Fatigue Life Estimation of Damaged Integral Wing Spar Using XFEM

Abstract

This paper presents the application of the extended finite element method (XFEM) in crack propagation simulation on the integral wing spar that should replace existing differential spar of the light aircraft UTVA 75. Numerical model of integral spar was developed in software Abaqus. Stress intensity factors (SIFs) were calculated using add-in Morfeo/Crack for Abaqus and obtained number of cycles that would propagate crack to certain length was compared to the experimentally obtained number of cycles for differential spar. Numerical analysis showed that integral spar with the same dimensions as differential spar has significant increase in fatigue life. Analysis that was carried out showed that XFEM could be efficient and cost beneficial tool for simulation of crack propagation in the 3D structures (such as wing spar) and that it should be used in the future for fatigue analysis of newly designed structures in all phases of development and production.

Keywords

• crack propagation
• fatigue life
• stress intensity factor
• XFEM