Experimental Investigation of Ti-6al-4v Alloy Fatigue Crack Growth Parameters

Analysis of stress and strain at the tip of fatigue crack by means of linear elastic fracture mechanics has led to the formulation of well known Paris’ equation which brings fatigue crack growth speed (da/dN) and stress intensity factor range at the crack tip (ΔK) in a relation.For the purpose of determining the fatigue crack growth parameters of titanium alloy Ti-6Al-4V a standard Charpy specimen was used and a three - point bending method on a resonating high - frequency pulsator. Standard fracture mechanics tests on notched specimens can provide insight into the fracture behaviour of materials under constrained deformation, i.e. under a threedimensional stress state. Specimens were taken from a plate with dimensions of 80x300x30 mm, made of Ti6Al-4V alloy. In order to monitor the increment of crack length, strain gauges were applied to the specimens. The obtained frequency was in the range from 215 to 235 Hz, while the stress ratio was R=0.1. Average load and it’s amplitude were registered with the ±3 Ncm accuracy. All tests were conducted at room temperature. Test results are intended for the finite element method (FEM) and extended finite element method (XFEM) analysis of bone fixation implants made of Ti-6Al-4V alloy