A heat energy dissipation approach has been formulated to assess the crack propagation rate of mode I fatigue cracks in AISI 304L stainless steel specimens. The proposed experimental approach relies on the heat energy converted from the plastic strain hysteresis energy at the crack tip. Practically, the heat energy is estimated starting from temperature measurements in the vicinity of the crack tip by means of an infrared camera. The approach evaluates the heat energy dissipated in a properly defined control volume surrounding the crack tip, reminiscent of Neuber’s structural volume to account for stress gradient effects caused by notches. The investigation performed has revealed that the control volume size varies with fatigue lifetime, in that the longer the fatigue life is, the smaller the control volume size. However, a fixed control volume size proved to correlate well the available crack growth data. The proposed experimental method has also been compared with the theoretical approach, which assumes the plastic strain hysteresis energy evaluated inside the cyclic plastic zone as a crack driving force.
A heat energy dissipation approach to elastic-plastic fatigue crack propagation
G. Meneghetti
;M. Ricotta
2020
Abstract
A heat energy dissipation approach has been formulated to assess the crack propagation rate of mode I fatigue cracks in AISI 304L stainless steel specimens. The proposed experimental approach relies on the heat energy converted from the plastic strain hysteresis energy at the crack tip. Practically, the heat energy is estimated starting from temperature measurements in the vicinity of the crack tip by means of an infrared camera. The approach evaluates the heat energy dissipated in a properly defined control volume surrounding the crack tip, reminiscent of Neuber’s structural volume to account for stress gradient effects caused by notches. The investigation performed has revealed that the control volume size varies with fatigue lifetime, in that the longer the fatigue life is, the smaller the control volume size. However, a fixed control volume size proved to correlate well the available crack growth data. The proposed experimental method has also been compared with the theoretical approach, which assumes the plastic strain hysteresis energy evaluated inside the cyclic plastic zone as a crack driving force.
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