Transient Response Analysis Of Frame Part Under High Speed Impact Load

Steel cable is an important load-bearing and force transmitting component.With the development of society,people have higher and higher requirements for the performance of steel cables,and the impact test is the last step and the most important link before the steel cables are put on the market.As the main body of the impact test,the rail impact test bench can respond to the test pieces according to the needs,so the structural strength of the frame impact part is very important.Based on Smoothed Particle Hydro-dynamics(SPH)algorithm,a special continuous elastomer simulation model is established for arresting cable.The process of high-speed impact of punch on steel cable is comprehensively and systematically studied.The fatigue life of the punch is analyzed and verified by the joint simulation of LS-DYNA and n Code.The specific research content and results are as follows:(1)For the first time,SPH algorithm is used to analyze the cable wave behavior under high speed impact.Aiming at the wave behavior of steel cable under high velocity impact,SPH algorithm and FEM algorithm combined with artificial viscosity and mirror particle method are used to simulate the impact process,and the propagation law of stress wave in steel cable under high speed impact is obtained.The results show that: when the deformation occurs at the center of the cable,the particles squeeze each other,and some particles on the inside and outside generate reaction forces;when the fracture occurs on the outside,the particles at the wave crest produce larger principal stress tangent to the direction of stress transmission,and the particles in the center are distributed in an arc shape;when the inner side is not fractured,some particles produce a larger absolute reaction force;after complete fracture,the main stress of particles at the center is The impact stress decreases with the increase of impact angle and increases with the increase of friction coefficient.The accuracy of the simulation model is verified by theory,which has important engineering reference value.The total energy loss of the two algorithms is similar,but the SPH algorithm is more accurate and efficient for numerical simulation,which shows the superiority of SPH algorithm.(2)The SPH-FEM coupling algorithm is used for the first time to analyze the transient response of special continuous elastic body impacted by rigid body at high speed.At the same time,Optistruct is used for lightweight design of the impact part of the frame to achieve weight reduction effect.The results show that: in the whole process of impact,there are two impacts between the punch and the cable,the first impact produces greater stress on the impact part,the second impact produces greater stress on the meshing part and the main part,but the value is far less than that of the first impact;the reverse acceleration of the punch in the second impact is greater than that of the first impact;the acceleration of the engagement part is greater than that of the first impact The radius of arc curvature has little effect on punch strength.The thicker the rib plate is,the greater the punch strength is.The maximum weight can be reduced by 3.8%,which improves the comprehensive performance of the punch and realizes the weight reduction target of lightweight.(3)Through the fatigue reliability analysis of the punch,the reliability of its structure is verified.In this paper,the method of LS-DYNA and n Code is used to simulate the fatigue life of punch.The load and action time data obtained from high-speed impact simulation are imported into the software,and S-N curves with different credibility are assigned to different parts.The results show that: the main part of the punch has the highest service life,which can be tested for about 250500 times;the service life of the engagement part of the punch is the second,which can carry out about 3000 impact tests;the life of the impact part of the punch is the lowest,only one impact test can be carried out;but the technical requirements of 1500 times of test can be met by changing the impact part.