Browse Topic: Foams
ABSTRACT For this particular effort, the U.S. Army Tank Automotive Research Development and Engineering Center (TARDEC) Center for Systems Integration (CSI) was tasked to develop a buoyancy/survivability kit that would serve multiple functions. The underbody kit would meet or surpass current required protection levels. Plus the kit was to ensure that the LAV-25A2 (Light Armored Vehicle) continues to meet the swim requirement. However, the overarching objective is to meet the survivability, ground mobility, and water mobility requirements. Combining the accomplishments in the TARDEC & PM-LAV (Program Manager for the Light Armored Vehicle) survivability program in 2013-2014 with the TARDEC & PM-LAV buoyancy/survivability kit developed in 2015-2016, the overall weight is decreased, water mobility is improved, and survivability is significantly improved. This is a unique challenge as a combination of buoyancy, mine blast, and structural requirement on a ground military vehicle is novel
One of the five major performances of vehicles, NVH(Noise, Vibration, Harshness), has recently emerged in electric vehicles, again. And, front loading NVH simulation is essential to respond nimbly to automotive industry these days. However, the two components of the simulation, mathematical sound absorption modeling equation, and the acoustic parameters, the input factor, is requiring improvement because of lack of robustness. In this study, we tried to strengthen, standardize, and refine the connectivity between micro (fine structure) and macro (acoustic parameter-related physical properties) characteristics, and improve the consistency with actual NVH performance. As a porous polymer material, polyurethane foam, which is widely used for the interior and exterior of automobiles, is treated as a target material. It is expected that further refining of the correlation between three-dimensional microstructure properties of foam such as pore, throat, strut, window, etc. and acoustic
Recent experiments by a team from the West Virginia University focused on how a weightless microgravity environment affects 3D printing using titania foam, a material with potential applications ranging from UV blocking to water purification. ACS Applied Materials and Interfaces published their findings
Researchers at the University of Bath working in collaboration with industrial partner, Integrated Graphene, have developed a new sensing technique based on graphene foam for the detection of glucose levels in the blood. Since it is a chemical sensor instead of being enzyme-based, the new technology is robust, has a long shelf-life and can be tuned to detect lower glucose concentrations than current systems
This specification covers the material and process requirements for fabricating sandwich radomes having hot-melt, addition-reaction polyimide-resin-impregnated quartz cloth shells and polyimide-resin syntactic foam cores
This specification covers the material and process requirements for fabricating sandwich radomes having polyimide-resin-impregnated quartz cloth shells and polyimide-resin syntactic foam cores
This specification covers expanded honeycomb core made from glass fabric impregnated with phenolic resin and oriented so the fabric weave is on the 45-degree bias with the ribbon direction and supplied in the form of blocks, slices, and ordered shapes
Polyurethane foam (PU foam) is widely used in automotive noise reduction palliatives. As a decoupling insulator its acoustic performance depends on intrinsic properties, called “Biot” parameters. An important decoupling parameter is the apparent stiffness of the PU foam cell structure, as this controls the transportation of vibrational energy, with “softer PU foam” being the preferred option. However, some areas of application, for example in automotive carpet design, requires stiffer PU foam in order to accommodate under foot comfort. For a comprehensive approach to automotive component design, it is necessary to calculate the appropriate spatial PU foam properties ideally without the need for series of prototypes. This paper describes the methods and processes used when compiling and validating a material database capable of predicting the acoustic performance of flat sample or spatially complex 3D component with minimal prototype manufacture
This recommended practice describes the materials, related equipment, and particular processing techniques utilized in process science curing of composite hardware where pressure is imparted specifically to the resin of curing composites. Included as Appendix "A" to this ARP is a discussion of the particular techniques developed for a processing science philosophy which has consistently produced void and porosity-free, large area, thick composite structures
Light weighting in modern automotive powertrains call for use of plastics (PP, PA66GF35) for cam covers, intake manifolds and style covers, and noise encapsulation covers. Conventionally, in early stage of design these components are evaluated for static assembly loads & gasket compression loads at component level. However, engine dynamic excitations which are random in nature make it challenging to evaluate these components for required fatigue life. In this paper, robust methodology to evaluate the fatigue life of engine style cover assembly for random vibration excitations is presented. The investigation is carried out in a high power-density 4-cylinder in-line diesel engine. The engine style cover (with Polyurethane foam) is mounted on cam cover and the intake manifold using steel studs and rubber isolators to suppress the radiated noise. The style cover mounting ribs experience higher dynamic bending stresses due to the overhang of the mounting bosses from cam cover and intake
The stair phase coding method is an important phase unwrapping method, but needs to project and capture many fringe patterns. Therefore, to reduce the number of fringe patterns, we propose a stair phase coding method based on arc cosine with only four patterns. We project and capture a set of three-step phase-shift sinusoidal fringe patterns and a cosine pattern encoding stair phase, and then we compute the wrapped phase and background light from the three-step phase-shift sinusoidal fringe patterns, normalized cosine pattern can be estimated via background light, and the cosine pattern encoding stair phase. Arc cosine calculation is applied to the normalized cosine pattern to obtain the stair phase, then the fringe order is determined from the stair phase. A semi-periodic fringe order correction algorithm based on the dilation image processing technique is proposed to ensure the accuracy of fringe order. The continuous phase is obtained from the wrapped phase and the fringe order
Weight reduction in automotive applications have led to the processing of thermoplastic polymers by foam injection molding. The density of the foamed polymer can be reduced up to 20%. Whilst, work has been reported on the weight reduction of the foamed polymer by using different types of blowing agent technologies, there has been limited studies in the areas of the sound transmission loss and sound attenuation properties of these materials. The present study is intended to understand the effect of chemical blowing agent (CBA) on the properties of polypropylene. The molded specimens were characterized using density, Differential scanning colorimetry (DSC), Thermogravimetric analysis (TGA), Fourier transform infra-red spectroscopy (FT-IR) and sound transmission loss (STL) measurements. Specimens were also tested for tensile properties, flexural properties, Izod impact strength and Heat deflection temperature (HDT) as per standard test protocol. Cell structures were observed using stereo
Electrification is one of the megatrends across the industries, like electric vehicles, electric aircraft, etc. which needs advancement in power electronics component technology. As technology advances in miniaturization of power electronics, thermal-management issues threaten to limit the performance of these devices. These may force designers to derate the device performance and ultimately these compromise in design may increase the size & weight of the application. One of the technologies capable of accomplishing these goals employs a class of materials know as metal foam. Metal foams are lightweight cellular materials inspired by nature. The main application of metal foams can be grouped into structural and functional and are based on several excellent properties of the material. Structural applications take advantage of the light-weight and specific mechanical properties of metal foam. Functional applications are based on a special functionality, i.e. a large open area in
This SAE Recommended Practice is applicable for determining the cold characteristics of flexible plastic materials, as applicable. It consists of three different methods for determining low-temperature properties of materials depending on type of material and end use. The method used shall be as specified by the contractual parties
The open-cell polyurethane foam has a significant influence on the dynamic response of the Seat-occupant Coupling System (SoCS). Hardness, as an important property of foam, significantly impacts the compliance of human body support. Therefore, it is necessary to study the effects of varying foam hardness on the vibration transmitted to the human body. In this study, the effects are investigated by combining the test and simulation. In the test, the vibration transmission characteristic is measured and analyzed using Transmissibility, Seat Effective Amplitude Transmissibility (SEAT) value, and Weighted Root-Mean-Square value (W-RMS). In addition, the properties o dynamic stiffness and damping are also discussed. In the simulation, combined with the test results of dynamic stiffness/damping, a three-degree-of-freedom (3-DOF) model of SoCS is established. Meanwhile, by introducing goodness of fit, the consistency of simulation and test results is evaluated and quantified. The results
Integration of acoustic material concepts into vehicle design process is an important part of full vehicle design. The ability to assess the acoustic performance of a particular sound package component early in the design process allows designers to test various design concepts before selecting a final solution and long before a design freeze. This paper describes an innovative acoustic material concept which is easily integrated in a design process through the use of vibro-acoustic simulation and a database of intrinsic properties of acoustic materials: The Biot Parameters. Biot parameters are widely used in simulation in many industries (and used the most in the automotive industry) to describe the physical interactions between the acoustic waves travelling through foams, fibers or homogeneous metamaterials and the solid and fluid phase of these poro-elastic materials. Therefore, the surface absorption, the insertion loss and the added damping provided by the acoustic treatments on
There are many opportunities for lightweighting with ductile iron castings. Current research shows ductile iron castings free of massive carbides can be achieved at under 2 mm (0.080”) through alloying or process changes which means that significant weight reductions are possible. In fact, for aluminum components over 4 mm thick, ductile iron may provide lightweighting opportunities at a cost savings. However, the conventional guidelines for casting design are inadequate when using ductile iron at dimensions less than the typical machine stock. This paper will discuss the current research on thin walled ductile iron, when it is superior to aluminum, design considerations, and current DOE SBIR funded research efforts to address these inadequacies. Research results on efforts to quantify and improve surface roughness in expanded polystyrene for lost foam casting are also discussed
During the vehicle design state, vehicle noise and vibration are taken into consideration. The tire is a large contributor to the noise and vibration experienced inside the vehicle cabin. Any unevenness or asperities in the road cause the tire structure to vibrate, which in turn causes components in the vehicle to vibrate and generate noise. It is common in the industry to use foam inserts inside the tire air cavity that reduces the noise generated. This foam is typically intended to reduce a specific resonance in the tire-the resonance due to the air cavity. Recently, there is interest in using foam as a structural damper to reduce structural resonances in the tire. A new analytical tire model for determining the effect that structural damping foam has on the noise and vibration characteristics of the tire has been developed. The theoretical formulation of this model is presented, as well as comparison with experiments and a parametric analysis of the model. The model shows good
From the microstructure point of view, the relationship of car seat comforts, including the static and dynamic comfort, and the polyurethane foam performance of its cushion has been analyzed. In this paper, polyurethane cushion performances associated with the seat static comfort have been mainly discussed. And their quantizing relation is obtained. How to apply the pressure gradient, one of body pressure distribution parameters, to optimize automobile seat comfort has been analyzed in detail. The findings suggest maximum and mean values of body pressures increase by 0.09 KPa and 0.04 KPa with the cushion foam hardness (Ph) increasing 1 KPa, respectively. The pressure gradient is little dependent on the cushion foam hardness within the range of Ph=4 ~ 5 KPa. Furthermore, the foam thickness under the hip should be greater 80 mm in order to reduce subcutaneous stresses under conditions of Ph= 6.2 KPa
This recommended practice provides a guideline for qualifying automotive aftermarket, two-component structural foams, and defines a classification system for such foams
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