Hello, I am trying to find stress and strain of a 68x12x3mm specimen under axial tension. I am using Al 6061-T6 as material. I am using ultimate strength=290MPa, yeild strength=245MPa, modulus of elasticity=69GPa, shear modulus=26GPa, poisson ratio=0.33, mass density=2700kg per cubic meter. While running the nonlinear static simulation, I am getting different strain at different time for the same load. Can you tell me why?