Constraint modified time dependent failure assessment diagram (TDFAD) based on C(t)-A2(t) theory for creep crack

Abstract

Due to the potential influence of constraint effect on failure assessment, a link is needed to bridge the constraint effect characterized by higher order term asymptotic solution and time dependent failure assessment diagram (TDFAD). In this paper, a modification method for creep toughness incorporating C(t)-A2(t) theory is proposed based on Nikbin-Smith-Webster model. The relation between Q-term and A2(t)-term is also presented for creep crack. Results show that the creep toughness can be influenced by constraint parameter remarkably. A modified TDFAD is proposed based on C(t)-A2(t) solution. Based on the creep data of 316H stainless steel and various compact tension specimens, the modified TDFAD curves considering constraint effect characterized with A2(t)-term is presented and discussed, which indicates the important role of constraint effect on the assessment boundary of TDFAD. The research given in this paper can provide an alternative method in which the constraint effect can be included in TDFAD under high temperature.

Characterizations of material constraint effect for creep crack in center weldment under biaxial loading

“…For crack in creep solids, it is generally denoted as the creep crack to distinguish the cracking in creeping solids and traditionally cracking in elastoplastic solids. For those flawed structures and materials under higher temperature, accurate characterizations and evaluations of crack tip field for creeping solids become a great challenge for industrial and scientific fields, and they are also one of the most important topics in recent years (Saber et al 2016;Xu et al 2017a;Xu et al 2017b;Dai et al 2017;Dai et al 2020a;Chao et al 2001;Wang et al 2010;Tan et al 2014;Ma et al 2016;Cui and Guo 2020;Guo et al 2018).…”

“…The critical challenge on quantifying the stress field of crack tip in those welded components is that the crack tip field can be influenced by many factors such as material mismatch (Kumar et al 2014), weldment geometry (Zhou et al 2014), residual stress (Ren et al 2009) and loading state, e.g., biaxial loading (Wang 2012;Shlyannikov et al 2011;Shlyannikov et al 2014;Wang et al 2014). Those factors can lead to the variations of microstructure (Kulkarni et al 2020), stress level (Han et al 2015), fracture toughness (Hemer et al 2020) as well as crack growth rate (Krishnan et al 2018;Alves et al 2020;Velu 2018) for the weldment, among which fracture toughness is an crucial fracture parameter to be determined as it can affect the border of failure assessment diagram which has been widely used as the evaluation tool by the industrial field (Dai et al 2020a). Note that the fracture toughness is always related to the so-called ''constraint effect.…”

Analysis on stress‐strain behavior and life prediction of P92 steel under creep‐fatigue interaction conditions

“…This requires the use of advanced oxidation and creep‐resistant materials with superior performances. The temperature of the next generation ultra‐supercritical (USC) power plants will be improved to over 600°C, even up to 700°C for advanced USC power plants 1–4 . Up to now, the suitable and mature materials and the matched welding materials for advanced USC power plants have not been developed.…”

Development of a Reliable Failure Assessment Diagram by Persian Curve

“…The unified Persian curve (PSU) is compared with the (FAD) from Eq. (28) (KII) (Zhao, 1989;Shetty, 1992;MacLennan, 1996;Talei-Faz, 2003;Shabakhty, 2004;Yusof, 2006;Bach et al, 2009;Lie and Yang, 2009;Hosseini, 2010;Schaser, 1994;Hosseini, 2014;Arafah, 2014;Vesga Rivera, 2014;Sahu et al, 2015;Akbar and Setiawan, 2016;Coêlho et al, 2019;Dai et al, 2020;Irfaee, 2019;Pillai et al 2019) in Fig. 7.…”

“…The (FAD) from Eq. (30) (KIV) by (Ainsworth et al, 1999;Dai et al, 2020) and the test data (TEST) by (Gibstein and Moe, 1986) are compared with the unified Persian curve (PSU) in Fig. 9.…”