Study on impact fatigue test and life prediction method of TC18 titanium alloy

To study the impact fatigue properties of TC18 titanium alloy and propose a new damage model for the impact fatigue life prediction of material, the impact fatigue test method and the impact response measurement scheme are designed. The impact fatigue tests are then implemented on a drop hammer impact test machine to obtain the fatigue lives and impact responses of the tested specimens under different impact conditions. A new impact damage model is proposed based on the theory of continuum damage mechanics considering the effect of strain rate. The calibration method of material parameters is presented, and the parameters of the impact damage model are obtained according to the test data of TC18. Afterward, the numerical implementation of impact damage calculation is established, and an ABAQUS user-defined subroutine is used to realize the finite element numerical simulation of impact fatigue damage accumulation. Finally, the damage evolution of TC18 under tensile impact fatigue loading is simulated and the corresponding fatigue life is predicted. The errors between the calculated impact fatigue lives and the experimental lives are less than 25%, which demonstrates the good validity and applicability of the proposed damage model and the numerical method.

Automated summary

This study aims to investigate the impact fatigue properties of TC18 titanium alloy and propose a new damage model for predicting the impact fatigue life of materials. By designing the impact fatigue test method and measurement scheme, the fatigue lives and impact responses of the tested specimens were obtained under different impact conditions. A new impact damage model considering the effect of strain rate was proposed based on the theory of continuum damage mechanics. The model parameters were calibrated using the test data of TC18. The numerical implementation of impact damage calculation was established, and a user-defined subroutine in ABAQUS was used for finite element numerical simulation. The simulation results of the damage evolution and fatigue life prediction of TC18 under tensile impact fatigue loading showed errors within 25% compared to experimental results, demonstrating the good validity and applicability of the proposed damage model and numerical method.