山形鋼部材の極低サイクル疲労破壊実験

Abstract

An experimental study is made of very low cycle fatigue failure of steel angle specimens under repeated loading. The primary objective is to extract decisive factors causing cracks and the ultimate failure in the course of loading repetitions of the order of a few to twenty cycles. The test specimen was subjected to axial loading repeatedly after undergoing inelastic buckling. The experimental investigation reveals that, regardless of loading patterns and deflection modes, visible cracks were initiated on the concave side of bending deformation when it was stretching. There is not a simple relationship between the state of fatigue failure and energy absorption capacity, but the energy absorption process of each member depends on the loading pattern and the deflection mode. The initiation of cracking due to the very low cycle fatigue is found to be related closely to the cumulative strain of the order of 25%-40% , regardless of the loading patterns, the deflection modes, and width-to-thickness ratios.