Robust Determination of Fatigue Crack Propagation Thresholds from Crack Growth Data期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

Robust Determination of Fatigue Crack Propagation Thresholds from Crack Growth Data

Authors:	Josef Arthur Schö nherr,Larissa Duarte,Mauro Madia,Uwe Zerbst,Max Benedikt Geilen,Marcus Klein,Matthias Oechsner

Affiliation:	1.Center for Structural Materials (MPA-IfW), Technical University of Darmstadt, 64283 Darmstadt, Germany; (M.B.G.); (M.K.); (M.O.);2.Bundesanstalt für Materialforschung und -Prüfung (BAM), Division 9.4, 12205 Berlin, Germany; (L.D.); (M.M.); (U.Z.)

Abstract:	The robust determination of the threshold against fatigue crack propagation $Δ K_{th}$ is of paramount importance in fracture mechanics based fatigue assessment procedures. The standards ASTM E647 and ISO 12108 introduce operational definitions of $Δ K_{th}$ based on the crack propagation rate $d a / d N$ and suggest linear fits of logarithmic $Δ K$ – $d a / d N$ test data to calculate $Δ K_{th}$ . Since these fits typically suffer from a poor representation of the actual curvature of the crack propagation curve, a method for evaluating $Δ K_{th}$ using a nonlinear function is proposed. It is shown that the proposed method reduces the artificial conservativeness induced by the evaluation method as well as the susceptibility to scatter in test data and the influence of test data density.

Keywords:	fatigue crack propagation threshold ISO 12108 ASTM E647 data evaluation methods experimental determination