Volume 4, Issue 4 (July 1976)
Constancy of the Tensile Test Machine Stiffness
A method is presented for determining the current value of the stiffness of a tensile machine during uniaxial loading tests. The method is based on stress relaxation tests and on the measurement of the slopes of the load-time curve at the moment when the crosshead speed is changed from zero to some finite value. This method has shown that the stiffness can be taken as a constant within fairly wide ranges of the load level, crosshead speed, and specimen dimensions.