Numerical Analysis of Transient Responses of Delaminated Layered Structure Using Different Mid-plane Theories and Experimental Validation

The present article mainly focuses on the fundamental frequency and the time-dependent deflection responses of the layered composite plate structure considering the effect of debonding between the adjacent layers introduced via sub-laminate approach. The responses are mainly obtained numerically using a newly developed finite element model of the delaminated composite plate using two types of higher-order mid-plane shear deformable kinematics. The debonded plate model is discretized using a nine-noded quadrilateral isoparametric Lagrangian element to obtain the elemental equation and assembled subsequently for the evaluation of the final form of equation of motion. The structural responses (natural frequency and time-dependent deflection) are obtained computationally using a specialized computer code via MATLAB with the help of currently proposed model. Further, the convergence and subsequent comparison study have been performed using the similar examples from the earlier published literature. In addition, the present results are also compared with those of the experimental responses of the fabricated glass-/epoxy-laminated composite plate including the different size of delamination. The elastic material properties and the frequency responses of the fabricated laminate are evaluated using tensile test and vibration measuring experimental set-up. Finally, the dynamic responses of debonded plate have been measured for different sets of structural parameters to show the influence of each parameter as well as the size of debonding on the final responses.