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Lee K.S.,Yonsei University | Jeon B.,Yonsei University | Cha S.W.,Yonsei University | Jeong K.-Y.,Hyundai and Kia Corporate Research and Development Division | And 4 more authors.
Polymer - Plastics Technology and Engineering | Year: 2011

Many currently produced plastic automotive parts use glass fiber reinforced plastic for enhanced strength and reduced vehicle weight. Apart from glass fiber, there are many manufacturing process factors concerning the production of the glass fiber reinforced plastic parts and their characteristics. This paper employed Taguchi's method, a correlation analysis, and an axiomatic design to study the optimizing process for glass fiber-reinforced plastic parts. The major factors affecting the characteristics of the plastic-based automotive parts were determined, and the optimal conditions for the parts were deduced. © Taylor & Francis Group, LLC.


Park C.,KAIST | Huh H.,KAIST | Kim J.,Korea Railroad Research Institute | Ahn C.,Hyundai and Kia Corporate Research and Development Division
Journal of Composite Materials | Year: 2012

This article is concerned with the tensile characteristics of polymers at various strain rates. Tensile characteristics at the high strain rate are important in the prediction of deformation modes of polymeric components which undergo high-speed deformation during car crashes. Uniaxial tensile tests at strain rates ranging from 0.001 to 100 s-1 were conducted using a tensile testing machine (INSTRON 5583) and developed high-speed material testing machine. Since the deformation of polymers is accompanied by localized deformation and a conventional extensometry method is no longer valid for strain measurement, a force equilibrium grid method (FEGM) is newly proposed to acquire accurate true stress-true strain curves of polymers. FEGM is utilized with images of the non-uniform distribution of deformation at each elongation stage captured by a high-speed camera in combination with a grid method. The relation between true stress and true strain at the desired strain rate and increment was determined by collecting the load data from the equilibrium and deformation images. © 2012 The Author(s).


Suh J.-Y.,Korea Institute of Science and Technology | Lee Y.-S.,Korea Institute of Science and Technology | Shim J.-H.,Korea Institute of Science and Technology | Park H.M.,Hyundai and Kia Corporate Research and Development Division
Computational Materials Science | Year: 2012

A methodology is proposed for predicting the elastic properties of precipitation-hardened alloys by combining different modeling techniques: the CALPHAD method, first-principles calculation, and elasticity models. The proposed procedure was applied to conventional aluminum cast alloys to predict their elastic moduli. The predicted Young's moduli are in reasonable agreement with values reported in the literature, which verifies the potential applicability of the methodology to the development of high-stiffness aluminum cast alloys. © 2011 Elsevier B.V. All rights reserved.


Kwon J.B.,Korea Advanced Institute of Science and Technology | Huh H.,Korea Advanced Institute of Science and Technology | Ahn C.N.,Hyundai and Kia Corporate Research and Development Division
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2016

This paper describes the experimental procedure to reduce the load ringing phenomenon in dynamic tensile tests. Reduction and prevention of oscillations in the force signal is an important criterion in the selection of the test jigs. A slack adaptor type jig system has been newly developed for acceptable response at high strain rates. Dynamic tensile tests were conducted using a servo-hydraulic machine with high strength steel sheets at the strain rate of 200 s-1. A piezo-electric load cell is used to measure the force. To confirm and determine the proportion of oscillations from bending effects on a specimen, two strain gauges are attached on the both sides of the gauge section for measurement of the difference in signals with deformation. A digital image correlation (DIC) method is employed to measure the strain during tensile tests. Experimental results show that the load ringing phenomenon in raw data of measured load signals has remarkably diminished with the slack adaptor jig newly developed at a strain rate of 200 s-1. © The Society for Experimental Mechanics, Inc. 2016.


Lee J.Y.,Hyundai and Kia Corporate Research and Development Division | Park H.D.,Hyundai and Kia Corporate Research and Development Division | Kim S.J.,Hyundai and Kia Corporate Research and Development Division | Han J.M.,Hyundai and Kia Corporate Research and Development Division | And 3 more authors.
SAE International Journal of Materials and Manufacturing | Year: 2010

Many engineers have been working to reduce brake noise in many ways for a long time. So far, a progress has been made in preventing and predicting brake noise. Nevertheless, there are some discrepancies of brake noise generation propensity between testing for the prototype and the production. As known in general, the reason for this unpredicted brake noise occurrence in production is partly due to the variation of the resonant frequency, material and the other unpredictable or unmanageable variations of the components in a brake system. In this paper, effects of chemical components and casting process of gray iron brake disc on its resonant frequency variation have been studied. Especially this paper is focused on the variation in material aspects and manufacturing parameters during disc casting in usual production condition. And their effects are investigated by the variation of out-of-plane modal resonant frequency. © 2009 SAE International.

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