The relation between fatigue crack growth rate and plastic energy dissipation in 7075-T6

Plastic dissipation accompanies fatigue crack growth in ductile materials. Previous studies presented a relation between plastic dissipation (dW/dN) and the fatigue crack growth rate (da/dN), where some researchers assumed a linear relation between both to enable crack growth predictions. To study the validity of this assumption, this paper reports an experimental study on fatigue crack growth in 7075-T6, an alloy widely used in aerospace. The experimental results suggest, however, a nonlinear relation between dW/dN and da/dN in 7075-T6. The value of dW/ da, indicating the plastic dissipation per unit fatigue crack growth, is not constant. Hence for 7075-T6 it is concluded that dW/dN cannot be used directly to predict da/dN.

Automated summary

Based on experimental data, this study concludes a non-linear relationship between plastic dissipation and fatigue crack growth rate in 7075-T6 alloy, which cannot be directly used to predict crack growth rate.