Abstract
This paper deals with the determination of the modulus of elasticity and of the modulus of rigidity of steel at elevated temperatures up to 500 C.
Both a static and a dynamic method were used and their results are compared. Whereas previously most of the static determinations of these moduli have been made under increasing load, in the tests described in this paper they were determined under decreasing load, according to the method proposed by F. L. Everett. The tests show that within certain limits the results obtained by this method are practically independent of the rate of loading. This appears to be due to a strain-hardening effect occurring upon loading and detected upon unloading.
The comparison between the static and the dynamic tests shows that the values of E, modulus of elasticity, and G, modulus of rigidity, determined statically under decreasing load are close to the values obtained dynamically. However they are somewhat lower for temperatures above 400 C.
The values obtained for E and G by static tests under increasing load are not reliable owing to the difficulty of discriminating between the elastic and the plastic deformation.
The values determined dynamically are the most reliable.
The variation of Poisson’s ratio with temperature is also presented, the values of μ being obtained by calculation from the values found for E and G.
