The Springback Analysis Of Granular Medium Bend Forming Under Vibration

The granular medium bending forming is the function of the granular medium instead of the punch,and the pressure is applied to the granular medium by the indenter,and the sheet is formed by the force of the particles to transfer the forming force.The granular media,as a loose body,has its unique properties such as good fluidity,easy sealing,high temperature resistance,etc.Therefore,the bending and forming of granular media can form micro-structures on the plate.And in the forming process,the forming pressure is distributed evenly,and the deformation area in the forming is wider.Vibration-assisted forming is used as an auxiliary forming method,which is combined with the bending forming process of the granular medium.In the bending forming of the granular medium,ultrasonic vibration is applied to the granular medium to improve the internal force transmission characteristics of the granular body and further enhance the fluidity thereof.When the ultrasonic vibration is transmitted to the plate forming area,the plastic limit,stress distribution,and stress accumulation characteristics of the plate material during forming can be influenced,thereby affecting the forming property of the plate and the springback property after forming.Based on the above investigation,this article mainly carried out the following work:1)Based on the finite element method,the transducer structure was simulated to verify the output linear relationship of the piezoelectric material,and the horn for ultrasonic vibration was designed and calculated according to the demand.The input and output characteristics were verified by the finite element method.2)Based on the Hertz theory,the theoretical model of sliding friction between metal plates under ultrasonic vibration excitation was established,and the law of friction coefficient with amplitude was obtained.According to the theoretical basis design,the friction test was conducted to verify the accuracy of the theoretical model.3)Using the DEM unit in Abaqus,a finite element and discrete element coupling method was used to simulate the bending process of sheet metal particles.The stress distribution law of sheet metal during the forming process and the forming force characteristics were analyzed.Explore the influence of particle size,loading height on process shaping.Based on the above forming results,a springback simulation model without die was established to simulate the springback of sheet bending..4)Design and implementation of plate bending the experiment under ultrasonic vibration,to verify the above simulation results,and establish a springback measurement method,through the springback test preliminary exploration of the springback characteristics of the granular media sheet bending process of ultrasonic vibration characteristics.In this paper,the influence of particle size,loading height and vibration amplitude on the bend forming and springback with the granular medium under ultrasonic vibration excitation was investigated through the combination of simulation and experiment.Provides a theoretical basis for the application of this process.