Research On Carbon Fiber Laminates For Impact Damage Property And Pedestrian Head Protection

In the automobile industry, energy saving, environmental friendly, safe and comfortablevehicles are at prospect of development in the future. And the carbon fiber reinforced plastic(CFRP) composites have been paid more and more attention for their excellent performances inreducing car mass, decreasing oil consuming and causing less pollution. Along with their goodanti-vibration property and long operating life, the characteristics of light mass with highstrength, easy to design and good impact property are the reasons the CFRP composites havebeen used as cover pieces and structural parts assembled in trucks, buses and cars. Laminate, oneof the most widely used composites structure, is inevitablely exposed to impact situationencountering damage and even failure during manufacturing, assembling, fixing and using. Thusthe important research around laminate impact property is extracted, and it makes this researchsignificant when CFRP composites are applied to engine hood with the relating pedestrianproperty laws and regulations to reach.In this article, the main research work includes:(1) Three laminates with different stacking sequences were designed as [0]10,[0/90/0/90/0]sand [0/90/45/-45/0]s. Basing on the Classical Laminate Plate Theory (CLPT), constitutiverelationships for lamina and laminate were derived and stiffness matrixes of the three laminateswere calculated.(2) Three laminates as described above were made using hot pressing laminating process,and then cut into six kinds of samples with their stacking sequences as [0]10,[90]10,[0/90/0/90/0]s,[90/0/90/0/90]s,[0/90/45/-45/0]sand [90/0/-45/45/90]s. Two levels of energy,5Jand25J, were applied in the drop-weight impact test. Impact force, deformation, energy and impact damage were analyzed to obtain the relationship between impact response and impactdamage. In the meantime, the effects of different impact energy and stacking sequences werediscussed.(3)Two-degree shell finite element model (FEM) of drop-weight impact on CFRP laminatewas established in the ABAQUS software. CFRP laminate property was defined following theHashin damage initiation and damage evolution criteria. This model was verified by comparingsimulation data with experimental results. And then four damage variables corresponding tofiber tension damage, fiber compression damage, matrix tension or shear damage, matrixcompression damage modes were used to help get a further understanding about damageposition and damage cause.(4) FEM model of the impact between head impactor and CFRP laminate was established inthe ABAQUS software. And the head injury criteria (HIC) value was calculated in theengineering software DIAdem. The relationships among HIC value, contact duration, maximumpenetration and energy absorption were discussed. And the pedestrian protection effects oflaminate Layups were investigated.