| Because of its low density,high thermal stability and excellent comprehensive mechanical properties,carbon fiber reinforced thermoplastic composites have been more and more used in automobile manufacturing,aerospace and artificial intelligence industries,and how to realize its efficient and stable connection has always been a research hotspot and frontier problem in this field.Traditional mechanical and adhesive bonding methods are difficult to meet the requirements of high efficiency and high reliability,while ultrasonic welding has the advantages of good sealing performance,high reliability,low energy consumption and high efficiency,and has a good prospect of development and application.In order to increase the welding heat affected zone and the applicable scope of welding parts,improve the forming quality and weld performance,this paper takes carbon fiber reinforced 66 composite as the research object,and proposes an ultrasonic welding process and method for the surface lap of medium thick plate of carbon fiber reinforced thermoplastic composite.The research is mainly carried out from the analysis of ultrasonic welding thermal mechanism,finite element simulation comparison and analysis of shear-type lap mode,establishment of weld curve model of curved joint,optimization of welding process parameters by orthogonal test,etc.The ultrasonic welding mechanics and temperature field models were established through dynamic mechanical analysis,and three shear lap modes,which were different from traditional plane lap,were designed.The applicable range of welding parts thickness was increased from 4mm to 8mm.The finite element software ANSYS was used to conduct thermodynamic analysis and temperature field simulation to study the strain and temperature distribution in the welding process.Based on three interpolation spline curve theory puts forward a design method of lap joints of surface,and to establish a carbon fiber reinforced nylon 66 composites mathematical representation model of curved surface fitting,select curve boundary conditions at the same time also the curve curvature,welding pressure,welding time for influence factors,pulled off force for welding performance evaluation criteria,three factors three levels orthogonal experiment was carried out,In order to find the best combination of process parameters of the optimal curve,the influence of different factors on the welding performance is obtained.Finally,the welding process parameters obtained from orthogonal test were used to test the performance of the three shear lap joints to verify the accuracy of the finite element analysis results.The results of this paper provide a theoretical basis for improving the quality of ultrasonic welding and broadening the applicable scope of welding parts and realizing the high quality and stable forming of large size prefabricated parts of carbon fiber reinforced thermoplastic composite with low energy ultrasonic welding. |
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