Numerical hygrothermal frequency of pre-damage shallow shell panel: A nonlinear FE approach

In this work, the nonlinear eigenvalues of the debonded composite panel (flat, single and doubly curve) are evaluated under unlike humidity and temperature conditions. To obtain the said modal responses a macro mechanical isoparametric finite element-based numerical model of pre-damage laminated composite is developed. The structural panel deformations are counted through two different kinematic theories with small deviations (related to the drilling degrees of freedom). The geometrical distortions of the panel component are expressed using the common Green's strain relation in Lagrangian scope. The governing differential equation (converted to nonlinear eigenvalue equations) is derived from a dynamic version of the variational principle. The direct iterative approach has been adopted to compute the nonlinear frequencies in association with the finite element steps. Also, the element sensitivity behavior of the obtained numerical solution is verified and extended further to check the efficacy (comparing the results from the published domain). In continuation, the nonlinear modal values are computed through a series of examples considering the role of debonding with the structural parameters in detail.