Thermo-Mechanical Response of Patched Plates

Abstract

A review, unie cation, and extension of the analysis and results pertaining to patched beam plates subjected to a uniform temperature e eld (heating and cooling ) and in-plane edge force (compressive or tensile ), is presented. A self-consistent nonlinear formulation has been derived, which lends itself to an exact analytical solution, to within the context of the model. Three nondimensional parameters are seen to characterize the response of the composite system. These are 1 ) a loading parameter, 2 ) a critical temperature, and 3 ) a critical membrane force. Critical behavior includes bifurcation buckling, asymptotic buckling, and sling-shot buckling, nontrivial ground states, and demarcation and transition in dee ection direction. Results for both heating and cooling are consolidated and presented in a unie ed manner, yielding a broader understanding of the problem of interest. UMEROUS aerospace, mechanical, and electronic structural components consist of a primary base structure with a secondary element bonded to it for the purpose of strengthening, stiffening, or providing thermal or electrical contact. Specie c examples are bonded sensors or repair patches on aircraft wings and fuselages or the attachment of electronic components to printed circuit boards. The combination of the primary and secondary structures forms a composite system. Because the structure has been changed with regard to its geometry and structural properties, the structural response canchangesignie cantly with theintroduction ofthepatch, with sometimes unanticipated performance as a result. In particular, the local stiffness has been changed, the neutral axis has been moved, and a thermal mismatch between the base structure and the patch may have been introduced. The last two will independently cause local bending, and together can induce novel behavior of the structure.