[재료] 무기력계수 및 하중속도효과를 고려한 고장력강의 극한강도 특성

This paper introduces a method to predict the effect of loading speed of high tensile steel materials of automobiles. The method is based on the lethargy coefficient concept and dynamic/impact failure characteristics by the tensile test. The lethargy coefficient is obtained from the simple tensile test such as failure time and stresses at fracture. These factors not only affect the static strength but also have a great influence on the fatigue of the joint and the adjacent structures. The purpose of this paper is presented a rational method of predicting dynamic/impact tensile tests on high tensile steel materials widely used for structural material of automobiles. It is known that the ultimate strength is related with the loading speed and the lethargy coefficient from the tensile test. Then this is strength used to analyze the failure life prediction of mechanical system by virtue of its material fracture. The dynamic/impact tensile strength analysis is performed to evaluate the life parameters due to loading speed with a numerical example using the proposed method. Also the evaluation of the dynamic/impact effect on the material tensile strength characteristics is compared with the result of existing equation to verify the composed method.