A partial hybrid stress method (PHSM) applied to the higher-order plate theory is established for orthotropic composite plates. The midplane stress resultants and midplane generalized strains are included in the flexural part and assumed transverse shear stresses are included in the transverse shear part. Therefore, the governing equations of the plate can be derived variationally from a modified Hellinger-Reissner principle, and this variational principle is illustrated to be consistent in itself in plate sense. This new PHSM plate element is demonstrated to be more accurate than finite element displacement formulation in analysis of thin, moderately thick and thick laminated plates, and a rational through thickness distribution of transverse shear stresses is obtained by present method.
