Experimental Investigation On Combined Hot Drawing Process Of Steel/CFRP Laminated Materials

With the continuous increasing of automobile production and ownership, energy consumption, safety and environmental problems are increasingly more serious around the world, automobile lightening has obvious advantage to dealing with these problems. Carbon fiber reinforced polymers(CFRP) has huge potential in automobile lightening because of lightweight, high specific strength, high specific modulus, outstanding design ability characteristic, high crash energy absorption, high structure size stability, facilitating integral forming etc. In the face of the current situation of high price of CFRP, Steel/CFRP laminated materials made up of steel plate and CFRP can be used to produce automobile structural parts. On the one hand, Steel/CFRP laminated materials can greatly reduce vehicle weight under the condition of meeting strength and stiffness. On the other hand, Steel/CFRP laminated materials help reduce total cost of automobile structural parts and meet demand of large quantities of production. In addition, the automobile structural parts produced by Steel/CFRP laminated materials can overcome the disadvantage of single material with better fatigue endurance, corrosion resistance and impact resistance. This paper put forward a combined hot drawing process which is suitable for mass production of Steel/CFRP laminated materials components, and the combined hot drawing process experiments of square box were carried out to research forming characteristics, forming defects, thickness distribution and bonding interfaces of Steel/CFRP laminated materials. The main research content involves:(1) Process principle and characteristic of combined hot drawing process of Steel/CFRP laminated materials were introduced, the combined hot drawing process experiments of square box of Steel/CFRP laminated materials, steel and CFRP were successfully carried out by independent development of non-isothermal drawing mold with heating and temperature control function. The research verified the feasibility and validity of combined hot drawing process used to produce lightweight auto-body components of Steel/CFRP laminated materials;(2) By analyzing the deformation of grids on the steel of Steel/CFRP laminated materials square box and comparing pure steel square box, forming characteristics of steel and the effect by CFRP of Steel/CFRP laminated materials were researched; By analyzing the variance characteristic of shear angle on the CFRP of Steel/CFRP laminated materials square box, forming characteristics of CFRP and the effect by steel of Steel/CFRP laminated materials were researched. The findings provided the theoretical basis for the determination of process scheme of complex auto-body covering and structure pieces made of Steel/CFRP laminated materials;(3) By macroscopic analysis, forming defects of Steel/CFRP laminated materials square box were discussed, generation mechanism was revealed and restrain measures were proposed, thickness distribution of Steel/CFRP laminated materials square box was researched. These researches contributed to improve forming quality of Steel/CFRP laminated materials components and its mechanical properties;(4) By scanning electron microscopy(SEM), the bonding interfaces on different areas of Steel/CFRP laminated materials square box were analyzed from micro aspect, the integrating state of interfaces was researched, the effects of deformation rule on bonding interfaces of Steel/CFRP laminated materials square box were revealed. It provided reliable basis for improving the mechanical properties by regulating the integrating state of interface.