Biaxial Tensile Behavior of Commercially Pure Titanium under Various In-Plane Load Ratios and Strain Rates

Abstract

The aim of the present work is to contribute to the characterization of the biaxial tensile behavior of commercially pure titanium, under various in-plane loading conditions at room temperature, by a non-contact digital image correlation system. Several loading conditions, with load ratio ranging from 4:0 to 0:4 and displacement rate ranging from 0.001 to 0.1 mm/s, are examined. It is found that the yield strength and ultimate tensile strength of biaxial sample are greater than that of uniaxial sample, where the equi-biaxial sample shows the highest strength. It is also observed that increase in strain rate leads to remarkable improvement of tensile strength. Fractographic analysis indicates that the shape and size of dimples are load ratio and strain rate dependent. Additionally, a modified Johnson–Cook constitutive model was proposed to account for the effect of strain rate on biaxial tensile deformation. The experimental results are in good agreement with the simulated results, indicating that the proposed model is reliable to predict biaxial tensile deformation of commercially pure titanium at different strain rates.

Numerical Analysis of Experiments on Damage and Fracture Behavior of Differently Preloaded Aluminum Alloy Specimens

“…predicts evolution of irreversible macroscopic strains caused by different damage processes on the micro-level in a phenomenological way. In Equation (8), μ denotes the equivalent damage strain rate, and N = 1 / √ 2J 2 dev T and M = dev S/ dev S are the normalized stressrelated deviatoric tensors with…”

“…In this context, development of accurate and practically applicable material models is demanded [5,6]. In addition, experiments covering different stress states and load histories are needed to validate the theoretical approaches for a wide range of engineering applications and to identify corresponding material parameters [7,8]. Special focus of the experimental and numerical analysis presented in this paper is on formation of localized shear bands and their effect on fracture modes.…”

Biaxial Testing of Thin Metal Sheets under Non-Proportional Loading Conditions

“…To study the effect of nearly zero-stress triaxialities caused by shear loading processes, new geometries of uniaxially loaded specimens have been presented by [2,[5][6][7]9,11,12]. However, the experiments with the uniaxially loaded specimens only cover a small range of stress states and, thus, new tests with biaxially loaded cruciform specimens have been developed by [13][14][15][16][17][18][19][20][21][22][23][24][25][26] to examine anisotropic plastic behavior or to study limit strains at fracture in metal sheets. These tests use specimens taken from metal sheets with moderate thicknesses between 3 mm and 5 mm, and notches in thickness direction have been milled to localize inelastic deformations as well as damage and failure processes in these critical regions.…”