The Research Of Calculation Method For Composites Structures On The Basis Of Higher Order Theory

An enhanced Reddy’s theory for laminated composite beams (ERT) based on theReddy’s theory is developed in this paper. The present theory includes the contribution of thetransverse normal thermal strain. According to the shear traction-free conditions at the top andthe bottom of the beam, transverse normal thermal deformation has been added into in-planedisplacement. Furthermore, another advantage of the present theory is that variables are thesame as those of Reddy’s theory. Afterwards, according to the principle of virtualdisplacements and the present ERT displacement functions, we get equilibrium equations withthe influence of thermal stress and the analytical results. The present ERT is assessed bycomparing to the exact2D thermo-elasticity solution and the existing RTC, RT, FSDT andHSDT-98results. By predicting the displacements and the stresses for composite symmetricmultilayered beams and sandwich beams subjected to thermal loading, it is found that thepresent ERT is much superior to the existing theories. The present theory is used to analysethe in-plane stress, the in-plane displacement and the transverse shear stress through thicknessof laminated beams with different type of temperature profile, the same span to depth ratio. Inaddition, laminated beams with the same type of temperature profile, different span to depthratio are also analyzed. Moreover, the ERT may be an inspiration for the thermal expansionproblems of the laminated composite and sandwich plates.