Molecular Dynamics Study Of The Effect Of Ultrasonic Vibration On The Interfacial Properties Of CFRP

Continuous fiber reinforced composites(CFRP)have high specific strength and specific modulus,better compressive stability and good design properties,and have reached the level of aerospace aluminum in some aspects,making them widely used in aerospace,wind power generation,marine equipment and other fields.CFRP manufacturing technology based on additive manufacturing combines advanced materials and digital manufacturing technology,providing a way to achieve lightweight,structural-functional integration and highly reinforced design and manufacturing of resin matrix composite products.Since the two-phase interface between CFRP fibers and matrix is an inert interface,it affects the load transfer between fibers/matrix,which in turn affects the performance of CFRP as a critical load-bearing component.In order to improve the interfacial properties of the fiber/matrix,this paper investigates the effect of ultrasonic vibration on the interfacial properties from the perspective of molecular dynamics and conducts the following studies:(1)investigate the effect of ultrasonic vibration on the interfacial bonding energy and static properties of the fiber/matrix based on molecular dynamics(2)investigate the effect of ultrasonic vibration on the molecular chain activity of the resin matrix(3)the construction of ultrasound-assisted CFRP forming platform and the preparation of specimens(4)the study of the effect of ultrasonic vibration on the macroscopic mechanical properties of CFRP,based on the results of theoretical analysis.The molecular dynamics results show that when the intensity of ultrasonic vibration is 50 m/s,the interfacial bonding energy between fiber/matrix can be increased by 6.9%,and the radius of gyration of resin matrix molecular chain can reach 12.76 ? when the distance between resin molecular chain and fiber center of mass is 10 ?.The resin molecular chain activity is significantly increased.The molecular dynamics results show that ultrasonic vibration can improve the interfacial properties of fiber/matrix by enhancing the activity of matrix molecular chains and the interfacial binding energy between fiber/matrix,and the theoretical analysis results show that ultrasonic vibration can improve the interfacial elastic modulus of fiber/matrix by 121.7%,and improve the shear modulus and bulk modulus of CFRP by 13.37% and 13.77%,respectively.ultrasonic vibration is highly feasible in enhancing the fiber/matrix interfacial properties and the overall CFRP properties.In order to verify the feasibility of the molecular dynamics results,an ultrasonic vibration-assisted additive manufacturing CFRP experimental platform was designed and built in this paper,and CFRP specimens with different ultrasonic power(0-30 W)were prepared and the related performance test experiments and SEM experiments of the specimen fracture were completed according to the mechanical experimental standards.The experimental results showed that the bending strength and interlaminar shear strength of CFRP were 111.5 MPa and 10.16 MPa,respectively,after the ultrasonic vibration treatment of 20 W,which were 30.11% and 20.50% higher than those of CFRP without ultrasonic treatment.The experimental results were consistent with the trend of molecular dynamics analysis results,which confirmed the effectiveness of ultrasonic vibration in enhancing the fiber/substrate interface properties and macroscopic properties of CFRP,and revealed the mechanism of the action of ultrasonic vibration in enhancing the interface properties from the perspective of molecular dynamics.