Vliv reziduálního napětí na šíření trhliny

Effect of the residual stresses on the slow crack growth

abstrakt

en

Using linear elastic fracture mechanics a new methodology for a lifetime assessment of internally pressurized polymer pipes was developed. The concept is based on the numerical calculation of stress intensity factors for pipes under different loading conditions in combination with experimentally determined creep crack growth kinetics. The main aim of the work is to estimate the effect of residual stresses on the creep crack kinetics. Based on FEM calculations, the evolution of a creep crack in the case of internal pressure loading taking into account residual stresses, is obtained. An approximate equation for the stress intensity factor in the pipe with residual stresses is presented and good agreement with the numerically obtained data is found. The results and methodology presented can be a powerful tool for estimation of a plastic pipes lifetime.

Za předpokladu lineárně elastické lomové mechaniky byla vyvinuta nová metodologie odhadu životnosti polymerních potrubí zatížených vnitřních tlakem. Tato koncepce je založena numerickém určení součinitele intenzity napětí pro různé podmínky zatěžování v kombinaci s experimentálně stanovenými parametry kinetiky růstu creepové trhliny. Hlavním cílem práce je odhadnout vliv reziduálních napětí na kinetiku růstu trhliny.

Using linear elastic fracture mechanics a new methodology for a lifetime assessment of internally pressurized polymer pipes was developed. The concept is based on the numerical calculation of stress intensity factors for pipes under different loading conditions in combination with experimentally determined creep crack growth kinetics. The main aim of the work is to estimate the effect of residual stresses on the creep crack kinetics. Based on FEM calculations, the evolution of a creep crack in the case of internal pressure loading taking into account residual stresses, is obtained. An approximate equation for the stress intensity factor in the pipe with residual stresses is presented and good agreement with the numerically obtained data is found. The results and methodology presented can be a powerful tool for estimation of a plastic pipes lifetime.

reziduální napětí, růst trhliny, součinitel intenzity napětí

residual stresse, crack growth, stress intensity factor

24.09.2012

XVI International Plastic Pipes Conference 2012