3. Some materials exhibit viscoelastic behavior that can be modeled by a spring (EA) attached in series with a parallel spring (EB) and dashpot (no) as shown below. \"c Write down all equations needed to determine the constitutive relationship between overall stress and total strain in this model. What is the constitutive equation for this model? Determine the constitutive equation for an applied step strain of em = so htt}. What is this type of response called? What is the glassy relaxation modulus? What is the equilibrium relaxation modulus? Given that EA = 20 GPa. E3 = 1 GPa. I] = 100 GPa'sec. plot [e.g., using excel} the stress for this model due to an applied strain ofO.5 for 100 sec. What is the initial stress at t=0+sec'? What is the stress at t = 100 sec'? Plot the relaxation modulus as a function of time for the constant applied strain in part ((1). Use a log axis for time ranging from 0.01 to 100 sec