Abstract
This work aims to evaluate the capability of the theory of critical distances (TCD) to predict the static failure of U-notched AISI 420 martensitic stainless steel specimens with different geometric features under pure bending loading. Theoretical estimates of the stress intensity factor during fracture onset were calculated according to the line (LM) and point methods (PM), which consider the characteristic length L, inherent strength σ0, and notch tip radius ρ. Initially, L and σ0 were determined on the basis of the material’s properties (i.e., fracture toughness KIc and ultimate tensile strength σu,t), resulting in imprecise estimates. Conversely, L and σ0 determined using the appropriate analysis of linear–elastic stress fields ahead of notches with different sharpness provided highly accurate predictions. The microscopic study of fractured specimens ensured better comprehension of the results. Moreover, the accurate values of L and σ0 were used to predict the failure of V-notched specimens.
Highlights
On-service failure of a component or equipment consists of an extremely undesirable occurrence in any industrial field, which can result in loss of human life, environmental pollution, and extensive material damage
The present study evaluates the capability of theory of critical distances (TCD) to predict the failure of U-notched AISI 420 specimens loaded under four-point bending and assesses the failure of V-notched specimens under bending loading and tensile stress
In TCD the presence of mechanisms that occur in the microstructural level is denoted by the characteristic length parameter L. In addition to this general effort to understand the mechanisms related to TCD, a specific issue arises and continues to intrigue researchers, i.e., if TCD is based on principles related to linear–elastic fracture mechanics (LEFM), why does it obtain accurate results for materials with elastic–plastic behavior? accurate results are obtained, this question stands open in the conclusion of many studies, either in the case of smallscale[11] or large-scale[12,13] plastic deformation
Summary
On-service failure of a component or equipment consists of an extremely undesirable occurrence in any industrial field, which can result in loss of human life, environmental pollution, and extensive material damage. Dimensional or shape variations, keyways, and notches are examples of geometric features that concentrate stresses around its apices during loading, becoming the most probable regions of crack onset[1]. Many investigations have proposed accurate methods for failure prediction of engineering materials in the presence of cracks and evaluation of the detrimental effects of notches on the general strength of components with different geometric attributes[2]. Among the currently discussed alternatives, the theory of critical distances (TCD) deserves special attention because of the simplicity of its mathematical formalization and accurate results obtained for different materials (i.e., ceramics, polymers, metals, and composites), geometries, and loading modes. The microscopic analysis of fractured specimens leads to a comprehensive understanding of the results obtained
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