Investigation on modal behaviour of FGM annular plate under hygrothermal effect

Abstract

This paper investigates modal characteristics of FGM annular plate under hygrothermal effect. The mechanical properties are supposed to have a continuous variation along the thickness of the plate. The power law or sigmoid law functions are used to govern the resultant mechanical properties. The MUMPS eigen solver which is exists in COMSOL Multiphysics® (version 5.2) software is employed to obtain the eigenfrequencies and corresponding mode shapes. The accuracy of the method is validated by comparing the results with the results published work for particular case. Effects of functionally graded index, radius- to-thickness ratio, and temperature and moisture changes on the natural frequencies are discussed in detail. An excessive stress due to drastic moisture and temperature gradients make the engineering structures susceptible to failure. Due to the fact that, continuously identified natural frequencies of vibration under temperature and moisture effect can provide unique information during both initial fabrication and service life of different mechanical structures. Hence, this study can be helpful directly or indirectly in development of highly efficient environmental sensors that are very necessary in a structural health monitoring perspective. It can be observed that the fundamental frequency decreases with increase in functionally graded index and the moisture content rise under the power law model whereas under sigmoid law model the frequencies remain almost constant with increase in functionally graded index.