How is stress strain response controlled?
At each time step, D-MOD2000 refers to the given stress-strain relation to obtain a value of shear stress (τ) from the current value of shear strain (γ). Because the shear stress is computed directly as a function of shear strain, the slope of the stress strain relationship, that is, the secant shear modulus (Gsec), does not have to be obtained explicitly. The new value of the shear modulus is then used in solving the equation of motion at the next time step. With this scheme mixed boundary conditions can be easily handled as the stresses, displacements or velocities at the boundaries are simply set to the required values (for the one dimensional shear wave propagation problem, the boundary conditions are different for the top and bottom layers but are otherwise the same for all intermediate layers).
