Transient Dynamic Characteristics Of Hydraulic Pile Hammer Impact Mechanism And Impact Properties

Hydraulic pile hammer is a pile-driving machine, which has low noise, no pollution, small vibration and high impact energy. Now, hydraulic pile hammer in the foreign country has become a series. But in china, the technique of hydraulic pile hammer is relatively backwards. There is no manufacturer in designing and producing it large-scale, so most of the hydraulic pile hammers are imported from other countries. There are many evaluating indicators for pile hammer, which the largest impact force, the impact efficiency and impact noise is very important. But many Hydraulic pile hammers produced in our country are small impact force, low impact efficiency and high impact noise. So this paper is abased on the impact structure, what are composed of hammer, hammer crash pad, pile cap, pile crash pad and pile, analyzed the influence of factor for the three indicators, and then optimize them.First, abased on the impact theory of Newton, this paper has obtained a new solution model for impact structure. we can obtain a ordinary differential equation for this model, and solve it, and we can know the relationship of length of penetration and parameters. Then using the transfer function to optimize the parameters, and obtain the best parameters at the special soil.Then, this paper analysis it with wave motion theories. According to different hammer shape, we can obtain the relationship between hammer wave drag and impact force, then know what shape of hammer we should select. Using the theory of Smith, we can obtain the displacement relational at any location. According to different soil, this paper has analyzed the back wave at the bottom of the pile. These can be referenced for pile test.The paper has used ANSYS/LS-DYNA to simulate for the single dynamic impact structure. We can obtain the stress change curve and displacement change curve, calculate the impact efficiency, and then analysis the relationship between crash cap parameter and impact efficiency, length of penetration, the largest impact force, acting time. Through changing the bulk modulus, we can analysis the wave in different boundary conditions. Through changing the radius of hammer, we can analysis the impact force in different wave drag.Using the theory of impact vibration and sound, then we can judge the relationship between impact noise and crash pad. We also test the frequency property of noise and measure the sound pressure in different distance.Finally, using instrument to measure the impact force of ZCYB7/130 hydraulic pile hammer, obtain impact efficiency of rubber and ebonite sheeting, and compare with the result of simulation, prove the simulation to be right.