Experimental Study And Numerical Simulation Of Low Velocity Impact Damage Of Thermoplastic Composite Laminates

With the continuous upgrading of the automotive industry,the lightweight of automobiles has become a very important part.The use of lightweight and highstrength fiber reinforced composite materials is one of the main methods to achieve lightweight vehicles.However,accidental impact loads are often encountered during the service of composite structures,such as gravel on the road,hail,and falling of tools during maintenance.Due to the sensitivity of the composite structure to impact damage,these small energy impact loads may cause damage to the composite structural matrix and internal delamination of the laminate,which in turn leads to a significant decrease in the strength of the composite structure.At present,the requirements for environmental protection are becoming more and more stringent,and higher requirements are also placed on the selection of composite materials.To this end,this paper selects environmentally friendly glass fiber reinforced polypropylene thermoplastic matrix composite(GFRPP),studies the low velocity impact response and compression failure mechanism of GFRPP laminates,and verifies the effectiveness of the proposed three-dimensional progressive damage model and establishes the impact.The post-compression model and discussed the effect of the layup on the residual compressive strength of the laminate.In this paper,the experimental study on the low-speed impact response and compression failure mechanism of GFRPP laminates is first carried out.Continuous glass fiber reinforced polypropylene composite laminates were prepared,and the mechanical properties of the single-layer panels were measured according to relevant standards.At the same time,the low-impact impact tests and impacts of different energy drop hammers were performed on the isotropically laminated laminates.Postcompression test to reveal the impact damage response of the glass fiber reinforced polypropylene composite and the post-impact compression failure mechanism.Then the numerical simulation model of 3D progressive damage of GFRPP laminates with low velocity impact is established.In-layer damage criterion selects the strain-based three-dimensional Hashin failure criterion,selects the stiffness degradation mode based on the fracture energy release rate,introduces the element feature length,reduces the dependence of the model on the grid,and uses the interface unit Cohesive element to simulate the interlayer delamination damage.The secondary stress failure criterion of ABAQUS software was selected,and the progressive damage analysis of the laminate was carried out based on the bilinear degradation mode of fracture toughness.Then,the experimental results are compared with the numerical simulation results to verify the accuracy and reliability of the model.Finally,by restarting the analysis and pre-defined fields to simulate the compression damage behavior of the laminate after impact,the results of the impact damage are defined as the initial state to the undamaged finite element model of the laminate,the boundary conditions are corrected,and the low speed of the composite laminate is established.The complete analysis process of impact and impact compression;the reliability of the model was verified by comparison with the test results;the model was further applied to study the structural parameters of the laminate such as interlayer angle,layup sequence and continuous layup to laminate The effect of residual compressive strength.The results show that the excessive interlayer angle is not conducive to the damage tolerance of the laminate.The 0° layer near the neutral layer can improve the damage tolerance of the laminate.The continuous layering is not conducive to the damage tolerance of the composite laminate.