Prediction of Residual Stress Relaxation in Ti-6Al-4V subjected to Laser Peening
Pp. 326-353 (28)
Anoop Vasu and Ramana V. Grandhi
Laser peening is an advanced surface enhanced method which induces
compressive residual stress on the critical regions of components prone to fatigue
failure. However, the residual stresses relax under the fatigue loading conditions.
Constitutive models have to be robust enough to predict the residual stress
relaxation mechanism. Although tensile cold working increases the tensile yield
strength, the compressive yield strength is reduced. As a result of this, a lower
compressive load can relax the initial compressive residual stress. This
phenomenon, termed as Bauschinger Effect, can be represented by an analytical
stress-strain model to predict the relaxation effects based on the cold working of
the material. Three dimensional finite element (FE) models are created to represent
residual stress relaxation in a low cycle fatigue regime for Ti-6Al-4V material. The
creation of the numerical model for simulating stress relaxation model involves
two phases. The first phase is modeling the stress gradient effect which relates to
the effect of cold working. This process utilizes a laser peening simulation model.
The second phase is modeling the stress-strain response of the material by creating
a mixed hardening model.
Finite element analysis, Laser peening, Low cycle fatigue, Mixed hardening, Residual stress relaxation, Surface enhancement
Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435, USA.