Time-Dependent Deflection Responses of FG Porous Structures Subjected to Different External Pulse Loads

Purpose This work deals with the time-deflection responses of functionally graded (FG) porous plates and spherical shells subjected to different external pulse excitations by means of an improved first order shear deformation theory (Im-FSDT) with improved transverse shear deformations.Methods Here a quadratic function is considered to allow for a parabolic distribution of the transverse shear stresses and a zero condition at the upper and bottom surfaces of the structure. The governing equations for the dynamic transient response is systematically derived using a variational principle and finite element method and they are solved numerically using the constant average acceleration Newmark's integration algorithm. The effective material properties are evaluated using a modified power-law distribution with a porosity parameter. The pores are assumed to be dispersed uniformly or randomly along the thickness of the shell leading to even or uneven porosity distributions.Results The model accuracy is checked by comparing the present time-deflection responses with the available data, where the percentage of relative error between the results does not exceeds 0.5% in average which outline the performance and usefulness of the proposed (Im-FSDT) model. Further, the effects of porosity volume fraction, types of distributions, external pulse loads, geometrical and material parameters are explored and discussed. It is found that, the porosity rate and the type of dispersion have a significant effect on the dynamic transient responses of FG porous plates and shells.Conclusion In such a way, the dynamic behavior of aerospace, automobile, naval structural components can be controlled passively by the percentage and types of added porosity within such structure.