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Equivalent Material Properties of Multi-Layer, Lightweight, High-Performance Damping Material and Its Performance in Applications

3M Company-Taewook Yoo, Ronald Gerdes, Seungkyu Lee, Thomas Herdtle
3M Deutschland GmbH-Georg Eichhorn
Published 2019-06-05 by SAE International in United States
In this study, we investigated two aspects of a multi-layer, lightweight damping treatment. The first aspect studied was an equivalent material property estimate for a simplified finite element (FE) model. The simplified model is needed for computational efficiency, i.e. so that Tier 1 and OEM users can represent this complex, multi-layer treatment as a single, isotropic solid layer plus an aluminum constraining layer. Therefore, the use of this simplified FE model allows the multilayer treatment to be included in large body-in-white structural models. An equivalent material property was identified by first representing three unique layers (two adhesive layers plus a connecting standoff layer) by a single row of isotropic solid elements, then an optimization tool was used to determine the “best fit” for two properties including Young’s modulus and material loss factor. Equivalent properties were validated for various substrate thickness and coverage areas heights by comparison to center-driven long bar test results.Secondly, the effect of damping treatment size was studied using the previously identified equivalent material properties. This was a damper placement study to determine…
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Acoustically Absorbing Lightweight Thermoplastic Honeycomb Panels

SAE International Journal of Vehicle Dynamics, Stability, and NVH

3M Company-James M. Jonza, Thomas Herdtle, Jeffrey Kalish, Ronald Gerdes, Taewook Yoo
3M Deutschland GmbH-Georg Eichhorn
  • Journal Article
  • 2017-01-1813
Published 2017-06-05 by SAE International in United States
The aerospace industry has employed sandwich composite panels (stiff skins and lightweight cores) for over fifty years. It is a very efficient structure for rigidity per unit weight. For the automobile industry, we have developed novel thermoplastic composite panels that may be heated and shaped by compression molding or thermoforming with cycle times commensurate with automotive manufacturing line build rates. These panels are also readily recycled at the end of their service life. As vehicles become lighter to meet carbon dioxide emission targets, it becomes more challenging to maintain the same level of quietness in the vehicle interior.Panels with interconnected honeycomb cells and perforations in one skin have been developed to absorb specific noise frequencies. The absorption results from a combination and interaction of Helmholtz and quarter wave resonators. Computer modeling was used to design panels that absorb one of the problematic frequency ranges (800-1,250 Hz), caused by tires on the roadway. This was achieved in thin (7-8 mm) panels of low density (0.25-0.35 g/cc). Experimental results of acoustic absorption and transmission loss of polypropylene…
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Comparison of Long Bar Test Method to Oberst Bar Test Method for Damping Material Evaluation

Daniel Stanley
3M Company-Taewook Yoo, Ronald W. Gerdes, Seungkyu Lee, Thomas Herdtle
Published 2017-06-05 by SAE International in United States
Several methods for evaluating damping material performance are commonly used, such as Oberst beam test, power injection method and the long bar test. Among these test methods, the Oberst beam test method has been widely used in the automotive industry and elsewhere as a standard method, allowing for slight bar dimension differences. However, questions have arisen as to whether Oberst test results reflect real applications. Therefore, the long bar test method has been introduced and used in the aerospace industry for some time. In addition to the larger size bar in the long bar test, there are a few differences between Oberst (cantilever) and long bar test (center-driven) methods. In this paper, the differences between Oberst and long bar test methods were explored both experimentally and numerically using finite element analysis plus an analytical method. Furthermore, guidelines for a long bar test method are provided.
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Designing of a Low Weight Dashmat With An Innovative Fibrous Material

3M Deutschland GmbH-J. Vent
Centro Ricerche Fiat-P. Chawla, C. Vicari
  • Technical Paper
  • 97A125
Published 1997-07-02 by Associazione Tecnica Dell'Automobile in Italy
In this paper we describe a case study for reducing weight but maintaining same acoustic efficiency of a dashmat, one of the heaviest NVH trimming parts on vehicles (4.5-10 kg). The task was achieved through a numerical optimization of the material multilayers used to construct the part: this kind of approach allowed a weight reduction of 3 kg/sqm without expensive and time consuming trial and error techniques. The multilayer of the new dashmat consisted of a lower weight heavy layer, a stiff and thin textile felt to give self consistency to the part and an innovative fibrous felt layer produced by 3M. This new material (Thinsulate) is a micro-fiber polypropylene and polyester felt with very high sound absorbing and decoupling properties but very low weight (600 gr/sqm). Numerical and experimental optimization of material layers was followed by the prototyping of a complete dashmat that was then tried on the vehicle during track tests and compared with the standard production version. The new solution gave the same acoustic performance as the standard production one even though…
 

Vehicle Ventilation Filters - Influence of Test Set-Up and Parameters on Performance Results

3M Filtrete BV-J. Klijn, J. Valkenburd, J. Waque
3M Deutschland GmbH-V. Neveling
  • Technical Paper
  • 954018
Published 1995-05-09 by Institution of Mechanical Engineers in United Kingdom
Cabin air filters for motor vehicles became a standard during the recent years. This article gives an overview of the reasoning for a related test methodology. This means to identify sets of performance parameters to be tested for different product types, furthermore, we will describe the test regimes under discussion. The relevance of the currently discussed test conditions for practical applications is discussed for particle filters, an alternative relating the obtained results more closely to practical conditions of use is proposed. As adsorptive filters for this market are a quite recent development experience with test regimes has to be gathered, still. Therefore, more basic questions regarding parameters potentially affecting the test results are discussed.