Determination of Effective Stress Intensity Factor Range of Mode Ⅱ Fatigue Crack Propagation Using Improved Experimental Method

摘要

Many cases of rolling contact fatigue failure, such as those that occur in railway rails, rolling bearings, and gears, are due to repeated high shear load. In order to prevent such fatigue failures, the resistance of a material against to repeated high shear load must be determined. The fatigue crack growth rate is dependent on the stress intensity factor range of Mode Ⅱ ΔK_(Ⅱ). However, Mode Ⅱ crack propagation characteristics vary according to the method by which they are determined. We improved the experimental method proposed by Murakami and measured the effective stress intensity factor range of Mode Ⅱ ΔK_(Ⅱeff). Changes to the jigs and specimen were made and the experimental method was such that the ideal mechanical model was expected to be approached. Furthermore, to measure the ΔK_(Ⅱeff), several strain gauges were applied to the specimen around the crack tip. Using the improved method, some ΔK_(Ⅱeff) values during the Mode Ⅱ fatigue crack propagation tests can be measured.