Correlating the stress-strain behavior of the ring expansion technique with the conventional tensile test

Abstract

Abstract Background The ring expansion technique is a non-standardized material testing used to evaluate round tubes’ mechanical properties such as burst pressure and stress-strain behavior, however, this technique has limitations such as lack of suggested specimen geometry, strain measurement technique, and friction coefficient(s) estimation. Objective This study primarily aims to evaluate the stress-strain property in the hoop direction for seamless pipes with a further correlation with the tensile stress-strain curve. Moreover, investigating the specimen’s geometry effect on the results was also considered throughout the study. Methods Experimental, simulation, and analytical techniques were carried out and through their conjunction, it was applicable to estimate hard-to-measure coefficients, identify and evaluate new correction factors, and validate the simulation and analytical results. Results Experimental strain measurements were performed by derived analytical equation rather than an external measuring device, novel evaluation of the hoop stress correction value (K) was performed by the comparison between experimental and simulation work, in addition to a convenient similarity between the standard tensile test and the non-conventional proposed technique results. Conclusion The ring expansion test is a promising technique to evaluate the seamless pipes' burst pressure, stress-strain behavior, and other mechanical properties. Furthermore, the authors recommend future work regarding estimating both pressure dissipation factor (α) in terms of friction coefficients and hoop stress correction value (K) in terms of ring’s geometry.