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Laminated steel body panels are used in different applications in vehicles, such as dash panels and wheel wells. A part made out of laminated steel has the potential to provide structure-borne noise reduction and also improve the airborne noise reduction of the part compared to a monolithic part. The use of laminated steel has been more critical when there are deep draws on the part as the deep draws cause localized resonances which degrade the acoustic performance significantly. However, due to lightweighting demands, hybrid laminated panels, commonly known as acoustic patch laminates have become very attractive. This paper discusses the damping and sound transmission loss performances of a dash panel part with monolithic, laminated, and acoustic patch panels.

Standards organizations develop standards depending on the need in the market place. With the change in vehicle design, lightweighting structures, and body panels made out of aluminum and composites, SAE’s Acoustical Materials Committee is developing a new damping standard. This standard is also very suitable in determining the damping performance of materials used in the off-highway applications, where the thickness of the steel body panel is much greater than in the automotive application. The general methodology of this standard is based on the mechanical impedance measurement method and has been developed with the general consensus of automotive engineers, suppliers, and independent test laboratories. This method is essentially based on the fact that a bar is excited at the center by a shaker. The force exerted by the shaker and the corresponding vibration is measured at that point to determine the frequency response function of the mechanical impedance signal.

A study was conducted to understand the acoustic viability of using post consumer rebond seat foam materials in vehicles for floor carpet underlayment applications. These foam materials were obtained from two different sources: 1) polyurethane foam dismantled from seats of end of life vehicles (ELV or scrap vehicles), and 2) polyurethane foam recovered and cleaned from auto shredder residue (ASR) by the Argonne National Laboratories (ANL) using their cleaning method. The study was conducted using three North-American cars, each serving different market segments. Based on both laboratory and on-road tests conducted on each vehicle, the study concluded that the acoustical performance of the floor carpet underlayment part made of post consumer rebond foam is comparable to that of the current production part mostly made of shoddy materials.

The SAE International standard for testing Oberst bars has been used in the industry for many years with predictable results. Growing interest in testing wider samples to incorporate more of the variability in liquid applied sprayable dampers has led to increased use of a center point damping test method based on a Japanese standard JIS G 0602. This method is similar to that of the ISO 16940 standard for testing laminated glass. Theory shows us that an Oberst test with a free length equal to the half length of a bar used for center point testing will provide the same resonances. This paper intends to show a relationship between the resonances of bars tested with the Oberst and center point test methods. A correlation between the composite loss factor for samples tested with each of the methods will be illustrated.

The Vehicle Recycling Partnership (VRP) initiated feasibility studies to evaluate the use of automated separation processes to recover plastics and polyurethane (PU) foams from shredder residue. One of the prevailing issues impeding the commercial success of these processes is contamination of the shredder materials. The contaminants include dirt, oils, glass, metal fines, polychlorinated biphenyls (PCBs) and heavy metals. The presence of PCBs and heavy metals was determined in a number of mixed plastics and PU foam samples separated using an automated separation process. An aqueous cleaning approach was investigated using various commercial surfactants to determine their effectiveness for removing oils, PCBs, and heavy metals. Mass balances of processed and cleaned materials were calculated to determine the cleaning efficiencies of the various surfactants.

The United States Council of Automotive Research (USCAR) under the Vehicle Recycling Partnership (VRP) along with our collaborators Argonne National Laboratory (ANL), American Plastic Council (APC) and the Association of Plastic Manufactures in Europe (APME) has been conducting research on automated recovery of plastics from shredder residue. A Belgium company Salyp NV located in Ypres, Belgium has been contracted by the VRP to demonstrate a recovery process that can separate several plastic types including polyurethane foam out of the shredder residue waste stream. One hundred metric tons of shredder residue was supplied from three different metal recycling companies (shredders) including a US metal recycler as well as two different European metal recyclers/shredders. This shredder residue was evaluated and processed by Salyp. This paper explains the separation processes along with processing efficiencies, material characterization, mass balances and the amount of plastics recovered.

The United States Field Trial was chartered by the United States Council for Automotive Research/Vehicle Recycling Partnership (USCAR/VRP) with the objective of evaluating the feasibility and viability of collecting and recycling automotive polymers from domestic End-of-Life Vehicles (ELVs). European concerns regarding vehicle abandonment risks, decreasing landfill capacity, and disposal practices have resulted in the legislated treatment of ELVs in Western Europe. The emergence of attendant material collection schemes promoting material recycling may not apply to the free-market economic conditions prevalent in North America vehicle recycling infrastructure. Although ELVs are among the most widely recycled consumer products, 15-25% of their total mass is currently discarded with no material recovery, although their residue, when permitted, is a preferred landfill day cover in some areas.

A research project to determine the feasibility of utilizing polyethylene post-consumer automotive fuel tanks as a source of raw material was funded by Visteon, ExxonMobil, and was conducted by Brooks Associates. Brooks Associates launched this project in the last quarter of 2000 to demonstrate the feasibility of utilizing high-density polyethylene (HDPE) post-consumer automotive fuel tanks in combination with wood fiber to create a new material suitable as an automotive substrate. The concept for the project was based on proven technology that processes wood into fiber utilizing steam explosion. The steam explosion process was commercialized to form wood fiber as a raw material for ‘Masonite’. The product of the explosion process has also been made into a mat for further processing. This mat process is generally referred to as the ‘air-lay’ process.

Sealant materials are used in todays automobiles for many applications such as, sealing of body seams, sealing access holes and the filling of hollow cavities. The primary reasons for these applications are to prevent corrosion, prevent water intrusion, and to reduce the noise level in the passenger compartment. However, the noise control capabilities of sealant materials have not been explored until recently. This paper discusses the requirements that a noise control material must possess, and reviews how a sealant material can fulfil these requirements. Properly designed sealant materials can possess sound transmission loss (barrier) properties, vibration damping properties over a given frequency and temperature range of interest, and often sound absorption properties with proper formulation. This paper provides case studies to substantiate the acoustical capabilities of sealant materials.

Traditionally, the damping performance of a visco-elastic material is measured using the Oberst bar damping test, where a steel bar is excited using a non-contacting transducer. However, in an effort to reduce the weight of the vehicles, serious effort is put in to change the body panels from steel to aluminum and composite panels in many cases. These panels cannot be excited using a non-contacting transducer, although, in some cases, a very thin steel panel (shim) is glued to the vibrating bar to introduce ferrous properties to the bar so it can be excited. In the off highway vehicles, although the panels are made of steel, they are very thick and are difficult to excite using the Oberst bar test method. This paper discusses a measurement methodology based on mechanical impedance measurements and has the potential to be a viable/alternate test method to the Oberst bar testing. In the impedance method, the test bar is mounted to a shaker at the center (Center Point method).

The performance of damping materials is generally evaluated by experimental methods. However most damping materials used in the transportation industry cannot be excited by itself. Therefore, the measurements are generally made by exciting a damped system, where the damped system extends from a bar to a panel. The paper reviews various damped systems and excitation methodologies and discusses some of the limitations of a bar to study the damping performance for different applications. It discusses a methodology where a damped panel is mounted on a fixture and the fixture is excited with a shaker. The paper discusses data acquisition and data reduction procedures to obtain the damping performance of laminated steel acoustic patch products on a third octave band frequency basis.

Approximately 20 percent by weight of each end of life automobile ends up in a waste stream known as shredder residue (SR) that goes to disposal into a land fill. When an automobile reaches the end of its useful life it enters a complex infrastructure designed to recover usable parts and materials of value, primarily the ferrous and non-ferrous metals. The remaining material, a mixture of glass, rubber, plastics and foam becomes part of SR. Based on earlier research, a new recycling process has been identified that can convert the organic material in this waste stream into a fuel oil. The Thermal Conversion Process (TCP) developed by Changing World Technologies (CWT) may make it possible to convert SR into useful products. The Vehicle Recycling Partnership (VRP) and its partners are investigating the capability of the TCP to process SR.

Polyurethane (PU) foams were recovered from European and U.S. shredder residues, which typically come from automobiles and other sources of durable goods, such as appliances, furniture, construction, etc. PU foams were characterized and glycolyzed. Glycolysis products were successfully treated for the removal of select substances of concern, heavy metals, and bromine-containing compounds and propoxylated into polyols for polyurethanes with 171 and 355 average equivalent weights. Properties of the glycolysis product and corresponding propoxylated polyols were evaluated, including their molecular weight distribution via gel permeation chromatography (GPC). The polydispersity index decreased from 5.8 to 2.1 by reaction of glycolysis product with 50 wt% of propylene oxide based on a total amount of the initiator. The recycled polyol of an average equivalent weight of 171 was evaluated in rigid polyurethane and urethane-modified isocyanurate foam formulations.

The use of sealant materials to improve interior acoustics has increased significantly in todays automobiles. One such application is to use expandable sealant materials in rails, pillars, and cavities to reduce noise propagation. However, there is no standardized method for evaluating the acoustical performance of these materials. This paper reviews the basics of noise control engineering and discusses a proposed laboratory based test methodology that has been developed for properly evaluating the acoustical performance or expandable sealant materials. The test method is intended to simulate actual applications so that different materials can be evaluated to achieve optimum acoustical performance within a channel representing the rails or pillars in automobiles.

The paper discusses the importance of a well documented standardized laboratory test procedure to evaluate damping material performance for the automotive industry, and to understand the parameters that influence the precision of the test method. The standard outlines a methodology which was developed with the general consensus of automotive engineers, suppliers, and independent test laboratories. The methodology is based on the Oberst bar test method where a damping material is bonded to a specific size steel bar and the system is excited at its various modes of vibration under a cantilevered configuration. The damping performance is expressed in terms of composite loss factor, ηc, within the frequency range of approximately 100 Hz to 1000 Hz, and over the useful range of temperatures for the given application.

Automotive noise control involves many aspects of the total vehicle design - the powertrain, body structure, chassis and so forth. Noise control materials in conjunction with intelligent vehicle design can help produce a pleasant, desirable vehicle. Understanding the basic functions and uses of noise control materials is one of the objectives of this paper. In some situation, thermal insulation materials are combined with or used in conjunction with noise control materials, and an understanding of the thermal properties of materials can be useful. Vibration isolators are important devices in controlling the transfer of sound and vibration energy and these are discussed.

Specular-reflectance infrared spectroscopy systems can identify the polymer material of an automotive part in about 5 seconds and are currently commercially available. Issues related to the rapid identification of plastics were recently examined at the Vehicle Recycling Development Center, which is operated by the United States Council for Automotive Research (USCAR). The accuracy of identification is a crucial concern in order to minimize co-mingling or contamination of sorted plastics in dismantling-sorting-recycling operations. Accuracy reports in the literature have ranged from 70% to >99%. Our investigation of the signal-to-noise levels of spectrometers, identification algorithms, and spectral reference libraries indicated that the quality-and-completeness of the reference library is the strongest determinant of accuracy when evaluating current commercial systems. With adequate spectral libraries, identification accuracy of 99% can be achieved.

Heat reactive expanding sealer materials are used as acoustical “baffles” to block noise propagation in rails, pillars, posts, and rockers. However, should moisture enter and collect in vertical pillars water damage may occur. Therefore, effort is being made to implement a drainage system for these problem applications. This paper discusses an effective way to prevent water damage by adding an acoustical drain plug to the baffle system with a minimal reduction in acoustical performance. The paper also discusses the performance and the effect of adding this plug to the baffle system. Finally, results of design variations of the plug on the baffle system are reported.

This paper discusses a development procedure that was used to evaluate the acoustical performance of one type of dashpanel construction over another type for a given application. Two very different constructions of dashpanels, one made out of plain steel and one made out of laminated steel, were studied under a series of different test conditions to understand which one performs better, and then to evaluate how to improve the overall performance of the inferior dashpanel for a given application. The poorly performing dashpanel was extensively tested with dashmat and different passthroughs to understand the acoustic strength of different passthroughs, to understand how passthroughs affect the overall performance of the dash system, and subsequently to understand how the performance can be improved by improving one of the passthroughs.

Each year approximately 12 million automobiles reach the end of their useful life and enter a complex infrastructure designed to recover usable parts and materials of value (primarily the ferrous and nonferrous metals). The remaining material, a mixture of glass, rubber, plastics, foam, and dirt, is referred to as shredder residue (SR) and is currently sent to landfills for disposal. However, a new Thermal Conversion Process (TCP) developed by Changing World Technologies may make it possible to convert this waste into a light hydrocarbon oil. TCP is a new technology under investigation by the Vehicle Recycling Partnership (VRP) and its partners. This process converts hydrocarbons and other organic materials into marketable oils and specialty chemicals for potential industrial and commercial use. Early research has demonstrated the ability to take SR and convert it into a light hydrocarbon oil, fuel gas, and carbon.