Research On Carbon Fiber Electrical Resistance Thermal Connection Technology Of CF/PPS Composite

The application of CF/PPS(Carbon Fiber/Polyphenylene Sulfide)thermoplastic composites on civil aircraft tends to be more and more extensive.The effective and reliable connection of its structure is the key factor in the application expansion of aircraft.The research goal of this paper is to design and build a resistance welding device for thermoplastic composites;to study the welding process technology using carbon fiber fabrics as resistance heating elements,to reveal the influence of main welding parameters on the quality and performance of CF/PPS laminates welded joints,and to propose the best process specification.The main research contents and results are as follows:The resistance welding device was designed and constructed.with the following functions: the pressure in the welded joint area is uniformly and steadily adjustable;the contact resistance between the carbon fiber resistive element and the electrode is greatly reduced,which met the welding requirements;the joint shape turns to be controllable;the acquisition of multi-point welding temperature ensures the accuracy and repeatability of the welding process.In addition,self-programming data acquisition programs are used to realize real-time monitoring and recording of welding parameters.The device meets the process requirements for resistance welding of CF/PPS laminates.The influence of forming pressure on the mechanical properties of CF/PPS laminates was studied.The experimental results show that the forming pressure has a significant effect on the tensile and bending properties of the laminates.It is expressed as the gradual increase of pressure,the mechanical properties of the laminates increase first and then decrease.When the molding pressure reaches 6 MPa,the CF/PPS laminate exhibits the highest tensile and bending strength.Through the detection and fracture analysis of the quality and performance of welded joints,the influence rule of the main welding parameters on CF/PPS laminates welded joints was studied.The experimental results show that: the shear strength of joints with the weldingtemperature(360 °C ~ 420 °C),the pressure(0.4MPa~0.8MPa)and the cooling rate of the welding(5°C/min~25°C/min)all showed a law of rising first and then decreasing.The peak inflection points of the three are 390°C,0.6MPa,and 20°C/min,respectively,which is the best process specification for CF/PPS resistance welding.The shear strength of the single/double lap joints under this specification reached 65% and 82% of the interlaminar shear strength(11.04149 MPa)of the laminates,respectively.In addition,the shear strength of CF/PPS double lap joints increases with the increase of lap length,but when the overlap area reaches a certain length,it has little effect on the joint shear strength.