Abstract
Background: For the standard ISO 16842 cruciform test specimen, stresses obtained from the gauge area are far below the ultimate tensile strength due to high stress concentrations at the slit ends which lead to premature failure. Objective: To introduce a new cruciform specimen design which has been optimized with respect to the determination of yield surfaces. Methods: The proposed design differs from the ISO standard by an additional thinning of the gauge area and wider slits in the arms to avoid stress singularities. Compared to other cruciform test piece designs found in the literature, the stress distribution is still homogeneous and there is no need to reduce the size of the gauge area, thanks to the specimen’s well-balanced proportions. Results: Biaxial tensile tests have been conducted with aluminium 5754 alloy samples of different thicknesses. For the standard cruciform test piece, the maximum strain achieved at the gauge area is only 25% of the fracture strain. The optimized cruciform test piece can attain about 66% of the fracture strain before breaking. Conclusions: The optimized specimen design enables the measurement of yield surfaces at higher stress levels. In case of other materials such as elastomers, the slit length has be to adjusted accordingly.
Highlights
Nowadays, the widespread use of metals and alloys as the main material in various applications have led to greater demands for the understanding of material characteristics including plastic behavior, damage and failure
Results from Standard Test Pieces”, cruciform test pieces according to International Organization for Standardization (ISO) 16842 are used which feature uniform thickness and seven equidistant parallel slits per arm made by laser cutting
Aluminium alloy sheets (AA5754, AlMg3) from various manufacturers have been acquired with the sheet thickness a varying between
Summary
The widespread use of metals and alloys as the main material in various applications have led to greater demands for the understanding of material characteristics including plastic behavior, damage and failure. In order to get the accurate information regarding the states of stress which enable plastic deformation, the required yield surfaces are often determined with the help of biaxial loading. This method is increasingly becoming the favoured material testing method in contrast to other multiaxial tests such as the Erichsen cupping test, the Marciniak test, the Nakajima test or the hydraulic bulge test as it can achieve. For the standard ISO 16842 cruciform test specimen, stresses obtained from the gauge area are far below the ultimate tensile strength due to high stress concentrations at the slit ends which lead to premature failure. In case of other materials such as elastomers, the slit length has be to adjusted
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
