The utilization of additive manufacturing in producing tubular honeycomb (THC) structures, leveraging capabilities of fused filament fabrication, enables the introduction of attributes, such as buckling initiators, to augment energy absorption characteristics. Increasing crush efficiency and/or energy absorption efficiency of THC structures bolsters payload and occupant protection in vehicular systems during impact scenarios such as collisions for ground vehicles or harsh landings for aircraft. In this investigation, THC structures composed of acrylonitrile butadiene styrene (ABS) plastic were additively manufactured so that buckling initiators (BIs) could be efficiently incorporated in the THC structure and readily positioned at the top, 3/4 height, or half height of the samples. Each configuration was subjected to quasi-static (0.03 mm/s) and constant (0.5 m/s) velocity testing employing an MTS machine, with three specimens manufactured for each test condition. Results demonstrated a notable 12.60% increase in energy absorption efficiency and a 15.75% increase in crush efficiency for specimens featuring BIs at the top of the sample as compared to those without BIs under quasi-static conditions. Furthermore, substantial improvements were also observed under constant velocity testing, indicating the efficacy of BIs at the top of the sample in promoting structural folding and progressive collapse, thereby increasing crush energy absorption and crush efficiency.

This project evaluates the effectiveness of various geometries created using advanced additive manufacturing (AM) of Kevlar fiber and chopped carbon fiber-reinforced filament for ballistic protection applications. This study expands on sandwich panel designs with woven Kevlar face sheets and investigates an optimal fiber-reinforced filament-core structure. A unit cell workflow was developed in nTop (nTop, New York, NY, USA) to leverage its custom cell modeling and Finite Element Analysis (FEA) capabilities. Unit cell types were simulated and tested from the hexagonal honeycomb, gyroid Triply Periodic Minimal Surface (TPMS), and re-entrant auxetic cell families. Core structure thickness and cell size were additive manufacturing parameters that were varied to assess impact absorption. Moreover, the additively manufactured cell structures were encapsulated with a damping material, particularly silica. To determine the best type of silica for ballistic applications, three types of silica with varying tensile strengths were molded into shapes matching the cores. The samples were then tensile tested using an Instron 8801 universal testing machine (Instron, Norwood, MA, USA) to determine which offered the best balance between strength and ductility. The experimental approach began by determining the material characteristics for test coupons for both continuous fiber and chopped fiber in 0- and 90-degree filament orientations. A technology demonstration was also conducted by performing ballistic testing in a shooting range with 9 mm rounds to assess failure modes of the fabricated cellular structures based on these ballistic impacts.

Automated Fiber Placement (AFP) is a key enabling technology for high-rate production of aerospace-grade composite structures. Although AFP provides precise and repeatable material deposition, prevailing inspection practices remain predominantly manual, interrupting production flow and limiting throughput. To mitigate these limitations, a novel In-Process AFP Manufacturing Inspection System (IAMIS) has been developed. IAMIS integrates advanced sensing hardware with machine learning (ML)–based analytics to autonomously detect, classify, quantify, triangulate, and respond to defects in real time during AFP operations. Comparative round-robin evaluations confirmed IAMIS's superior accuracy, sensitivity, and robustness in detecting and categorizing diverse defect types when compared with commercially available inspection systems. Beyond real-time defect detection, IAMIS incorporates an AI-based predictive analytics module (IAMIS-AI) that leverages inspection data acquired by IAMIS to support continuous process optimization. Trained on historical manufacturing data—including process parameters, defect characteristics, and part geometry—the IAMIS-AI framework predicts defect occurrence and visualizes potential defect regions on a 3D digital layup model during AFP program planning. These predictive insights enable proactive process adjustments, targeted quality-assurance actions, and reduced downstream rework and downtime. This paper presents the IAMIS system architecture, ML and AI framework design, and experimental validation methodology, and demonstrates how integrating data-driven intelligence into AFP can significantly enhance quality assurance and production efficiency. The adoption of IAMIS establishes a transition from labor-intensive, post-process inspection to a fully automated, intelligent inspection and optimization ecosystem aligned with stringent aerospace manufacturing requirements, while substantially reducing cycle time and cost.

Additive manufacturing (AM) of fiber-reinforced composites has garnered significant interest for its versatility in creating intricate parts and rapid prototyping. Short fiber-reinforced composites are typically fabricated through fused deposition modeling (FDM), but they possess several challenges including limited fiber volume fraction (Vf), low printing speed, and low throughput for industry scales. Composite-based additive manufacturing (CBAM) is a novel sheet lamination-based AM process, combining non-woven fabric reinforcement with thermoplastic materials to fabricate three-dimensional objects. CBAM offers notable advantages over FDM, including the potential for achieving higher Vf and faster production rates, making it a promising technology for further investigation in composite manufacturing. This paper investigates the microstructural characteristics and porosity analyses of non-woven carbon fabric reinforced nylon composites (CF-PA12) manufactured by CBAM and FDM. Test coupons were fabricated in flatwise and edgewise printing orientations. CBAM flatwise specimens were less porous than edgewise specimens attributed to the comparatively higher number of sheets in edgewise orientation. This study highlights the microstructural characteristics of mechanical test specimens prepared using CBAM and FDM. It reveals that CBAM specimens exhibit a higher Vf, lower porosity, and smaller, more randomly distributed closed pores compared to FDM specimens, which enhance its material integrity and performance, offering a foundation for further development in composite AM technology.

State of the art Type V pressure vessel design utilizes metallic bosses for connecting the pressure vessel to surrounding structures and fluid systems. These metallic bosses add a significant mass to the overall weight of the structure. In addition, they impose the problem of a mismatch between the coefficient of thermal expansion between metal and CFRP, especially in cryogenic use cases. Therefore, replacing these metallic bosses with CFRP would increase pressure vessel performance. In this study, two different concepts of CFRP bosses are investigated. A Type V manufacturing concept is developed using towpreg-winding. First, a SMC boss design is investigated on a 1.2 L pressure vessel geometry. The performance of the SMC boss is compared to an aluminum boss manufactured with an identical tank layup. Burst pressure testing was carried out which proved the SMC design. Second, a prepreg boss is investigated on a 20 L pressure vessel geometry. The prepreg boss was manufactured using prepreg layers with different fiber orientations optimizing the mechanical performance of the boss. The weight performance was compared to a steel-boss. The results of this study proved the design of CFRP bosses by using SMC as well as prepreg-material for future pressure vessel concepts.

Trains play an important role in the sustainable mobility of the future. The changes in the market are reflected in the number of newly approved series by the German Federal Railway Authority (EBA); 226 new designs and redesigns of train cars were approved for use on German rails in 2019. Phenol-formaldehyde resins are used extensively specifically for railcar interiors. However, phenol-formaldehyde resins release carcinogenic vapors during and even after production if not completely sealed. As a result, European production standards and requirements have been increased, making the material less economical and increasingly difficult to enter the market. Further bans aimed at lower formaldehyde release limits are currently being considered by the European Union's Committee for Risk Assessment (RAC) and Committee for Socioeconomic Analysis (SEAC). In order to develop and design alternative materials, it is important to meet the requirements for stiffness, light weight, insulation and sustainability simultaneously. This research aim is therefore to develop a new class of material for interior components with improved stiffness, lower weight, lower CO2 footprint and no health hazards. The approach is to develop advanced composite sandwich panels that retain the ability to be molded into complex structures for interior applications. This is done through a thermoplastic honeycomb core structure that is manufactured directly from sheet material and fiber reinforced organo-sheets as the outer layers. The base matrix for all layers is kept uniform for better recyclability and consists of polycarbonate (PC) with sufficient flame retardant properties to provide an environmentally friendly alternative to existing phenolic resin and aramid epoxy honeycomb solutions while still complying with the security norms.

Manufacturing of ceramic matrix composites (CMCs) with carbon fiber and carbon matrix includes a time- and labor-intensive ceramic infiltration step that is responsible for more than half of the total manufacturing cost. To make CMCs cost-competitive in price-sensitive markets, like concentrated solar power, it is essential to develop a CMC manufacturing process that skips the ceramic infiltration process. In this work, we will show how a high-char-yield preceramic resin can eliminate the infiltration step while maintaining material density and evaluate the technoeconomic impact of our CMC manufacturing process. We monitor both morphology and porosity to determine the quality of CMCs made with different preceramic resins and evaluate the impact of polymer infiltration and pyrolyzing cycles.

Marine energy structures are typically made of advanced composite materials and are subjected to extreme ocean environments in service. In extreme ocean environments, seawater currents and waves load structures repeatedly, which cause two environmental conditions: water intrusion and mechanical fatigue. In prior research, the two environmental conditions were applied sequentially, where composite specimens were aged and then mechanically tested. To understand the combined effects of dynamic loading and water intrusion on composite materials, the present study involves the static and fatigue four-point bend testing of composite coupons in a water tank. The water tank was designed and built to fit either a 100 kN or a 250 kN load frame. Flexural strength value, cycles to failure, and failure mode results from submerged fatigue testing will be used to inform marine energy structure designs. The coupon-scale test method will be used to scale up to and inform methods for subsequent subcomponent testing and standards development. The benefits of designing marine energy structures to informed standards are decreased lifetime costs and increased reliability and energy production, ultimately leading to a sustainable and low-carbon energy system.