Thermal Buckling Analysis Of Composite Laminated Reddy Plate Based On New Modified Couple Stress Theory

When analyzing the scale effect of materials,the classical couple stress theory has more material scale parameters,which is extremely inconvenient for engineering applications.To this end,researchers have proposed a modified couple stress theory that contains only one material scale parameter.Although it is convenient to apply,but it is only suitable for isotropic materials,and is not suitable for laminates with strong anisotropy.In order to solve this problem,this paper uses the new modified couple stress theory proposed by Chen for anisotropic materials,and establishes the thermal stability of micro-scale Mindlin laminates and Reddy laminates under the combined action of mechanical load and thermal load for the first time.In both theoretical models,we only introduced one material scale parameter and the curvature tensor is asymmetrical.Considering the variable temperature load,the strain caused by the variable temperature load is written into the constitutive equation,the governing equation is derived by the virtual work principle,and the buckling temperature is solved by the Navier solution.At the same time,the buckling critical load considering the temperature load is compared and compared with the buckling critical load when the temperature load is neglected,and the buckling critical load obtained under the two theoretical frameworks is compared when considering the temperature load.The analysis shows that the model constructed in this paper can be used to analyze the thermal buckling problem of Mindlin laminates and Reddy laminates at micro-scale.For the micro-scale laminate buckling problem,the influence of temperature load on scale effect cannot be neglected,when analysis thick plate the Reddy laminate theory is more suitable.The buckling critical temperature calculated by the model in this paper is always higher than that calculated by classical theory,which indicates that there is scale effect;the scale effect varies with different laying angles;the larger the material scale parameters,the more obvious the scale effect is.The critical buckling temperature increases with the increase of material scale parameters;when the span-thickness ratio increases,the scale effect decreases and tends to the critical buckling temperature under the macro-theoretical framework;when the material scale parameters are large,with the increase of the span-thickness ratio,the critical buckling temperature decreases greatly,and the scale effect becomes more obvious.When the plate is subjected to heat load and mechanical load,the scale effect becomes more and more obvious as the temperature?T increases or h/(?) decreases.