Papers by Author: Sung In Bae

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Authors: Do Hyun Jung, Sung In Bae, Joung Woo Phark
Abstract: It is well-known that the noise and vibration from the torque change of the engine and the inertia change of its accessories (alternator and water pump) have severe effects on both the quality and the life expectancy of the engine belt system. An automatic belt tensioner is generally used not only to reduce the noise and vibration of such belt system, but also to enhance the life cycle. In the present research, measurement of the user running conditions and the data analyses were performed to try to derive an evaluation method of life cycle of such an automatic belt tensioner system. As a part of results, a running condition for the evaluation was suggested from the study of conditions loaded on an automatic belt tensioner. This running condition was divided into two parts, the Structure part and the Pulley one, and suggested separately for the accelerated life-test of the system. As the other part of the results, an accelerated life-test condition was derived using Palmgen-Miner rule for structure part. And a modified accelerated life-test condition, which uses temperature as an acceleration factor, was suggested for pulley part.
1797
Authors: Byeong Wook Noh, Young Woo Choi, Sung In Bae
Abstract: Automobile pedal which is loaded by driver’s input is transmitting load to throttle cable, braking device and clutch device and controlling automobile. Measuring working condition and applying equivalent damage are needed for reliability of developing pedal. The measuring working condition is requiring more investigation with various respects because of widely ranged drivers, road condition and environmental condition. Additionally, when equivalent damage is applied, there are not suitable for test condition if equivalent damage is too high level to apply or unused region. In this study, load history is measured with 95percentile customer. Measured load history is converted to stress history about critical area of pedal by FEM. There are drawn up histogram of pedal cycles and load from stress history with rain flow cycle counting method, calculated relative damage of extended stress history with Palmgren-Miner rule. From the results, calculated total relative damage is applied to calculation method of test time and load. Calculation method for test condition is carried out with three methods which are enforcing with total stress by rain flow cycle counting, representative load and blocked load. Accelerated durability test condition of pedal using with relative damage and acceleration factors are proposed.
1273
Authors: J.I. Song, Sung In Bae, Kyung Chun Ham, Kyung Seop Han
1267
Authors: Do Hyun Jung, Sung In Bae
Abstract: Time domain approach with S-N approach and local strain approach were used for fatigue life estimation. But these days, using PSD (Power Spectral Density) method is highlighted, because of short amount of time in measurement and analysis. Especially, PSD method is useful for analysis of fatigue failure which is caused by vibration damage, also FRF (Frequency Response Function) is useful for efficient prediction of fatigue life when the same product is employing different motor vehicle or test condition. In order to estimate fatigue life of compressor for air conditioning, time domain analysis and frequency domain analysis were performed and the results were compared. As a result, results of analysis in frequency domain and time domain were similar. With this, there is recognition of decreasing the period of measuring and analysis in PSD analysis. Moreover, in case of FRF pursued of a part, using FRF is applicable at fatigue life prediction in different testing condition. There was investigated an analysis method with curtailed analysis period by FRF.
1776
Authors: Do Hyun Jung, Sell Song, Pilsu Shin, Sung In Bae
Abstract: Automatic belt tensioner for stabilization of Engine accessory belt system is made increase its life, decrease noise and vibration and increase its commercial value. Therefore, it is important finding test mode to assess life of automatic belt tensioner. However, measurement and analysis test result in practical test condition on real road needs requiring much test time and finance. In this study, there is analyzed and established test mode which is loaded measured equivalent damage in real working condition, compared test condition of pre-established test mode and FTP- 75 mode of fuel efficiency test and verified advantages and disadvantages of each mode. Because FTP-75 Mode is for measuring fuel efficiency related with engine, applying FTP-75 mode is estimated suitability for test of engine accessory. Comparison and assessment of damage is investigated structure and pulley part. Equivalent damage is calculated with Palmgren-Miner Rule and representative stress method, test condition of automatic belt tensioner is investigated. This investigation is regarded as being useful to life evaluation of both automatic belt tensioner and other engine accessory component.
133
Authors: Koeng Wook Ko, Hyun Soo Kim, Sung In Bae, Eui Seok Kim, Yuan Shin Lee
Abstract: It is not easy to simulate realistic mechanical behaviors of elastically deformable objects with most existing mass-spring systems for their lack of simple and clear methods to determine spring constants considering material properties (e.g. Young's modulus, Poisson’s ratio). To overcome this obstacle, we suggest an alternative method to determine spring constants for mechanical simulation of deformable objects under compression. Using the expression derived from proposed method, it is possible to determine one and the same spring constant for a mass-spring model depending on Young's modulus, geometric dimensions and mesh resolutions of the 3-D model. Determination of one and the same spring constant for a mass-spring model in this way leads to simple implementation of the mass-spring system. To validate proposed methodology, static deformations (e.g. compressions and indentations) simulated with mass-spring models and FEM reference models are compared.
369
Authors: Byeong Wook Noh, Sung In Bae, Kyung Chun Ham
Abstract: A fatigue analysis program to calculate fatigue lives of mechanical components and structures from FE(Finite Element) results is developed. The useful characteristic of this program is operated under Web environment. So, any designer who design fatigue strength of components and structures can use without other program installation. For the assessment of multi-axial fatigue damage, signed equivalent stress method and critical plane approach have been employed. Each method is compared and the results of Signed von Mises stress method has similar to the results of Smith-Waston-Topper's parameter using critical plane approach. The results were compared with those from commercial program FE-Fatigue6.0 and it was observed that fatigue life and cumulative damage distribution calculated applying same fatigue resistance curve. The results of calculated fatigue life using Web based program agree well with those from FE-Fatigue6.0.
1265
Authors: Byung Il Kim, Byeong Wook Noh, Young Woo Choi, Sung In Bae, Jung I. Song
Abstract: Impact behaviors of Aluminum Honeycombs Sandwich Panel (AHSP) by drop weight test were investigated in this study. Two types of specimens with l/2" and l/4" cell size were tested by two impactors with the weight of 5.25kgf and 11.9kgf respectively. Transient, contact and elastic-plastic analyses were performed by finite element method. Impact behavior of AHSP about impact sites appeared nearly the same in low impact energy, but it was different in high impact energy. Face was the strongest about impact and short-edge was the weakest. The damaged area of AHSP was enlarged with the increase of impactor weight that is corresponding to impact energy. After 3-point bending test, fracture modes of AHSP were analyzed with AE counts, lower face sheet was fractured in the long-edge direction first, and then separation between face sheet and core happened. In the short-edge direction after core wrinkled, lower face sheet was torn, impact behavior by FE analysis were increased localized damage in high velocity because the faster velocity of the impact was, the smaller the stress of core was. Consequently, impactor weight had an effect on widely damaged area, while the impact velocity gave rise to localized damaged area.
67
Authors: J.H. Kim, K.H. Kim, K.K. Joung, Kyung Chun Ham, J.I. Song, Sung In Bae
1029
Authors: Byeong Wook Noh, Young Woo Choi, Jung I. Song, Sung In Bae
Abstract: The Combine is necessary equipment in the agricultural industry. The components of the Combine are worked for a long time under inferior environmental condition. Especially reaping knife is worked in high frequency domain, and submit fatigue load while use. So, fatigue test was performed to obtain the S-N curve of real component, and load history is measured through field test. The local stresses due to these loads have been calculated by FEM. These results have been used as the input values for the multi-axial fatigue analysis of real components. For the assessment of multi-axial fatigue damage, the critical plane methods have been employed. The used parameters of critical plane methods are Morrow’s, Smith-Waston-Topper’s, and Brown-Miller’s, those were modified for the high cycle fatigue region within elastic behavior. In addition, design improvement is performed about shape of reaping knife to increase the endurance limit, and durability test for improved knife is performed. It is found that the fatigue life of improved reaping knife is increased, and durability test result show that life of reaping knife is increased enough.
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