Vibration Simulation Study On The Shaft Of The Linear Piston And Connecting-rod Type Hydraulic Motor

As an important actuator of hydraulic system,hydraulic motor has a direct impact on the performance of the entire hydraulic system.Therefore,it is necessary to optimize its working performances during the design process.This paper mainly researches the linear piston and connecting-rod type hydraulic motor which its shaft will be subjected to a variety of impact and periodic fluctuating force in the process of rotating.Resonate will happen if the excitation frequency is as same as the natural frequency.It not only lead to fatigue damage on the shaft but also form the secondary excitation which result in vibration and trouble on other machines,affecting the smooth operation of the motor consequently.Therefore,the study on the Shaft of the linear piston and connecting-rod type hydraulic motor has important significance,more than the further optimization design and later production.And it is also beneficial for the normal work and trouble diagnosis analysis.To this end,research work is made on the following aspects:To begin with,the concept of linear piston and connecting-rod type hydraulic motor has been put forward,also the construction and principle of it have been represented.Analysis and calculation of the following areas:excitation forces of hydraulic oil,reciprocating inertia excitation force of the moving parts and amplitude and frequency of each excitation force;rotational inertia of the rotating parts;torsional and longitudinal stiffness of motor shaft system.Then,carried out vibration analysis on the shaft of the linear piston and connecting-rod type hydraulic motor,established torsional and longitudinal vibration model of hydraulic motor and then get the free vibration and forced vibration equation.The inherent frequency of torsional vibration and the corresponding mode of torsion were calculated by Holzer method.Modeled the motor eccentric shaft,connecting rod and piston by Solidworks software.Obtained the first 10 order natural frequency and vibration mode and done a modal analysis by using the Ansys Workbench finite element software.Proposed the frequency region that should be avoided during design conditions and pointed out parts prone to deformation based on the analysis of natural frequency and vibration mode,which provide theoretical guidance for the design and optimization of hydraulic motor.The simulation results are compared with the actual calculation results to verify the correctness.The constrained modal analysis is performed on the eccentric shaft of the hydraulic motor,and the working load is applied to simulate the actual vibration response.The main resonance frequency and the corresponding response amplitude were obtained.Besides,the influence of the main bearing journal width and the main bearing spacing on the vibration of the hydraulic motor shaf have been analyzed.In the low frequency region,we choose smaller bearing width to decrease the low-frequency amplitude of the free end and the power output of the eccentric shaft.And without affecting the hydraulic cylinder and other equipment installed,reduce the main bearing spacing to reduce the amplitude of vibration response.