A multiple constant displacement-rate tensile testing machine

This paper describes a computer-controlled, multiple, constant, slow-displacement-rate tensile testing machine. The primary use of this machine is for investigating the durability of adhesive bonds. It also has application in the study of the hydrogen embrittlement of metals. A simple design facilitates manufacture of the mechanical parts of the test machine. The computer-controlled stepper-motor drive permits variation of the displacement-rates over a wide range while maintaining long-term stability. The computer also monitors the load and displacement during the course of the experiment. Several different displacement rates may be applied successively to a single specimen for defined regions of displacement. This capability allows the overall testing time to be reduced when determining the effect of the displacement rate on the elastic energy release rate, G(1) (also known as the crack extension force).