Limit loads for pipe bends under combined pressure and out-of-plane bending moment based on finite element analysis

• Limit loads for pipe bends under small & large displacement are different.
• Parametr r/t is the main factor influencing the limit bending moment.
• Internal pressure has a stiffening effect on the bending moment for pipe bends.
• Yield strain has an obvious effect on limit load under large displacement analysis.
• Limit load equations for pipe bends under combined loads have been proposed.

In present work, limit loads for pipe bends under combined internal pressure and out-of-plane bending moment have been investigated systematically via finite element simulation based on both small displacement analysis and large displacement analysis. By normalized methods, a wide range of non-dimensional parameters were considered and limit bending moment expression has been suggested which shows that r/t is the main factor affecting the limit bending moment. In addition, the effect of internal pressure on the limit loads was studied in detail which is significant for thin walled pipe bends. It is found that yield strain ε0 has an obvious effect on limit load based on large displacement analysis. According to the finite element results, practicable engineering assessment equations of limit loads have been proposed for pipe bends under combined loads. These proposed equations are validated with experiment data and also justified to be a good choice for limit loads assessment.