| Automobile lightweight is one of the important measures to solve the increasing energy crisis,and CFRP(Carbon Fiber Reinforced Plastic)and its adhesive bonding process are important methods to realize the lightweight of automobiles.However,the bonding strength of CFRP component with the traditional adhesive bonding process is low,unstable and uncontrollable.Thus,a novel ultrasonic vibration strengthened adhesive bonding method was proposed in this study.In this thesis,the adhesion of CFRP-to-aluminum was studied along the route of "process method-numerical study-mechanism analysis-practical application".Based on the platform of ultrasonic vibration assisted molding,the experimental platform of ultrasonic vibration strengthened adhesive bonding of CFRP-to-aluminium plate was set,and a relatively perfect ultrasonic vibration strengthened bonding process of CFRP-to-aluminum was established.The effect of ultrasonic vibration on CFRP-to-aluminium plate was found through experiment,and the optimal bonding process of ultrasonic vibration strengthened adhesive bonding of CFRP-to-aluminium plate was optimized by orthogonal experiment,which enhanced the bonding strength by 40% and improved the bonding stability by 60%.So,the results showed that the ultrasonic vibration has a significant effect on the quality improvement of adhesion.A finite element model of ultrasonic vibration strengthened adhesive bonding of CFRP-to-aluminium plate was established,and the process of ultrasonic vibration strengthening adhesion was analyzed by two-way flow-solid coupling method.The results showed that ultrasonic vibration promoted the flow and filling of the adhesive in the adhesive area,and the adhesive was filled to the bonding gap in the surface of the adhesive,enhancing the wetting effect of adhesive on the adhesive.Therefore,the quality of adhesion was strengthened.The strengthening mechanism of ultrasonic vibration-strengthened adhesive bonding method was studied.The aspect of the interface bonding: It was found that the ultrasonic vibration enhanced the bonding properties of adhesive to the aluminum plate through the analysis of the failure of the joint;The adhesive layer of the failure joint was analyzed,and the bonding interface was studied by means of the sessile drop method and SEM(scanning electron microscopy)observation,and it was found that the wettability of the adhesive on the adherends was improved under ultrasonic vibration,thus the compactness of interface bonding was improved and the bonding quality was strengthened.The aspect of adhesive flow and filling: The adhesive flow process was analyzed by the high-speed camera,it was found that ultrasonic vibration enhanced the flow rate and filling area of the adhesive.it was shown that ultrasonic vibration improved the flow rate of the adhesive and increased the adhesive filling area,and the high-frequency vibration caused bubbles in the adhesive layer to stretch,deform,and ultimately,burst at the flow front,making the layer uniformly distributed and strengthening the bonding quality.The FSAE car CFRP suspension structure and the adhesive bonding joints was designed,and the process of ultrasonic vibration strengthened adhesive bonding of CFRP-to-aluminium tube was established and optimized,which enabled the joint of CFRP-to-aluminum tube to withstand at least 20 kN tensile load and improving the bonding stability.The bonding quality of the FSAE car CFRP suspension was strengthened under the ultrasonic vibration,and FSAE car with the suspension passed tests in multi-condition,proving the reliability of the CFRP suspension.This thesis has been systematically studied the process,mechanism and practical application of the ultrasonic vibration strengthened adhesive bonding of CFRP-to-aluminum joints,which proved to have great scientific significance and application value. |
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