Micromechanical elastoplastic limit analysis of in-plane bending of Functionally Graded Pipe elbows

Pipe elbows, also known as pipe bends, are important components of a piping system. These curved elements are very flexible when compared to their straight counterparts, and are often responsible for reducing the reaction forces and moments within the piping system. However, due to large deformations, the elbows are more likely to exceed their stress limits. The effect of in-plane bending on plastic limit loads of Functionally Graded (FG) pipe bends is presented using three-dimensional non-linear finite element analysis and a micromechanical constitutive model. The effective properties of the material are estimated by the Mori–Tanaka homogenization scheme and the TTO plasticity model. The analysis was carried out for different loading cases, geometries and volume fraction distribution. The results showed that an FG elbow has a very distinct behavior comparatively to a similar homogeneous elbow made out of metal, specially in terms of limit moments and stress distribution. Finally, an analytical model to estimate the limit moment of FG elbows is presented. •Functionally Graded pipe elbows provide wear resistance and ductility without the associated interfacial problems.•The volume fraction distribution of ceramic inclusions was found to play a major role on the overall behavior of FGM pipes.•Micromechanical Elastoplastic models can be easily employed to simulate the behavior of FGM metal-matrix pipe elements.•The volume fraction distribution of ceramic inclusions plays a major role on the overall bending behavior of FGM pipe elbows.•A predicting equation for bending of FGM pipes was developed for limit bending moments.