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The free vibration frequency responses of the laminated composite structure with a cut-out of variable shapes (square/circular/elliptical), position (center/eccentric) and orientation (parallel/inclined) are investigated for the first time in this research including geometrical shapes. The eigenvalues are obtained computationally for the cut-out borne structure via a linear isoparametric finite element model of the composite structure in association with cubic-order of displacement kinematics. Also, a coupled code is prepared in MATLAB environment by joining the higher-order formulation and the simulation model (ABAQUS) to achieve the generic form to investigate the influential cut-out parameter (shape, size and position) on their eigenvalues. Further, a series of experimentations are carried out using the cut-out borne composite panel and compared with the computational frequency, including the experimental properties. Finally, the key behavior is surveyed through different kinds of numerical examples for various design constraint parameters including the cut-out relevant factors (shape, position and orientation) to show the subsequent inclusiveness of the proposed model.

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The effect of cut-out parameters (shapes: square and circular; position: concentric/eccentric) on the dynamic deflection values of the curved/flat layered composite panel are verified experimentally with the higher-order finite element solutions first-time. The solutions are obtained using the linear finite element model in the framework of cubic-order displacement filed functions. The necessity of higher-order kinematic model is verified by comparing the experimental transient data by conducting the different test to show the accuracy of the finite element solution. Moreover, the theoretical finite element solutions are obtained using the own experimental elastic property data for the comparison (numerical and experimental) purpose. Finally, the critical behaviour of the proposed numerical model for the dynamic analysis of damaged composite structure is examined by solving different types of example by varying the design constraint parameter including the cut-out factors (shape, size, location and eccentricity). The inclusiveness of each parameter on the time-dependent deflections is expressed in details from the various example including the comparison.

Thermal frequency responses of the hybrid laminated composite panel are theoretically computed using the finite element model and for the first time compared with in-house experimental data. The structural model for hybrid panel is derived using higher-order displacement polynomial functions (to maintain the necessary stress/strain continuity) and discretized through the isoparametric finite elements. Moreover, the elastic properties of the composite are evaluated suitably including thermal and physical parameters of the advanced fibers (Glass/Carbon/Kevlar) with the help of experimentations and numerical tool (via ABAQUS using mean-field homogenization). The variation of modal responses due to the change in temperature increment is computed through a generic computer code generated via the higher-order mathematical model. The numerical frequency values are compared with the earlier published numerical results and the experimentally recorded eigen frequencies. The experimental verifications related to the end boundaries indicate that the incorporation of the clamped boundary for one edge doubles the frequency, whereas the fraction of Kevlar fiber does not influence the stiffness (due to longitudinal modulus) parameter irrespective of the temperature change. Further, the conclusive understandings of the hybrid composite structural panel due to the inclusion of different advanced fibers and other design parameters (geometry, boundary and temperature) are deliberated in detail.

The influences of crack and delamination on the natural frequency and strain energy release rate of the laminated doubly curved shell structure are computed via a commercial finite element tool (ABAQUS). The effect of individual damages (crack and delamination) is modeled using the virtual crack closure technique (VCCT), considering the curvature effect. Initially, the model validity is established by comparing the results with the available results in the open domain. Additionally, the model validity has been verified via in-house experimentation for frequency responses. Further, the natural frequency and strain energy release rate (SERR) have been calculated for the structure to examine the influences of the individual or combined effect of damages by varying the design-dependent input geometrical parameters. The inclusive characteristics of the current model in conjunction with geometrical configurations are summarized for subsequent references.