Browse Topic: Polymers
Noise phenomena in automobiles caused by the stick-slip effect are increasingly among the most frequent reasons for customer complaints and therefore represent a critical vehicle quality attribute. To proactively address such issues, stick-slip testing of contacting material pairs is commonly applied during development. However, the predictive capability of current stick-slip test methods remains limited, particularly when highly flexible materials and realistic, stochastic excitation conditions are involved. The flexibility of sealing systems often allows the actual relative motion at the contact interface to be accommodated through adhesion and elastic deformation, thereby delaying or even preventing sliding. To date, this effect has not been represented by any characteristic parameter in conventional stick-slip testing. Instead, existing evaluations focus exclusively on the analysis of occurring stick-slip oscillations. For the initiation of stick-slip phenomena, however, not only
Aerospace and defense systems demand materials capable of maintaining performance under extreme environmental and operational stressors, including wide thermal cycling ranges, exposure to hydrocarbon fuels, vacuum conditions, and repeated mechanical strain. Silicone-based materials have become essential in these environments because they can retain elasticity, stability, and functionality where many traditional materials fail. Silicones are widely used as coatings, adhesives, sealants, and elastomers in aircraft and spacecraft applications. Their chemical structure enables resistance to both high and low temperatures, while also providing durability against solvents and fuels such as jet fuel. In contrast, many conventional elastomers degrade under prolonged thermal exposure or become brittle at cryogenic temperatures.
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
This SAE Aerospace Recommended Practice (ARP) describes standard methods of heat application to cure thermosetting resins for commercial aircraft composite repairs. The methods described in this document shall only be used when specified in an approved repair document or with the agreement of the Original Equipment Manufacturer (OEM) or regulatory authority.
AMS6885/5 is the Material Specification (MS) which defines the requirements of a unidirectional carbon fiber tape epoxy repair prepreg capable of curing under vacuum for repair of carbon fiber reinforced epoxy structures. It also defines the requirements of an epoxy film adhesive to be applied in a co-bonding process with the prepreg for solid laminate and sandwich bonding.
We present a nonlinear topology optimization framework for designing crash--tolerant rotorcraft substructures by maximizing plastic work under prescribed crush displacement and volume constraints. The quasi-static response is modeled using a rate-independent elastoplastic formulation to capture path-dependent inelastic deformation of metallic components. A path-dependent adjoint method is developed to efficiently compute sensitivities of accumulated plastic work, revealing a mechanistic decomposition into elastic stiffness, deviatoric response, and yield surface contributions. Optimized 2D and 3D subfloor structures develop emergent plastic hinge networks and distributed deformation paths, significantly enhancing energy absorption compared to uniform designs. The results demonstrate that topology optimization can directly embed energy-dissipating mechanisms into primary rotorcraft structures, providing a practical framework for crashworthy rotorcraft and eVTOL airframe designs.
Cold spray deposition is a kinetic-based deposition method that uses an inert gas flow to accelerate particles, where kinetic energy causes plastic deformation upon impact with a substrate, as discussed in Reference 1. Cold spray has been investigated as a method to deposit metal coatings on polymer-based composites, such as aerospace carbon-fiber-reinforced plastics (CFRP's), as discussed in Reference 2. These methods also exhibit low deposition efficiency (15-45%) as shown in Reference 3. In this work, to achieve high deposition efficiency and create an erosion-resistant coating, we use metal-polymer composite powders for cold spray, to make polymer-on-polymer bonding the dominant and effective bonding mechanism; this method lowers impact velocities relative to pure metal deposition to avoid substrate damage. The polymer can also lower the effect of material mismatch, while the nickel can help enhance the erosion performance of the final coating above that of pure polymer. This paper
This paper investigates the feasibility of using flax fiber-reinforced composites in combination with additively manufactured polymer cores for helicopter rotor blades. A new rotor blade with flax composite spar and skin laminates and a 3D-printed ASA Aero core was designed to be geometrically equivalent to an existing carbon fiber/foam reference blade of the MERIT rotor test rig and manufactured using identical tooling. Material characterization included compression testing of the printed core at ambient and elevated temperatures, single-lap shear adhesion testing with epoxy laminates, and hygroscopic conditioning of core and laminate specimens. Structural testing comprised static beam bending, experimental modal analysis with axial pre-loading to approximate centrifugal stiffening, and sustained-load creep and recovery testing of the flax blade. The results show that the 3D-printed core provides sufficient compressive stiffness at curing temperature and adhesion to epoxy laminates
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
This specification covers a synthetic rubber in the form of sheet, strip, tubing, extrusions, and molded shapes. This specification should not be used for molded rings, compression seals, O-ring cords, and molded in place gaskets for aeronautical and aerospace applications without complete consideration of the end use prior to the selection this material.
This SAE Recommended Practice is intended to cover plastic safety glazing for use in motor vehicles and motor vehicle equipment. Nominal specifications for thickness, flatness, curvature, size, and fabrication details are presented principally for the guidance of body engineers and designers. For additional information on plastic safety glazing materials for use in motor vehicles and motor vehicle equipment, please refer to SAE J673.
The scope of this SAE Recommended Practice is to promote compatibility between child restraint systems and vehicle seats and seat belts. Design guidelines are provided to vehicle manufacturers for certain characteristics of seats and seat belts and to child restraint system (CRS) manufacturers for corresponding CRS features so that each can be made more compatible with the other. The CRS accommodation fixture (see Figure 1) is used to represent a CRS to the designers of both the vehicle interior and the CRS for evaluation of each product for compatibility with the other. The features of the accommodation fixture are described as each is used.
Foam material models for automotive structural analysis typically require tensile and compressive data at multiple strain rates. The testing is costly and may require a long time to complete. For many applications, foams of similar chemistry are used and the foam structural responses, such as stiffness and compression force deflection, are controlled by the foam density. In such cases, Machine Learning (ML) lends itself as an ideal tool to detect the trends in material response based on density and strain rate. In this paper, two sets of polyurethane (PU) foams of different densities were tested at four strain rates ranging from 0.01/s to 100/s. ML models capable of predicting compressive stress-strain response for a range of densities were developed. The models demonstrated good prediction capability for intermediate strain rates at all foam densities and in extrapolating stress-strain curves at higher densities at all strain rates. The strain rate trends for density outside of the
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. Master Bond Inc., Hackensack, NJ To reduce its environmental impact and pollution, the shipping industry is investigating methods to construct more lightweight ships. One potential method is using adhesive bonding techniques to replace traditional welding and riveted joints on ships to fabricate lighter ships with smaller carbon footprints. However, adhesives age and deteriorate when exposed to moisture, high temperatures, and ultraviolet light. This makes it necessary to understand how they age in maritime environments to determine whether they can truly replace traditional welding techniques. To this end, researchers at Centro de Investigación en Tecnologías Navales e Industriales (CITENI) and Centro de Investigación TIC (CITIC) developed a new
This recommended practice describes two methods for determining the tendency of interior materials used in automobiles and other vehicles to (a) produce a light scattering deposit (fog) on a glass surface, or (b) produce a measurable deposit (mass) on aluminum foil.
This specification covers a 100% homopolymer of polychlorotrifluoroethylene (PCTFE) in the form of molded sheet 0.250 inch (6.35 mm) and under in nominal thickness.
This specification covers a 100% homopolymer of polychlorotrifluoroethylene (PCTFE) in the form of rods, sheets, and molded shapes.
This specification covers a 100% homopolymer of polychlorotrifluoroethylene (PCTFE) in the form of sheet 0.250 inch (6.35 mm) and over in thickness, rod, heavy wall tubing, and large molded and machined parts.
The scope of this document is to define a test method for performing the Compression Stress Relaxation (CSR) Test with the Automotive Standard (ASD) or HP CSR Jig using the appropriate test fixtures, configurations, and procedures. This standard defines the equipment needed, guidelines for running the test, and the format for generating the results and analyzing the data.
This specification covers a standard acrylonitrile butadiene (NBR-H) rubber stock with medium-high acrylonitrile content in the form of molded test slabs.
This SAE Recommended Practice provides a system for marking thermoset rubber parts to designate the general type of material from which the part was fabricated.
AMS3217/7C has been declared “STABILIZED” by SAE AMS Committee AMS CE Elastomers and will no longer be subjected to periodic reviews for currency. Users are responsible for verifying references and continued suitability of technical requirements. Newer technology may exist.
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