Viscous Property of Steel and Its Effect on Strain Wave Front

Abstract

When an axial step load is applied experimentally at one end of a semi-infinite bar, the stress wave front is not an exact step but is accompanied with some finite rising time. In this paper, the effect of the viscous property of the material on the shape of the wave front is considered.To express the viscoelastic property of the material, a Voigt model is used for the analysis. The approximate solutions for the strain wave and the stress wave are obtained and it is clarified that the rising time is proportional to √(τt), where t is the elapsed time after the impact and τ is the relaxation time.The relaxation times for steel and stainless steel are also measured experimentally and it is revealed that the values of the relaxation time of steels are less than 10^-8 sec.