Damage and residual bending strength in glass-polyester molded grating composite panels after low-velocity impact

摘要

Glass-polyester molded grating composites (MGC) are brittle and sensitive to the damage caused by the impact. In this study, a finite element model has been proposed to predict the strength of the molded grating composite panels against low-velocity impact loads. Molded grating composites have unidirectional reinforcement fibers, except in the intersections where behave as a blocked bidirectional reinforced materials. Hashin failure criteria and a proposed sudden degradation model have been employed to distinguish damage initiation and formulate damage evolution, respectively. The proposed degradation rule basically is Tserpes model with a small modification for shear dominant tension-compression degradation. In order to validate the results a series of experimental impact tests were carried out by means of a drop weight tower in different states of the height and mass of the drop weight. Three-point bending tests on the intact specimen and impacted specimens were performed in order to determine the reduction of strength and stiffness after impact. The results show that the numerical analysis based on the proposed modified Tserpes model predicts the ultimate force and the slope of the load-displacement diagram with a reasonable accuracy that correlate well with the experimental results.