Comparison of Pipe Bend Ratchetting/Shakedown Test Results With the Shakedown Boundary Determined via a Simplified Technique

Scarce experimental verification exits in the open literature concerning determination of the shakedown boundary for pipe bends subjected to steady internal pressure and cyclic bending loading. The objective of the present paper is to test the capability of a simplified technique presented by the authors in recent ASME JPVT publications and PVP conferences [1–4] in adequately predicting the shakedown boundary obtained through experimental testing. Recently, Chen et al. [5] published experimental and finite element (FE) simulation results on ratchetting of low-carbon steel pressurized 90-degree pipe bend specimens subjected to cyclic reversed in-plane bending forces. Chen et al. [5] performed experimental testing on a pipe bend specimen subjected to a steady internal pressure magnitude of 20.0 MPa. Through FE simulations employing a modified form of the Ohno-Wang non-linear kinematic hardening (KH) rule, Chen et al. [5] predicted a shakedown boundary for a steady internal pressure spectrum ranging from 10.0 to 25.0 MPa. Chen et al. [5] experimental and FE outcomes are utilized for comparison with the simplified technique outcomes. The simplified technique outcomes showed very good correlation with Chen et al. [5] shakedown boundary predictions for the 18.0 – 25.0 MPa steady internal pressure spectrum. On the contrary, noticeable disagreement was found for the lower magnitudes of steady internal pressure. Reasons behind the discrepancy are discussed.