Browse Topic: Composite materials

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Identification and Assessment of Damage to Composite Aircraft Structures Training DocumentAIR6825 (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
AMS CACRC Commercial Aircraft Composite Repair Committee
Unidirectional Carbon Fiber Tape Epoxy Repair Prepreg, Vacuum Curing Part 0 - IntroductionAMS6885 (Current)6/10/2026
This document (Technical Specification) gives information about qualification rules and the relation between the different specification parts involved, such as the Technical Specification (TS), the Material Specification (MS), and the Purchasing Specifications (PS).
AMS CACRC Commercial Aircraft Composite Repair Committee
Unidirectional Carbon Fiber Tape Epoxy Repair Prepreg, Vacuum Curing Part 1 - General RequirementsAMS6885/1 (Current)6/10/2026
AMS6885/1 gives information about the technical requirements and qualification procedure for unidirectional carbon fiber tape epoxy repair prepreg capable of curing under vacuum for repair of carbon fiber reinforced epoxy structures. The repair system includes an epoxy film adhesive to be applied in a co-bonding process with the prepreg for solid laminate and sandwich bonding.
AMS CACRC Commercial Aircraft Composite Repair Committee
Design-Driven Sustainability of Automotive Components: A Comparative LCA from Conventional to Metal and Composite Additive Manufacturing2026-37-00376/9/2026
The increasing pressure to decarbonize manufacturing systems is pushing industry beyond conventional lightweighting strategies toward material and process paradigms, capable of delivering functional performance with radically lower environmental impact. In this context, polymer-based composite Additive Manufacturing (AM) offers an underexplored yet highly promising pathway for sustainable production of load-bearing components. This study presents a preliminary comparative cradle-to-gate Life Cycle Assessment (LCA) of a Formula SAE brake pedal, assessing the environmental transition from conventional sheet metal fabrication and finishing operations of Aluminum 7075-T6 to additive manufacturing solutions, with specific focus on Carbon-Fiber-Reinforced Polymer (CFRP) composites. Two topology-optimized designs, respectively for Powder Bed Fusion (PBF) in AlSi10Mg and Material Extrusion (MEX) in Polyethylene Terephthalate Glycol with Carbon Fiber (PETG-CF) are compared to conventional
Dalpadulo, Enrico, Russo, Mario, Apté MD, Raphaëlle, Leali, Francesco
Improvement of rCF Behaviour through the Introduction of NF2026-37-00396/9/2026
This study investigates the structural improvement of recycled carbon fibre composites through hybridisation with continuous flax fibres to address sustainability concerns and performance limitations. Recycled carbon fibres, while environmentally beneficial, suffer from short, randomized orientations and lower mechanical properties limiting their application beyond decorative uses. This research explores whether incorporating unidirectional flax fibres can enhance rCF behaviour for structural applications. Six hybrid composite layup variants and two plain composites were manufactured using cold compression moulding with Ampro Bio Resin. Each hybrid configuration comprised eight layers, divided into four layers of recycled carbon and four layers of flax fibres oriented at 0°. Complete mechanical characterization was performed following ISO standards for tensile (ISO 527), flexural (ISO 178), and impact (ISO 179) testing. Results demonstrated significant performance improvements in
Hnatyk, Dawid, Chrysanthou, Andreas, De Vuyst, Tom, Ismail, Sikiru
European Researchers Develop Self-Healing Composite Material for Spacecraft26AERP06_116/1/2026
Researchers from CompPair and the European Space Agency have developed a new composite material for spacecraft with an embedded healing agent. European Space Agency, Paris, France Healable spacecraft structures could soon be possible thanks to cutting-edge composite technology. Swiss companies CompPair and CSEM, and Belgian company Com&Sens have partnered with the European Space Agency (ESA) to modify their self-healing carbon fiber product for use in space transportation. Project Cassandra - an abbreviation for Composite Autonomous Sensing and Repair - includes sensors and a heating element within a composite carbon-fiber material, allowing spacecraft to autonomously repair initial stages of damage.
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
Senthilkumar, N.
Investigation of Aluminium Alloy Composites Reinforced with Zirconium oxide and Solid Lubricant Attributes for Brake and Clutch Components of Aircrafts2026-26-07526/1/2026
For brake and clutch components of aircraft vehicles which require higher mechanical strength and wear resilient, light-weight aluminium composites were developed infusing solid lubricant. In this study, hybrid composites were developed using powder metallurgy route with aluminum alloy AA356 and various amounts of zirconium oxide (ZrO2) (0, 5, 10, 15, and 20 wt.%) as reinforcements. A solid lubricant hexagonal boron nitride (hBN) at a fixed 5 wt.% is considered. Following the appropriate ASTM guidelines, the specimens were mechanically characterized by measuring their density, porosity, micro-hardness, compression strength, impact strength, and flexural strength, among other properties. The findings showed that the composites' mechanical and physical behaviour were greatly affected by the inclusion of ZrO2. Porosity increased as a result of particle clustering and interfacial voids, while density increased gradually as ceramic content increased. Consistently increasing ZrO2 addition
Senthilkumar, N.
Wear Resilience Characteristics of Silicon Nitride Strengthened AZ31 Magnesium Composite2026-26-07406/1/2026
To develop magnesium matrix composites, ceramic silicon nitride (Si3N4) particles are added to the magnesium (AZ31) matrix at 2 wt.%. The composite is produced via disintegrated melt deposition vacuum-stir-casting procedure. Microstructural studies reveal the presence of Si3N4 particles and their uniform spreading. An L9 orthogonal array, planned using Taguchi’s experimental design, is selected for three wear parameters; axial load (AL), rotational speed (RS), and time duration (TD) with trials as per the G99 standard in the pin-on-disc apparatus to assess the wear resilient of the composite. Experimental results show an increase in axial stress, and wear loss (WL) increases dramatically. Because the area of contact shrinks as RS increases, WL diminishes dramatically. When the AL is low, the friction coefficient (CoF) increases, and when the AL is large, CoF drops. When the RS is increased, CoF decreases. To optimize multiple responses effectively, the TOPSIS (Technique for Order
Senthilkumar, N., Dhinakar Raj, C K
Porosity Matters: Multiscale Simulation of Composite Panel Performance in Aerospace Structures2026-26-07316/1/2026
Porosity in carbon fibre reinforced polymers (CFRP) remains a critical concern for aerospace engineers, as even minor voids introduced during manufacturing can undermine the reliability of structural components. This work explores the influence of Interply porosity on composite panel behavior, employing a multiscale simulation approach that bridges material characterization and full-scale structural analysis. The study begins with virtual coupon testing using Digimat-VA and Digimat-MF, enabling the prediction of material allowable and the assessment of defect variability. Homogenized material properties derived from these simulations are then applied to detailed panel models constructed in MSC Apex, ensuring accurate representation of layup and orthotropic behavior. The workflow can support a range of structural load cases, allowing for the evaluation of stiffness, buckling, or other relevant scenarios as dictated by aerospace certification requirements. Nonlinear finite element
Savane, Vishal, Kumar, Rajat
Lightweight Magnesium Nanocomposites with Enhanced Wear Resistance for Landing Gear Application2026-26-07516/1/2026
This study systematically evaluated the wear resilient performance of AZ61 magnesium alloy reinforced with 15 wt.% SiC and diverse amounts of multi-walled carbon nanotubes (MWCNTs) under dry sliding circumstances adopting pin-on-disc apparatus (ASTM G99). To identify the influence of factors like sliding speed (SS) (1-3 m/s), axial load (AL) (10-30 N), and MWCNT concentration (0-3 wt.%) that affect tribological performance, experiments were developed using a Central Composite Design (CCD) under Response Surface Methodology (RSM). SEM micrographs revealed a dispersion optimum near 2 wt.% MWCNT, where CNTs anchor to SiC and bridge the α-Mg matrix, while 3 wt.% shows agglomerates and micro-voids. Findings showed that wear loss (WL) and friction coefficient (CoF) was greatly amplified by increasing AL owing to localized heating and contact stresses. A compacted tribolayer was formed by increasing SS, which decreased WL but marginally raised the CoF. At low AL (10 N), SS (2.09 m/s), and
Senthilkumar, N.
Predictive Model and Analysis of the Resultant Force in the Dry Machining of Mg-4Zn/Si 3 N 4 Nanocomposites2026-26-07626/1/2026
The development of lightweight materials for use in aerospace and automotive applications is extremely significant. Magnesium (Mg)-based alloys and composites are good candidate materials from the perspective of low density, good specific strength, and abundance. The Mg-4Zn alloy is one such alloy, which is a lightweight, biocompatible, and eco-friendly Mg-based alloy. In spite of these advantages, there is a strong need and scope to improve its wear resistance and mechanical properties. Mg-4Zn nanocomposites with Si3N4 reinforcements (a biocompatible bioceramic) are hypothesized to possess superior properties. Microstructural analysis of the vacuum stir-cast nanocomposites confirms grain refinement and a consequent increase in microhardness with an increase in Si3N4 reinforcement wt.%. The addition of Si3N4 reinforcement to improve the properties of the Mg-4Zn alloy could introduce challenges in machining. To make products from the nanocomposites, machining them with minimal
N, Anand, Shaju, Tony M, G, Nagamalleswara Rao, D, Bijulal, K, Jayaprakash Reddy, K, Vijayan, Chaman, Joji J
Conceptual Design of CFRP Sandwich Structures Interfacing Cryogenic Tankages in Rockets2026-26-07616/1/2026
The study proposes the use of Carbon Fiber Reinforced Plastic (CFRP) sandwich composites configurations for structures interfacing cryogenic tankages. To address the design challenge posed by high thermal contractions in metallic tanks after cryogenic propellant filling, the study incorporates slits near the tank interfaces. Additionally, to minimize the transfer of cryogenic temperatures into these interfacing parts, the sandwich structure features interface end attachment made of thermally insulating Glass Fiber Reinforced Plastic (GFRP) material. Analytical and Finite Element (FE) studies were conducted on a typical cylindrical cryogenic intertank structure to demonstrate the proof of concept. These studies included analytical design using MATLAB based codes, parametric analyses with simplified shell element models and detailed 3D sector models using solid elements. The parametric studies assessed the effects of the number and dimensions of slits to achieve an optimal design, while
Bhalerao, Sandesh Popat, Gupta, Yogesh Kumar, Madhukumar, P.
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
S, Thirumalvalavan, Senthilkumar, N., Selvarasu, S
From Racing Car to Rocket Tank26AERP06_086/1/2026
German startup Blackwave is building carbon parts for rocket tanks. Technical University of Munich, Munich, Germany Carbon fiber has become indispensable in high-performance industries such as automotive engineering and aerospace. It's lightweight, extremely durable, and can be shaped in almost any way. The start-up Blackwave, founded at the Technical University of Munich (TUM), specializes in this versatile composite material. What began with custom components for sports cars and aircraft has evolved into the development of high-pressure tanks for space applications. As is so often the case in engineering, a small detail determines technological progress. In the case of rockets, it is the high-pressure tanks that are specially designed for the fuel systems. As rockets are designed to be as light as possible, they lose structural stability when the fuel tanks, known as primary tanks, are emptied. A trick is used to counteract this: alongside fuel combustion, noble gases are released
Thermal Management System in Commercial Aircraft: A Case Study on Passenger Egress System2026-26-07606/1/2026
It is known fact that Thermal management systems are essential to the safety, operational efficiency, and structural integrity of present-day commercial aircraft. Very critical insulation and thermal protection materials are utilized across various aircraft zones to mitigate extreme temperature challenges, ranging from cryogenic conditions at high altitude to pyrotechnic conditions at low altitude/ sea level. Some of the examples where specific materials at their functional role are, In engine pylons and nacelles, high temperature alloys such as Titanium and Inconel, along with ceramic Matrix composites (CMCs) serve as firewalls and heat shields, which are designed to contain fires and protect primary structures. In bleed air ducting, fiberglass or silica insulations blankets are employed to prevent thermal degradation of surrounding aluminum and composite components, when air at temperatures above 200 degree C flows. This paper focuses on the critical insulation and thermal protection
Govindaraju, Parthasarathy, Nanjundegowda, Harshavardhana
Assessment of Injection Gate Location Effects on Mechanical Performance of Short Fiber Reinforced Plastic Components Using Digimat2026-26-07466/1/2026
The mechanical performance of short fiber-reinforced plastic (SFRP) components is highly sensitive to fiber orientation, which is significantly influenced by the injection gate location during the molding process. Traditionally, gate placement decisions are driven by warpage minimization strategies, often overlooking mechanical performance under diverse load cases. This research introduces an automated workflow within Digimat-MS that integrates injection gate optimization into the early design phase, leveraging Integrated Computational Materials Engineering (ICME) principles. The proposed methodology enables engineers to upload either Marc, Abaqus or Ansys input decks, select a component of interest, assign material cards, and define gate scenarios. A Design of Experiments (DOE) is then executed locally or remotely, allowing Digimat to evaluate multiple gate configurations. The system aggregates results and identifies optimal gate locations based on the initiation of failure under
Kauthale, Tanmay, Madhavan, Vinay, Soni, Ganesh
Digitalization of Mechanical Labs for Enhanced Traceability and Virtual Verification2026-26-07156/1/2026
Digitalization is the process of leveraging digital technologies to transform business operations, processes, and models, enabling organizations to improve efficiency, create new value, and enhance customer experiences. It is essential as it enables data-driven decisions and reduces product development time. It’s easier to Digitalize new products however, transforming existing products and processes is a challenging task, as constituents are in various phases of lifecycle. Also, the existing/ legacy data acts as a starting point for future programs. Currently, teams are spending hours to weeks finding the right processes and data, costing ~$14,000 per test based on labor hours. To tackle this challenge, Mechanical labs are digitalizing their data and processes alongside physical tests via 3DEXPERIENCE application to capture data in digital models and ensure traceability for which Requirement Functional Logical Physical (RFLP) framework is leveraged. This traces Requirements to its
Karpur, Anoop, Inapakolla, Bharat Kumar, Harris, Jason
Development of Graphene Filled Polypropylene Nanocomposite for Aerospace Application2026-26-07396/1/2026
Polypropylene, a commodity plastic, is the semi-crystalline thermoplastics widely used in high volume for general purpose application. Polypropylene is the macro molecules of soft and weak backbone, which by reinforcement of fillers in different forms such as fiber, spheroids, nanotubes, flakes, etc., can influence its mechanical, thermal, electrical, creep resistance, and flame resistance properties for use in aerospace applications. Currently, polycarbonate and nylon plastics are used in aerospace applications, however, they are expensive compared with polypropylene. In this thesis, efforts are put to study the effect of reinforcement fillers in the properties of polypropylene composite, primarily the mechanical and flammability properties. The matrix element, polypropylene co polymer and reprocessed polypropylene blended in equal ratio, are coupled with the dispersing phases such as graphene, mica, fumed silica, and polydimethylsiloxane polymer. Effect of graphene as reinforcing
Govindaraju, Parthasarathy
Investigating the Electrochemical Corrosion Behaviour of Bamboo Fiber-Marine Waste Reinforced Polymer Matrix Hybrid Composites for Light Weight Applications2026-26-07336/1/2026
This study investigates the corrosion behaviour of bamboo-crab shell fortified polymer matrix hybrid composites. Three unique hybrid composites were created utilizing the hand layup approach, with epoxy as the matrix material, 15 wt.% bamboo fibers (BFs), and varying quantities (3, 6, and 9 wt. %) of marine resource crab shell (CS). Electrochemical corrosion tests were utilized to evaluate the hybrid sustainable composite's corrosion behaviour. The testing results reveal that epoxy-15 wt.%BF-6 wt.%CS (P2) composite has better corrosion resistance than epoxy-15 wt.%BF-3 wt.%CS (P1) and epoxy-15 wt.%BF-9 wt.%CS (P3). A potentiodynamic polarization test revealed an icorr value roughly five times lower than P1 and three times lower than P3 composites. Furthermore, the Nyquist plot obtained from the EIS study revealed that the P2 composite has a larger capacity loop than the P1 and P3 composites. It also indicates that the P2 composite is more resistant to corrosion than the other two. The
Senthilkumar, N., Srinivasan, D, G, Perumal, Balakrishnan, Deepanraj
Electrical Harnessing in Satellite Launch Vehicles of ISRO – Methods for Sustainable, Safe and Reliable Systems2026-26-07796/1/2026
The electrical harness system of satellite launch vehicles functions as the backbone of spacecraft avionics; inter connecting subsystems through complex networks of wires and connectors. An electrical harness is a group of wires bunched together and terminated in connectors. The common insulations used for launch vehicle applications include PTFE, Polyimide, ETFE and TKT. The connectors used are of aerospace grade and connectors tailored for space applications. With over 5000 connectors and 200 km of cables constituting nearly 20% of vehicle mass, the design, fabrication, and sustainability of these systems are critical. The insulations of connectors inserts or the wires are critical for the durability of harness elements. Nevertheless, these insulations are non-expendable and pose disposal challenges and some releases toxic gases when burned or due to vacuum outgassing phenomenon. Also, the cadmium plating which is often used for the environmental resistance of connector shells
K S, Nithish, TR, Binny, D S, Praveen Kumar
Improvement of Mechanical Properties of Synthetic Fiber Reinforced Composites through Addition of Graphene Oxide2026-26-07536/1/2026
Unmanned Aerial Vehicles (UAVs) demand structural materials that are lightweight, strong, impact-resistant, and durable in diverse environments. The synthetic fiber reinforced polymer composites have varying mechanical performance depending on the fiber matrix interfacial properties. This research analyzes the influence of Graphene Oxide (GO) nano fillers on mechanical properties of composites. Firstly, the epoxy resin was modified by incorporating different weight percentage of Graphene Oxide. This resin was used to make an composite laminate using different materials (Carbon, Glass and combination of these fibers). Then the composites were put through the tensile, compression, flexural tests. The synthetic fiber reinforced polymer composites have a significant improvement in mechanical properties due to the addition of Graphene Oxide.
Manoharan, Dinesh, Langford, Peter, M.K., Padmanabhan, R, Prithviraj, Rajkumar, Subbiah, Karthikeyan, Ravikumar, Veeramuthu, Balasubramaniyan, Gunaseelan, John, T, Thangaraj
Research on Optimization Method for Composite Material Layup of 14MW-Class Wind Turbine Blade Structure2026-99-17265/22/2026
As the trend toward larger wind turbines continues, the increasing length of blades imposes higher demands on their structural properties. And in actual engineering, wind turbine blade accidents occur frequently. Consequently, ultra-long flexible blades at the hundred-meter scale typically employ composite materials. However, due to the high cost of composites, it is necessary to minimize blade weight to control costs. This study utilizes the MATLAB simulation platform combined with pattern search algorithms to optimize the composite layup of large wind turbine blade structures. The structural properties of the optimized design are then compared and analyzed against those of the reference structure. Simultaneously investigate the impact of different loads on the optimization results. The results demonstrate that the pattern search algorithm can optimize blade layup thickness, spar chordwise position, and spar width, yielding a new blade structure with improved performance. During
Cao, Guangchuan, Guo, Xia, Meng, Hang
The Spatial-Temporal Evolution of Coupling Coordination Degree Development of Carbon Emission-Passenger-Freight in Five Northwest Provinces2026-99-17165/22/2026
Taking China’s five northwestern provinces as the study area, this paper investigates the spatial-temporal interactions among carbon emissions, passenger transport, and freight transport from 2010 to 2020. An entropy-weighted composite index is constructed for each system and integrated into a coupling coordination degree model to quantify interaction. It is found that (1) the average annual growth of provincial coupling coordination degree is 4.7%, but the gradient difference between regions is significant, and the extreme difference of coupling coordination degree between east and west reaches 4.5 times in 2020; (2) Spatially, it shows a unipolar leading pattern, with Shaanxi achieving a significant decrease in carbon emission intensity and Qinghai achieving a lesser coupling coordination degree of 23% in Shaanxi due to the high proportion of highway freight transport and single energy structure; (3) the driving mechanism analysis shows that the improvement of transport network
Qian, Yongsheng, Li, Shaoyuan, Zeng, Junwei, He, Qingling
Advanced Composites Prepreg - Nominal 250 °F (121 °C) Cure - 12K Tow Carbon Fiber and Epoxy Resin, Plain Weave FabricAMS3914B (Current)5/15/2026
The intent of this specification is for the procurement of plain weave fabric epoxy prepreg product with 250 °F (121 °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).
AMS P17 Polymer Matrix Composites Committee
Research on the Friction Performance of EVA Insulating Mats for Live Working in Smart Grids2026-99-07145/15/2026
Live-line operation is a critical technique for maintaining the reliability and continuity of power supply in modern distribution networks. Insulating mats serve as essential protective equipment during such operations by providing both electrical insulation and mechanical shielding. In practical service conditions, insulating mats are subjected to repeated mechanical contact and friction against conductors, metallic fittings, and ground surfaces, which progressively deteriorates their surface integrity and compromises operational safety. Current performance standards for insulating mats emphasize dielectric and tensile properties, while tribological durability remains unaddressed. In this study, an EVA – PA6 composite film fabricated via the tape casting method was selected as the representative outer insulating layer of insulating mats. Reciprocating friction tests were conducted using an SDR339 abrasion tester to evaluate the effects of normal load and sliding speed on wear behavior
Sun, Xin, Wen, Libin, Kou, Hanpeng
Advanced Composites Prepreg - Nominal 250 °F (121 °C) Cure - Carbon Fiber and Epoxy Resin, Unidirectional TapeAMS3960B (Current)5/15/2026
The intent of this specification is for the procurement of carbon fiber epoxy prepreg product with 250 °F (121 °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).
AMS P17 Polymer Matrix Composites Committee
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
Liu, Haolong, Sun, Qingping, Liu, Yang, Zhao, Qi, Liu, Yue
Paste Adhesive for Core Restoration Part 1 - General RequirementsAMS2950/1 (Current)4/28/2026
This Technical Specification gives information about technical requirements and qualification procedures of adhesive paste with or without thickening agent for core restoration of aircraft components.
AMS CACRC Commercial Aircraft Composite Repair Committee
Characterization of a Low-Cost Insulator Substrate for Traction Power Modules2026-01-01194/7/2026
Demand for cost-effective automotive traction inverters requires improved power module packaging. This paper presents a packaging method using an epoxy composite insulator applied directly to the cold plate surface, replacing Direct Bonded Copper (DBC) and Active Metal Brazed (AMB) substrates. This integration removes the substrate-to-cold plate solder interface and eliminates two material layers from the thermal path. The epoxy composite demonstrates a dielectric strength greater than 60 kV/mm. Thermal resistance (junction-to-coolant) measured approximately 0.17 K∙cm2/W. Electrical characterization showed a relative permittivity of 3.9, which is lower than standard ceramics and results in reduced parasitic capacitance. Initial thermal cycling tests indicated no significant degradation in thermal or electrical performance. These results suggest the epoxy composite insulator could be a promising alternative for traction power modules.
Chen, Yu, Mena-Garcia, Javier, Chen, Hao, Xiao, Kewei, Gupta, Man Prakash, Degner, Michael
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
Gao, Zhongfang, Fang, Siyuan, Gerini-Romagnoli, Marco, Yang, Lianxiang
High Strain Rate Behaviors of Fiber Reinforced Composites in Principal and Off-Axis Directions2026-01-01754/7/2026
Materials can exhibit significantly different mechanical behaviors compared to quasi-static conditions at high strain rates (> 100 s-1). High strain rate tests using setups such as SHPB (Split-Hopkinson Pressure Bar) can provide, in a practicable manner, the stress-strain relations for a material at high strain rates. Such properties are vitally needed for activities such as simulation-driven impact safety design of composite structures deployed in the form of automotive body parts and assembly, and other sub-systems. Although the behaviors of isotropic and ductile materials such as various metallic alloys appear to have been extensively studied and reported in literature, dependence of mechanical properties of fiber-reinforced composites especially in different off-axis directions are extremely difficult to come across. To fill up this void, a detailed experimental study has been carried out on high strain rate mechanical characterization of a laminated orthotropic glass/epoxy
Bawa, Prashant, Deb, Anindya, Barui, Ananya, Zhu, Feng
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
Takuno, Sougo, Isono, Toshiyuki, Urakawa, Kazushi, Goto, Suguru, Kawamura, Hiroaki, Niisato, Eita, Ishigami, Yuta
Anisotropic Mechanical Property Simulation of Fiber Reinforced PEEK Using Composite Theory and Comparison to Experimental Results2026-01-02564/7/2026
The mechanical properties of 3D printed composites have been shown to vary due to the manufacturing infill direction due to artifacts from the printing process. PEEK (Polyether Ether Ketone) and PEEK reinforced with carbon fiber were studied for these experiments because they are widely used for their high strength properties. 3D printed composites that behave with anisotropic characteristics have been evaluated under Laminate Composite Theory (LCT), which can be used to determine the mechanical properties of these 3D printed composites. By changing the orientation of the extruded strands in a 3D printed part, the structure can be optimized in a specific orientation for specific loading conditions, and LCT can be applied for simulating mechanical responses. Three point bending tests were performed on rectangular 3D printed samples and compared to a 3D simulation using LCT for a similar bending load. This allows for the use of LCT in combination with a finite element software such as
Bradley, Coilin, Garcia, Jordan, Sibley, Brian
Multi-Objective Topology Optimization for Cost and Time Minimization in Fiber Reinforced Additive Manufacturing2026-01-02574/7/2026
Fiber Reinforced Additive Manufacturing (FRAM) combines the geometric freedom of additive manufacturing with the high stiffness-to-weight advantages of composite materials, making it a promising approach for lightweight automotive components. The mechanical performance of fiber-reinforced composites is strongly influenced by fiber orientation, which highlights the importance of optimization methods that can effectively exploit anisotropic behavior. Existing FRAM optimization research has focused primarily on structural performance and has given limited attention to manufacturability challenges. This gap is significant, as overhangs and the resulting need for support structures can substantially increase print time, material consumption, and production cost, restricting broader industrial uptake. This research introduces a multi-objective topology optimization framework that incorporates Design for Additive Manufacturing (DfAM) principles by minimizing both structural compliance and
Wotten, Erik, Kim, Il Yong
Development of an Advanced Tensile Testing Method for HDPE Composites in High Draw Molded Hollow Circular Regions: Effect of Sample Preparation, Asymmetry, Thermal Conditions, Pull Speeds and Fixture Parameters2026-01-02044/7/2026
High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE) and Ethylene Vinyl Alcohol (EVOH) composite, particularly in high draw molded hollow circular configuration, present unique challenges in evaluating mechanical performance under tensile stress due to anisotropic deformation, geometric asymmetry, and localize thermal gradient. This study introduces an advanced tensile testing methodology designed specifically to assess such regions with greater precision and reproducibility. The method incorporates refines sample preparation protocols, tailored fixture geometry, and adjustable pull speed to accommodate varying thermal histories and draw ratios inherent to molded sections. Systematic variation of asymmetrical, temperature conditions, and clamping techniques revealed significant impact on tensile strength, elongation at break, and strain distribution. Findings emphasize the necessity of customized testing frameworks for molded composites geometries and demonstrate that
Bhalerao, Saurabh Shankar
Modification of Composite Cathode for Sulfide-Based All-Solid-State Batteries2026-01-70372/27/2026
All-solid-state batteries (ASSBs) based on sulfide electrolytes hold great promise for next-generation energy storage, yet their performance is critically constrained by unstable cathode–electrolyte interfaces. Here, we report a dual-modification strategy utilizing ionic liquids (ILs) in combination with lithium salts to simultaneously improve interfacial wettability, ionic transport, and electrochemical stability in NCM811 composite cathodes. Three ILs (EMIMTFSI, Pyr₁₄FSI, and PP₁₃FSI) and three lithium salts (LiTFSI, LiDFOB, and LiBOB) were systematically evaluated and screened. While neat ILs improved initial capacities by reducing solid–solid contact resistance, they also triggered parasitic reactions with sulfides, resulting in capacity fading. Among the lithium salts, LiBOB was identified as the most chemically compatible additive, forming thin and uniform hybrid interphases enriched with B–O species. This interphase effectively suppressed high-voltage side reactions and reduced
Gu, Yu-Yang, Tian, Shi-Yu, Qi, Ji, Yang, Li-Peng, Zhan, Wen-Wei, Yang, Xiao-Guang, Yi, Yong
Composite Current Collectors and Aramid Separator Enabled Safer High-Nickel Batteries2026-01-70322/27/2026
The requirement on high energy density Li-ion batteries demands high energy chemistry system, this rise concerns on batteries’ safety issue. Battery non-active components, including current collectors and separator play important role in improving battery safety. Composite current collectors, which are consisted of a polymer layer between two plated thin metal layers, are widely treated as a solution to reduce safety concerns caused by high nickel layered cathode materials, e.g. LiNi1-x-yCoxMnyO2, LiNi1-x-yCoxAlyO2 and LiNi1-x-y-zCoxMnyAlzO2 with Ni content higher than 0.8. In the meantime, composite current collectors can reduce most weight of current collectors and improve the cell’s gravimetric energy density without replacing cathode or anode materials. Moreover, high thermal stable separator could effectively prevent internal short circuit for it melts in higher temperature. In this work, we came up with a cell design which contains composite current collectors as positive
Liu, Jingyuan, Lu, Yong, Liu, Haijing
Teaching Points for a Class on “Critical Issues in Composite Maintenance, Repair, and Overhaul”AIR5719B (Current)2/13/2026
This document is to be used as a checklist by curriculum developers to create courses or training for critical composite repair, maintenance, and overhaul issues. This document will not take the place of courses or training requirements for specific job roles of a composite repair technician, inspector, or engineer.
AMS CACRC Commercial Aircraft Composite Repair Committee
Modelling and Analysis of Complex Shaped Cracks2026-28-00482/12/2026
This study provides an extensive analysis through finite element analysis (FEA) on the effects of fatigue crack growth in three different materials: Structural steel, Titanium alloy (Ti Grade 2), and printed circuit board (PCB) laminates based on epoxy/aramid. A simulation of the materials was created using ANSYS Workbench with static and cyclic loading to examine how the materials were expected to fail. The method was based on LEFM and made use of the Maximum Circumferential Stress Criterion to predict where cracks would happen and how they would progress. Normalizing SIFs while a crack was under mixed loading conditions was achieved using the EDI method [84]. We used Paris Law to model fatigue crack growth using constants (C and m) for the materials from previous studies and/or tests. For example, in the case of titanium Grade 2, we found Paris Law constants with C values from 1.8 × 10-10 to 7.9 × 10-12 m/cycle and m values from 2.4 to 4.3, which illustrate differing effects of their
T, Lokesh, Bhaskara Rao, Lokavarapu
Vibrational Analysis of Hybrid Composite Laminated Plates of E – Glass and Areca Fibers with Brake Pad Waste Powder2026-28-00732/12/2026
This study focuses on the vibration analysis of hybrid composite laminated plates fabricated from E-glass Fiber and areca Fiber reinforced with epoxy resin. The hybrid laminates were prepared using the Vacuum Assisted Resin Transfer Moulding (VARTM) process with different stacking sequences and Fiber ratios, where brake lining powder was also incorporated as a filler in selected configurations to enhance mechanical and damping properties. The fabricated plates (280 × 280 mm) were subjected to experimental modal analysis using an impact hammer and accelerometer setup, with data acquisition carried out through DEWESoft software. Natural frequencies and damping ratios were determined under three boundary conditions (C- C-C-C, C-F-C-F, and C-F-F-F). The results revealed that Plate 1, with E-glass outer layers, areca reinforcement, and filler addition, exhibited the best vibration performance, achieving a maximum natural frequency of 332.8 Hz under C-C-C-C condition, while Plate 2 showed a
D R, Rajkumar, O, Vivin Lenin, R, Saktheevel, R G, Ajay Krishna, Ng, Bhavan
Genetic Algorithm Based Optimization of Chaboche Kinematic Hardening Parameters along with the Validation of FE Model through Characterized Crack Initiation2026-28-00862/12/2026
In the context of electro-mobility for commercial vehicles, the failure analysis of a connector panel in a DCDC converter is crucial, particularly regarding crack initiation at the interface of busbar and plastic component. This analysis requires a thorough understanding of thermo-mechanical behavior under thermal cyclic loads, necessitating kinematic hardening material modeling to account for the Bauschinger effect. As low cycle fatigue (LCF) test data is not available for glass fiber reinforced polyamide based thermoplastic composite (PA66GF), we have adopted a novel approach of determining non-linear Chaboche Non-Linear Kinematic Hardening (NLK) model parameters from monotonic uniaxial temperature dependent tensile test data of PA66GF. In this proposed work a detailed discussion has been presented on manual calibration and Genetic Algorithm (GA) based optimization of Chaboche parameters. Due to lack of fiber orientation dependent test data for PA66GF, here von Mises yield criteria
Basu, Parichay, Srinivasappa, Naveen
Effect of Sebastiana Rostrata Fiber Loading on the Tribological Behaviour of Polycaprolactone Biocomposite2026-28-00212/12/2026
This study investigates the tribological behaviour of Sesbania rostrata fiber (SRF) reinforced polycaprolactone (PCL) biocomposites using a pin-on-disc wear couple. The stationary SRF/PCL composite specimen interacted with a rotating EN31 steel disc (64 HRC), establishing the sliding wear interface in accordance with ASTM G99 standards. Composite laminates containing 10, 20, and 30 wt% SRF were evaluated at a sliding velocity of 1 m/s over a fixed distance of 1000 m under varying normal loads. The incorporation of SRF significantly enhanced the wear performance relative to neat PCL, with 20 wt% fiber loading achieving the lowest coefficient of friction and specific wear rate due to improved load transfer, stronger interfacial adhesion, and a more uniform laminate structure. In contrast, the 30 wt% composite exhibited fiber agglomeration, reduced homogeneity, and weakened fiber–matrix interactions, resulting in increased wear. SEM microstructural analysis confirmed the formation of a
Raja, K., Senthil Kumar, M.S.
Aerospace & Defense Technology: February 202626AERP022/5/2026
Plasma Surface Activation for Stronger, More Durable CFRP Bonds in Aerospace Smarter Pyrovalve Alternatives for Modern Missile and Munition Launcher Applications Aerospace Aluminum Laser Welding: Advancing Material Performance for the Future of Flight Model-Based Design Is Shaping the Next Phase of eVTOL Systems Development How RF-over-Fiber is Providing the Backbone of Next Generation Mil/Aero Networks NASA Demonstrates a First-of-Its-Kind Space Communications A Rainfield Simulator for Hypersonic Testing The U.S. Army Space and Missile Defense Command Technical Center's Aerophysics Research Facility, (ARF), fired a successful hypersonic shot to test its new rainfield simulator. Next Generation Carbon Fiber Composites 3D Printer for Hypersonic Research Auburn University's Applied Research Institute in Huntsville is adding some serious fiber to its diet. The Critical Impact Of SAE Aerospace Standards: Certified AS1895/7 and /23 Metal Seals How engineers can ensure safety, reliability
Next Generation Carbon Fiber Composites 3D Printer for Hypersonic Research26AERP02_082/1/2026
Auburn University's Applied Research Institute in Huntsville is adding some serious fiber to its diet. Auburn University, Auburn, AL In collaboration with Auburn University's Center for Polymers and Advanced Composites (CPAC) and the Department of Aerospace Engineering, the institute recently acquired a CF3D Enterprise Cell - a next-generation 3D carbon fiber composites printer set to define the future of the nation's hypersonic programs. Developed by Idaho-based Continuous Composites, the CF3D system represents a highly specialized advanced manufacturing capability and is the only system of its kind currently operating in Alabama.
Plasma Surface Activation for Stronger, More Durable CFRP Bonds in Aerospace26AERP02_012/1/2026
Carbon fiber-reinforced polymers (CFRPs) have become essential in modern aerospace structures, from fuselage skins and wing components to nacelles, interior structures, and a growing range of primary load-bearing parts. Their high strength-to-weight ratio delivers major benefits in fuel efficiency, payload capacity, and fatigue performance. Yet achieving reliable adhesive bonds on CFRP surfaces remains a persistent engineering challenge. The low intrinsic surface energy of composites - particularly under thermal cycling, vibration, and moisture exposure - limits bond durability unless surfaces are properly prepared. Plasma surface treatment has emerged as a pivotal solution, offering a fast, controllable, and non-destructive way to increase surface energy, improve wettability, and enhance adhesion across complex geometries. This is especially important as the aerospace industry transitions from thermoset to thermoplastic composites (TPCs), which enable faster processing, lower
Aerospace Aluminum Laser Welding: Advancing Material Performance for the Future of Flight26AERP02_032/1/2026
Between the 1920s and 1930s, aluminum started replacing wood as the primary material in aircraft construction and soon became the backbone of modern aviation. Its popularity stemmed from a combination of properties, high strength-to-weight ratio, corrosion resistance, and ease of forming that made it ideal for demanding aerospace applications. Throughout much of the 20th century, high-strength aluminum alloys dominated aircraft design, accounting for 70-80 percent of commercial airframes and more than half of many military aircraft. Even after the introduction of fiber-polymer composites in the early 2000s, aluminum has remained a critical material because it continues to offer the strength, lightness, and versatility needed for modern aviation. Industry forecasts predict that commercial air travel will double in the next 25 years, which means more pollution will be released into the atmosphere. One way to help reduce these emissions is by building airplane fuselages and wings with
Design and Development of a Lightweight Aluminium Cascade System for Type IV COPVs for Stationary and Mobile Applications2026-26-04851/16/2026
The global push for clean energy has made hydrogen a central element in decarbonizing transport, industrial processes, and energy systems. Effective hydrogen storage and distribution are critical to supporting this transition, and type IV Composite Overwrapped Pressure Vessels (COPVs) have emerged as the preferred solution due to their lightweight, high pressure capacity, hydrogen embrittlement and corrosion resistance. However, the cascade infrastructure used to house and transport these vessels has lagged behind in innovation. Steel-based cascades, while strong, are heavy prone to corrosion, and unsuitable for mobile deployment. This paper introduces a custom designed aluminium cascade system offering a 65% weight reduction while maintaining structural integrity and safety. Designed for mobile use, the system features modularity, better damping, and enhanced corrosion protection. The paper outlines design methodology, material selection, fabrication process, and comparative
Parasumanna, Ajeet Babu, Muthusamy, Hariprasad, Ammu, Vnsu Viswanath, Kola, Immanuel Raju
Bioadhesive Sponge Stops Internal BleedingTBMG-544071/1/2026
Researchers combined mussel adhesive protein with decellularized extracellular matrix (dECM) to develop a composite hemostatic sponge that offers both strong tissue adhesion and biocompatible biodegradability.
Study on the Influence of Liquid Composite Swivel Arm Positioning Nodes on the Dynamic Performance of High-Speed Trains2025-99-025512/23/2025
Rubber components are an important part of the suspension system of high-speed trains, and the complex nonlinear characteristics of rubber parts have a significant impact on the vehicle dynamic performance. This paper establishes a nonlinear dynamics model of the liquid composite swivel arm positioning node, which can reflect the dynamic stiffness and dynamic damping characteristics of the rubber components that change nonlinearly with the frequency and amplitude, and also has a fast calculation speed. The vehicle dynamics simulation model considering the longitudinal stiffness nonlinear characteristics of the arm node is established, and the influence of the stiffness nonlinearity of the liquid composite arm positioning node on the dynamic performance of the vehicle, such as straight-line stability and curve passing ability, is studied in depth through numerical simulation.
Cheng, Junqiang, Yang, Chen, Li, Longtao, Cong, Rilong, Hu, Tingzhou
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