An inverse method based on finite element model to derive the plastic flow properties from non-standard tensile specimens of Eurofer97 steel. (December 2016)

• Record Type: Journal Article
• Authors: Knitel, S.; Spätig, P.; Seifert, H.P.
• Is Part Of: Nuclear materials and energy. Volume 9(2016)
• Page Start: 311
• Page End: 316
• Publication Date: 2016-12
• Subjects: Disk tensile specimens -- Inverse method -- Finite element simulations -- Tempered martensitic steels -- Necking behavior; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2016.06.017
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Determination of the plastic behavior to large strain by a new inverse method. Assessment of the stress/strain state in the neck region of tensile specimen. Application of the inverse method on non-standard disk tensile specimens. Disk tensile specimens of are proposed for spallation neutron irradiation. Disk tensile specimens are made of reduced activation tempered martensitic steel. Abstract: A new inverse method was developed to derive the plastic flow properties of non-standard disk tensile specimens, which were so designed to fit irradiation rods used for spallation irradiations in SINQ (Schweizer Spallations Neutronen Quelle) target at Paul Scherrer Institute. The inverse method, which makes use of MATLAB and the finite element code ABAQUS, is based upon the reconstruction of the load-displacement curve by a succession of connected small linear segments. To do so, the experimental engineering stress/strain curve is divided into an elastic and a plastic section, and the plastic section is further divided into small segments. Each segment is then used to determine an associated pair of true stress/plastic strain values, representing the constitutive behavior. The main advantage of the method is that it does not rely on a hypothetic analytical expression of the constitutive behavior. To account for the stress/strain gradients that develop in the non-standard specimen, the stress and strain were weighted over the volume of the deforming elements. The method was validated with tensile tests carried out at room temperature on non-standard flat disk tensile specimens as well as on standard cylindrical specimens made of the reduced-activation tempered martensitic steel Eurofer97. While both specimen geometries presented a significant difference in terms of deformation localization during necking, the same true stress/strain curve was deduced from the inverse method. The potential and usefulness of the inverse method is outlined for irradiated materials that suffer from a large uniform elongation reduction.