On a technique for generating stress-strain curves from flexural data

A technique is developed in this paper to utilize a four-point-bend test for piecewise construction of the stress-strain curve for the outer fibers (tension and compression) of the sample. The generated flexural stress-strain curves are compared to uniaxial tension and compression stress-strain curves. Initial agreement is excellent while in the latter stages the flexural curves are stiffer and exhibit significantly higher failure stresses. This technique fully allows for the material softening (nonlinear material behavior) due to the onset of damage well below ultimate fracture as well as different stress-strain behavior in tension and compression. The potential importance of this technique in providing corrected estimates of both tensile and compressive elastic moduli and failure stress, cf. ASTM D 790-91, is discussed.