변후(變厚)용접판재에서의 피로균열성장거동에 미치는 잔류응력의 영향에 관한 파괴역학적 연구

차용훈 한국산업안전학회 1993 한국안전학회지 Vol.8 No.1

The welding implementation used widely in the industrial field is gradually increasing due to weight reduction unlimited material thickness simplified structure design, and 1 manufacturing time and cost reduction. The most significant factor that influences the fatigue crack growth rate is the residual stress generated during the welding process. Many researchers have studied the effect of the residual stress on crack growth behavior. Through a fatigue test in a various-thickness welded specimen redistributed residual stress is measured as the crack is developed. Then, by superposing the measured residual stress on the K value obtained by the finite element method.

신경회로망을 이용한 용접잔류응력 예측 및 최적의 용접조건 선정에 관한 연구

차용훈,이연신,성백섭 한국안전학회 2001 한국안전학회지 Vol.16 No.5

In this study, it is developed that the system for effective prediction of residual stresses by the back-propagation algorithm using the neural network. To achieve This goal, the series experiment were carried out and measured the residual stresses using the sectional method. Using the experimental results, the optional control algorithms using a neural network should be developed in order to reduce the effect of the external disturbances during GMA welding processes. Then the results obtained from this study were compared between the measured and calculated results, weld guality might be controlled by the neural network based on backpropagation algorithm. This system can no only help to understand the interaction between the process parameters and residual stress, but also improve the quantity control for welded structures.

광탄성법을 이용한 압력용기 용접부의 잔류응력 영향 평가

차용훈,성백섭,이연신,김덕중,박영문,김충환 한국경영공학회 2002 한국경영공학회지 Vol.7 No.2

인장-전단하중을 받는 점 용접재의 변형률 분포 특성 평가

차용훈,김덕중,이연신,성백섭 한국공작기계학회 1999 한국생산제조학회지 Vol.8 No.6

In order to evaluate strength of spot welded joint, at first it is importent that we should know strain distribution near nugget zone. During loading, in HAZ, compressive strain increase with Increase of load, but in nugget zone, tensile strain increase. During unloading, on the other hand, even though the load decreases, the strain variation is not almost appeared in nugget zone and HAZ. In nugget boundary zone, the strain range increases continuously along with load increase on outer surface, but the strain increases continuously and decreases rapidly beyond yield strength on inner surface. In this paper, strain distribution are measured in inner and outer surface with variation of thickness and load under tensile-shear load. Tensile-shear strength increased as with increase of specimen thickness. As for thickness increase rates are 25%, 50%, 100%, and 150%, tensile-shear strength increase rates are 40%, 81%, 130% and 228%.

CIM을 이용한 수문 설계시스템 개발

차용훈,성백섭 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.2

Today manufacturing industries are at the threshold of utilizing innovative and improved computer related technologies for the betterment of manufacturing industries. Characteristics of the present world market include demanding and sophisticated customers, requirement of high quality and innovative products, greater product diversity, increasing labour and products costs, availability of diverse alternatives to the customers and smaller batch sizes to satisfy a variety of customer profiles. To fulfil these characteristics, manufacturing companies need to be flexible adaptable, proactive and able to produce variety of products in short time at low cost. The aim of this research is to develop a computer-aided design system for water-gate on AutoCAD R2000 system. The developed system has been written in AutoCAD and VisualLISP with a personal computer, and is composed four modules which are the gate-lifter input module, guide-frame input module, template input module and upgrade module. Based on knowledge-based rules, the system is designed by considering several factors, such as width and height of a water-gate, material, object of product and maximum depth of water.

알루미늄 合金 熔接部의 疲勞龜裂成長擧動에 關한 破壞力學的 硏究

차용훈,김덕중 한국공작기계학회 1996 한국생산제조학회지 Vol.5 No.3

the objective of this study is to investigate the influence of welding residual stresses on the fatigue crack growth behavior of cracks located transverse to the weld bead. For this purpose G.T.A. (Gas Tungsten Arc) welding was performed on the A1 alloy 1100-O plate and the same initial crack is made on HAZ(Heat Affected Zone), weld metal and base metal respectively. Specimens were used CT(Compact Tension) specimens. Initial welding residual stresses were measured by using strain gage sectioning method. All specimens were tested under constant amplitude load with stress ratio R=01, It is possible to predict fatigue crack growth behaviors and the fatigue life, using numerical analysis together with distribution of initial residual stress and the values of C and m obtained from da/dN-ΔK

신경회로망을 이용한 평판 맞대기용접의 잔류응력 예측시스템 개발

차용훈,성백섭,이연신 대한용접접합학회 2003 대한용접·접합학회지 Vol.21 No.1

This study develops a system for effective prediction of residual stresses by the backpropagation algorithm using the neural network. To achieve this goal, a series of experiments were carried out to and measured the residual stresses using the sectional method. With the experimental results, the optional control algorithms using a neural network could be developed in order to reduce the effect of the external disturbances during GMA welding processes. Then the results obtained from this study were compared between the measured and calculated results, weld guality might be controlled by the neural network based on backpropagation algorithm.. This system can not only help to understand the interaction between the process parameters and residual stress, but also improve the quantity control for welded structures.

高張力鋼 被服 아아크熔接에서의 入熱量의 影響에 관한 硏究

차용훈,정종안 조선대학교 동력자원연구소 1992 動力資源硏究所誌 Vol.14 No.2

To study the effect of heat input on cracking ratio of high tensile strength steel weld metal, Y groove cracking test method was adopted and the samples were prepared by manual welding. Then the cracking ratio, microstructure and fracture surface were examined. The obtained results are as follows: 1. As heat input is increased, the hardness of fusion line in weld metal is decreased, but the hardness is increased. 2. As heat input is increased, the metal structure of HAZ consists of pearlite and ferrite. 3. Increasing the heat input results in the grain growth and the brittle fracture.

SS400강판 맞대기용접부의 Out-of-plane 변위측정

차용훈,성백섭,김덕중,김성현,김충환 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1

Currently knowledge of strain in welds has mainly been obtained from strain gaging method which is directly attaching the gage to most of the material. The few non-contact method are still in the early stage. One of the non-contact methods is the use of the laser that has high-level of the accuracy for the measurement, and this laser also has excellent characteristics on which many studies for its applications are focused in the lot of fields. This study is focused on the measurement of the displacement caused by the characteristics and the temperature change of the CO2 welded zone which is used with 3-D ESPI (Electronic Speckle Pattern Interferometry) system that is functionally modified the laser ESPI system. This system employed the SS400 which are mainly used for the steel plate such as general welded structure, bridge, industrial machine and especially using structure of the Absorption Chiller-Heater.

熔接熱影響部의 破壞擧動에 關한 實驗的 硏究

車龍勳 조선대학교 기초과학연구소 1984 自然科學硏究 Vol.7 No.1

In order to investigate the fracture behavior of welded materials, specimens were welded by submerged are welding method, and the investigation of annealing effect on mechanical properties of test material carried out by changing the annealing temperature from 600℃ to 900℃. In the experiment, the investigation of mechanical properties to distinguish among base metal, heat affected zone and welded metallic zone. The experimental results obtained in this tests are as follows : (1) The tensile strength of test welded joint decreases in accordance with the increase of annealing temperature, and the tensile strength shows maximum value when annealed at 600℃ (2) Hardness distribution of welded joint brings about the maximum hardness in the fusion zone. (3) Hardness value was highest in the fusion zone of the toe HAZ of the heat affected zone. (4) The impact value of heat affected zone increases according to the rise of annealing temperature, and the maximum value of impact test occurs are 800℃, and the minimum value of impact test occurs at 600℃ (5) The impact value of the HAZ-fine was high when the toe HAZ was at room temperature and was lowest at under -25℃.