Browse Topic: Foams

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Test Method for Determining Cold Cracking of Flexible Plastic MaterialsJ323_202109 (Current)9/15/2021
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.
Textile and Flexible Plastics Committee
5 Ws of Microlattice Pads for Improved HelmetsTBMG-359842/1/2020
Football players and other athletes, motorcycle riders, soldiers, and anyone wearing protective helmets made with the new microlattice pads will have greater protection from both single hits and a series of impacts.
Hardening Lightweight Metal Foams with NanocoatingTBMG-358181/1/2020
Bones are strong and stable and can cope with loads almost as well as steel. But despite their strength, they are light enough to be easily moved by humans and animals. The secret lies in the combination of a hard, exterior shell that encases a porous lattice-like network of bone tissue in the interior of the bone. This structure saves on material and reduces weight.
Products of Tomorrow: December 2019TBMG-3570712/1/2019
This column presents technologies that have applications in commercial areas, possibly creating the products of tomorrow. To learn more about each technology, see the contact information provided for that innovation.
Optimization of Multi-Layer Panel Constructions Using Experimental Modeling via Transfer Matrix Method2019-01-15776/5/2019
In a previous paper [1], a method was introduced to predict the sound transmission loss (STL) performance of multi-layer panel constructions using a measurement-based transfer matrix method. The technique is unique because the characterization of the poro-elastic material is strictly measurement based and does not require modeling the material. In this paper, it is demonstrated how the technique is used to optimize the STL of lightweight, multi-layer panel constructions. Measured properties of several decoupler materials (shoddy and foam) are combined with sheet metal and barrier layers to find optimal combinations. The material properties are measured with the impedance tube per ASTM E2611 [2].
Green, Edward Ray, Anton, John
Q&A: Professor Jaime Grunlan, Texas A&M University, College Station, TXTBMG-341414/1/2019
Professor Grunlan and his team are developing a new flame-retardant coating using renewable, nontoxic materials readily found in nature that could provide effective fire protection for several widely used materials.
The Application of Additive Manufacturing to the 2018 SAE Aero Design Challenge2019-01-13283/19/2019
This project focuses on the application of polymer additive manufacturing to the 2018 SAE Aero Design Regular Class competition for North Carolina A&T State’s 2017/2018 senior project team. The Regular Class SAE Aero Design challenge requires participating teams to create a high lift, high efficiency remote controlled aircraft that is designed to carry as many passengers and additional cargo mass as possible while still being able to meet land and air performance requirements defined by the competition rules. Constraints set by the competition rules include material constraints, a max gross weight of 55 lb, a limited power supply of 1000 W, a 12-ft wingspan limitation, enclosed cargo and passenger bays, the ability to unload and load all cargo and return the plane to a flight ready configuration within 1 minute, and a takeoff distance of 200 ft. The wide use of additive manufacturing and hot wire foam cutting for this aircraft design has allowed for accurate and efficient component production, as well as increased design complexity compared to traditional manufacturing methods seen at competition. Most importantly, the use of these manufacturing methods has allowed for efficient design change implementations and quick turnaround times. Specific examples include the light weight, high fineness ratio fuselage that efficiently used space and integrated landing gear and mounting structures, which was made with ABS and polycarbonate polymers. Additional examples include the implementation of shock absorbing landing gear wheels, which were made of fatigue resistant PETG. Results show that the use of innovate manufacturing methods such as additive manufacturing and hot wire foam cutting helped to increase prototyping and testing efficiency, and enabled quick production of an organically shaped, high performing RC aircraft.
Blake, Nathan David, Waters, Cynthia, Esau, Simon, Kizito, John
Nanoscale Pillars Act as Memory FoamTBMG-339363/1/2019
A customizable nanomaterial was developed that combines metallic strength with a foam-like ability to compress and spring back. The material can store and release mechanical energy on the nanoscale, and fits into existing industrial semiconductor processes.
Artificial “Blubber” Protects Divers in Frigid WaterTBMG-324828/1/2018
When Navy SEALs carry out dives in Arctic waters, or when rescue teams are diving under ice-covered rivers or ponds, the survival time even in the best wetsuits is very limited — as little as tens of minutes. Researchers have discovered a process to triple that survival time.
An Overview of Microstructural Approaches for Modelling and Improving Sound Proofing Properties of Cellular Foams: Developments and Prospects2018-01-15646/13/2018
Significant advances have been made over the last 15 years in the field of modelling the acoustic properties of foams from the description of their microstructures. It entails a multidisciplinary work at the junction between physico-chemistry and mechanics of porous media, which involves a dialogue between different disciplines and requires the joint development of several techniques (imaging, upscaling, numerical computations, and experimental identification). It seems to be of timely interest to take stock of the methodological developments that have provided guidance on how to manufacture the new generation of foams with enhanced properties and to identify possible future methodological developments.
Perrot, Camille, Hoang, Minh Tan, Chevillotte, Fabien
Initial Steps Towards Quadcopter-based Brick Placement for ConstructionF-0074-2018-129105/14/2018
ABSTRACT We propose the possibility of using an autonomous quadcopter in a construction setting to build meaningful structures. In this paper we demonstrate these ideas using a quadcopter tasked with carrying bricks to locations specified by a notional blueprint. In our demonstrations, the quadcopter carries a foam brick to a predetermined position and places it with respect to the other bricks to create a 2-dimensional structure as specified by the blueprint. Computer vision techniques are used to verify brick positions and motion capture is used to localize the quadcopter. A custom-built 3D printed pick up/drop mechanism is used to carry the brick from the initial point to the final point. We demonstrated that a variety of structures can be created autonomously in practice using a quadcopter. We measure performance in terms of positional correctness of the structure as measured by the lateral placement error and orientation angle error. This paper discusses the theoretical approach to path generation and control systems, computer vision algorithms, blueprint algorithms, and the pick-up and drop mechanism.
Hagaribommanahalli, Sachin, Wagner, Alan
Modeling the Effect of Foam Density and Strain Rate on the Compressive Response of Polyurethane Foams05-11-02-00145/8/2018
Due to the high deformability and energy dissipation capacity of polymer foams in compression, they are used in automotive applications to mitigate mechanical impacts. The mechanical response of the foams is strongly affected by their density. Phenomenological relations have been proposed to describe the effect of foam density on their stress-strain response in compression at a fixed loading rate and the effect of loading rate at a fixed foam density. In the present work, these empirical approaches are combined allowing for the dependence of loading rate effect in compression on foam density. The minimum experimental data set for calibration of the proposed model consists of compression test results at two different loading rates of foams with two different densities. Rigid closed-cell polyurethane foams with apparent density in the range of ca. 100 to 300 kg/m3 have been produced and tested in compression up to a ca. 80% engineering strain at low (0.00167 to 0.5 s−1) and intermediate (~102 s−1) strain rates. The model parameters were evaluated from test results of the largest and smallest-density foams at low loading rates, differing by two orders of magnitude. The relative root mean square error of stress prediction for intermediate foam densities was found to range from ca. 6 to 12% at low strain rates and reach up to 34% at the higher strain rate. The proposed approach for modeling of foam behavior is expected to be useful in preliminary design of structural parts with impact mitigation functionality.
Japins, Guntis, Kalnins, Kaspars, Kirpluks, Mikelis, Cabulis, Ugis
Development of a Simulation Tool for High Capacity Metal Foam Heat Exchanger with Phase Change Material2018-01-07834/3/2018
Metal foam with their high porosity and heat storage capacity can be combined with phase change materials to be a powerful heat storage device. Numerical simulations of metal foam behavior can be challenging due to their complex geometric patterns necessitating high mesh requirements. Furthermore, simulations of the inner workings of a metal foam heat exchanger comprising of a large number of individual metal foam canisters can be impossible. The objective of the current work is to develop a computational model using a proprietary CFD tool Simerics-MP/Simerics-MP+® to simulate the workings of a metal foam heat exchanger with phase change element. A heat transfer coefficient capturing this heat transfer between wax and metal is used to formulate the “simplified” mixture model. The versatility of the proposed model is in the universality of its application to any shape or structure of metal foam. The computational model developed is tested to replicate the results of the 3D simulation. Very good agreements for the coolant temperature rise between the model and 3D simulation are obtained. Metal foam heat exchangers comprising of 89 such individual single metal foam canisters are simulated using the “simplified” model. Different arrangements of the single metal foam canisters to make up the metal foam heat exchanger are explored. Simulation results show pure steel has a better heat transfer performance, followed by metal foam canister with phase change material and finally aluminum. However, weight and other material considerations can make the metal foam canisters a practical alternative for effective heat storage.
Srinivasan, Chiranth, Slike, Jody, Wang, De Ming, Gao, Haiyang
Magnesium Alloy, Processes for Pretreatment and Prevention of Corrosion onAMSM3171 (Historical)2/25/2018
This specification covers general requirements for the apparatus, material, and procedures to be used in the processing of magnesium base alloys for the purpose of increasing their corrosion resistance and by producing surfaces suitable for organic paint finish systems.
AMS B Finishes Processes and Fluids Committee
Aerospace & Defense Technology: December 201717AERP1212/1/2017
High-Reliability Capacitors When the Mission Just Can't Fail WIAMan High-Tech Test Lab Focuses on Saving Soldiers' Lives Improving the Surface Finish of Additive Manufactured Parts A new chemical immersion treatment could revolutionise the aerospace industry Using Thermoplastic Composites for Aerospace Applications Identifying and Isolating Signals Using Radio Frequency Photonics Bioinspired Surface Treatments for Improved Decontamination: Commercial Products Investigation seeks to determine which coatings shed fluids most effectively. Mechanical Characterization and Finite Element Implementation of the Soft Materials Used in a Novel Anthropometric Test Device for Simulating Underbody Blast Loading Understanding the mechanical behavior of components made from eight soft polymer materials is necessary to ensure the predictive capability of WIAMan FE models. Processing and Characterization of Lightweight Syntactic Materials Hollow spheres encapsulated in a metal matrix, syntactic metal foam offer significant potential as lightweight energy-absorbing materials. High Temperature Graphene-Peek Adhesive Compounding graphene into polymers has the potential to improve various material properties, even at very low concentrations. Stress Corrosion-Cracking and Corrosion Fatigue Impact of IZ-C17+ Zinc-Nickel on 4340 Steel New protective material could replace cadmium and aluminum coatings on critical components.
Processing and Characterization of Lightweight Syntactic MaterialsTBMG-2795912/1/2017
Conventional composite materials, in which a matrix material is reinforced by particulates, whiskers, and/or continuous fibers, have long been of interest as potential materials solutions to engineering needs. Typically, the benefits of these reinforcements are observed for cases of tensile loading, with only minimal improvement for cases of compressive loading. As a result, recent attention has grown in the use of hollow spheres as a potential reinforcement in metallic systems.
Functionally Graded Metal-Metal Composite StructuresTBMG-2770010/1/2017
NASA Langley Research Center has developed a functionally graded metal-metal composite structure. The structure is created using a method that avoids deleterious reactions between the different metal constituents, as would be observed via conventional melt processing. The results are unique alloy compositions and arrangements not typically available through conventional processing routes.
Contaminants for Aircraft Turbine Engine Fuel System Component TestingAIR4246D (Current)9/27/2017
This SAE Aerospace Information Report (AIR) is intended as a guide toward standardization of descriptions and specifications of fluid contamination products.
AE-5B Aircraft and Engine Fuel and Lubricant Sys Components
Corrosion-Inhibiting Self-Expanding FoamTBMG-272017/1/2017
Surfaces such as metal and other corrodible surfaces are often exposed to extreme weathering, temperatures, moisture, impurities, and otherwise damaging external forces that accelerate corrosion. Conventional methods of corrosion protection include applying paints and other coatings, such as petroleum-based undercoatings, with a sprayer to the exposed surface. To be effective, the entire exposed surface must be covered or the corrosion process will be accelerated at the unprotected areas. While open-area surfaces may be easier to protect, those surfaces found in internal cavities within an overall framework can be more challenging to protect. Achieving full coverage on internal surfaces can be extremely difficult, and in some cases impossible without drilling several access openings in the structure. These extraneous openings can compromise the strength of the structure as well as create more entryways for water and debris. This increases the opportunity for corrosion to initiate at the edges of the openings.
Highly Porous and Mechanically Strong Ceramic Oxide AerogelsTBMG-268365/1/2017
NASA's Glenn Research Center (GRC) has developed and produced ultra-lightweight polymer cross-linked aerogels (X-Aerogels). These mechanically robust, highly porous, low-density materials are three times denser than native aerogels, but more than 100 times stronger. Aerogels are ultra-lightweight glass foams with extremely small pores (on the order of 10 to 50 nanometers). These materials are extremely good thermal insulators, with R values ranging from 2 to 10 times higher than polymer foams. Unlike multilayer insulation, aerogels do not require a high vacuum to maintain their low thermal conductivity, and can function as good thermal insulators at ambient pressure. In addition, they are good electrical insulators and have low refractive indices, both approaching values close to air. Aerogels are also excellent vibration-damping materials. Traditional aerogels, however, suffer fragility and poor environmental durability.
Stable and Accurate LS-DYNA Simulations with Foam Material Models: Optimization of Finite Element Model Parameters2017-01-13383/28/2017
Cellular foams have found a predominant application in automotive industry for efficient energy absorption so as to meet stringent and continuously improving vehicle crashworthiness and occupant protection criteria. The recent inclusion of pedestrian protection regulations mandate the use of foams of different densities for impact energy absorption at identified impact locations; this has paved the way for significant advancements in foam molding techniques such as dual density and tri-density molding. With increased emphasis on light-weighting, solutions involving the use of polymeric or metallic foams as fillers in hollow structures - foam encapsulated metal structures - are being explored. Another major automotive application of foams is in the seat comfort area, which again involves foams of intricate shapes and sizes. In addition, a few recently developed foams are anisotropic, adding on to the existing complexities. Complexities associated with controlled/ uncontrolled spatial variation in density and the geometry of molded parts and use of foams in sandwich composites offer several challenges for the CAE community in modeling the foam components. As a first step to capture these complexities, optimal settings of available LS-DYNA modeling features have to be determined to enable effective Finite Element Analysis (FEA) of foam components. This paper aims to investigate the various underlying parameters such as element formulations and size, contact stiffness and hourglass control, governing stability and accuracy of foam material models and to identify the optimal settings of these parameters. The optimal settings for the identified parameters are elucidated in the context of the rate dependent foam model in LS-DYNA (Fu-Chang Foam).
Ramaswamy, Karthik, Patham, Bhaskar, Savic, Vesna, Tripathy, Biswajit
The Heavy Impact of Advanced Lightweight MaterialsTBMG-265143/1/2017
Historically, high-strength materials have been heavy and dense. The need for high-strength but lightweight materials has become more widespread when designing everything from vehicles and aircraft, to buildings and wind turbines. These advanced materials are enabling engines to operate efficiently at higher temperatures, use less fuel, and emit fewer pollutants, as well as finding uses in many other applications.
AerofoamTBMG-2601612/1/2016
Aerofoam is a unique foam composite insulation with improved thermal and acoustic insulation properties. The novelty of this invention comes from combining a polymer foam with a unique inorganic filler in a way that maximizes thermal performance while maintaining mechanical performance, chemical resistance, fire resistance, and acoustic insulation capabilities. The development of new manufacturing processes has also allowed for the development of these unique composite materials.
Potting Compound, Epoxy Bisphenol A-Type Syntactic Foam, Heat CureAMS3731/6C (Current)9/22/2016
This specification covers a glass or silica micosphere-filled epoxy resin formulation, supplied as a two-component system, requiring an oven cure for attainment of maximum properties.
AMS P Polymeric Materials Committee
Experimental Setup to Assess Blast and Penetration- Induced Secondary Debris in a Military Operations in Urban Terrain (MOUT) EnvironmentTBMG-251988/1/2016
As part of Project Agreement on Military Operations in Urban Terrain (MOUT), the US Army Research Laboratory’s (ARL’s) Explosives Effects Branch supported a series of experiments conducted in Meppen, Germany (DEU), to understand loading on personnel protective equipment (PPE) produced during urban weapon attacks. These experiments were conducted by detonating an explosive charge placed on a brick wall to create secondary debris that would impact the US-designed collection medium.
Experimental Setup to Assess Blast and Penetration-Induced Secondary Debris in a Military Operations in Urban Terrain (MOUT) Environment16AERP08_128/1/2016
Testing demonstrates effects of blast debris on personnel protective equipment. Army Research Laboratory, Aberdeen Proving Ground, Maryland As part of Project Agreement on Military Operations in Urban Terrain (MOUT), the US Army Research Laboratory's (ARL's) Explosives Effects Branch supported a series of experiments conducted in Meppen, Germany (DEU), to understand loading on personnel protective equipment (PPE) produced during urban weapon attacks. These experiments were conducted by detonating an explosive charge placed on a brick wall to create secondary debris that would impact the US-designed collection medium. The experimental area consisted of 3 separate rooms (Figure 1). The first room was used as the blast room. The second and third rooms contained the collection medium. A double thick brick wall separated rooms 1 and 2 and was used to create the secondary debris.
Aluminoborosilicate Supplement for Thermal Protection of a Re-entrant VehicleTBMG-249677/1/2016
The Toughened Uni-piece Fibrous Reinforced Oxidation-Resistant Com posite (TUFROC) allows for much more affordable and sustainable operations involving Space Launch Services and other systems that utilize Earth reentry vehicles. TUFROC has an exposed surface design and appropriate materials combination that will allow a space vehicle to survive both the mechanical stresses of the initial ascent, and the extreme heating and stress of re-entry. It provides a thermal protection tile attachment system that is suitable for application to a space vehicle leading edge, and for other uses in extreme heating environments (up to 3600 °F, and possibly higher, for short time intervals).
Aromatic Thermosetting coPolyester (ATSP) Composites for High-Temperature and Cryogenic ApplicationsTBMG-249647/1/2016
Advanced composite materials processable by cost-effective manufacturing play an important role in developing lightweight structures for future space and planetary exploration missions. With the growing demand for improved performance in the aerospace sector, advances in polymer systems with extreme thermomechanical properties are critical in providing excellent retention of performance in high-temperature environments, and high resistance to microcracking at cryogenic temperatures.
A Numerical Study of a Method for Estimating Sound Absorption Coefficient under a Synthesized Diffuse Acoustic Field2016-01-18476/15/2016
A method for estimating the sound absorption coefficient of a material under a synthesized Diffuse Acoustic Field was recently proposed, as an alternative to classical sound absorption measurements in reverberant rooms (Robin O., Berry A., Doutres O., Atalla N., ‘Measurement of the absorption coefficient of absorbing materials under a synthesized diffuse acoustic field’, J. Acoust. Soc. Am., 136 (1) EL13-EL19, 2014). Using sound field reproduction approaches and a synthetic array of acoustic monopoles facing the material, estimation of the sound absorption coefficient under a reproduced Diffuse Acoustic Field in a hemi-anechoic room was shown to be feasible. The method was successfully tested on a few samples of melamine foam of close thicknesses and areas, but the influence of several parameters such as the source height, or the samples dimensions together with the nature of the porous material was not fully investigated. In this paper, the robustness of the method is numerically studied by examining the influence of the aforementioned parameters on the estimated sound absorption coefficient, with various square samples of homogeneous materials and a synthetic array of fixed dimensions. The principle of the method will be first recalled, and the main results of these numerical experiments will be then reported.
Sgard, Franck, Doutres, Olivier, Robin, Olivier, Amedin, Celse Kafui, Berry, Alain, Atalla, Noureddine
Thermal Management of Power Batteries for Electric Vehicles Using Phase Change Materials: A Review2016-01-12044/5/2016
As one of the most crucial components in electric vehicles, power batteries generate abundant heat during charging and discharging processes. Thermal management system (TMS), which is designed to keep the battery cells within an optimum temperature range and to maintain an even temperature distribution from cell to cell, is vital for the high efficiency, long calendar life and reliable safety of these power batteries. With the desirable features of low system complexity, light weight, high energy efficiency and good battery thermal uniformity, thermal management using composite phase change materials (PCMs) has drawn great attention in the past fifteen years. In the hope of supplying helpful guidelines for the design of the PCM-based TMSs, this work begins with the summarization of the most commonly applied heat transfer enhancement methods (i.e., the use of thermally conductive particles, metal fin, expanded graphite matrix and metal foam) for PCMs by different researchers. Newly developed TMS configurations such as the multi-layer PCMs and sandwiched ones are also discussed in detail. In addition, the hybrid TMS combining PCM cooling with air or liquid cooling, and battery heating by these PCM-based TMSs under cold environment are also summarized. Based on the analysis of previous studies, several possible research topics on PCM cooling are finally proposed in the conclusion/summary part.
Pan, Dongchang, Xu, Sichuan, Lin, Chunjing, Chang, Guofeng
Design of Catalytic Devices by Means of Genetic Algorithm: Comparison Between Open-Cell Foam and Honeycomb Type Substrates2016-01-09654/5/2016
Metallic foams or sponges are materials with a cell structure suitable for many industrial applications, such as reformers, heat catalytic converters, etc. The success of these materials is due to the combination of various characteristics such as mechanical strength, low density, high specific surface, good thermal exchange properties, low flow resistance and sound absorption. Different materials and manufacturing processes produce different type of structure and properties for various applications. In this work a genetic algorithm has been developed and applied to support the design of catalytic devices. In particular, two substrates were considered, namely the traditional honeycomb and an alternative open-cell foam type. CFD simulations of pressure losses and literature based correlations for the heat and mass transfer were used to support the genetic algorithm in finding the best compromise between flow resistance and pollutant abatement. The CFD analysis was conducted by means of numerical simulations carried out on a geometry sample obtained by the micro-tomography technique to investigate the flow regime type and to extract pressure drop information. The result of this analysis was used to set guideline for the design of foam type substrate and to provide a first estimation of cost effectiveness of new type of substrates.
Falfari, Stefania, Micci, Giacomo, Bianchi, Gian Marco, Brusiani, Federico, Montenegro, Gianluca, Della Torre, Augusto, Onorati, Angelo
Flexible, High-Temperature Polyimide/Urea AerogelsTBMG-242484/1/2016
Cross-linked silica-based aerogels with polymeric materials, as well as incorporating a flexible linkage into the underlying metal oxide, have been proven to improve strength and resilience over their native, or non-cross-linked, counterparts without adversely affecting porosity and density. In this invention, high-temperature, stable, all-organic polyimide aerogels are prepared as reacting linear polyimide chains with a functional monomer to create branchings that are further room-temperature-cured with multifunctional isocyanate to form a three-dimensional network.
Deodorant, Aircraft ToiletAMS1476C (Historical)1/12/2016
This specification covers a biodegradable deodorant in the form of a liquid concentrate, solid, or gel.
AMS J Aircraft Maintenance Chemicals and Materials Committee
Sandwich Cores for the FutureTBMG-2356812/1/2015
by Bruce Morey
Aerogel-Filled Foam Core Insulation for Cryogenic Propellant StorageTBMG-2320911/1/2015
Current cryogenic insulation materials suffer from various drawbacks including high cost and weight, lack of structural or load-bearing capability, fabrication complexity, and property anisotropy. A need clearly exists for lightweight thermal insulation that is isotropic and structurally capable with high thermal performance, while also offering reduced fabrication and installation complexity, and lower cost.
Smart MMOD Thermal BlanketTBMG-2321111/1/2015
This innovation provides for significantly improved protection from micrometeoroid and orbital debris (MMOD) particles, and reliably determines the location, depth, and extent of MMOD impact damage.
Lightweight Metal Foam Blocks RadiationTBMG-227788/19/2015
A strong, lightweight metal foam created by a North Carolina State University researcher absorbs the energy of high-impact collisions and effectively blocks X-rays, gamma rays, and neutron radiation. The device offers new shielding possibilities for use in CT scanners.
Acoustics Characterization of Nano Enhanced Open Cell Foams2015-01-22056/15/2015
A comprehensive and systematic investigation of the acoustical performance of carbon-nanotube-enhanced polyurethane (PU) foams was performed. The complete foam making process was carried out carefully in order to create stable foams to be integrated with many carbon nanotube materials. A total of eight design parameters were evaluated. Both normal incidence sound transmission loss (STL) and absorption coefficient were measured by use of an impedance tube. It was found that there is an optimum value for most of the design parameters. In general, nanotube-enhanced PU foam definitely demonstrated improvements in both absorption coefficients and sound transmission loss. The improvement of absorption could reach up to 14% and the improvement in STL was quite substantial, i.e. up to 97.5%. This significant improvement in STL with a better absorption coefficient could represent a potential breakthrough in acoustical PU foam manufacturing.
Cherng, John G., Xing, Simeng, Wu, Weiwei, Ladewig, Jan, Balte, Rolf, Venegas, Maurice
Modeling and Characterization of a Novel Porous Metallic Foam Inside Ducts2015-01-22036/15/2015
A novel porous metallic foam has been studied in this work. This composite material is a mixture of resin and hollow spheres. It is lightweight, highly resistive to contamination and heat, and is capable of providing similar or better sound absorption compared to the conventional porous absorbers, but with a robust and less degradable properties. Several configurations of the material have been tested inside an expansion chamber with spatially periodic area changes. Bragg scattering was observed in some configurations with certain lattice constants. The acoustic properties of this material have been characterized from the measurement of the two-port matrix across a cylindrical sample. The complex density and speed of sound can be extracted from the transfer matrix using an optimization technique. Several models were developed to validate the effect of this metallic foam using Finite Elements and the Two-port Theory. There was a good agreement between both models and the measurement results.
Farooqui, Maaz, Elnady, Tamer, Glav, Ragnar, Karlsson, Tony
Multi-Criteria Optimization of Foam Reinforced Thin-walled Tube Shape under Crashworthiness Requirements2015-01-13644/14/2015
The design of aluminum foam reinforced thin-walled tubes has garnered much interest recently due to the high energy absorption capacity of these tubes. As a new kind of engineering composite material, aluminum foam can hugely increase the crashworthiness capacity without sacrificing too much weight. In this paper, axisymmetric thin-walled hollow tubes with four different kinds of cross-sections (circular, square, hexagonal and octagonal) are studied to assess their performance for crashworthiness problems. It is found that the tube with square cross-section has the best crashworthiness performance under axial impact. To seek optimal designs of square aluminum foam reinforced thin-walled tubes, a surrogate modeling technique coupled with a multi-criteria particle swarm optimization algorithm has been developed, to maximize specific energy absorption (SEA) and minimize peak crash force (PCF). To improve the accuracy of the optimization process, meta-models of SEA and PCF were constructed using the response surface method and radial basis function method, respectively. Crash simulations carried out using LS-DYNA demonstrate that the optimal design has better crashworthiness characteristics than the baseline design. These results suggest that the proposed method can be of benefit in design optimization for other crashworthiness problems.
Wang, Tao, Wang, LIangmo, Wang, Yuanlong, Zou, Xiaojun, Guo, Fuxiang
The Use of Intumescent Coatings with Polymer Composites for High Temperature Automotive Applications2015-01-07134/14/2015
To meet corporate CO2 emission targets polymer composites are being explored for light-weighting vehicle applications. Operational requirements may demand that such materials function above glass transition temperatures or heat deflection points. Intumescent coatings are traditionally used in construction to protect steelwork during fire. This paper presents a novel experimental investigation of two intumescent technologies to thermally protect a reinforced polyamide, for use as a semi-structural vehicle component. Coatings were assessed against the thermal requirement to withstand 500°C for 10 minutes. The differences in performance observed between water and epoxy based coatings as well as when an insulation layer was introduced are reported. Ultimate Tensile Stress (UTS) and modulus values were obtained at −40°C, ambient, and 85°C for uncoated specimens before and after thermal cycling. Results indicated although samples did not surpass the heat deflection point of the material (220°C), exceeding the glass transition temperature led to a reduction in mechanical properties. Considering electrified vehicles it may be beneficial if materials are electrically resistant Therefore, the surface and through-thickness resistivity of uncoated and coated plaques was measured. The resistance of coated samples before and after thermal cycling exceeded the threshold of 1×106Ω, however, when coated samples were environmentally pre-conditioned, these materials failed to meet the required surface resistance. There are a number of parameters that need to be understood: light-weighting, electrical resistance, thermal protection, and manufacturing demands for automotive structures; this work demonstrates the potential of selected intumescent coating technologies to provide a balance between the protection of composite performance while achieving light-weighting targets for high temperature automotive applications.
Simmonds, Helena, Cox, Sophie, Nicholls, Steve, Williams, Geraint
Toughened Uni-piece Fibrous Reinforced Oxidation-Resistant Composite (TUFROC)TBMG-205179/1/2014
TUFROC has an exposed surface edge design and an appropriate materials combination for a space vehicle that will survive the mechanical stresses induced in the initial ascent, and will subsequently survive the extreme heating and mechanically stressful environment of re-entry. It provides a thermal protection tile attachment system, suitable for application to a space vehicle leading edge, and for other uses in extreme heating environments [up to 3,600 °F (1,982 °C), and possibly higher, for short time intervals].
Sandwich Panels with Corrugated Core - A Lightweighting Concept with Improved Stiffness2014-01-08084/1/2014
Sandwich panels with high modulus/high strength skin material and low density/low modulus core material have higher stiffness-to-weight ratio than monolithic panels. In this paper, sandwich panels with corrugated core are explored as a lightweighting concept for improved stiffness. The skin and the core materials are a high strength steel, aluminum alloy or carbon fiber-epoxy composite. The core has a triangular corrugation, a trapezoidal corrugation and a rectangular corrugation. The stiffness of the sandwich panels is analytically determined and compared with monolithic panels of equal mass. It is shown that the stiffness of the sandwich panels is 5 to 7 times higher than that of the monolithic panels.
Mallick, Pankaj K., Boorle, Rajesh
Featherweight Composites Manufactured by Selective Nanobridization with Potential Applications in the Automotive Industry2014-01-10614/1/2014
Nanobridization is a nano-inspired process by which scalable material structures can be designed and manufactured by combining the concept of ‘Nano Free Volume’ with specific material molecules defining a systemic density (nano-density). This approach explores nanotechnology from a porosity perspective rather than nanoparticles thus minimizing health concerns with nanotechnology, while providing nanoporosity throughout the entirety of the composite system. Nanobridization may be viewed as a density system transformation of material heterogeneity utilizing a unified class of materials such as Polynanomers and in developing next generation structures such as Featherweight Carbon Fiber Reinforced Polymers (CFRP). Polynanomers are further defined by the incorporation of hollow carbon fibers, electrospun nano-fibers, nano-pores and carbon nanotubes (CNT) into this newly established type of matrix. Nanobridization involves fractal structural design and constitutes a scalable structure from the nano- to the macro- scale and vice versa, resulting in a spatial density with significant overall weight reduction. Featherweight composites are a characteristic example product of nanobridization process, as they include novel bio-inspired fractal structures which are combined with unprecedented mechanical and transport properties. Porosity is designed both at the macro- (honeycomb/foam type) and micro- (hollow carbon fiber foamed matrix and interphase) scales and can find immediate applications such as tooling and nonstructural or failure critical applications. Featherweight composite manufacturing introduces a new production process which includes novel steps, such as electrospinning of carbon fibers and aligned CNT incorporation into the novel polynanomeric matrix system, and an innovative, integrated, roll-to-roll (R2R) process sequence. The main objective of this work is to discuss the manufacturing scalability of polynanomeric composites through nanobridization and to highlight potential relevant uses for this technology in the automotive industry. This type of material establishes a unique framework for creating the next-generation of composites technology that will be 25 to 40% lighter, while maintaining structural load-bearing characteristics such as stiffness and strength. Various polynanomers have been investigated in the Polymeric Composites Laboratory and will be discussed in this article.
Kamp, Carl Justin, Seferis, James, Arnold, Michael, Drakonakis, Vasileios
Characterization of PU Foam for High Temperature Applications in Automobiles2014-01-10354/1/2014
Due to continuous demands from OEM's to reduce weight and make more compact vehicles, high heat generation from vehicle has become common phenomenon. Thermal insulation is a need of the hour to cater to such demands. The temperature rise is more critical around engine areas. OEM's use many design solutions to cater to such heat build up's. One of the design solutions includes use of thermally insulating materials e.g. Foams, insulating fabrics etc… First section of this paper deals with comparative study of polyurethane (PU) soft foam and rigid skin polyurethane foam. To define the base line, the samples were subjected to various tests to determine physical, thermal and chemical properties. Also both the types of foams were subjected to high temperature and low temperature heat ageing. From the experiments, it was observed that soft PU foam provides better re-bounce property than rigid skin PU foam. This is an important property to be considered, when foam is subjected to compression load during fitment. Foam would regain its shape and size on removal of load and hence provides better stability. Also, thermal conductivity of both the foams is compared to check for their ability to provide thermal insulation. Based on above results, soft PU foam was further tested for performance level tests to understand the foam behavior under simulated thermal test conditions. The thermal test method was developed to simulate heat generation during actual driving conditions. Foam was also subjected to physical test till failure including compression set. The test results are discussed and concluded for selection of better foam for the under the hood application. The results of this study were useful for determining optimum foam structure providing good insulation with lower weight.
Mehta, Shruti, Hatwalne, Mrunal, Dhule, Mangesh
Effect of Flow Regime in the Horizontal Inlet Header on Refrigerant-Oil Mixture Distribution in a MAC Microchannel Evaporator2014-01-07014/1/2014
The effect of lubricant on distribution is investigated by relating the flow regime in the horizontal inlet header and the corresponding infrared image of the evaporator. Visualization of the flow regime is performed by high-speed camera. R134a is used as the refrigerant with PAG 46 as lubricant, forming foam in all flow regimes. Quantitative information including foam location, foam layer thickness is obtained using a matlab-based video processing program. Oil circulation rate effect on flow regime is analyzed quantitatively.
Li, Huize, Hrnjak, Predrag
Estimation of Nonlinear Viscoelastic Parameters from Estimated Linear Models of Behavior around Multiple Settling Points of a Foam-Mass System2014-01-08514/1/2014
Flexible polyurethane foam is the main cushioning element used in car seats. Optimization of an occupied seat's static and dynamic behavior requires models of foam that are accurate over a wide range of excitation and pre-compression conditions. In this research, a method is described to estimate the parameters of a global model of the foam behavior from data gathered in a series of impulse tests at different settling points. The estimated model is capable of describing the responses gathered from all the impulse tests using a unique set of parameters. The global model structure includes a nonlinear elastic term and a hereditary viscoelastic term. The model can be used to predict the settling point for each mass used and, by expanding the model about that settling point, local linear models of the response to impulsive excitation can be derived. From this analysis the relationship between the local linear model parameters and the global model parameters is defined. A series of experiments are conducted using different sized masses on the foam block. For each mass, the settling point is measured and the free response after an impulsive excitation is modeled as a Prony series whose parameters can be related to the parameters in the local linear dynamic model. By using the relationship between the local and global model parameters and estimates of the local models' parameters, the parameters of the global model are estimated. The estimation method is first applied to simulation data and then used to identify models of the uniaxial dynamic behavior of polyurethane foam blocks.
Azizi, Yousof, Sundaram, Vaidyanadan, Davies, Patricia, Bajaj, Anil
Dispersion of Carbon Nanotubes Into Polymer Matrices to Produce Unique PropertiesTBMG-193724/1/2014
The present invention addresses the effective dispersion of carbon nanotubes (CNTs) into polymer matrices. The nanocomposites are prepared using polymer matrices and exhibit a unique combination of properties, most notably, high retention of optical transparency in the visible range (i.e., 400 to 800 nm), electrical conductivity, and high thermal stability.
Using Molded Foam Makes Assembly a SnapTBMG-190472/1/2014
Today, medical devices are made using a variety of plastic materials and manufacturing processes. Advances in plastic processing make it possible to obtain virtually any shape, form, or function. In addition, the vast assortment of plastics available allows designers to design for the optimal balance of functionality, performance, and cost. Expanded polypropylene (EPP) is a plastic material that is starting to gain traction in the medical device market as product designers become more familiar with the multiple benefits it can provide.
Wing Leading Edge RCC Rapid Response Damage Prediction Tool (IMPACT2)TBMG-172229/1/2013
This rapid response computer program predicts Orbiter Wing Leading Edge (WLE) damage caused by ice or foam impact during a Space Shuttle launch (Program “IMPACT2”). The program was developed after the Columbia accident in order to assess quickly WLE damage due to ice, foam, or metal impact (if any) during a Shuttle launch. IMPACT2 simulates an impact event in a few minutes for foam impactors, and in seconds for ice and metal impactors.
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