6.A rod made of composite material is placed between rigid supports (This could be similar to a frp composite bridge deck). At 25C the rod fits perfectly between the rigid supports and there is no stress in the system. What temperature would the composite need to be cooled to in order for the composite to crack if it has a coefficient of thermal expansion of 30x10-6 mm/mm/C, a strength of 15 ksi, and an elastic modulus of 20,000 ksi. Assume the composite behaves as a linear elastic material