The Reddy-type higher-order theory has been widely used for analysis of Functionally Graded Material (FGM) structures. However, the theory neglects transverse normal strain, and will thus encounter difficulties in analysis of the thermomechanical behaviors of the functionally graded beam. To improve the performance of Reddy's theory, a Reddy-type higher-order theory considering transverse normal thermal strain with three displacement parameters is proposed. Although transverse normal thermal strain is taken into account, the number of displacement parameters is not increased in the theory. The model proposed is used to investigate thermomechanical response of the functionally graded beam, and also the effect of volume fraction on stress and displacement of functionally graded beam. Numerical results showed that the proposed model can calculate accurately the thermomechanical response of the functionally graded beam, and can improve the calculation accuracy of the models for transverse normal thermal strain.
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