Multiaxial notch fatigue life prediction based on the dominated loading control mode under variable amplitude loading

Abstract

A new calculation approach is suggested to the fatigue life evaluation of notched specimens under multiaxial variable amplitude loading. Within this suggested approach, if the computed uniaxial fatigue damage by the pure torsional loading path is larger than that by the axial tension-compression loading path, a shear strain-based multiaxial fatigue damage parameter is assigned to calculate multiaxial fatigue damage; otherwise, an axial strainbased multiaxial fatigue damage parameter is assigned to calculate multiaxial fatigue damage. Furthermore, the presented method employs shear strain-based and axial strain-based multiaxial fatigue damage parameters in substitution of equivalent strain amplitude to consider the influence of nonproportional additional hardening. The experimental data of GH4169 superalloy and 7050-T7451 aluminium alloy notched components are used to illustrate the presented multiaxial fatigue lifetime estimation approach for notched components, and the results reveal that estimations are accurate.

Modeling of fatigue failure mode in U‐rib to deck joints in orthotropic bridge structures

“…The local stress concept, including the notch structural stress method with various fictitious notch radii, is investigated and considered by Karakas et al 19–22 Besides, the notch stress method has been extended for evaluating fatigue performances of welded structures in multiaxial stress states by Tao, 23 Luca, 24 and Ran 25 . The recommended evaluation methods on the fatigue properties of OBD are associated with some limitations 15,26–29 .…”

“…[10][11][12] Researchers have conducted theoretical studies and fatigue tests on U-rib-todeck connections, including single-sided weld joints, [13][14][15] butt weld joints, 16,17 and double-sided weld joints. 18 The local stress concept, including the notch structural stress method with various fictitious notch radii, is investigated and considered by Karakas et al [19][20][21][22] Besides, the notch stress method has been extended for evaluating fatigue performances of welded structures in multiaxial stress states by Tao, 23 Luca, 24 and Ran. 25 The recommended evaluation methods on the fatigue properties of OBD are associated with some limitations.…”

Fatigue life prediction for notched specimen considering modified critical plane method

“…11 The damage at the notch prior to selecting the critical plane is considered. 12 After considering the damage characteristics of the notched members, a new damage plane was constructed by coupling the fatigue characteristics of the maximum shear stress plane and the maximum tensile stress plane. 13,14 A critical plane is obtained considering the damage at the notch before loading and coupling the two planar properties.…”

“…In notched members, the selection of the critical plane is more important 11 . The damage at the notch prior to selecting the critical plane is considered 12 . After considering the damage characteristics of the notched members, a new damage plane was constructed by coupling the fatigue characteristics of the maximum shear stress plane and the maximum tensile stress plane 13,14 .…”

Fatigue life prediction method of face‐centered cubic single‐crystal metals under multiaxial nonproportional loading based on structural mechanical model

“…Many researchers have also studied multiaxis nonproportional loading. Paper 25–28 uses new theories or experimental methods to evaluate the fatigue life of notched specimens under multiaxis nonproportional loading; Then, different fatigue damage accumulation models 29–31 were proposed to evaluate the fatigue damage of metal materials under nonproportional loads; Pinto et al 32 proposed a new fretting fatigue life assessment to predict crack propagation path under nonproportional loads; Gu et al 33 used a 3D constitutive model to predict the stable thermomechanical stress state of shape memory alloys subjected to multiaxial nonproportional cyclic loading. These methods have good results for specific materials and structures, but they are all macroscopic phenomenological analyses and do not consider the influence of the damage mechanism of the microscopic metal cell structure on the fatigue life under multiaxial nonproportional loading.…”