buckling, revealing quantitative selection rules that have not previously been reported for tri-layer structures. The results show that the tri-layer film/substrate structure exhibits two instability modes: film-intermediate co-buckling and film-only wrinkling. By simply varying the middle layer’s elastic modulus or its thickness, one can move the structure across the boundary that separates the film-only and bi-layer buckling regimes, providing a direct mechanical selection for on-demand mode. In addition, the wrinkle amplitude increases monotonically with the applied initial strain. Those findings offer a theoretical reference for designing flexible electronics based on film/substrate structures.
Chen, Hao, Zhang, Wulin, Song, Yahui
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
Measurement and Regulation of Residual Stress in Door Opening Welds of Wind Turbine Towers2026-99-01977/31/2026
Weld residual stress is a critical factor affecting the structural integrity and service life of wind turbine towers. In this study, a systematic investigation was conducted on the residual stress distribution and control methods for door corner welds of an in-service wind turbine tower after approximately 20,000 hours of operation. X-ray diffraction (XRD) measurements revealed significant tensile residual stress in the weld and heat-affected zone, with peak values reaching 315 MPa, particularly concentrated at depths of 5-7 mm. To mitigate these stresses, two post-weld treatment methods were employed: ultrasonic impact treatment (UIT) and localized heat treatment. UIT effectively transformed surface tensile stress into compressive stress, achieving a maximum compressive residual stress of -372 MPa within a depth of 3 mm, while simultaneously refining grains and increasing surface hardness. In contrast, localized heat treatment at 460 °C for 5 hours led to a broader stress relief effect, reducing residual stress by approximately 100 MPa without causing significant changes to the macrostructure, but inducing substructural rearrangements beneficial for stress relaxation. Mechanical testing confirmed that both treatments improved tensile strength, ductility, and toughness of the welds. The combined findings demonstrate that ultrasonic impact treatment is highly effective for enhancing fatigue performance at the surface, while localized heat treatment offers advantages for deep stress redistribution and long-term structural stability. This comprehensive approach provides valuable technical guidance for residual stress management in complex welded structures of wind turbine towers.
Sun, Wanting, Zhong, Zhenqian, Zhang, Bo, Liu, Hui
Desulfurization and Acid Resistance of Multifunctional Protective Coatings in Severe Environment2026-99-02387/31/2026
Desulfurization equipment in electric power industry is in a multi-field coupled corrosion environment with high temperature, high humidity, strong acid and solid-containing slurry. The annual direct economic loss of corrosion exceeds 5 billion yuan, and the equipment replacement cycle is only 1.5-2 years. Traditional protective coatings are difficult to meet the needs. The concept of “bionic barrier-intelligent response-in-situ purification” is proposed to construct multifunctional protective coatings: The Langmuir-Blodgett technique was used to alternately assemble MXene nanosheets and polysilazane. Ti-O-Si covalent bonds enhanced the interface bonding, resulting in a coating hardness of 4H and an elongation of 200%. After 1500 hours of extreme environment test, the coating has low weight loss rate, high self-repair and antibacterial rate, and its service life is extended by 8 times. The engineering application makes the maintenance period of desulfurization tower of a 660MW unit extended from 8 months to 6 years, saving 1.2 million yuan annually, and increasing 200,000 yuan annually by recovering H ˇ SO 2. It provides a cross-scale scheme for electric power corrosion protection.
Nie, Pengfei, Gao, Jiangyu, Chen, Wei
Temperature Distribution and Effects of Heat-Affected Zone on the Mechanical Microstructure and Properties of Steel Pipes during Cutting2026-99-01257/31/2026
This paper examines the temperature distribution during pipe cutting and the impact of the heat-affected zone on the mechanical microstructure and properties of steel pipes. Utilizing testing equipment such as K-type thermocouples, a MESTL-WELD thermocouple spot welding machine, and a DC5516H 16-channel temperature data logger, temperature tests were conducted on Φ 1016 × 17.5 mm X70M spiral seam submerged arc welded steel pipes and Φ 1016 × 21 mm X70M straight-seam submerged arc welded steel pipes. The results indicate that the maximum test temperatures during cutting were 953.8 °C and 1216.6 °C, respectively, with the duration of temperatures exceeding 400 °C at each test point not exceeding 30 seconds. By fitting the relationship curve between the peak temperatures of each test point and the cutting distance using the ExpDec3 model, it was found that the cutting distance corresponding to a temperature of 580 °C was 12 mm. Furthermore, mechanical microstructure and property tests were performed on the pipe body at different positions of the HAZ. Except for an anomaly in the yield strength of the rod-shaped tensile specimens of the Φ 1016 × 21 mm X70M welded pipe body, no other abnormalities were detected. Macroscopic metallographic examination revealed that the axial length of the HAZ at the end of the cut pipe did not exceed 7 mm. Microhardness testing showed significant fluctuations in the microhardness of the pipe body at the end of the cut pipe, while the microhardness of the pipe body beyond 10 mm from the end gradually returned to normal.
Xu, Yan, Bai, Qiang, Feng, Zhenjun, Chang, Yonggang, Li, Liang, Peng, Shibi
Researching on Small Deformation Control Technology of Large Vertical Vacuum Vessels2026-99-01767/31/2026
This paper investigated the small deformation control of a large vertical vacuum vessel, a critical component in aerospace testing with stringent deformation limits under specific test conditions. Building on engineering experience and economic considerations, we designed oversized and multi-array external reinforcement rings tailored to the vessel’s spatial geometry to enhance its stiffness and stability. A novel integrated structural design was proposed, which mechanically couples the vacuum vessel with the concrete foundation via embedded components, specifically, by configuring optimized embedded parts at the vessel’s base and external reinforcement ring bottom, and then welding and binding these parts to the foundation’s embedded elements. This design significantly boosted the vertical vessel’s overall structural strength, rigidity, and stability. Ansys Workbench was used to simulate and analyze the vacuum vessel under different experimental conditions, and finite element simulations of the vessel under diverse experimental conditions validated that the integrated design achieves low stress and minimal deformation, compliant with test requirements. Post-installation deformation measurements further confirmed good agreement between experimental data and simulation results, verifying the model’s accuracy. The proposed fixed support structure addresses the limitations of traditional support systems for small-deformation applications and offers a new design paradigm for vertical vessel supports in high-precision engineering scenarios.
Bo, Yang, Shizeng, Lv, Xiao, Hao, Jie, Gong
Surface Modification of SiCw Optimises Impact Resistance of Dual-Polymer Composites2026-99-08627/30/2026
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
Research on Welding Deformation of the Car Body Based on 3D Laser Scanning2026-99-08217/30/2026
This study aims to verify the accuracy and stability of a system used for measuring and analyzing the welding deformation of vehicle bodies under different welding parameters. A 3D laser scanner was employed to capture the surface topography data of the vehicle’s front deck before and after welding. In order to determine the welding deformation, PolyWorks software was utilized for deformation analysis, which processed the 3D scanning data and compared the post-welding data set. A dedicated vehicle body welding deformation measurement system was developed, including hardware configuration and software development. The BP neural network algorithm was adopted to predict the welding deformation, and the results indicated that the deviation between the predicted values and the average experimental measurements was less than 10%. This confirmed the practicality of the BP neural network in predicting welding deformation and highlighted its effectiveness in technical support for the optimization of welding parameters and deformation control in automotive manufacturing.
Li, Lina, Zhang, Yiqi, Sun, Hongchang, Wei, Xiezhen
Three-Dimensional Transient Thermal-Fluid Coupling Numerical Simulation of the Molten Pool in Aluminum Alloy Laser Welding2026-99-08547/30/2026
Laser welding technology for aluminum alloy electrode and busbar connections: addressing challenges in battery module assembly. In this work, a CFD framework was built in ANSYS Fluent using a Gaussian rotating heat-source representation, while a VOF approach was used to capture the transient gas–liquid interface in deep-penetration welding. A three-dimensional, transient, thermal-fluid coupled numerical model of the dual-layer heterogeneous aluminum alloy laser deep penetration weld pool was established concurrently with laser deep penetration welding experiments. Results indicate: Peak flow velocities in the weld pool during welding are concentrated along the weld centerline, with flow vectors predominantly directed axially along the weld. Once a quasi-steady keyhole regime is established, vaporization-induced recoil pressure becomes the primary driver governing melt circulation. The liquid metal first impinges on the pool bottom along the keyhole wall and then recirculates upward near the pool boundary, producing strong vortical motion. These findings are intended to support parameter selection and process optimization for laser welding of layered dissimilar aluminum components used in battery tab–busbar assemblies.
Lv, Wenjun, Wu, Yan
Research on the Hysteresis Performance of Welded Hollow Spherical Joints under Low Temperature2026-99-16417/24/2026
The extreme cold environment has a significant impact on the mechanical properties of welded hollow ball nodes, which are crucial components in large-span steel structures. In this paper, based on the comprehensive test data of drum-shaped welded hollow sphere nodes from Beijing Daxing International Airport, a sophisticated finite element model incorporating welding residual stress is established. Through detailed static loading analysis and systematic hysteresis performance studies, the research thoroughly explores the influence mechanisms of low temperature on node bearing capacity, deformation capability, and energy dissipation performance. The investigation reveals that while the bearing capacity of the nodes increases significantly in low-temperature environments, both their plastic deformation capacity and energy consumption performance are notably reduced. These findings provide valuable theoretical references for the design and optimization of large-span mesh frame structures in cold regions, enabling engineers to better account for temperature effects in structural calculations and safety assessments. The results have important implications for improving the reliability and durability of steel structures in extreme cold environments.
Luo, Yanzhi, Jin, Changming
Research on the Microstructure and Properties of X80 Steel Circumferential Welds Under Different Automatic Welding Processes2026-99-16367/24/2026
Two sets of X80 pipes with a diameter of 1219 mm × 27.5 mm were welded using a fully automatic welding process (GMAW) and a combined automatic welding process (GTAW + FCAW-G), respectively. By analyzing the microstructure, strength, impact toughness, and fracture toughness of welded joints, the differences in microstructure and properties of circumferential weld joints under different automatic welding processes were studied. The results showed that the design of multi-layer and multi-pass welding and appropriate heat input controlled the microstructure of the weld seam and heat-affected zone area of the circumferential weld joint. Both automatic welding processes obtained welded joints with finer microstructure, thereby ensuring the strength and toughness of the joint. The tensile strength and yield strength of the welded joints under two automatic welding processes reach over 680 MPa and 600 MPa, respectively. The welded joints under both automatic welding processes have good impact toughness and fracture toughness at - 10 °C, with a ductile-brittle transition temperature below -50 °C and crack tip opening displacement (CTOD) values greater than 0.254 mm. The tensile strength, yield strength, impact toughness, and fracture toughness of the fully automatic welding ring weld joint are better than those of the combined automatic welding.
Liu, Jian, Niu, Huli, Wang, Hong, Sun, Xinyan, Yang, Huaqing, Bai, Qian
CONNECTOR, PLUG, ELECTRIC, SOLDER TYPE LANYARD, PUSH-PULL COUPLING, SERIES 1 (CLASS E, P, AND J)AS31381B (Current)7/8/2026
AE-8C1 Connectors Committee
SAE TOMORROW TODAY UNPLUGGED - Regulation, Risk, and the Rise of L2++135757/2/2026
What exactly is L2+? And what about L2++? As the industry embraces these increasingly common terms, is liability slowing the path to Level 3 automation? In this Unplugged episode of SAE Tomorrow Today, join host Grayson Brulte to explore the automation liability concerns keeping OEMs awake at night and why companies like NVIDIA, Mobileye, Qualcomm, Stellantis, and Mercedes-Benz are using terminology that isn't formally defined. As adoption accelerates and regulation struggles to keep pace, one thing is clear: that extra "plus" may just be the industry's way of navigating a self-driving future that's arriving faster than the rules can keep up. Have your own thoughts on this topic? We'd love to hear from you! Share your comments, questions or ideas for future topics with Grayson on Twitter or send them to podcast@sae.org. Follow SAE on LinkedIn, Instagram, Facebook, Twitter, and YouTube.
Patterson, Lori
Metallic Materials Properties Development and Standardization (MMPDS) Handbook - 2026 - Volume IIB-994_VOLUME27/1/2026
Volume II publishes the framework for generating and analyzing the data so that material sponsors can generate the right data, knowing how it will be analyzed by the Battelle Memorial Institute. MMPDS-2026 Volume II Process Intensive Materials and Joining Technologies does not currently have any material properties, focusing on additive manufacturing of metallic materials. MMPDS-2026 Volume II focuses on non-conventional processes and will be published each year. Volume I: Conventional Materials and Joint Allowables.
Metallic Materials Properties Development and Standardization (MMPDS) Handbook - 2026 - Volume IB-994_VOLUME17/1/2026
The Metallic Materials Properties Development and Standardization MMPDS-2026 supersedes MMPDS-25 and prior editions of the MMPDS Handbook as well as all editions of MIL-HDBK-5, Metallic Materials and Elements for Aerospace Vehicle Structures Handbook that were maintained by the U.S. Air Force. The last edition, MIL-HDBK-5J was cancelled by the U.S. Air Force in March 2006. This document contains design information on the mechanical and physical properties of metallic materials and joints commonly used in aircraft and aerospace vehicle structures. All information contained in this Handbook has been reviewed and approved using a standardized process. The development and ongoing maintenance process involves certifying agencies, including the FAA, DoD, and NASA, and major material suppliers and material users worldwide. The information and procedures in this Handbook are continuously reviewed and modified or removed as determined to be appropriate. With advances in materials and fastener systems, and with the review process of existing information, periodic updates of the MMPDS should be expected. As such, it is recommended that the latest version of the MMPDS be used. Volume II: Process Intensive Materials and Joining Technologies.
A Review of Welding Techniques in Metal Additive Manufacturing: Advancements, Challenges, and Future Directions05-19-04-00296/10/2026
The present review evaluates recent advances in the development of Welding-Based Additive Manufacturing (WBAM) technologies using arc, high-energy density, solid-state, and hybrid welding systems by providing an interdisciplinary assessment of technological aspects, sensing, process optimization, and multi-process strategies. It is concluded that, in spite of considerable progress in process optimization and control, there exist numerous paradoxes associated with relationships among process conditions, structure, and properties, especially those related to heat input effects on material microstructure and performance. An important finding is the fragmentation of predictive modeling approaches, where physics-based and data-driven methods remain inadequately integrated, limiting generalizability and accuracy. Another important conclusion is related to the dominance of the effect of thermal history and multi-physical phenomena on the mechanical performance of the material produced by WBAM technologies. Besides, the complexity and contradiction in defect generation mechanisms, monitoring, and evaluation methodologies restrict the development of process standardization and certification. New directions in intelligent fabrication based on artificial intelligence and digital twins are identified.
Santhana Babu, A.V., John Rajan, A., Mishra, Aishwary, Chakravarthy, P., Jayabalakrishnan, D.
Neutrons Help Improve 3D-Printed SuperalloysTBMG-552776/1/2026
Additive manufacturing, or 3D printing, is a new way of making metal parts and other types of materials by building them layer by layer. This research project, by researchers at General Electric, the Edison Welding Institute, and Oak Ridge National Laboratory (ORNL), printed an alloy composed of Inconel 718 and René 41 at two ends with a compositional graded region in the middle. The study evaluated the stress and composition variations of the alloy. To do so, the researchers conducted neutron experiments at the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at ORNL, both Department of Energy Office of Science user facilities. Neutrons are ideally suited to study internal stresses in materials because they can penetrate dense metals.
Zero Waste Manufacturing in Aerospace: Circular Design Approaches from Concept to End-of-Life2026-26-07756/1/2026
Achieving zero-waste manufacturing in aerospace requires a shift from end-of-pipe waste mitigation toward circular design principles embedded early in product development. This paper presents a practical framework for integrating circularity into aerospace systems through five design pillars: design for modularity and disassembly, material substitution to enhance recyclability, waste segregation and characterization, component-level circularity readiness scoring, and collaborative supplier engagement. To operationalize this approach, a Circularity Readiness Assessment Tool (CRAT) is developed to evaluate design alternatives against criteria such as disassembly ease, material recyclability, manufacturing waste potential, end-of-life recovery pathways, and supplier take-back mechanisms. The framework supports multi-criteria decision-making by complementing traditional aerospace design drivers including weight, performance, cost, and safety. The methodology is demonstrated through a case study of an aircraft seating system. Scenario-based analysis indicates that targeted circular design interventions can reduce material waste and lifecycle carbon emissions while maintaining functional and regulatory requirements. Emphasizing practical engineering workflows rather than exhaustive lifecycle modeling, this work provides a scalable foundation for embedding circular design into aerospace product development and advancing zero-waste manufacturing objectives.
S, Chaitra
Drilling Studies on Sustainable Lightweight Hybrid Polymer Matrix High-Performance Nanocomposites2026-26-07326/1/2026
Worldwide, engineers are exploring the possibility of using polymer composites in their quest for lightweight materials. In this study, injection moulding was used to develop a biodegradable polymer PLA composite containing 20 wt.% vetiver fibers (VFs) and 2 wt.% nano-silica (nSiO2) obtained from pearl millet, which is sustainable. Materials need machining as secondary operation that required joining. Desirability analysis was used to examine and optimize machining (drilling) studies that were designed with Taguchi's design (L9 orthogonal array). Surface roughness (SR) and delamination factor (Fd) were taken as outputs, while spindle speed (SS), feed rate (FR), and drill diameter (DD) were the inputs. Drilling studies were performed on a single vertical machining center (VMC). ANOVA identifies that the FR had the most decisive influence on SR (F=559.24, p=0.001785), followed by DD and SS. FR is the dominant contributor to Fd (F=379, p=0.00263), followed by SS and DD. At low SS and high FR, excessive thrust and heat cause fiber-matrix tearing and poor hole finish. Higher SS softens the PLA matrix, improving surface quality. Fd decreases with increasing SS, whereas it rises with extreme FR and DD due to elevated thrust and matrix cracking. The optimized parameters SS of 3000 rpm, FR of 15 mm/min, and DD of 6 mm achieved a maximum combined desirability of 1. A non-traditional meta-heuristic technique, the frog leaping algorithm (FLA), is adopted to optimize the inputs based on the developed regression model. FLA also provides the identical optimal condition as the desirability function, predicting the outputs SR=2.2195 μm and Fd=1.0383, which are very close.
Senthilkumar, N.
Evaluation of Thermal Behaviour of Ramie Fiber/Delrin Composites for Aircraft Cabin Components2026-26-07546/1/2026
This research investigates the fabrication and evaluation of Delrin (polyoxymethylene, POM) composites reinforcing 5-20 wt.% chopped ramie fiber (RF). The polymer composites were fabricated via the injection moulding technique. Glass transition temperature (Tg), thermal conductivity, Vicat softening temperature (VST), heat deflection temperature (HDT), melt flow index (MFI), and coefficient of linear thermal expansion (CLTE) were the various thermal characteristics of the sustainable composites that were systematically evaluated as per the ASTM standards. The addition of RF drastically altered the Delrin matrix's performance. Among the formulations, the composite with 15 wt.% RF had the best combination of properties: higher VST and HDT values, which provide greater dimensional stability at high temperatures; lower CLTE, resulting in less thermal expansion; comparatively better thermal conductivity; and improved heat dissipation. Eventually, there was a moderate drop in the MFI, indicating more rigid polymer chains that restrict the flowability of the composite, thereby increasing its heat-withstanding capabilities. DSC analysis revealed a slight upward shift in Tg and increased crystallinity, suggesting restricted polymer chain mobility and enhanced load transfer at 20 wt.% RF loadings, agglomeration effects, and weaker interfacial bonding with the matrix led to deterioration in properties. Aircraft cabin components like interior panels, ducting supports, and lightweight non-structural fittings requires dimensional stability, thermal resistance, and mechanical reliability under fluctuating flight conditions.
S, Thirumalvalavan, Senthilkumar, N., Selvarasu, S
Evaluation of Mechanical Tensile Properties on TIG-Welded AISI 304L Austenitic Stainless Steel Using Principal Component Analysis05-19-04-00275/14/2026
The reliability of welded joints is a vital factor in modern manufacturing, directly affecting product performance and durability. This study investigates methods to enhance the mechanical and metallurgical quality of butt joints in AISI 304L stainless steel welded by the gas tungsten arc (GTA) process. A systematic experimental design was implemented using the Taguchi method with an L9 orthogonal array, considering welding current, gas flow rate, and travel speed as the main parameters. To determine overall weld performance, the joints were characterized by measuring ultimate tensile strength (UTS), yield strength, percentage elongation, and examining their microstructural morphology. An experimental strategy based on the Taguchi approach has been implemented. The welding performance of the material was investigated, and the process parameters were optimized using multiresponse optimization through principal component analysis (PCA), incorporating an orthogonal array design, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA). C1G1S3—the predicted optimal parameter combination—is the ideal factor configuration as determined by PCA (welding current = 100 A, gas flow rate = 10 L/min, travel speed = 2 mm/sec). Results demonstrate that precise control of process parameters significantly enhances weld quality. The methodology also provides a systematic framework that engineers and practitioners can apply to produce reliable stainless steel welds with improved accuracy and predictability.
Ghosh, Nabendu, Roy, Angshuman
An Analytical Piecewise-Linear Joint Stiffness Model for Predicting Load Distribution in Multi-Bolt Metal–Composite Joints05-19-04-00285/14/2026
Accurate prediction of load distribution in multi-bolt metal–composite joints relies heavily on high-fidelity modeling of single-bolt joint stiffness. Current models, however, inadequately capture the complex effects of bolt–hole clearance, including delayed load take-up and reduced bearing chord stiffness, as well as multi-interface friction interactions. To overcome these limitations, quasi-static tests were conducted on single-bolt, single-lap aluminum–CFRP joints with varying clearances. By integrating experimental findings with an analysis of the load-transfer mechanisms, we identified five distinct loading states and formulated corresponding analytical load-deformation equations along with explicit transition criteria, culminating in a novel piecewise-linear stiffness model. Enhancements over traditional tri-linear models encompass: (a) subdivision of the transition region into separate local and global slip phases, facilitating an accurate representation of asynchronous slip initiation at different frictional interfaces and (b) the implementation of a nonlinear correction approach to quantify the reduction in bearing chord stiffness induced by clearance. The proposed model exhibits excellent agreement with experimental observations across all clearance settings, affirming its predictive accuracy. Consequently, it offers a robust theoretical basis for improving load distribution prediction and facilitating design optimization in multi-bolt M-C joints. Furthermore, the methodology presented here shows considerable potential for adaptation to composite–composite joints.
Liu, Haolong, Sun, Qingping, Liu, Yang, Zhao, Qi, Liu, Yue
Optimal Heat Transfer and Coolant Flow Correlations in a Cylindrical Cell Format, Production-Based Battery Pack Model under Constant Discharge, Winter–Summer Driving14-15-02-00115/6/2026
A full lithium-ion battery (LIB) pack has hundreds to thousands of cells, coolant flow lines and channels, and channel bends to control cell temperature within its operating window and minimize cell internal resistance, aging, and fire risk. A 75 kWh LIB pack has four modules, and each has 23–25 bricks. Two challenges in battery state predictions for hot and subzero temperatures are battery temperature (Tbatt ) and coolant flow within the whole pack. In this work, a 1D 75 kWh full-pack model with its thermal management system is developed using a holistic reverse-engineering method, which can predict Tbatt at any bricks/modules and inlet/outlet coolant flow characteristics. A Tesla Model Y equipped with dual e-motors is tested on an in-house state-of-the-art chassis dynamometer. The test data at V = 60–80 km/h, 100–150 A constant discharge, and Tbatt = −10°C to 40°C are used to develop the model. The 75 kWh pack model features 4000+ cylindrical cells (96S46P, Panasonic 21700-format), 20+ coolant lines (or plates, tubes), and 700+ flow channels. The model considers heat exchange from cells to the ambient air via coolant (water-glycol), coolant channel walls, adhesive bonding, trays, and cases. Four forced convective heat transfer coefficient correlations (α) from the coolant to the walls are used to predict coolant outlet temperature (T cool, out ) and Tbatt at different bricks. Three coolant flow losses correlations (K) due to pipe friction, and pipe bends are used to predict the coolant pressure drop ∆Pcool across the pack. Optimal α and K correlations are identified using the fully validated pack model, and the transient temperatures at any cell in bricks and the inlet/outlet coolant flow characteristics are well predicted with over 90% accuracy. This work provides guidelines for selecting optimal α and K correlations to develop any 1D fully liquid-based battery pack models for all-weather driving.
Sok, Ratnak, Kusaka, Jin
Multiphysics Modeling and Performance Assessment of Ultrasonic Welding for Thermoplastic CompositesF-0082-2026-01205/5/2026
Ultrasonic welding (UW) provides a rapid and efficient method for joining composite components by inducing resin flow through thermally driven diffusion and crystallization at the bonded interface. However, in the absence of a multiphysics modeling framework or a digital twin approach, current practice still depends on extensive trial-and-error testing to determine key welding parameters such as vibration amplitude, weld time, weld pressure, hold time, and downspeed. While in-situ thermal cameras can monitor surface temperatures, the internal temperature at the bonded interface is often significantly higher, introducing the risk of thermal degradation and inconsistent bond quality. To overcome these limitations, GEM developed a high-fidelity multiphysics model to establish a quantitative relationship between process parameters and the evolving temperature field within welded thermoplastic parts. The model integrates coupled mechanical, thermal, and acoustic physics to simulate high-frequency vibrations and static pressure, capture the generation and spatial distribution of heat, and represent the temperature-dependent viscoelastic response that governs bond formation. A validation test matrix was designed by systematically varying weld time and vibration amplitude. Through-thickness temperature distributions were measured using infrared thermal imaging, enabling direct comparison with model predictions. Upon validation, the model was applied for process tailoring, allowing precise control of temperature distribution to achieve target bond strength. This integrated modeling and validation approach demonstrated substantial benefits, including reduced design iterations, accelerated process optimization, and improved quality and performance of welded composite structures.
Walthers, Mark, Li, Rui, Wei, Qingxuan, Lua, Jim
How Electroadhesion Can Hold Materials TogetherTBMG-550885/1/2026
Is there a way to stick hard and soft materials together without any tape, glue, or epoxy? A new study published in ACS Central Science shows that applying a small voltage to certain objects forms chemical bonds that securely link the objects together. Reversing the direction of electron flow easily separates the two materials. This electroadhesion effect could help create biohybrid robots, improve biomedical implants, and enable new battery technologies.
Investigation of Metallurgical and Mechanical Behaviors of AA6061-AA2017 Joints Produced by Single- and Double-Pass Friction Stir Welding: Influence of Base Material Position and Post-Weld Shot Peening Technique05-19-04-00264/13/2026
The growing demand for lightweight, high-strength materials in marine and aerospace structures has promoted the use of friction stir welding (FSW) for welding dissimilar aluminum alloys. However, tensile residual stresses and microstructural heterogeneities often degrade weld integrity. This study investigates the combined impact of base material positioning, single- and double-pass FSW, and post-weld shot peening (SP) on the metallurgical and mechanical properties of AA6061–AA2017 joints. Five welding configurations were examined to evaluate how varying base material positions on the advancing and retreating sides affect material flow and mechanical behavior. Post-weld SP effectively presented compressive residual stresses, reduced surface defects, and refined surface grains. The average grain size in the stir zone was reduced from 5.2 μm (single-pass) to 2.0 μm (double-pass U-turn) after SP, confirming significant grain refinement through dynamic recrystallization. Mechanical testing revealed that double-pass FSW with opposite weld direction (U-turn) followed by SP achieved the highest performance, with ultimate tensile strength (UTS) improving from 246 MPa to 289 MPa (≈17% increase) and tensile elongation rising from 8.78% to 9.41%. Microhardness in the heat-affected zone improved up to 127 VHN, countering thermal softening effects. The synergistic effect of double-pass welding and SP enhanced homogeneity, fatigue resistance, and surface integrity. The results establish SP as an efficient post-FSW treatment for dissimilar aluminum joints, offering quantifiable improvements in strength and ductility, making the process highly suitable for demanding marine and aerospace structural applications.
Nukathoti, Raja Sekhar, Battina, N. Malleswara Rao, Vanthala, Varaha Siva Prasad, Chirala, Hari Krishna, Maloth, Balu
Effective Prediction of the Mechanical Properties of Glue-Laminated Motor Stator Core with Consideration of Glue Disposition2026-01-01774/7/2026
This study presents an effective predictive methodology for determining the mechanical properties of glue-laminated motor cores, with explicit consideration of glue disposition, including bonding pattern, configuration, location, and coverage. In laminated stator cores, glue bonding and stacking processes jointly govern the mechanical integrity of the lamination stack. Practical production bonding schemes are typically nonuniform and localized, leading to spatial variations in stiffness and to locally anisotropic, orthotropic material behavior. These effects influence both the in-plane and through-thickness stiffness of the stator core. They can significantly affect the accuracy of structural simulations, such as NVH responses of high-speed traction motors and e-drive systems. Given the constituent material properties of the electrical steel laminations and the glue, this work distinguishes the governing mechanisms underlying the equivalent core properties. The in-plane stiffness is primarily controlled by the stacking factor, which statistically characterizes the glue contribution in the axial direction. In contrast, out-of-plane properties (e.g., elastic modulus and shear modulus in the stack direction) are determined jointly by the glue’s axial thickness contribution and its in-plane spatial distribution. To capture these coupled effects, an enhanced homogenization framework is developed using a representative volume element (RVE) formulation implemented through finite element analysis (FEA). The laminated structure is represented as an equivalent orthotropic material, enabling directional stiffness variation induced by nonuniform bonding and lamination material. Parametric simulations establish quantitative relationships between macroscopic core properties and glue configuration, bonding pattern, and stacking factors. A closed-form analytical solution is also derived for simplified cases to support verification. The predicted effective properties show good agreement with experimentally correlated values from production cores, and with analytical solutions under simplified bonding assumptions as well. The proposed methodology enables practical inclusion of glue-disposition effects in early-stage predictive models, thereby improving the fidelity of laminated motor-core NVH assessments and generic structural analysis.
Nie, Zifeng
Integrated Welding Simulation and Experimental Characterization of Weld-Metal and Heat-Affected-Zone Strength in AA6063-T62026-01-02304/7/2026
In the context of automotive lightweighting and efficient manufacturing, welding is a key joining method for aluminum body structures due to its maturity, versatility, and cost effectiveness. This study investigates MIG butt welding of AA6063-T6 sheets using a sequential thermo-mechanical finite element model with a double-ellipsoid heat source. Thermocouple histories and macroscopic metallography of the weld-pool morphology are used to validate the predicted temperature field, and post-weld deformation measured by a coordinate measuring machine is compared with the simulation to confirm overall model reliability. Hardness mapping across the joint partitions the material into weld metal (WM), heat-affected zone (HAZ), and base metal (BM). Miniature tensile specimens extracted along the weld provide local mechanical properties, from which linear strength–hardness relations are established. Building on these results, a five-material equivalent strength model covering WM, HAZ-I, HAZ-II, HAZ-III, and BM is formulated to enable region-wise elastoplastic parameter assignment. The model reproduces the load–displacement response of transverse joint tests and accurately identifies necking in HAZ-II. An integrated workflow that combines simulation, measurement, property characterization, and modeling provides robust support for weld-strength assessment and process optimization in aluminum body structures.
Shao, Jiyong, Meng, Dejian, Xiang, Yao, Gao, Yunkai
A Study on Fatigue Life Prediction Method for Point-Based Joints Considering Multiple Fracture Modes – FDS, Blind Rivet, and Blind Nut Focus2026-01-01804/7/2026
The application of multiple materials in vehicle bodies is accelerating as the adoption of lightweight aluminum alloys and composite materials advances rapidly. These materials play a crucial role in reducing overall vehicle weight, enhancing fuel efficiency, and complying with increasingly strict environmental regulations. As the automotive industry continues to evolve toward electrification and sustainability, the integration of lightweight and high-performance materials has become a key design strategy. However, the use of multiple materials creates new challenges in manufacturing, particularly for joining technologies. Since different materials have varying mechanical properties, thermal behavior, and surface characteristics, the selection of appropriate joining methods is essential for ensuring structural integrity and durability. Depending on material types, thicknesses, production processes, and cost constraints, various joining techniques—such as mechanical fastening, welding, and adhesive bonding—are selectively applied. This study focuses on fatigue life prediction for point-based joints commonly used in automotive structures, including flow drilling screws (FDS), blind rivets, and blind nuts. Fatigue fractures in these joints typically propagate in multiple directions: through the sheet thickness and along the in-plane direction. Accurate fatigue life prediction requires numerical simulations that account for both crack propagation paths and the interaction of these paths with joint geometry and loading conditions. Traditional fatigue models often assume a single fracture mode, limiting the ability of these models to evaluate multiple failure mechanisms simultaneously. To address this issue, this study proposes a simplified modeling approach that enables the simultaneous consideration of multiple fracture modes. This paper introduces a numerical analysis-based method capable of predicting the fatigue strength of point joints, and describes the fatigue tests that were conducted to validate the proposed approach. This research contributes to the development of more reliable and efficient design strategies for multi-material automotive structures.
Takuno, Sougo, Isono, Toshiyuki, Urakawa, Kazushi, Goto, Suguru, Kawamura, Hiroaki, Niisato, Eita, Ishigami, Yuta
A Novel Spot Joint Finite Element for Rapid Stress Analysis of Fasteners in Automotive Structures2026-01-01824/7/2026
Due to the spot weld and mechanical fastener share the similar characteristics to join sheets together with differences in deformation behavior around joint region, a novel spot joint element (user-defined element) consists of regular Mindlin shell elements and equations for different kinematic constraints is proposed to simplify the spot joint representation in lightweight automotive structures. The novel spot joint element can not only provide accurate deformation behavior around joint region but also output mesh-insensitive structural stresses at virtual nodes with the use of traction-based structural stress method for fatigue failure analysis. In this investigation, the structural stress distributions around joint circumference in the lap-shear specimens with spot weld or fastener are first calculated to validate the accuracy of the novel spot joint element. Then, the structural stresses along different cross-sections emanating from joint are also calculated for the specimens with fasteners to investigate the potential different failure modes. Finally, the fatigue data correlation based on the novel spot joint element and traction-based structural stress method using available literature data are presented and served as example applications.
Wu, Shengjia, Zhang, Lunyu, Dong, Pingsha
Investigation on Microstructure and Mechanical Properties in the Dissimilar Joining of WE43 to AA7075 Alloy using FSW2026-01-02294/7/2026
This research investigates the alterations in microstructure, microhardness, and joint strength resulting from the dissimilar friction stir welding (FSW) of WE43 magnesium alloy to AA7075 aluminium alloy. The study specifically analyses the role of FSW process parameters in the formation of intermetallic compounds (IMCs), the evolution of grain structure, the resultant microhardness distribution across the weld zone, and the joint tensile strength. A comprehensive microstructural characterization was performed utilizing optical microscopy (OM), field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDS), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). These analyses confirmed significant grain refinement in the stir zone and the identification of various IMCs at the weld interface. Microhardness mapping indicated a gradient profile, with the weld nugget exhibiting superior hardness attributed to its dynamically recrystallized, fine-grained microstructure. Crucially, the low-heat-input FSW (LFSW) variant yielded a substantial increase in average microhardness, reaching 126 HV in the stir zone (SZ), due to grain refinement induced by severe plastic deformation. This configuration achieved a joint efficiency of approximately 68.7% relative to the WE43 base material. The enhancement in mechanical performance is directly linked to a modified joint preparation strategy that successfully suppressed the formation of brittle AlMg IMCs, instead fostering the formation of harder MgZn, Al2CuMg, and AlMgZn compounds. These findings underscore the efficacy of the LFSW technique in fabricating dissimilar WE43-AA7075 joints with favourable mechanical properties and a consistent microhardness profile. The process parameters are strategically selected to achieve better joint properties and form defect-free joints.
Ahmad, Tariq, Khan, Noor Zaman, Ahmad, Babar, Siddiquee, Arshad Noor
Conjugate Heat Transfer Modeling for Predicting Thermal Behavior of X76 Emotor Windings2026-01-01184/7/2026
A computational study based on a conjugate heat transfer (CHT) method in SimericsMP+ was performed to predict the winding temperatures in an X76 emotor. In this study, the thermal load was represented in the simulation through the solution of electromagnetic equations in SimericsMP+, where heat generation was driven by root-mean-square (RMS) current, while liquid cooling was applied at flow rates ranging from 1 LPM to 6 LPM. Simulations were conducted to measure the temperature on three thermocouple locations on each side of the winding crown and weld regions under steady operation. The computational strategy employed a loosely coupled approach. A fluid-only simulation was first carried out to establish stable flow conditions, followed by coupling with solid conduction where the winding acted as the heat source. The predicted temperature distributions were then compared with test data. Results obtained show good agreement, with differences remaining within an acceptable range, thereby confirming the accuracy of the numerical method. Findings demonstrate that the CHT approach not only reproduces measured winding temperatures but also provides detailed insight into local flow and temperature fields inside the emotor, information not accessible through physical testing alone. The validated methodology offers a reliable tool for guiding thermal management design and optimization of electric machines under varying cooling conditions.
Jia, Kun, Schlautman, Jeff, Srinivasan, Chiranth
Optimizing Weld Placement in Automotive Structures Using Topology and Multi-Disciplinary Approaches2026-01-05144/7/2026
This work presents two approaches for weld optimization aimed at reducing manufacturing cost and process time, while meeting structural performance requirements in automotive structures. The first approach uses topology optimization to identify the most efficient weld layouts. A design space is generated along mating flanges, joints, and panel interfaces, where potential weld locations are defined. Welds are treated as discrete design variables, and the topology optimization systematically evaluates their contribution to global stiffness and load path integrity. Non-critical welds, those with minimal impact on stiffness, durability, or crashworthiness, are eliminated, resulting in a minimized weld pattern that maintains structural performance. The second approach applies Multi-Disciplinary Optimization (MDO) to balance weld reduction with performance targets across multiple domains, including linear and non-linear stiffness, crashworthiness, and fatigue. Using a preprocessing tool, welds are parameterized to allow flexible control of their placement. A Design of Experiments (DoE) is generated to simulate various weld configurations under relevant load cases. Surrogate models are then developed to approximate the relationship between weld layout and key performance metrics. These response surfaces enable efficient optimization that minimizes weld count while satisfying all structural requirements. Together, these strategies form a data-driven, simulation-based framework for weld design that supports aggressive cost and time reduction targets without compromising safety or durability. The results demonstrate the potential for integrating advanced optimization techniques into early design phases for more efficient and manufacturable vehicle structures.
Koppaka, Vinaya, Yoo, Dong Yeon, Chavare, Sudeep
Development of Automotive Hood Using Multi-Material Double Injection Molding – An Overview2026-01-04764/7/2026
This paper presents the multidisciplinary development of a hybrid automotive hood manufactured using double-shot injection molding with overmolded brackets. Conventional steel and aluminum hoods, while structurally reliable, pose challenges in terms of weight reduction, pedestrian head protection, and manufacturing cost. Composite and thermoplastic alternatives supported by computational analysis and advanced molding processes provide opportunities to address these challenges. Finite element analysis (FEA) was employed to evaluate torsional and bending stiffness, locking load, and crashworthiness, while pedestrian headform simulations following ECE R127 and EEVC WG17 guidelines were conducted to assess compliance with safety regulations. Adhesion and bonding strength of overmolded polymer–polymer interfaces were studied to validate manufacturing feasibility. Results confirm that hybrid hoods fabricated using multi-material double-shot molding can achieve weight reductions of up to 30% compared with steel, maintain structural stiffness equivalent to aluminum, meet head injury criterion (HIC) thresholds, and reduce assembly complexity by consolidating brackets and reinforcements into a single integrated structure.
Ganesan, Karthikeyan, Seok, Sang Ho, Jo, Hyoung Han
Role of Advanced Polishing Techniques in Enhancing Al-Cu Diffusion Bonding for EV Application2026-01-02354/7/2026
The demand for lightweight, high-efficiency components in electric vehicles (EVs) highlights the critical need for reliable Al-Cu joints with superior electrical and thermal conductivity. While diffusion bonding has emerged as a promising approach, interfacial impurities and voids often degrade joint quality and conductivity. Conventional manual polishing was initially employed to prepare Cu and Al surfaces; however, this method proved insufficient in consistently removing oxides and contaminants, leading to non-uniform bonding. In addition, the larger surface area of the samples made traditional polishing impractical, further motivating the use of electropolishing. To overcome these limitations, we introduce electropolishing pretreatment to achieve cleaner, void-free interfaces. Electropolishing effectively dissolves surface asperities and contaminants, enabling intimate atomic contact during bonding and minimizing the formation of brittle intermetallic phases. A systematic investigation of bonding parameters was conducted using a custom-designed graphite clamping system. Microstructural analyses reveal that advanced polishing plays a pivotal role in producing uniform, impurity-free interfaces, resulting in reduced intermetallic thickness, improved bonding strength, and enhanced current-carrying capability. This study demonstrates the clear advantages of electropolishing over conventional polishing and establishes a scalable pathway to manufacture high-performance conductive joints for next-generation EV motor and power distribution systems.
Abbasi, Hossein, Liu, Yi, xiao, Yaohong, Wang, Andy, Su, Jinrong, Wang, Qigui, Chen, Lei
Strain-Based Fracture Assessment of Tailor Welded Blanks under Complex Loading Conditions2026-01-02314/7/2026
Tailor Welded Blanks are critical for automotive lightweighting yet prone to premature failure due to differential thickness and strength across the weld. This study utilized digital image correlation (DIC) to analyze the maximum in-plane principal Hencky strain (E₁max) and axial strain (εₐₓₐₗ) of TWBs under complex loading conditions, including biaxial and plane-strain states. Twelve distinct material stack-ups were tested to evaluate the impact of material difference on formability. Results indicated that differential properties significantly altered strain distribution, often forcing localization onto the thinner or softer sheet. While UHSS welds provided high load capacity with limited ductility, combinations using HSLA or IF substrates were susceptible to early localization and unstable fracture. Comparative heatmaps illustrate strain evolution across all samples, providing spatial insights beyond conventional force–displacement analysis. Metallurgical characterization confirmed a strong correlation between failure behavior and microstructural features, specifically heat-affected zone softening and martensitic transformation. Notably, once the strength ratio exceeds 2.0, biaxial stretchability drops sharply and failure transitions from base-metal necking to weld-initiated cracking, indicating a severe mechanical mismatch effect. The observed hierarchy of critical strains (E₁ biaxial > E₁ plane-strain > E₁ uniaxial) confirms that biaxial testing represents the upper-bound deformability condition for these welded blanks. Collectively, these findings provide actionable guidance for optimizing TWB design in battery electric vehicle structures, where material heterogeneity and complex loadings are prevalent challenges.
Aminzadeh, Ahmad, Sheng, ZiQiang, Huang, Lu, McCarty, Eric, Biro, Elliot
Optimizing Joint Efficiency in Stainless Steel-Aluminum Alloy FSW Joints through Advanced Parameter Control2026-01-02284/7/2026
The present study investigates optimization of ultimate tensile strength (UTS) in FSW of AA2024-T3 and SS304 in a butt joint configuration. An L18 mixed-level orthogonal array was used to design 18 experiments, varying tool rotational speed (450, 560, and 710 rpm), traverse speed (20, 25, and 40 mm/min), and pin offset (1 and 1.5 mm toward the Al side). The tool rotational speed had the greatest influence on UTS, contributing nearly one-third of the total variance, followed by pin offset and traverse speed. The optimal combination, 450 rpm, 20 mm/min, 1.5 mm offset, yielded a UTS of 344.7 MPa and a joint efficiency of 78.3%. At this setting, peak temperatures reached ~356 °C, ensuring sufficient plasticization and uniform mixing of the Al–SS interface, producing a refined stir zone with an average grain size of 4.2 μm. Fracture analysis revealed ductile failure at the optimal parameters, whereas suboptimal conditions resulted in brittle or mixed fractures due to either insufficient or excessive heat input. These results demonstrate that Taguchi optimization effectively correlates process parameters, thermal profile, material mixing, and mechanical performance, enabling reliable, defect-free dissimilar FSW joints for structural and aerospace applications.
Mir, Fayaz Ahmad, Khan, Noor Zaman, Pali, Harveer Singh
Kissing Bonds Inspection by Comparing Natural Frequencies Using Digital Holography2026-01-02074/7/2026
Accurate detection and evaluation of kissing bonds in composite materials is essential to ensure the integrity of the component structure, but traditional NDT (non-destructive testing) methods struggle to identify imperfect bonds and zero-volume debonds. In this study, a vibration analysis method based on holography was applied to detect kissing bonds by monitoring the changes in natural frequencies of the same sample before and after fatigue loading. Both pristine and kissing bond samples were tested under identical conditions, and their vibration characteristics (natural frequency, amplitude, and mode shape) were measured using holography. The experimental results show for the intact sample exhibited no changes in natural frequency amplitude or mode shape after fatigue loading, confirming that the applied fatigue test did not affect the integrity of its adhesive layer. In contrast, for the sample with a kissing bond, after fatigue loading, the natural frequency decreased by up to 22 Hz due to debonding or delamination, while the vibration amplitude increased, and new localized modes appeared around the debond area. This indicates that in practical engineering applications, kissing bonds can be identified by observing the frequency change of a single sample before and after fatigue testing. This method improves the applicability of this technique, making it more suitable for industrial non-destructive testing conditions.
Gao, Zhongfang, Fang, Siyuan, Gerini-Romagnoli, Marco, Yang, Lianxiang
Multi-Joint Topology Optimization Method with Interface Geometry Control2026-01-05034/7/2026
Topology optimization (TO) has become a reliable and lightweight design approach which was widely adopted in multiple industrial applications. Over the past decades, TO has advanced through three major development stages to increase its practicality and application scope: single-material topology optimization (SMTO), multi-material topology optimization (MMTO), and multi-joint topology optimization (MJTO). SMTO involves only one candidate material, whereas MMTO takes multiple candidate materials into consideration, which widen the application scope of TO. In terms of MJTO, it not only considers multiple candidate materials but also considers the bonding material between dissimilar candidate materials, improving practicality over MMTO. However, prior MJTO methods overlook the geometry of dissimilar material interfaces, a factor that may impact material bonding effect. In this paper, a novel MJTO algorithm is introduced to enable explicit control over interface geometry in MJTO. Central to the method is a Newton’s law of gravitation-inspired dissimilar material interface orientation detection approach, which accurately calculates the bonding material’s orientation. Using the orientation detection approach, the bonding material’s Young’s modulus can be penalized when undesired orientations occur, thus enforcing geometric control of the interface. In this paper, the proposed algorithm is evaluated through multiple academic models to demonstrate its effectiveness. Numerical study results demonstrate that the horizontal dissimilar material interface can be effectively controlled using the proposed method, leading to improved producibility of TO-derived designs.
Shi, Yifan, Huang, Yuhao, Kim, Il Yong
Lightweight Bubble Sheet Panel To Reduce Inverter Noise and Vibration for Electric Vehicles2026-01-04424/7/2026
Inverters are typically integrated into electric drive units for electric vehicles (EVs) to reduce packaging size and cost. However, coupled vibrations from the electric motor and gears are transmitted to the inverter, which can become a dominant noise source due to its large radiative panel. Metal panels are required for electromagnetic interference (EMI) compliance, yet these covers usually lack sufficient stiffness or damping for noise control. Adding ribs and applying damping treatments result in excessive mass, cost, and packaging challenges. A new bubble sheet panel design has been developed to enhance the structural strength and damping performance of the inverter cover while significantly reducing its mass. A thin sheet of aluminum is welded onto the cover in an optimized pattern that enhances stiffness and damping performance while accommodating packaging requirements. The welding pattern can include logos or artistic designs to improve the panel’s appearance. The metal sheets are blown apart between the welds to form a 3D structure that is three times stiffer and twice as strong as a flat monolithic sheet of the same thickness. The composite dual bubble sheets can effectively reduce structural vibration. Damping materials, such as liquid-applied sound deadener (LASD), can be injected into the bubble sheet cavities to significantly improve its damping performance. Prototype bubble sheets have been designed, analyzed, and tested for an integrated inverter used in front-wheel-drive (FWD) electric drive unit for EV applications. Analysis and modal tests show a reduction of 10 to 15 dB at panel resonances with close to 30% reduction in mass. The bubble sheet panel is installed on an integrated inverter and tested in the electric drive unit. Sound power measurements confirm a reduction of up to 10 dB in inverter panel vibration.
He, Song, Bobel, Andrew, Naismith, Gregory, Yi, Wenwen, Patruni, Pavan Kumar
NASA Tech Briefs: April 202626AERP044/2/2026
Leonardo DRS Expands Production Capacity to Advance Naval Power, Sensors, and AI-Driven Mission Systems Success at Sea: NIWC Atlantic Uncrewed Surface Vessel Completes Fastest Transatlantic Crossing High‑Speed Spindles Unlock Five‑Axis Machining Innovation with Smaller Tools Why CFD is Stuck in the File Era Accurate and Resilient GNSS Timing Modules for Critical Infrastructure Undetectable Ship-to-Ship Laser Communications EP40: Structural Epoxy Used for Steel Bonding in Marine Applications Master Bond EP40 is a two-part, room temperature curing epoxy for bonding, sealing, coating, and encapsulating. EP40 bonds well to a variety of substrates, including naval steel, the primary structural metal used in the shipbuilding industry Vortex Research to Solve Aviation's Efficiency Tradeoff with Active Strakes A research team developed a smart strake system that dynamically adapts to flight conditions, showing a promising drag reduction in the wind tunnel with respect to passive strakes. This approach has the potential to save airlines hundreds of kilograms of fuel per flight. New 3D-Printing and Manufacturing Techniques Grant More Control Over Energetic Material Behavior A newly developed tool could enable more control over how energetic materials function throughout manufacturing processes.
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