Abstract
The goal of the analysis was to determine the strain localization for various specimen shapes (type A and type B according to PN-EN ISO 26203-1 standard) and different loading conditions, i.e. quasi- static and dynamic. Commercially pure titanium (Grade 2) and titanium alloy Ti6Al4V (Grade 5) were selected for the tests. Tensile loadings were applied out using servo-hydraulic testing machine and tensile Hopkinson bar with pre-tension. The results were recorded using ARAMIS system cameras and fast camera Phantom V1210, respectively at quasi-static and dynamic loading conditions. Further, specimens outline was determined on the basis of video data using TEMA MOTION software. The strain distribution on the specimen surface was estimated using digital image correlation method. The larger radius present in the specimen of type B in comparison to specimen of type A, results in slight increase of the elongation for commercially pure titanium at both quasi-static and dynamic loading conditions. However this effect disappears for Ti6Al4V alloy. The increase of the elongation corresponds to the stronger necking effect. Material softening due to increase of temperature induced by plastic work was observed at dynamic loading conditions. Moreover lower elongation at fracture point was found at high strain rates for both materials.
Highlights
A normalized specimens are usually applied for the determining of mechanical properties of titanium and its alloys using tensile Hopkinson bar
Results of strain distribution measurement were used to develop methodology based on inverse modelling for estimating visco-plastic material parameters at high strain rate conditions
This paper presents analysis of the necking phenomenon during quasi-static and dynamic tensile tests of commercially pure titanium (CPT) and Ti6Al4V titanium alloy
Summary
A normalized specimens are usually applied for the determining of mechanical properties of titanium and its alloys using tensile Hopkinson bar. The technique was applied to determine stress-strain behaviour of Ti6Al4V titanium alloy using both high strain rate in-plane shear and tensile tests. As well as local displacements were measured using high speed photography in conjunction with planar digital image correlation [12]. Application of digital image correlation method enables to investigate differences between low and high strain rate deformation of those materials
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