Mechanical behavior, microstructural deformation mechanisms, and reliability evaluation of titanium alloy helical springs in extreme space environments with magnetic fields

Revealing the failure mechanisms of metallic elastic structural components under multi-physics field coupling in deep space and analyzing their mechanical behavior is crucial for evaluating long-term performance and predicting reliability and safety events in advance. This paper investigates the failure mechanisms and mechanical behavior evolution of Ti–6Al–4V cylindrical helical compression springs under the multi-physical field coupling in deep space exploration missions through high-fidelity environmental simulation experiments. Specifically, the microstructural evolution mechanisms of Ti–6Al–4V springs in the deep space multi-physical field coupling environment were characterized using electron microscopy, and the potential failure behaviors were analyzed. Furthermore, a time-dependent constitutive model for the mechanical properties of Ti–6Al–4V springs was established to describe the degradation trend of their mechanical performance quantitatively. Finally, a statistical model for evaluating the life and reliability of Ti–6Al–4V springs under complex multi-physical fields, considering multiple stress factors such as temperatures and magnetic fields, was developed using the unified log-linear equation and the maximum likelihood estimation method optimized by the differential evolution algorithm. The main findings and methods developed in this paper will effectively serve in the design and performance evaluation of metallic elastic structural components in deep space probes, ensuring the successful execution of deep space exploration missions.