Multi-scale Integrated Design Based On Carbon Fiber Non-woven Reinforced Composite

The increasing number of automobiles leads to the increasingly serious energy and environmental problems.Lightweight is an effective way to realize energy conservation and environmental protection.Carbon fiber reinforced composite is considered as a potential lightweight substitute for automobile because of its excellent mechanical properties such as high strength,high modulus and low density.Nevertheless,the high price and complicated manufacturing process remain challenges for the large-scale application of conventional carbon fibers.In this study,a novel plane isotropic composite reinforced by long carbon fiber non-woven is introduced and a multi-scale and multi-objective optimization method is proposed.It realizes the lightweight design of auto parts and the improvement of mechanical properties,and further promotes the process of automobile lightweight.In this paper,the carbon fiber non-woven fabric reinforced composites is studied systematically.The advantages of low cost and rapid manufacturing make it possible to apply it in large-scale on body parts.The isotropic performance in the plane makes it better able to bear the actual complex external load.Secondly,the mechanical properties of the composites were predicted by the finite element method of homogenization,and the predicted results were verified by tensile test.The application scope of high precision homogenization model is discussed in detail.In the effective volume fraction range,the relationship between the micro parameters and the macro properties of the composite is analyzed in detail through the finite element simulation.The results show that the volume fraction of the composite has a great effect on the properties.There is a critical value for the influence of the aspect ratio on the properties of the composite.In order to break through the optimization limit of traditional single scale,the coupling effect between macro scale and microstructure is fully considered in this paper.From the multi-scale point of view,the integrated design of macro thickness and micro volume fraction of materials is realized to maximize the potential of output materials.Finally,the carbon fiber non-woven fabric is applied to the optimization design of automobile engine hood.By applying the corresponding constraints and loads,the lateral stiffness,torsional stiffness and modal performance of the engine hood are analyzed.On the premise of meeting the performance requirements of various working conditions,the non-dominated sorting genetic algorithm(NSGA-II)is used to optimize the thickness of components at the macro scale and the volume fraction at the micro scale simultaneously,so as to realize the lightweight design of components and improve the lateral stiffness.The results showed that the weight of automobile hood was reduced by 38%,while exhibiting better stiffness and strength performance in comparison with the conventional steel.In this paper,the lightweight design of automobile engine hood is realized,and it can be used for reference to realize the application of carbon fiber non-woven fabric reinforced composite in body parts.