Dynamic impact force in an axial member with coupled effects of structural vibration and various support conditions

作者：Malla Ramesh B^*; Vila Luis J

来源：Engineering Structures, 2017, 144: 210-224.

DOI：10.1016/j.engstruct.2017.04.040

• Contact force
• Impact
• Nonlinear dynamics
• Mode superposition
• Vibration
• Support conditions
• Finite element analysis
• Damping effects

Longitudinal impact of a mass (or hammer) on a drill rod has been used over the years on a number of terrestrial applications such as pile driving, rock drilling, and soil testing as well as in drilling devices designed to explore the subsurface of Lunar, Martian, and other planetary bodies. Previous studies have investigated the effects of the boundary conditions on the wave propagation on the rod. However, the coupled effect of the dynamic response, damping and the boundary conditions of the rod on the contact/impact force has not been considered. This paper presents the dynamic contact analysis of the longitudinal impact of a mass on a rod with rigid, free, deformable, and slip support conditions including the effect of damping of the rod. Focus is given to capture how and under what conditions the impact force is affected by the support conditions. The contact force was obtained using Hertz force-indentation relation coupled with the structural vibration of the rod. Both the contact force and the rod dynamic response are determined using mode superposition method as well as an in-house finite element code. A very good agreement is found between the results from the two methods. The results are verified with experimental data previously available in literature and using Abaqus FEA. It is found that for the undamped case the force is affected by the support condition only if the duration of contact between the striker and the rod is larger than the time that the displacement wave takes to travel through the rod to the other end and return back to the contact end. On the other hand, when damping of the rod is considered the contact force is observed to be affected by the support condition before the arrival of the reflected wave to the contact end. However, the effect of the support conditions in the damped case is significantly higher when the duration of contact is larger than the time of arrival of the reflected wave from the far end. When the rod penetrates into the supporting medium while the contact is present the contact force decreases at a higher rate compared with the case where penetration is not present during contact.

• 出版日期2017-8-1