The effect of interfacial contact and damage gradient on fretting fatigue of Ti-6Al-4 V dovetail assembly using a multiaxial fatigue framework

Abstract

In this study, fretting fatigue tests were performed on dovetail assemblies. The displacement and strain of the components during testing were recorded using Digital Image Correlation (DIC) equipment. The results revealed that the dovetail assembly gradually exhibited a sticking phenomenon, stabilizing after approximately 10,000 cycles, with relative slip significantly reduced compared to the initial cycles. Surface wear and temperature were also monitored. The findings showed that during the fretting tests, a considerable amount of wear debris accumulated in the contact zone, increasing the coefficient of friction (COF) and intensifying the sticking phenomenon. This led to reduced frictional energy, causing minimal changes in surface temperature. Consequently, for fretting fatigue in dovetail assemblies, localized stress concentration emerged as the primary factor affecting fatigue life, surpassing influences from relative slip, surface wear, and frictional heat generation. Additionally, a finite element model of the dovetail assembly was developed, incorporating the Chaboche material constitutive model to calculate the stable stress–strain distribution under cyclic loading. The model’s predictions were validated against the DIC test results. Based on an established multiaxial fatigue framework, a program was developed to post-process the simulation results, producing diagrams for critical angles and damage distribution. To address the characteristics of local damage gradients, a method for selecting the critical distance and applying damage gradient correction was proposed. This approach was successfully applied to the SWT and FS models, demonstrating excellent validation.