Criteria

Text:
Topic:
Display:

Results

Viewing 1 to 30 of 295
2017-06-05
Journal Article
2017-01-1765
Albert Allen, Noah Schiller, Jerry Rouse
Abstract Corrugated-core sandwich structures with integrated acoustic resonator arrays have been of recent interest for launch vehicle noise control applications. Previous tests and analyses have demonstrated the ability of this concept to increase sound absorption and reduce sound transmission at low frequencies. However, commercial aircraft manufacturers often require fibrous or foam blanket treatments for broadband noise control and thermal insulation. Consequently, it is of interest to further explore the noise control benefit and trade-offs of structurally integrated resonators when combined with various degrees of blanket noise treatment in an aircraft-representative cylindrical fuselage system. In this study, numerical models were developed to predict the effect of broadband and multi-tone structurally integrated resonator arrays on the interior noise level of cylindrical vibroacoustic systems.
2017-03-28
Technical Paper
2017-01-0363
Karthik Ramaswamy, Vinay L. Virupaksha, Jeanne Polan, Biswajit Tripathy
Abstract Expanded Polypropylene (EPP) foams are most commonly used in automotive applications for pedestrian protection and to meet low speed bumper regulatory requirements. In today’s automotive world the design of vehicles is predominantly driven by Computer Aided Engineering (CAE). This makes it necessary to have a validated material model for EPP foams in order to simulate and predict performance under various loading conditions. Since most of the automotive OEMs depend on local material suppliers for their global vehicle applications it is necessary to understand the variation in mechanical properties of the EPP foams and its effect on performance predictions. In this paper, EPP foams from three suppliers across global regions are characterized to study the inter-supplier variation in mechanical properties.
2017-01-10
Technical Paper
2017-26-0195
Sachin Kumar Jain, Manasi Joshi, Harshal Bankar, Prashant Kamble, Prasad Yadav, Nagesh Karanth
Abstract The paper discusses the methodology for measuring the sound absorption of sound package materials in a different sizes of reverberation chambers. The large reverberation chamber is based on test methods and requirements as per ASTM C423 and ISO 354 standards. Both the test standards are similar and recommend a reverberation chamber volume of at least 125 m3 and 200 m3 respectively for sound absorption measurements from 100 Hz to 5000 Hz. The test sample size requirements are from 5.5 to 6.7 m2 as per ASTM C423 and 10 to 12 m2 as per ISO 354. In the automotive sector passenger car, heavy truck, and commercial vehicle, the parts that are used are much smaller in size than the size prescribed in both the standards. The requirement is to study the critical parameters such as the chamber volume, sample size, reverberation time and cut-off frequency etc. which are affecting the sound absorption property of acoustic material.
2016-06-15
Technical Paper
2016-01-1851
Arnaud Duval, Minh Tan Hoang, Valérie Marcel, Ludovic Dejaeger
Abstract The noise treatments weight reduction strategy, which consists in combining broadband absorption and insulation acoustic properties in order to reduce the weight of barriers, depends strongly on surface to volume ratio of the absorbing layers in the reception cavity. Indeed, lightweight technologies like the now classical Absorber /Barrier /Absorber layup are extremely efficient behind the Instrument Panel of a vehicle, but most of the time disappointing when applied as floor insulator behind the carpet. This work aims at showing that a minimum of 20 mm equivalent “shoddy” standard cotton felt absorption is requested for a floor carpet insulator, in order to be able to reduce the weight of barriers. This means that a pure absorbing system that would destroy completely the insulation properties and slopes can only work, if the noise sources are extremely low in this specific area, which is seldom the case even at the rear footwells location.
2016-04-05
Technical Paper
2016-01-1432
Alexander Siefert
Abstract Predicting the vibration comfort is a difficult challenge in seat design. There is a broad range of requirements as the load cases strongly vary, representing different excitation levels, e.g. cobblestones or California roads. Another demand is the driver expectation, which is different for a pickup and a sports car. There are several approaches for assessing the vibrations of occupants while driving. One approach is the evaluation of comfort by integral quantities like the SEAT value, taking into account a weighting based on the human body sensitivity. Another approach is the dimension of perception developed by BMW, which is similar to psychoacoustics as the frequency range is separated with respect to occurring vibration phenomena. The seat transmissibility is in the focus of all activities. In the frequency range it defines the relation between the input at the seat slides and the output at the interface of human body and trim.
2016-04-05
Journal Article
2016-01-0521
Ronald S. Grossman
Abstract The lightweighting of auto components is a crucial strategy for OEMs to achieve increasingly challenging CAFÉ requirements. Research from MIT has found that every 10% reduction in passenger vehicle weight reduces fuel consumption by about 7%. Since fuel economy requirements have already increased by 18% from MY 2012 to 2017, the weight savings strategies that are easiest to implement have largely been exhausted. Seating is the largest interior component by weight, but the foam is often overlooked from lightweighting consideration due to the perception that higher weight, higher density seating is an important aspect of the vehicle’s comfort. It has become almost a truism that the physical properties associated with seating comfort -- load bearing, resilience, durability - are directly related to foam density. A new auxiliary blowing agent known chemically as HFO 1233zd(E) is commercially available as Solstice® LBA.
2016-04-05
Journal Article
2016-01-0965
Stefania Falfari, Giacomo Micci, Gian Marco Bianchi, Federico Brusiani, Gianluca Montenegro, Augusto Della Torre, Angelo Onorati
Abstract 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.
2016-04-05
Technical Paper
2016-01-1396
Kai Liu, ZongYing Xu, Duane Detwiler, Andres Tovar
Abstract This work proposes a new method to design crashworthiness structures that made of functionally graded cellular (porous) material. The proposed method consists of three stages: The first stage is to generate a conceptual design using a topology optimization algorithm so that a variable density is distributed within the structure minimizing its compliance. The second stage is to cluster the variable density using a machine-learning algorithm to reduce the dimension of the design space. The third stage is to maximize structural crashworthiness indicators (e.g., internal energy absorption) and minimize mass using a metamodel-based multi-objective genetic algorithm. The final structure is synthesized by optimally selecting cellular material phases from a predefined material library. In this work, the Hashin-Shtrikman bounds are derived for the two-phase cellular material, and the structure performances are compared to the optimized structures derived by our proposed framework.
2015-09-22
Technical Paper
2015-36-0106
L. F. Cóser, A. Oliveira, B. N. Hualpa, J. R. F. Arruda, D. A. Siviero
Abstract Poroelastic materials are commonly used in passive noise control due to their low cost and relative efficient acoustic absorption characteristics in the middle to high frequency range. They are constituted by a rigid and a fluid phase responsible for the dissipation mechanisms attenuating the propagation of acoustic waves inside the material. The understanding of these phenomena and their translation into parameters existing in the mathematical formulations for poroelastic materials are of paramount importance in the design of optimized structures for choosing the proper materials for each application. This work presents studies on the validation of a melamine foam characteristics using the equivalent fluid model from Johnson-Champoux-Allard (JCA) and a rigid structure.
2015-09-22
Technical Paper
2015-36-0333
Carlo Vezzá, Eider Moraes, Fernando Ooki
Abstract The acoustic comfort inside the vehicle justifies important attention during its development phase, because customers desire a quiet interior to have a more relaxing environment, easier to have conversations and to listen to the radio. Generally, acoustic insulators are distributed on vehicle body to minimize the portion of noise that enters the vehicle and, in the interior, absorber components are used to reduce the cabin noise reverberation. Internal noise absorption is mainly performed by headliners, carpets and seats. In order to contribute to the sound absorption inside the vehicle made through the seats and to propose a foam and fabric configuration that demonstrates the best acoustic performance, this work aims to compare combinations of three different foam densities with eight different fabrics using the Kundt´s tube.
2015-06-15
Journal Article
2015-01-2203
Maaz Farooqui, Tamer Elnady, Ragnar Glav, Tony Karlsson
Abstract 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.
2015-06-15
Technical Paper
2015-01-2205
John G. Cherng, Simeng Xing, Weiwei Wu, Jan Ladewig, Rolf Balte, Maurice Venegas
Abstract 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.
2015-04-14
Technical Paper
2015-01-0725
Mohamed Eghfaier, Nassif E. Rayess
Abstract Cellular materials in general and metal foams in particular are becoming more accessible to the automotive industry as technologies get further developed and the supply chain expands. Among the recognized properties of metal foams are high plastic deformation energy and light weight, which is a combination that could be leveraged advantageously in impact and crash applications. In this study, cylindrical shells with aluminum foam cores were crushed in the longitudinal direction, an embodiment that approximates those found in vehicle crumple zones and roof pillars. The cores were made of Duocel®, which is an aluminum foam of the open cell variety. The foam is made of 6101 T6 aluminum and has a 10 % relative density (90% of the volume is air) and a linear pore density of 20 pores per inch. The materials investigated for the shell were aluminum and carbon fiber composite.
2015-04-14
Technical Paper
2015-01-1483
Anindya Deb, N Shivakumar, Clifford Chou
Abstract Rigid polyurethane (PU) foam finds wide applications as a lightweight material in impact safety design such as improving occupant safety in vehicle crashes. The two principal reacting compounds for formulating such foam are variants of polyol and isocyanate. In the present study, an alternative mechanical engineering-based approach for determining, with confidence, the desirable ratio of reacting compounds for formulation of a rigid/crushable PU foam for mechanical applications is demonstrated. According to the present approach, PU foam samples are prepared by varying the mixing ratio over a wide range. The desirable mixing ratio is shown to be the one that optimizes key mechanical properties under compression such as total absorbed energy, specific absorbed energy and energy absorption efficiency.
2015-04-14
Technical Paper
2015-01-1364
Tao Wang, LIangmo Wang, Yuanlong Wang, Xiaojun Zou, Fuxiang Guo
Abstract 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).
2015-03-10
Technical Paper
2015-01-0065
Kong Byungseok
Abstract In order to reduce the cost and weight of the soft-foamed instrument-panel (IP), we developed the new IP which is made by the 2 kinds of injection methods. One is the compression-injection with back-foamed foil inserted, and the other is two-shot injection with the passenger-side airbag (PAB) door. We named it ‘IMX-IP’ which means that all components (‘X’) of the IP with different resins are made In a Mold. The development procedure of this technology was introduced (1) Design of the new injection mold through TRIZ application, (2) Optimization of the injection conditions and back foamed-foil for minimizing the foam loss and thickness deviation, (3) Development of CAE method for two-shot injection compression, (4) Reliability performance test and application to the mass production. The reduction of the processes through the two-shot molding with back foamed-foil inserted made it possible to enhance soft feeling on IP and reduce the cost and weight simultaneously.
2014-09-30
Technical Paper
2014-36-0172
Angela Harris, Ellen Lee, Walmir Peraro, Sandro Nunes, Cristiane Gonçalves, Andrea Latado
Abstract The microcellular foam injection molding process for thermoplastic materials provides design flexibility and cost savings opportunities not found in conventional injection molding. This process allows for plastic part design with material wall thickness optimized for functionality. The combination of density reduction and design for functionality can result in material and weight savings of up to 20%. With the correct equipment configuration, mold design, and processing conditions, these microcellular voids are uniform in size and distribution. The use of microcellular foam molding provides significant reductions in cycle time, material consumption, injection pressure, and clamp tonnage. In this work, a physical foam molding process, MuCell, is applied to a polypropylene (PP) composite.
2014-05-05
Journal Article
2014-01-9099
Lindsay J. Miller, Susan Sawyer-Beaulieu, Edwin Tam
Polyurethane (PU) foam is used for many automotive applications with the benefits of being lightweight, durable, and resistant to heat and noise. Applications of PU foams are increasing to include non-traditional purposes targeting consumer comfort. An example of this is the use of PU foam between the engine and engine cover of a vehicle for the purpose of noise abatement. This addition will provide a quieter ride for the consumer, however will have associated environmental impacts. The additional weight will cause an increase in fuel consumption and related emissions. More significant impacts may be realized at the end-of-life stage. Recycling PU foams presents several challenges; a lack of market for the recyclate, contamination of the foams, and lack of accessibility for removal of the material.
2014-04-01
Journal Article
2014-01-0539
N. Shivakumar, Anindya Deb, Clifford Chou, H. Chittappa
Polymeric foams are known to be sensitive to strain rate under dynamic loads. Mechanical characterization of such materials would not thus be complete without capturing the effect of strain rate on their stress-strain behaviors. Consistent data on the dynamic behavior of foam is also necessary for designing energy-absorbing countermeasures based on foam such as for vehicle occupant safety protection. Strain rates of the order of 100-500 s−1 are quite common in such design applications; strain rates of this range cannot be obtained with an ordinary UTM (universal testing machine) and a special test set-up is usually needed. In the current study, a unique approach has been suggested according to which quasi-static tests at low strain rates and low velocity drop tests at medium strain rates are utilized to arrive at an empirical relation between initial peak stress and logarithm of strain rate for a rigid closed-cell PU foam.
2014-04-01
Journal Article
2014-01-1033
Seishiro Murata, Hiroyuki Ito, Steven Sopher
Flexible polyurethane (PU) foam has been widely used for seat cushions in automotive passenger vehicles due to the excellent cushioning performance and the ability to shape mold. Originally introduced in the late 1950's, it has been used for more than 50 years. However, there is a limitation using polyurethane foam with efforts to reduce the weight and address ever increasing risks to environment. This paper provides information about a new automotive seat concept which does not use polyurethane foam at all. Expanded polyolefin foam is used for this application to replace polyurethane foam and achieve comparable cushioning performance. Other features of the material include 100% recyclability, and no VOC's. By replacing polyurethane foam with expanded thermoplastic foam, hazardous outgassing is eliminated during the seat cushion production, thus improving workplace environmental health and safety.
2014-04-01
Journal Article
2014-01-0851
Yousof Azizi, Vaidyanadan Sundaram, Patricia Davies, Anil Bajaj
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.
2014-04-01
Technical Paper
2014-01-1035
Shruti Mehta, Mrunal Hatwalne, Mangesh Dhule
Abstract 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.
2013-05-13
Technical Paper
2013-01-1944
David Stotera, Terence Connelly, Bryce Gardner, Eric Seifferlein, Ricardo de Alba Alvarez
The excitation of structural modes of vehicle roofs due to structure-borne excitations from the road and powertrain can generate boom and noise issues inside the passenger cabin. The use of elastomeric foams between the roof bows and roof panel can provide significant damping to the roof and reduce the vibration. If computer-aided engineering (CAE) can be used to predict the effect of elastomeric foams accurately on vibration and noise, then it would be possible to optimize the properties and placement of foam materials on the roof to attenuate vibration. The properties of the different foam materials were characterized in laboratory tests and then applied to a flat test panel and a vehicle body-in-white. This paper presents the results of an investigation into the testing and CAE analysis of the vibration and radiated sound power of flat steel panels and the roof from the BIW of an SUV with anti-flutter foam and Terophon® high damping foam (HDF) materials.
2013-05-13
Technical Paper
2013-01-1947
Arnaud Duval, Jean-Francois Rondeau, Ludovic Dejaeger, Francis Lhuillier, Julien Monet-Descombey
In order to reach the new 2020 CO2 emissions regulations, we have developed a wide range of lightweight noise treatment technologies going from pure absorbing to highly insulating ones, depending on the pass-through quality situation. This Generalized Light-Weight Concepts family was first optimized using the 2D Transfer Matrix Method (TMM) combined with quick SEA approaches. Taking into account thickness 3D maps with TMM is an efficient and quick intermediate “2,5D” optimization method, but it is not a real 3D approach. This work presents a new 3D optimization procedure based on poroelastic finite elements including intermediate cavities (like Instrument Panels) for designing these Generalized Light-Weight Concepts. A parallel reflection deals with products and processes in order to check the feasibility of the resulting 3D optimized insulator designs.
2013-04-08
Journal Article
2013-01-0669
Horst Lanzerath, Carsten Tragsdorf
In this paper polymer structural foams are being investigated in body structure applications. There are two major polymer foam technologies for structural applications: the well-known epoxy based insert solutions and the PUR injection foams. Here we focus only on the PUR injection foams and its structural applications. It will be shown where such structural foams can be applied in the body structure in order to enable lightweight design or to scale the structural performance. Reliable CAE methods for crash simulation as well as several body structure application examples will be presented and evaluated.
2013-01-09
Technical Paper
2013-26-0071
Dhananjay Kale
This paper will explore concepts of next-generation radiators that can adopt the high performance. The goal of this project is to design an advanced concept for a radiator for use in automobiles. Utilize the recently developed high conductivity carbon foam for thermal management in heat exchangers. The technique used to fabricate the foam produces mesosphere pitch-based carbon foam with extremely high thermal conductivity and an open-celled structure. An engineering model is formulated to account for the effects of porosity and pore diameter on the hydrodynamic and thermal performance of a carbon-foam finned tube heat exchanger. The thermal resistances are obtained from well-established correlations that are extended herein to account for the influence of the porous carbon foam.
2012-04-16
Technical Paper
2012-01-0783
Gayan Rathnaweera, Yvonne Durandet, Dong Ruan, Michael Hajj
Hybrid structures were made using an epoxy based polymer foam, Terocore®, and aluminium tubes of different alloy grades and wall thicknesses. Three-point bending, under quasi-static and dynamic loadings, was carried out on empty and hybrid tubes. It was found that the peak force and total energy absorption of the tubes increased by 20% to 40% with foam-filling, but there was no significant difference in specific energy absorption between the empty tubes and the foam-filled tubes. In addition, finite element analysis was performed using the commercial software package LS-DYNA®. Finite element simulations showed good agreement with experimental data. The finite element model will be used in a future parametric study and energy dissipation analysis.
2011-05-17
Technical Paper
2011-01-1736
Gang Glenn Yin, Tariq Sami Oweimreen, Jan Ladewig
Flexible molded polyurethane foams are widely used in automotive industry. As porous-elastic materials, they can be used as decoupler layers in conventional sound insulation constructions or as sound absorbers in vehicle trim parts. Flexible molded polyurethane foams are produced by reacting of liquid Isocyanate (Iso) with a liquid Polyol blend, catalysts, and other additives. Their acoustic performance can be changed by varying the mixing ratio, the weight proportion of two components: Iso and Polyol. Consequently, the sound insertion loss (IL) of barrier/foam constructions and acoustic absorption of a single foam layer will vary. In this paper, based on one industry standard flexible molded polyurethane foam process, the relationship between foam mixing ratio and foam acoustic performance is studied in terms of IL and sound absorption test results.
2011-05-17
Technical Paper
2011-01-1637
Ahad Khezerloo, Amin owhadi Esfahani PhD, Sina Jalily lng
One of important problems in railway transportation systems is control of noise and vibration. Metal foams are very good medias for absorbing noise. So in this paper, noise of motion of a train is simulated by MATLAB software and the reduction of noise level in a compartment of passenger car that is equipped by metal foam sheets is considered. Commonly, the sound absorption coefficients are obtained experimentally and they are available in datasheets and references. The different parameters that influence on the capability of this equipment were considered. For example the microstructure, thickness, magnitude of compaction, relative density and etc of metal foam is effective parameters. High porosity has good effect on the performance of absorber sheet. By increasing of compaction ratio, in frequency domain we will have enhancing of absorption of the noise. Compaction process is done by two different ways: one is direct and else is progressively.
2011-05-17
Technical Paper
2011-01-1624
Prasanth B, Sachin Wagh, David Hudson
Baffle plates with heat reactive expandable foam sealants have increasingly found their applications in automotives. They are used to separate body cavities and to impede noise, water and dust propagation inside of body cavities, thus control noise intrusion into the passenger compartment. Use of these sealant materials has grown significantly as the demands to improve vehicle acoustic performance has increased. Traditionally quantification of the acoustic performance of expandable baffle samples involved making separate vehicles with and without expandable baffles and measure the incab noise to know the effect. The absolute acoustic evaluation of the baffles is very difficult as number of other vehicle parameters is also responsible for vehicle incab noise. Also, it is a time consuming and a costly method to evaluate.
Viewing 1 to 30 of 295

Filter