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Fast Accurate Non-Destructive Measurement of Absorber Impedance and Absorption

3M Company-Jon Alexander
Bruel & Kjaer Sound and Vibration A/S-Jason Kunio, Flemming Larsen
Published 2019-06-05 by SAE International in United States
Cabin acoustic comfort is a major contributor to the potential sales success of new aircraft, cars, trucks, and trains. Recent design challenges have included the increased use of composites, and the switch to electrically powered vehicles, each of which change the interior noise spectral content and level. The role of acoustic absorption in cabins is key to the optimisation of cabin acoustic comfort for modern vehicles, with acoustic impedance data needed in order to assess and optimise the impact of each component of a given lay-up.Measurements of absorbing interior trim are traditionally performed using either sample holder tests in a static impedance tube (impedance and absorption), or through tests in reverberation rooms (absorption only). Both of these procedures present challenges. In-tube absorption and impedance measurements are destructive, requiring highly accurate sample cutting and sealing. Reverberation room absorption measurements are subject to the effects of varying room diffusion, along with the impact of edge diffraction, sample geometry, and location. Finally, while non-destructive methods using hand-held probes also measure absorption, they are not able to measure impedance…
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Design of Lightweight Fibrous Vibration Damping Treatments to Achieve Optimal Performance in Realistic Applications

3M Company-Thomas Herdtle
Herrick Laboratories, Purdue University-Yutong Xue, J Stuart Bolton
Published 2019-06-05 by SAE International in United States
In recent work, it has been shown that conventional sound absorbing materials (e.g., lightweight fibrous media) can provide structural damping when placed adjacent to vibrating structures, including infinite panels, partially-constrained panels and periodically-supported panels typical of aircraft structures. Thus, a fibrous layer may serve two functions at once: absorption of airborne sound and the reduction of structure-borne vibration. It has also been found that the damping is primarily effective below the critical frequency of the structure, and that the damping results from viscous interaction between the fibrous layer and the evanescent near-field of the panel, in the region where incompressible flow caused by the panel vibration oscillates primarily parallel with the panel surface. By using a near-field damping (NFD) model based on the Biot model for acoustical porous media, it has been shown that a properly-optimized fibrous layer can provide levels of damping comparable with those provided by conventional, constrained-layer, visco-elastic, damping treatments. Based on the idea that vibrating structures exhibit a certain wavenumber/frequency response spectrum, the focus of the current study has been on…
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Equivalent Material Properties of Multi-Layer, Lightweight, High-Performance Damping Material and Its Performance in Applications

3M Deutschland GmbH-Georg Eichhorn
3M Company-Taewook Yoo, Ronald Gerdes, Seungkyu Lee, Thomas Herdtle
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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Real World Performance of an Onboard Gasoline/Ethanol Separation System to Enable Knock Suppression Using an Octane-On-Demand Fuel System

3M Company-Scott Seitz, Ravi Kolakaluri
Massachusetts Institute of Technology-Emmanuel Kasseris, John B. Heywood
Published 2018-04-03 by SAE International in United States
Higher compression ratio and turbocharging, with engine downsizing can enable significant gains in fuel economy but require engine operating conditions that cause engine knock under high load. Engine knock can be avoided by supplying higher-octane fuel under such high load conditions. This study builds on previous MIT papers investigating Octane-On-Demand (OOD) to enable a higher efficiency, higher-boost higher compression-ratio engine. The high-octane fuel for OOD can be obtained through On-Board-Separation (OBS) of alcohol blended gasoline. Fuel from the primary fuel tank filled with commercially available gasoline that contains 10% by volume ethanol (E10) is separated by an organic membrane pervaporation process that produces a 30 to 90% ethanol fuel blend for use when high octane is needed. In addition to previous work, this paper combines modeling of the OBS system with passenger car and medium-duty truck fuel consumption and octane requirements for various driving cycles. Medium duty driving cycles were included; HHDDT cruise mode for long-haul heavy truck cruising and HTUF 4 for delivery truck duty. Commercial vehicle modeling was done under unloaded, half and…
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Acoustically Absorbing Lightweight Thermoplastic Honeycomb Panels

SAE International Journal of Vehicle Dynamics, Stability, and NVH

3M Deutschland GmbH-Georg Eichhorn
3M Company-James M. Jonza, Thomas Herdtle, Jeffrey Kalish, Ronald Gerdes, Taewook Yoo
  • 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 Deutschland GmbH-Georg Eichhorn
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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Acoustic Performance Prediction of Micro-Perforated Panels Using Computational Fluid Dynamics and Finite Element Analysis

3M Company-Ronald Gerdes, Jonathon Alexander, Thomas Herdtle
Published 2013-05-13 by SAE International in United States
In recent years, interest in microperforated panels (MPPs) has been growing in the automotive industry and elsewhere. Acoustic performance prediction is an important step toward understanding and designing MPPs. This paper outlines a start-to-finish procedure to predict the transfer impedance of a particular MPP based on its hole geometry and to further use this information in a simple plane wave application. A computational fluid dynamics (CFD) approach was used to calculate the impedance of the MPP and the results compared to impedance tube and flow resistance measurements. The transfer impedance results were then used to create a computationally efficient acoustic finite element (FE) model. The results of the acoustic FE model were also compared to impedance tube measurements.
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The Deleterious Effects of Organic Binder on Intumescent Mat Mount Material

SAE International Journal of Materials and Manufacturing

3M Company-Nathan Brunner, Anne De Rovere, Patrick Fischer, Ryan Shirk
  • Journal Article
  • 2008-01-0452
Published 2008-04-14 by SAE International in United States
For decades, ceramic fiber mats have been used to mechanically support substrates in catalytic converters. Intumescent mats, those that expand with heat, are composed primarily of ceramic fibers, vermiculite, and organic binder. The binder is required for manufacturing, handling, and installation. Unfortunately, under cool operating conditions, its effects on mat performance are often negative.While residual binder is not an automatic precursor to premature failure, it can amplify the effects of other factors such as gap control and vibration. As the mat mount material is heated, sections can become soft and pliable. In the absence of sufficient heat for complete binder removal, regions of the mat may become rigid during the cooling cycle. This results in a decrease in mat resiliency.Several tests can be used to show the relationship between binder level and material performance. These tests typically characterize expansion properties and pressure performance. By comparing test results of intumescent mats with various binder levels, one can quantify the deleterious effects of residual binder on mat performance.This paper will present a possible failure mode associated when…
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Test Method Development and Understanding of Filter Ring-off-Cracks in a Catalyzed Silicon Carbide (SiC) Diesel Particulate Filter System Design

3M Company-Jim L. Bauman, L. Russ Hornback, Hyung-Suk Joo, David D. Lindeman
Hyundai Motor Company-Jong-Hag Kim, Jin-Ha Lee, Jung-Min Seo
Published 2008-04-14 by SAE International in United States
As the use of diesel engines increases in the transportation industry and emission regulations tighten, the implementation of diesel particulate filter systems has expanded. There are many challenges associated with the design and development of these systems. Some of the key robustness parameters include regeneration, efficiency, fuel penalty, engine performance, and durability.One component of durability in a diesel particulate filter (DPF) system is the filter's ability to resist ring-off-cracking (ROC). ROC is described as a crack caused primarily by thermal gradients, differentials, and the resulting stresses within the DPF that exceed its internal strength. These cracks usually run perpendicular to the substrate flow axis and typically result in the breaking of the substrate into separate halves. Unlike an oxidation catalyst converter where conversion efficiency is mainly dependent on surface area, a ROC in a filter can have a very detrimental effect on filtration efficiency performance.This paper will focus on a test methodology associated with consistently producing the ROC phenomenon. Also summarized will be the following related sub-topics: (1)The effects of soot loading and resulting temperature…
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The Permeation Effect of Ethanol-containing Fuels on Fluoropolymers

3M Company-Steven Brinduse
Dyneon LLC (A 3M Company)-Nobuaki Ando, Peter Harrison, Tatsuo Fukushi, Denis Duchesne
Published 2007-07-23 by SAE International in United States
The barrier properties of fluoropolymers exposed to ethanol-containing fuel blends were investigated using the permeation cup, weight loss method. More specifically, permeation constant data for Fuel C, CE10, CE15, CE22, CE50, CE85 and ethanol through fluoropolymers; THV, PVDF and FEP were measured at 20, 40 and 60°C. Additional techniques such as the measurement of vapor pressure of fuel-ethanol blends using a permeation cup equipped with a pressure transducer are discussed. Vapor pressures for fuel blends were also derived using equations of state such as UNIQUAC, NRTL and Peng-Robinson models. The weight changes and volume changes of fluoropolymers in ethanol-containing fuels were measured. Finally, the crystallinity index and glass transition temperature of fluoropolymers were also measured.
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