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The rocker arm has a function to lead the cam shaft rotation to the valve operation. There are cases when damages are caused due to abnormal wear at the sliding part, causing certain problems. Authors classified the wear phenomenon, and realized a systematic analysis on the possible cause of the damage. As a result, it was revealed that the damage was of two types, and to prevent the hard wear, it is effective to apply shot peening before plating. The prototype rocker arm was test under various lubricating conditions, thus actually confirming that the occurrence of wear was largely reduced.

The effects of strain rate on the deformation behavior of steels were investigated to find the most appropriate micro structure of steel for anti-crash parts of automobiles, such as front-side-members. The dual phase steel absorbed a higher amount of energy during dynamic deformation than other steel with the same static yield strength. The increase of volumetric fraction of the austenite phase in the dual phase steel deteriorates the dynamic deformation behavior. The FEM analysis for crash test of member also showed the superior performance of the dual phase steel.

The effects of strain rate on the deformation behavior of several steels were investigated to find the most appropriate material for anti-crash parts of automobiles, such as front-side-members. Dual phase steel, TRIP steel, and work hardened steel showed higher dynamic to static yield strength ratios than solid-solution hardened steel. The dual phase steel absorbed a higher amount of energy during dynamic deformation than other steels with the same static yield strength due to its high strain rate sensitivity and high work hardening coefficient during dynamic deformation.