Higher Mode Buckling of Bimetallic Beam

An analysis is made of the thermal buckling and snap-through action of an initially curved bimetallic beam, supported by two hinges at the extremities. A beam theory solution is obtained for the bimetallic element, which shows that the deflection and snap-through response of the bimetallic beam, to increasing temperature, is considerably different from the approximate solutions obtained by Timoshenko and by Burgreen. The validity of the earlier treatments is dependent upon the maintenance of a first mode deflected shape, whereas in the present analysis this restriction is removed. It is found that thermostatic snap-through is obtainable at low temperatures, only when there is a large difference in the coefficients of expansion of the bimetallic constituents, but that snap-through will always take place at sufficiently high temperatures. This high temperature behavior of the beam was not obtained in the approximate one-mode solutions.