NONLINEAR AND CHAOTIC OSCILLATIONS OF COMPOSITE PLATES AND SHELLS UNDER PERIODIC HEAT LOAD

In the present research study we attempt a computer simulation of nonlinear dynamic oscillations of laminated composite plates and shells under the action of a periodic heat load, We show that the inclusion of the geometrical stiffness accounting for certain membrane forces caused by a thermal gradient in conjunction with damping forces can trigger thermal oscillations with an explosive growth of amplitudes that can eventually lead to erratic, irregular and even catastrophic response. We address both plates and shells in which damping forces are accounted for, The nonlinear thermoelastic dynamic problem is solved using our implicit cubic Hermitian scheme which can easily accommodate a change of material properties with temperature. All computations are conducted with the multilayer flat triangular shell element LACOT which comprises 6 natural rigid-body and 12 straining modes. The findings of the present study can be used to study more elaborately thermal flutter phenomena occurring in composite structures under the action of periodic heat loads. Further ramifications of the computer simulations point to the importance of an accurate and economical shell element capable of revealing peculiar structural behaviour. This latter point substantiates our triangular element and the physical arguments that led to its development.