Abstract
In this work, various tensile tests, including Brazilian disc test (BDT), flattened Brazilian disc (FBD) test and semi- circular bending (SCB) test, were carried out on a highly particle-filled composite by using a split Hopkinson pressure bar (SHPB). With the consideration of low strength and low wave impedance of the materials, a quartz crystal transducer was embedded in SHPB to measure the loading forces. A high-speed camera was used to capture the deformation and fracture process of materials. Digital image correlation (DIC) method was used to process these digital images to obtain the dynamic deformation information. Based on the measured strain fields, the crack growth path was determined and the failure mechanism of samples was analyzed. Combining SHPB and DIC method, the indirect tensile stress strain plots of disc samples were obtained, and the dynamic fracture toughness of materials was measured using both FBD and SCB tests. The results show that the tensile failure strength and fracture toughness increases with the increase of strain rates, exhibiting strain rate dependence. The high-speed DIC method combined with SHPB is effective to study the dynamic tensile behaviour of brittle materials with low strengths.
Highlights
In studying brittle solids, such as rocks, concrete and explosives, it is inconvenient to use conventional direct tensile test to measure the tensile properties of these materials due to difficulties both in specimen preparation and test operation
The results show that the tensile failure strength and fracture toughness increases with the increase of strain rates, exhibiting strain rate dependence
The high-speed Digital image correlation (DIC) method combined with split Hopkinson pressure Bar (SHPB) is effective to study the dynamic tensile behaviour of brittle materials with low strengths
Summary
In studying brittle solids, such as rocks, concrete and explosives, it is inconvenient to use conventional direct tensile test to measure the tensile properties of these materials due to difficulties both in specimen preparation and test operation. Some alternative methods were used to determine the tensile strength of brittle materials, such as Brazilian test [1,2,3], ring test [4] and bending test [5]. These methods aim at generating tensile stress in the sample by far-field compression and are easier to operate than conventional direct tensile tests. Combining the split Hopkinson pressure Bar (SHPB) with Brazilian test and semi-circular bending test, some researchers have studied dynamic tensile behaviour of rocks and explosives [6,7,8,9]
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