Experimental and numerical investigations on dynamic and acoustic responses of a thermal post-buckled plate

Experiments were carried out for a clamped rectangular aluminum plate to study the dynamic and acoustic behaviors in both pre- and post-buckling ranges under thermal loads. Plate temperature was elevated from ambient value to the level above the theoretical critical buckling temperature of the plate. In the whole test temperature range, the measured frequencies decreased to the minimum values in sequence, and then turned to increase as temperature rose. The softening effect of thermal stresses played the leading role in the decreasing stage and the stiffening effect of thermal buckling deflection became the major influence factor in the increasing stage. The later one could drive the temperature equilibrium point of the heated plate to move towards lower temperature range. All the frequencies would not drop to zero due to the inherent initial deflection which provides additional stiffness to the plate. Dynamic responses state two variation trends in different temperature ranges, shifting toward the lower frequency range and closing up in the mid-frequency range. The characters of spectrum responses changed gradually as the temperature was elevated. Numerical simulations gave predictions with same variation trend as the test results.