An alloy to be used for a spring application must have a modulus resilience of at least 0.71 x 10⁶ J/m³ (0.71 x 10⁶P a). What must be its minimum yield strength (in MPa)? Assume that the modulus of elasticity for this alloy is 102 GPa

Using Ur=Sig²/2E, I am getting 401.447E6 Mpa but apparently thats wrong.