Free vibration of porous FG magneto-electro-elastic microbeams in the hygrothermal environment based on differential transformation method

Free vibration of the porous functionally graded magneto-electro-elastic (FGMEE) microbeams in hygrothermal environment is investigated. Four kinds of distributions of porosities including uniform porosity, “O,”“X,” and “V” type porosities are assumed in this paper. For the functionally graded microbeam, the physical neutral surface is considered. The modified couple stress theory is adopted to capture the size effect. The equations of motion for the porous FGMEE microbeam are derived and solved by differential transformation method. In the numerical examples, the effect of electric and magnetic loadings, material length scale parameter, the temperature rise, the moisture concentration, material gradient index, and porosity volume fraction on the natural frequency are analyzed and discussed in detail. The results indicate that different porous distribution modes have different effects on natural frequency. Moisture concentration/temperature rise can reduce the natural frequency regardless of what the temperature and moisture modes is. These results will be useful for the design of the porous FGMEE structures.