Microstructure Mechanics Analysis And Numeric Computation For The Thermal Deformation Of Grid Sandwich Strucutres

Since the complexity and discontinuity of the structure of the core, it is difficult to analyse the deformation of the grid sandwich structure under loads. Especially for the thermal bending deformation of the grid sandwich structure under the temperature load, the bending of the face sheets and the shear deformation of the core should be considered apart from the thermal expension of the face sheets and the webs. The deformation theory for grid sandwich structure under pure mechanical force, which considered the stretch of the face sheets and the shear deformation only, is no longer suitable to analyse the deformation of the structure in the situation of temperature load. On the basis of microstructure mechanics analysis of the cell, the homogenization equivalent theory model for the grid sandwich structure was established in this article, and the thermal deformation of one and two dimensions grid sandwich structures were systematically analyzed. The main research works are as follows:1. By analysing the cell structure and considering the interaction between the thermal expend face sheets and webs, the theory models for the thermal deformation of the grid sandwich structures were established, respectively, in the situations that the bending effect of the webs were considered or not. The relationship of generalized internal forces and generalized deformations at at two sides of the cell was given. Using the transfer matrix method, the thermal deformation of the grid sandwich cantilever beam was calculated. The numerical results were in good agreement with that calculated by three-dimensional finite element analysis software and it demonstrated the validity of the theory model provided in this article.2. For the thermal deformation of the grid sandwich elastic plate structure, besides the effect of the thermal expansion of the face sheets and the webs, the bending of the face sheets and the deformation of the webs in plane stress situation caused by the shear stress between them were considered. The thermal deformation of the grid sandwich plate was analysed by using cell analysis. The homogenization equivalent orthotropic plate model was established under displacement and stress continuity conditions at the interface of the face sheets and webs. The analytical expressions of equivalent thermal expansion coefficient were given. The numerical results were in good agreement with that calculated by three-dimensional finite element analysis which demonstrated the validity of the theory model provided in this article.3. In order to analyze the micropolar effect in thermal deformation of the grid sandwich elastic beam further, the theory model of the homogenization equivalent micropolar thermal elastic beam was established based on the micropolar thermoelastic theory. The equivalent micropolar thermoelastic parameters for the grid sandwich beam were received by cell energy equivalent. The numerical results show that the equivalent micropolar thermoelastic beam model presented in this article can precisely simulate the thermal deformation of grid sandwich beam structures.4. The equivalent micropolar thermoelastic beam model was generalized. By the method of cell displacement equivalent, the equivalent micropolar plate theory for the thermal deformation of the grid sandwich elastic plate was established and some numerical examples were given.