Extraction of uniaxial stress–strain curve from bending test using DIC measurements

Obid, Štefan (author), Starman, Bojan (author), Urevc, Janez (author), Halilovič, Miroslav (author)

This paper presents a novel methodology for the analytical determination of the uniaxial tensile/compressive stress–strain curve derived from the four-point bending test without a pre-assumed constitutive model. While the concept of extracting the stress–strain curve from a bending test is not new, the proposed methodology differs from existing methods by recognising the force equilibrium in a deformed configuration, resulting in a temporal variation of both a bending moment and an axial force. In addition, the deformation of the beam cross-section is taken into account according to the principles of finite strain theory either via Poisson’s ratio or by assuming volume conservation. The crucial data for this methodology are obtained from an experimentally conducted bending test in which the loading force, displacement and strain fields at the top, bottom and front faces of the specimen are measured using a stereo DIC. While the method is completely analytical, it reconstructs the stress–strain curve in discrete form by solving a system of linear equations. While the existing methods for the four-point bending test allow extraction of the stress–strain curve from a single experiment only for strains up to a few per cent, our methodology allows the extraction of the stress–strain curve in tension and compression up to five times the strains obtained with methods that neglect the above features.

• Language: English
• Keywords: four-point bending test, stress–strain curve, tension–compression asymmetry, digital image correlation, finite strains, material testing
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 15 str.
• Numbering: Vol. 106, art. 105346
• PID: 20.500.12556/RUL-158175
• UDC: 620.174:539.3
• ISSN on article: 0997-7538
• DOI: 10.1016/j.euromechsol.2024.105346
• COBISS.SI-ID: 196922883
• Publication date in RUL: 28.05.2024

Record is a part of a journal

• Title: European journal of mechanics. A, Solids
• Shortened title: Eur. j. mech. A, Solids
• Publisher: Elsevier
• ISSN: 0997-7538
• COBISS.SI-ID: 16874501

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: štiritočkovni upogibni preizkus, sigma-epsilon diagram, natezno-tlačna asimetrija, korelacija digitalnih slik, velike deformacije, materialno testiranje