3. A thin-walled tube, closed at both ends is internally pressurized. Assume that the material obeys the Holloman equation = with K = 325 MPa and n = 0.3. Suppose that the tube has an initial diameter of 14 mm and a thickness of 0.75 mm. a. Determine the von Mises effective strain at which deformation becomes unstable with respect to pressure. b. Find the pressure at the point of instability.