Misconception of the Use of 2D Plane Stress Solutions for Free Surfaces of Cracked Bodies and Its Significance for Full Field Measurement Techniques

journal article in Web of Science

en

Although 2D fracture mechanics solutions have been successfully applied, many analyses are affected by the wrong presumption of the 2D plane stress state at the free surface intersected by a crack front. The significance of this presumption and the related confusion have grown rapidly with the progress of strain field measurement techniques, such as the digital image correlation. The article demonstrates this wrong presumption on two of the most commonly measured and studied entities, which are the plastic zone in front of the crack tip and the crack tip opening displacement. 3D stress and strain solution is necessary to be performed. A realistic crack front curvature is required to be considered. Only such solutions can be used for comparison with the experimentally obtained strain fields. Other solutions are wrong and can bring confusion, wrong conclusions about material behavior, and slow down the progress in the field of fracture mechanics due to the incompatibility of the presumed stress state and the stress state present in experiments. The presumption of the 2D plane stress state at the free surface of bodies with cracks is wrong. Due to the corner-point singularity, the stress and strain fields are different. This is significant namely for the rapidly developing strain field measurement techniques, such as digital image correlation. 3D solutions are required to obtain correct results.image (c) 2024 WILEY-VCH GmbH

Although 2D fracture mechanics solutions have been successfully applied, many analyses are affected by the wrong presumption of the 2D plane stress state at the free surface intersected by a crack front. The significance of this presumption and the related confusion have grown rapidly with the progress of strain field measurement techniques, such as the digital image correlation. The article demonstrates this wrong presumption on two of the most commonly measured and studied entities, which are the plastic zone in front of the crack tip and the crack tip opening displacement. 3D stress and strain solution is necessary to be performed. A realistic crack front curvature is required to be considered. Only such solutions can be used for comparison with the experimentally obtained strain fields. Other solutions are wrong and can bring confusion, wrong conclusions about material behavior, and slow down the progress in the field of fracture mechanics due to the incompatibility of the presumed stress state and the stress state present in experiments. The presumption of the 2D plane stress state at the free surface of bodies with cracks is wrong. Due to the corner-point singularity, the stress and strain fields are different. This is significant namely for the rapidly developing strain field measurement techniques, such as digital image correlation. 3D solutions are required to obtain correct results.image (c) 2024 WILEY-VCH GmbH

3D effects; corner point singularities; crack tip plastic zones; rack closures; strain field measurements

11.06.2024

WILEY-V C H VERLAG GMBH

WEINHEIM

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