A universal rig for mechanical testing of thin specimens using a novel loading assembly controlled by computer

Abstract

This paper describes an apparatus which is able to perform tensile true constant stress or strain rate, stress-relaxation and creep tests on a thin strip specimen up to a maximum load of 20 N, in vacuum or in an inert atmosphere and at high temperature. The machine applies the load on the specimen by means of a balance beam, whose counterweight is partially submerged in a container filled with oil. The load, strain and temperature are measured with a load cell, a linear variable differential transformer and two thermocouples, respectively, and they are monitored by a personal computer through an analogue - digital interface. The computer-based control and data acquisition software was written in QBasic language and it works on the power stage through the digital outputs. The power stage consists of two pumps that change the fluid level in the container. The temperature on the specimen is achieved by using an electrical furnace controlled by a PID controller. The performance of the machine is illustrated with results on aluminium 3003 foil alloy and amorphous alloys.