The effect of constraint on elastic-plastic fracture

Abstract

The influence of the local constraint in the near field zone of cracks in terms of the parameter (Ym/u,= f (r, e, s) on fracture initiation and fracture resistance is investigated for several crack configurations in specimens and components. Experimental results from various authors are compared with corresponding numerical findings. Methods to transfer test results obtained for specimens to more complex situations in components are reported.Uber den EinfluB der Verformungsbehinderung auf den elastisch-plastischen Bruch. Der EinfluB der 6rtlichen Verformungsbehinderung im Nahfeld von Rissen, dargestellt durch den Parameter a.Jtr; = f (r, e, s), auf die Bruchinitiierung und den Bruchwiderstand wird fur mehrere RiBkonfigurationen in Proben und Bauteilen untersucht. Experimentelle Ergebnisse von verschiedenen Autoren werden mit entsprechenden numerischen Resultaten verglichen. Uber die Obertragbarkeit von Versuchsergebnissen von Proben auf komplexere Situationen in Bauteilen wird berichtet.

Effects of crack depth and specimen size on ductile crack growth of SENT and SENB specimens for fracture mechanics evaluation of pipeline steels

“…It is now well understood that crack tip constraints due to specimen geometries, loading modes and yield strength mismatches as well as residual stresses [1][2][3][4][5][6][7][8][9][10] affect the stress distribution around a crack and consequently preclude the use of a single parameter characterization of the crack tip stress field. A second parameter based on the elastic T-stress has been proposed by Betegon and Hancock [11] to describe the crack tip stress field.…”

Crack Initiation Under Generalized Plane-Strain Conditions

“…The near-tip model of a blunted notch employed in this study is a modified version of the Rice-Johnson (RJ) model of a blunted notch under plane strain conditions [32,23,24]. The modified RJ model presented here is formulated to analyze a blunted notch under generalized plane strain conditions and is identical to the RJ model under plane strain conditions.…”

“…Following [32], a deformation theory of plasticity is used to describe the strains, so that the path independent J-integral [23] can be used to obtain simple relations between J, R max , and 8 t .…”

“…3) and corresponds to the case E^/^Q = 0. Detailed finite-element near-crack-tip results obtained by assuming K-dominated far-field conditions [16] and from various compact-tension specimen geometries [32] indicate that the apex shear strain £ a is on the order of a few times the yield strain EQ. Note that there is actually a stress singularity predicted in the hardening cases at X = 0, although the singularity is weak and dominates over a very small distance relative to 8 t as shown in Fig.…”

Der Einfluß des Spannungszustandes auf den Versagensablauf angerissener Bauteile aus Stahl

“…4 sind die den Gleichungen (35) Durch die p-Abhangigkeit der aus FormschluR verursachten Spannungszustande gemaB Gleichungen (35) folgt fur q eine weitere Minimumbedingung, die zwar von p aber nicht von (tF/afc) abhangt, wenn aus Zwangung plastisches FlieRen, also p = 0,5, ausgeschlossen ist. Dies gilt fur eine Isolinie E(q, q = const) mit 1 -2 p fl, p < 0 s = 2(1 + p) (37) die durch den Punkt Ps des (q, E)-Diagramms (Abb.…”