A UNIVERSAL RIG FOR MECHANICAL TESTING OF THIN SPECIMENS USING A NOVEL LOADING ASSEMBLY CONTROLLED BY COMPUTER

This paper describes an apparatus which is able to perform tensile tru e 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 a n inert atmosphere and at high temperature. The machine applies the lo ad on the specimen by means of a balance beam, whose counterweight is partially submerged in a container filled with oil. The load, strain a nd temperature are measured with a load cell, a linear variable differ ential transformer and two thermocouples, respectively, and they are m onitored 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 perfo rmance of the machine is illustrated with results on aluminium 3003 fo il alloy and Fe73.5Si13.5-xAlxB9Cu1Nb3 amorphous alloys.