The Creep Deflexion of Magnesium Alloy Struts

Abstract

This work was undertaken to examine the possibility of predicting the creep deflexion of magnesium alloy struts from tensile creep data. Creep deflexion tests on magnesium alloy struts at room temperature, under four loads, and lasting 1,000 hours, have been made and interpreted by the use of tensile creep test data for the same magnesium alloy. For strut deflexions small compared with length, and such that plane sections of the strut remain plane, it appears that the following assumptions arc reasonable: (i) during bending and compression creep of the strut similar relations exist between the stress, time and creep strain, as under conditions of simple tensile or compressive creep; and (ii) the rate of creep in any fibre of the strut is a function only of the current stress and time and not of the path by which the current conditions arc reached. These assumptions appear to lead to an average error in computed values of deflexion of an order which for practical purposes is small. It seems reasonably possible that the above mentioned assumptions may be expected to hold for struts of heat resistant material at elevated temperatures such as are met with in practice, provided that the order of deflexion is analogous to that occurring in the current tests, and the creep characteristics of the material are of a generally similar nature.