Influence of the non-singular stress on the crack extension and fatigue life

• Published in: Nuclear engineering and design 2012-07, Vol.248, p.293-300
• Main Authors: Cheng, C.Z., Recho, N., Niu, Z.R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Controled nuclear fusion plants; Crack propagation; Cracks; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fatigue failure; Fatigue life; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels; Nuclear reactor components; Paris; Series expansion; Stresses
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2012.03.017

► BEM is combined by characteristic analysis to calculate the singular stress field. ► A new method is proposed to evaluate the full stress field at crack tip region. ► Effect of non-singular stress on the propagation direction of the fatigue crack is analyzed. ► The influence of non-singular stress on the fatigue crack life is evaluated. The complete elasticity stress field at a crack tip region can be presented by the sum of the singular stress and several non-singular stress terms according to the Williams asymptotic expansion theory. The non-singular stress has a non-negligible influence on the prediction of the crack extension direction and crack growth rate under the fatigue loading. A novel method combining the boundary element method and the singularity characteristic analysis is proposed here to evaluate the complete stress field at a crack tip region. In this new method, any non-singular stress term in the Williams series expansion can be evaluated according to the computational accuracy requirement. Then, a modified Paris law is introduced to predict the crack propagation under the mixed-mode loading for exploring the influence of the non-singular stress on the fatigue life duration. By comparing with the existed experimental results, the predicted crack fatigue life when the non-singular stress is taken into consideration is more accurate than the predicted ones only considering the singular stress.