Very High Cycle Fatigue and Damage Behavior of Ti6Al4V

Abstract

High frequency fatigue tests were carried out with a 20 kHz ultrasonic testing facility to investigate the cyclic deformation behavior of Ti6Al4V in the Very High Cycle Fatigue (VHCF) regime in detail. The S,Nf -curve at the stress ratio R = -1 shows a significant decrease of the stress amplitude and a change from surface to subsurface failures in the VHCF regime for more than 107 cycles. Microscopic investigations of the distribution of the α-and β-phase of Ti6Al4V indicate that inhomogeneities in the phase distribution are reasons for the internal crack initiation. Scanning electron microscopy as well as light microscopy were used to investigate the internal crack initiation phenomenon in the VHCF-regime. Beside the primary fatigue crack additional defects like micro cracks and crack clusters were observed in the fatigued specimens. SEM-investigations of specimens which were loaded up to 1010 cycles without failure show irreversible microstructural changes inside the specimens. Two step tests were performed to evaluate the influence of internal fatigue induced defects observed in specimens which did not fail within 1010 cycles.

Fatigue Analysis of 5000 GT Ferry Ro-Ro’s Car Deck Using Finite Element Method

“…In the next stage, after the pressure value is obtained, meshing process the car deck construction model and running on a finite element based application to find the maximum stress value that works on the car deck construction, as to the results of running on element-based software [16], The meshing result of the car deck construction model is shown in Figure 2, and the result for 110% plate thickness variations is shown in Figure 3. The meshing process sets the distance between the elements that must be carried out using finite element-based software to go through the pre-processing stages before doing the analysis.…”