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Lee P.-C.,Korea Automotive Technology Institute | Kim B.-R.,Korea Automotive Technology Institute | Jeoung S.K.,Korea Automotive Technology Institute | Lee G.,Korea Automotive Technology Institute | And 4 more authors.
AIP Conference Proceedings | Year: 2016

Polyurethane (PU) is an important class of polymers that have wide application in a number of different industrial sectors. The goal of this work was the synthesis of flame-retarded PU foam with expandable graphite (EG) or commercial graphene. The flame retardancy and thermal stability of the foams has been studied through cone calorimeter analysis, the limited oxygen index and thermal conductivity. The presence of expandable graphite brings an improvement in fire behavior. In particular, the limited oxygen index increases in a linear way and the highest limited oxygen index values are obtained for EG-PU foams. The results from the cone calorimeter are in agreement with those of oxygen index; EG filled foams show a considerable decrease of maximum-heat release rate (M-HRR) with respect to unfilled foams. The results of thermal conductivity show that an increase in expandable graphite amount in PU foams lead to an increased conductivity. © 2016 AIP Publishing LLC.

Choi J.M.,VP Korea Inc. | Lyu S.J.,VP Korea Inc. | Seol Y.S.,VP Korea Inc. | Jun I.K.,VP Korea Inc. | Yi C.,NVH KOREA Inc.
SAE Technical Papers | Year: 2013

The BSR(Buzz, Squeak and Rattle) noise is the perceived noise of annoyance and caused by impact or friction in the gap between parts of a system. It is one of the major factors that influence the perception of quality. The BSR noise emerges along the gap, joint and contact surface of a system under external forces such as the road loads and the engine vibration input. Major causes of BSR phenomena are the degradation of materials and the resonance characteristics of a system. BSR issues can be generally found in the field, after the system has seen several cycles of use. BSR issues are challenging to find in the virtual development stage. Our aim is to develop BSR evaluation process driven by CAE, in order to identify the occurrence of BSR at the early stage of the design. Whereas subjective evaluations have been typically required in order to assess the perception of quality, a virtual evaluation method is proposed in this study. An analytical methodology is presented here to detect the location and threshold level of BSR, through a finite element analysis for a gap model and a pre-loaded model. Implicit and explicit FEA and sound generation will be addressed in this study. The effect of environmental and material property changes is considered in the time domain transient analysis used to predict sound. Copyright © 2013 SAE International.

Lyu S.J.,VP Korea INC. | Jun I.K.,VP Korea INC. | Choi J.M.,VP Korea INC. | Lee W.K.,NVH Korea INC. | Woo J.C.,Duckyang Ind. Co.
Transactions of the Korean Society of Mechanical Engineers, A | Year: 2013

BSR noise emerges in a vehicle as a result of road vibrations, engine vibrations, and speaker vibrations. BSR noise occurs with an irregular impact or stick slip friction phenomenon as the influence of the resonance mode when the vibration input load is transferred along poor joint and contacting pairs of the system. A sub-structure method of finite element analysis is required to detect impacts and slip in the full vehicle model. This study presents a method for substructure modeling and a rattle and squeak detection methodology that considers the characteristics of road vibration inputs. © 2013 The Korean Society of Mechanical Engineers.

Woo C.S.,Korea Institute of Machinery and Materials | Park H.S.,Korea Institute of Machinery and Materials | Jo J.H.,NVH Korea INC. | Kim J.H.,NVH Korea INC. | And 2 more authors.
Transactions of the Korean Society of Mechanical Engineers, A | Year: 2012

Engineering plastics are used in instrument panels, interior trim, and other vehicle applications, and the thermomechanical behaviors of plastic materials are strongly influenced by many environmental factors such as temperature, sunlight, and rain. As the material properties change, the mechanical parts create unexpected noise. In this study, the dynamic mechanical property changes of plastics used in automobiles are measured to investigate the temperature effects. Viscoelastic properties such as the glass transition temperature and storage modulus and loss factor under temperature and frequency sweeps were measured. The data were compared with the original ones before aging to analyze the behavior changes. It was found that as the temperature increased, the storage modulus decreased and the loss factor increased slightly. © 2012 The Korean Society of Mechanical Engineers.

Lee J.W.,Hyundai Motor Company | Lee W.,NVH Korea Inc. | Lee S.N.,NVH Korea Inc. | Park S.W.,Woongjin Chemical Company
SAE Technical Papers | Year: 2013

Usually, fibrous materials with porosity can dissipate the energy of the sound wave penetrating them, so can be the useful sound absorbing materials to reduce the noise in the vehicle. The fibrous materials have been used for the various types of automotive components as the sound absorbing materials, which can be placed close to the noise source, in the noise paths and near the receiver such as passengers. Although all materials can absorb a little amount of sound energy, the term acoustical material has been primarily applied to those materials that can provide the higher sound absorption performance above the ordinary levels. One of the examples of fibrous acoustic materials for automotive components is the sound absorbing felt composed of the fibers which have the several characteristics such as the material type, the cross-sectional shape and the fiber density (can be expressed as denier) related to the sound absorbing performance. Therefore, we have studied about the acoustic materials using the hollow fiber to reduce the material weight as well as to improve the performance. Compared with the normal fiber, the hollow fiber has the larger specific surface area to be contacted while the sound wave propagated through the acoustic materials. In this study, porous fibrous materials using the hollow PET (polyethylene terephthalate) fibers are developed and evaluated to meet the acoustic requirement of the current automotive components, which can be reduce the weight and achieve the higher acoustic performance. Copyright © 2013 SAE International and Copyright © 2013 TSAE.

Jeoung S.K.,Korea Automotive Technology Institute | Ha J.U.,Korea Automotive Technology Institute | Ko Y.K.,Korea Automotive Technology Institute | Kim B.-R.,Korea Automotive Technology Institute | And 5 more authors.
International Journal of Precision Engineering and Manufacturing | Year: 2014

The biodegradability of the environmental dash isolation pad was determined under aerobic conditions (ISO-14855-1). The environmental dash isolation pad was fabricated with polyester fiber and low-melting PLA fiber (LM-PLA), instead of low-melting polyester fiber. The results showed a biodegradation of 27% under aerobic conditions within a period of 45 days of composting. The commercial dash isolation pad using LM-PET (polyethylene terephthalate) fiber did not biodegrade under aerobic condition. The decrement of tensile strength and weight loss of PET/30% LM-PLA composite after 40 days were 50% and 24%, respectively, since the LM-PLA was degraded due to the progression of biodegradation. The change of molecular weight of LM-PLA fiber was examined by Gel Permeation Chromatography (GPC). The degradation of the polymer chains was caused by aerobic bacteria and its molecular weight was gradually reduced. The environmental dash isolation pads were left with 18 months under atmospheres, however, the change of tensile strength were lowing 19.8%, while the commercial dash isolation pad resulted in 19.6%. It showed a reduction of 50% in its tensile strength under aerobic conditions, no deformation or cracks were observed after the durability test. © 2014 Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg.

Hyundai Motor Company, Nvh Korea Inc. and Kia Motors | Date: 2013-04-11

Disclosed is a highly heat resistant sound absorbing material for a vehicle capable of maintaining a shape even at high temperatures of about 200 C. or above and which satisfies UL 94V-0 flame retardancy. More particularly, the a highly heat resistant sound absorbing material includes a fiber material having a limiting oxygen index (LOI) of at least about 25% and capable of maintaining a shape at a temperature of about 200 C. or above, and a thermosetting binder resin capable of maintaining a shape at a temperature of about 200 C., wherein the fiber material and thermosetting binder resin are provided at a specific proportion.

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