Total fatigue life analysis of a nodular cast iron plate specimen with a center notch

Abstract

The crack initiation and propagation phases of the fatigue life of a plate specimen with a center hole are analyzed. The local transient stress-strain relationship is investigated by means of finite element simulations with a nonlinear kinematic hardening model. Modifications are proposed for the conventional notch analysis with the strain-life methodology considering the effect of mean stress relaxation and strain ratchetting. With the proposed modifications, the crack initiation life at the notch is less dependent on the load ratio, as it is in classic analysis methods. The initiated cracks are further investigated with fracture mechanics methods to evaluate total fatigue life. The eXtended finite element method and analytical formulas are applied to obtain the crack path and stress intensity factors, the results of which are in excellent agreement. Propagation life is estimated with the NASGRO crack-growth model fitted on the experimental results.

Automated calibration of advanced cyclic plasticity model parameters with sensitivity analysis for aluminium alloy 2024-T351

“…The cyclic loading is often not just uniaxial, which has been covered very well in the literature, 1,2 but multiaxial and, moreover, non-proportional. 3 The commercial software such as ANSYS or Abaqus supports some advanced plasticity models with limited potential for customization. There is definitely an option for implementing a user material definition to the commercial codes, but this is still rather expensive and time-consuming.…”

Global‐local fatigue assessment of an ancient riveted metallic bridge based on submodelling of the critical detail

“…Local approaches to fatigue assessment have been proposed according to detailed stress/strain analyses, which can consider the elastoplastic due to stress concentration in the local structural discontinuity. Attempts have been made to better understand the fatigue performance of riveted joints in conjunction with local approaches . Previous studies addressed the fatigue issues of riveted bridges mainly based on experiments of simple riveted joints or localized numerical simulation, which cannot fully consider the global effect of a structure on the fatigue response of various riveted joints for unrealistic boundary conditions.…”

“…Attempts have been made to better understand the fatigue performance of riveted joints in conjunction with local approaches. [11][12][13] Previous studies addressed the fatigue issues of riveted bridges mainly based on experiments of simple riveted joints or localized numerical simulation, which cannot fully consider the global effect of a structure on the fatigue response of various riveted joints for unrealistic boundary conditions. Additionally, few attempts were focused on the deterioration of material, which significantly affects the fatigue performance of riveted joints after service for long period.…”

Investigation of microstructure and mechanical properties of A131 EH36 steel additively manufactured by selective laser melting and direct laser deposition

“…The underlying assumption is for same stress concentration factor and loading, the fatigue life cycle is the same [156]. The local stress and strain can be calculated using methods such as the critical distance, highly stressed volume and gradient based methods [157], which can be imported into S-N curve to calculate the fatigue life. Strain-life method is a local method which count the local stress and strain (with local cyclic plastic deformation) at stress concentrators, which can be used for both high cycle and low cycle fatigue life analysis.…”