Hydraulic Impact Test Machine

Abstract

In this study, a hydraulic system that controls a mechanical linkage intended for impact testing is designed. This is achieved in such a manner, that when a predetermined position is reached, the hydraulic system switches from accelerating the mechanical system to floating mode. This is done so no further force is provided upon impact, whilst also protecting the hydraulic system from damage on impact. A hydraulic circuit which enables acceleration of the load is first designed. The aim is that the beam should reach an angular velocity of 0.5 rad/s. In order to achieve this, modelling the mechanical system and finding the relation to a hydraulic circuit which has this capability, resulted in a hydraulic configuration with a HPU, two 4/3-way servo valves, and an asymmetrical cylinder. This configuration remains unchanged for accelerating the beam. Allowing the hydraulic system to switch to a floating mode configuration is achieved by two methods, passive and active. Passive floating mode is a fixed hydraulic configuration designed such that the pressure forces are reduced to zero as fast as possible. This is best accomplished in passive floating mode by connecting both chambers to tank. It requires three additional on/o? valves in the hydraulic circuit. Active floating mode is achieved by controlling the pressures in the cylinder's chambers. The presented issue is solved by utilising active floating mode controlled by means of a P controller and a PI speed controller