Parametric Study On The Impact Responses Of Composite Laminates Based On Finite Element Method And Analytical Model

To analyze the effect of dynamic parameters on the response ofcomposite laminates due to impact load, the impact was simulated by finiteelement (FE) analysis and differences of response between differentstiffness reduction strategies have been studied. A parametric modelingprogram for three dimensional composite laminate model was developed.The analytical models of impact response for large mass impactor andsmall mass impactor are established in which the delamination is alsopresented, and the elasto-plastic contact law is employed to calculate thepermanent indentation using the contact force. The effects of impactormass, velocity, radius, laminates radius, thickness and material property oncontact force and permanent indentation are studied based on FE analysisand analytical model. Results show that the analytical model is able torepresent the response characteristics.For the impact caused by large mass impactor, maximum contactforce goes up with the increase of the impactor mass, velocity, diameter,laminate thickness and material properties. The permanent indentation isproportional to the impact energy and inversely proportional to the squareroot of impactor diameter. It rises with the increase of laminate thicknessand drops with the increase of laminate dimension and material stiffness.For the spring mass model, when the ratio of contact stiffness to bendingstiffness is above200, the single freedom model should be used. When theratio is less than20, the two freedom model should be adopted. When theratio is between20and200, the two models are both applicable.For the composite laminate response due to small-mass impact, the contact force elevates with the increase of impactor mass, velocity,diameter, laminate thickness and material parameters. The permanentindentation increases with impactor mass, velocity and laminate thickness.It decreases with the increase of impactor diameter and material stiffness.Laminate dimension does not influence the response. When laminatethickness increases or impactor mass decreases, the type of impactresponse transforms into half space model from infinite plate model.Secondary impact is related with laminate stiffness and impact energy.Finally the effect of ply stacking on the impact response is studiedand a damage variable related to the number of fiber orientations wasdeveloped. A method of damage resistance optimization based onsolid-shell coupling finite element model was presented. Solid element wasused to simulate the impact region and shell element is used in the otherregion of the laminates in the model. They are connected by the couplingconstraint. Progressive damage material constitutive relationship was usedand optimization was implemented by using genetic algorithm. Resultsindicated that the method of genetic algorithm optimization based onsolid-shell coupling model is efficient and convergent. It improved theperformance of laminates against impact loading.