Modelling of Axial Spring Stiffness in Active Vibration Controlled Drilling

During drilling process, substantial amount of vibration and shock are induced to the drill string. Active vibration controlled drilling is introduced to reduce the vibration and increase the efficiency of drilling process. In this system, two main components that determine the damping stiffness are MR damper and spring assembly. Performance of vibration damping system is depending on the viscosity of MR fluid in the damper and spring constant of spring assembly. One of the key issues that are unclear from the design is the correlation between the axial spring stiffness configuration and the damping force which needs to be tuned actively. There has been lack of studies on how the viscosity of MR fluid on the active vibration damper affects the damping stiffness of the whole system. The first objective of the project is to investigate the relationship between the damping coefficient and power input to the system. Second objective is to develop the correlation between the viscosity of magnetorheological (MR) fluid and axial spring stiffness. To achieve the objectives, model of vibration damping system is created using MATLAB Simulink. The model is built with reference of experimental data conducted by APS Technology. Inputs of the simulation such as force exerted, mass of mandrel, spring constant and step time are based on the experimental data and can be adjusted to suit different experiments. By having the model, behavior of the system can be studied and analyzed. From the simulation, it is also observed that the relationship between damping coefficient and power input of the system is linear.