Abstract
This paper presents some of the results of dynamic compression, splitting and direct-tensile tests of gabbro-diabase using two split Hopkinson bar apparatus. The results of laboratory experiments on specimens without and with notch for a wide range of loading parameters are given. Strength and deformation characteristics of gabbro-diabase were determined experimentally at high strain rates up to 10 3 s −1 . Mechanical characteristics were found to be strongly depended on the strain rate. A uniform interpretation of the rate effects of fracture of the tested gabbro-diabase is given on the basis of structural-temporal approach based on a set of fixed material constants. It is shown that temporal dependences of both the compressive and tensile strengths of the tested material can be effectively calculated using the incubation time fracture criterion.
Highlights
The dynamic characterization of rocks under high loading rates is fundamental to understand the material behaviour in case of dynamic events
Due to the stress-state of the disk, the failure is caused by tension when tensile stresses reach the tensile strength of the material on the diametric loading plane
The high strain-rate tests in tension were performed using a Split Hopkinson Tensile Bar (SHTB) [3], that consists of two circular aluminium bars, called input and output bars, having a length of 3 and 6 m respectively, with a diameter of 20 mm to which the specimen is glued on using a bicomponent epoxy resin
Summary
The dynamic characterization of rocks under high loading rates is fundamental to understand the material behaviour in case of dynamic events. The dynamic mechanical properties of rocks can be very different from those exhibited in quasi-static conditions Specific investigations in such dynamic ranges appear necessary to correctly understand their behaviour under intermediate and high strain rate conditions. The dynamic characterization has been carried out by means of traditional Split Hopkinson Pressure Bar (SHPB) and a Split Hopkinson Tensile Bar (SHTB) placed respectively at the Laboratory of Dynamic Investigation of Materials of Nizhny Novgorod and at the DynaMat Laboratory of the University of Applied Sciences of Southern Switzerland. These equipment are briefly described and the results of dynamic tension/compression tests at different high strain-rates on gabbro-diabase are discussed. The objective of this work is the comparison between both tensile and compressive dynamic and quasistatic tests, and analysis obtained results with incubation time approach
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