Estimating damage laws from bend-test data

Abstract

Bend-test curves were calculated for materials obeying three very different damage laws. One result of the calculations is that the neutral axis migrates towards the compression face as the load-point displacement increases. For the three damage laws investigated, there is a simple relationship between the location of the neutral axis and the secant modulus derived from the bend-test record; this relationship is quite insensitive to the exact form of the damage law. The stress at a point 20 per cent of the beam depth from the tensile outer fibre is also fairly insensitive to the form of the damage law. Combining these two observations, it is possible to use bend-test data to make a good estimate of the tensile stress-strain curve of a material subject to damage.