Modeling Of Repeated Impact Of The Elastic Plastic Point Contact Hammer-Rod

Impact phenomenon is very common in mechanical dynamics. Two body collision impact are likely to have high stress in the contact area, and resulting in plastic deformation. Generating continuous impact in mechanical system, plastic deformation and residual stress generated will impact in the next impact of the collision, so the state of impact will varies with the time of the impact. In this paper, using the hammer drill impact collision model for the study, take ANSYS / LS-DYNA finite element program for its repeated impact collision numerical simulation, and the specific contents are as follows:Firstly, when point contact hammer-rod in the first impact, the yield region encased the contact region, at the initial segment Hertz contact stress of theoretical solution lower than the simulation, this is due to the large plastic deformation resulted in point contact stiffness increased. When the yield region is in agreement with the contact region, it meets the Hertz contact in initial segment.Secondly, point contact hammer-rod under the same impacted speed, in the yield region encased the contact region, the contact force are increased. This is because with the increase in the number of impact, deformation become less, the release of stress is less. At the same time, with the increase of impact times, the contact time is reduced. Also with the increase of impact times, work hardening, residual deformation become less, contact force and deformation and tends to be linear stiffness, the point contact red hammer-rod in the repeated impact process by point contact slowly into the surface(curved surface) contact.Thirdly, numerical simulation of point contact hammer-rod in the process of yield region is consistent with the contact region, as can be seen, the deformation is small. With the increase of impact times and plastic deformation is decrease with the impact times of increase, but contact force and displacement of the Hertz contact index features still exist.Through the above research, hedge hammer drill process repeated impact collision are simulated using ANSYS / LS-DYNA finite element program, we can see the impact of the hammer is also changed from point contact to surface(curved surface) contact and the impact of the plastic deformation impact on collision process. This is of certain value in practical engineering.