Research On The Mechanisms And Design Theories Of Thenovel VSR Devices With Nonlinear Superharmonic Vibration

Vibration Stress Relief(VSR)is an effective method to reduce residual stress,which has the characteristics,such as pollution-free,high efficiency,low cost of time and energy,cost saving etc.The rule to reduce the residual stress is that the composition of loaded dynamic stress and residual stress being lager than the limit of yielding of the material of the workpiece.But how to achieve the resonance and dynamic stress so as to reduce the residual stress of high stiffness workpieces remains a hot potato because during use the exciting frequency of traditional VSR devices is far lower than the lower order natural frequency of the high stiffness workpiece.A novel method of VSR with nonlinear superharmonic vibration is proposed and the mechanism and design theories of the corresponding devices are studied based on the former research results.Firstly,a novel VSR device with nonlinear superharmonic vibration and its mathematical model are proposed in this paper.The mechanisms to reduce the residual stress of this device is studied from the points of exciting frequency and exciting force.Then the condition of the device system to happen the superharmonic vibration is obtained.The parametric relations of the system elements are gained from the relation of dynamic stress and the response amplitude of the superharmonic vibration.Secondly,this paper puts forward a simplified dynamics model of the high stiffness workpiece as well as the mathematical model of VSR device with nonlinear superharmonic vibration based on the mode of action of the device and the workpiece.Finally,with the example of the high stiffness workpiece roll this paper studies the design of VSR with nonlinear superharmonic vibration.The natural frequency and the formation of the roll are obtained through the software of ANSYS.The exciting force of the device is calculated with the residual stress of the roll.The parametric relations of the system elements are calculated and the values of the elements are determined.The 3D solid model of this device is designed with the software of CATIA.The feasibility of the device to reduce the residual stress is checked by the dynamic simulation.Then this paper proposes the design theories of the VSR for this type workpieces with high stiffness based on the above researches.