Study On The Effect And Mechanism Of Ultrasonic Vibration Assisted Adhesive Injection Process On Interfacial Anchoring Of Adhesive Joints

Lightweight is one of the development trends of today’s industrial products,and the application of carbon fiber reinforced polymer(CFRP)is becoming more and more extensive.Adhesive bonding is the main connection method of CFRP.However,with the continuous enrichment of application scenarios,especially in the fields of automobiles,aerospace and even military defense,higher requirements for bonding technology are put forward.The bond line is open and no external force can be applied to interfere with the flow of the adhesive.How to obtain better bonding quality is an urgent problem to be solved.Therefore,this thesis proposed an ultrasonic vibration assisted adhesive injection process.The CFRP/aluminum alloy adhesive bonding was selected as the research object.The effect and mechanism of ultrasonic vibration assisted adhesive injection process on interfacial anchoring of adhesive joints were studied.The main research contents are as follows:Ultrasonic vibration assisted adhesive injection process method.Based on the ultrasonic vibration platform,an ultrasonic vibration sonotrode and a single lap adhesive joint fixture for ultrasonic vibration assisted injection were designed and processed.The anodizing process of aluminum alloy was optimized with time as variable.On this basis,a complete set of ultrasonic vibration assisted adhesive injection process was established.Optimization of ultrasonic vibration assisted adhesive injection process.The orthogonal experiment was conducted to obtain the degree of influence of ultrasonic vibration assisted adhesive injection parameters on bonding strength.According to the results of orthogonal experiment,the multiple regression model of bonding strength and process parameters was fitted.Genetic algorithm was conducted to obtain the optimal process parameters by global optimization.Finally,the optimal process was verified by experiment,and the bonding strength was increased by 29.4%.The effect of ultrasonic vibration assisted adhesive injection on interfacial anchoring.The failure mode of bonded joints was analyzed through macro observation.Ultrasonic vibration assisted adhesive injection process led to the failure mode of bonded joints changed from interface failure to mixed failure.The micro morphology and element distribution were analyzed by scanning electron microscope(SEM),scanning probe microscope(SPM)and energy dispersive spectrometer(EDS).Ultrasonic vibration assisted adhesive injection process resulted in that more adhesive residue on the surface of aluminum alloy plate.The cross section morphology and adhesive layer surface morphology of the bonded joints revealed that ultrasonic vibration assisted adhesive injection can form a closer connection between the adhesive and the surface of the adherend,and enhance the interfacial anchoring.The strengthening mechanism of ultrasonic vibration assisted adhesive injection.The adhesive layer pressure test platform was built to measure the changes of adhesive layer pressure in the process of ultrasonic vibration assisted adhesive injection.The maximum pressure of adhesive layer increased due to ultrasonic vibration assisted adhesive injection process.Observing the change of pressure within 0.01 s,it was found that the pressure changes violently and the fluctuation range increases after applying ultrasonic vibration,indicating that ultrasonic vibration leads to the continuous and high frequency impact of adhesive on the surface of adherend.Thermogravimetric analysis(TGA)showed that ultrasonic vibration assisted adhesive injection improved the thermal stability of the adhesive at 100～390 ℃.In this thesis,the ultrasonic vibration assisted adhesive injection process was explored,the process parameters were optimized,the effect of the process on the interfacial anchoring was analyzed,and the strengthening mechanism was studied,which has important reference significance for the application of ultrasonic strengthening adhesive interface and composites.