Simulation Research On Low-velocity Impact Responses Of Laminates Based On Cohesive Element

Fiber reinforced composite has abroad application in many fields, which are theaerospace industry, weapon equipment, energy engineering, automobile industry, and windpower generation as well as the marine industry, owing to its excellent properties, such ashigher specific strength and stiffness, light weight and being designable in structures.However, actually, the composite laminated structures are often subjected to low-velocityimpact loading coming from external objects, such like the dropping tools and the nearequipment, and so on, while they are in use, under the manufacturing process or maintenance.The composite laminate shows its poor damage resistance and impact strength since it has aweak interlaminar shear strength. Therefore, some barely invisible or barely visibleinterlaminar or intralaminar damages are often caused, when the laminates are subjected totransverse load, for instance, the low-velocity impact, which would lead to a great decrease inmechanical properties of the laminates and cause a security problem. These damages arematrix cracking, interlaminar delamination, and fibre fracture and so on. Thus, it is greatlysignificant to investigate the low-velocity impact responses of the composite laminates.In this study, the low-velocity impact model was established in ABAQUS/Explicit byusing the cohesive interface element, which was based on the traction-separation constitutivelaw and Bengeggagh-Kenane energy-based damage evolution criterion. The Hashin failurecriterion was also applied into the model in order to well capture intralaminar damages of thecomposite laminates. Then, the viability of the established model was validated by comparingto the results taken from the literature.On the basis of the established FEA model, the influences of some factors on the impactresponses of composite laminates were investigated herein, which were the geometry shape of the impactors, the impact orientations of the impactor, and the hybridizations of carbon fiberand aramid fiber, respectively. The results were achieved through the simulations, which wereillustrated as following:(1) When the geometry shape of the impactor became sharper, itwould cause much more damage to the laminates.(2) When the impact orientations were on2D plane which was vertical to the laminate, the incidence angle had a great effect on theimpact responses. The caused damage extents increased firstly and then decreased with theincrease of the incidence angles. And when the incidence angle reached45o, the most extentof damage was caused. While a certain angle was formed between the impact orientation andlaminated plane, the variation of the incidence angle did not have a significant effect on theresponse.(3) As for the hybrid laminates with carbon and aramid fibers, the increase of thecontents of the carbon fiber helped to increase the impact resistance of the laminates. Andwhen content of carbon fiber was equal to the one of aramid fiber, the laminate with aalternating stacking sequence had better impact resistance.