Abstract
Mechanical behavior of materials at medium and high strain rates (101∼104 s−1) is the foundation of developing mechanical theories, building material models, and promoting engineering design and construction. The torsional split Hopkinson bar (TSHB) is an effective experimental technique for measuring the pure shear mechanical properties of materials at high strain rates. In this study, the state-of-the-art in TSHB experimental technique is presented. Five typical types of TSHB loading mechanisms, i.e., prestored energy loading, explosive loading, direct impact loading, flywheel loading, and electromagnetic loading, were systematically reviewed. The TSHB fundamentals were outlined, which include elementary components, basic assumptions, working principles, the pulse shaping technique, specimen design, and the single-pulse loading technique. In addition, the combined loading and high/low temperature experimental techniques, which were developed based on TSHB, were also discussed in detail. Nearly all necessary elements for conducting a TSHB experiment and analyzing the experimental data were provided. Some research directions should be further pursued, such as extending the range of applicable materials and developing the combined loading techniques.
Highlights
As early as the 19th century, scientists gradually realized that the mechanical properties of materials under dynamic loads were significantly different from those under static loads, which led to the development of experimental techniques on testing materials under high strain rates. ereafter, during World War II, the strong military demand rapidly propelled studies of dynamic mechanical properties on materials
According to the strain rate of materials, mechanical experiments can be roughly divided into three ranges, i.e., creep experiment, quasistatic experiment and dynamic experiment. e strain rate of the creep experiment is 10−8∼10−6 s−1 and the strain rate of the quasistatic experiment is 10−5∼10−1 s−1. e dynamic experiment can be further divided into medium strain rate experiment, high strain rate experiment, and ultrahigh strain rate experiment, which correspond to the strain rates of 10−1∼101 s−1, 102∼104 s−1, and >104 s−1, respectively. ere are many mature experimental techniques for compression and tension at a high strain rate
The torsional split Hopkinson bar (TSHB) was reviewed according to the loading mechanisms, such as prestored energy loading, explosive loading, direct impact loading, flywheel loading, and electromagnetic loading. e main work of Baker and Yew [19], Duffy et al [40], Nie et al [41], and Fang et al [42, 43] were reviewed in detail
Summary
As early as the 19th century, scientists gradually realized that the mechanical properties of materials under dynamic loads were significantly different from those under static loads, which led to the development of experimental techniques on testing materials under high strain rates. ereafter, during World War II, the strong military demand rapidly propelled studies of dynamic mechanical properties on materials. For high strain rate compressive experiments, drop weight [2], split Hopkinson pressure bar (SHPB) [3], and gas guns [4] are commonly used. SHPB was used for split [9], spalling [10], and threepoint bending [11] experiments to measure the approximate tensile behaviors of materials under high strain rates. E punch-shear technique, which uses SHPB to test the specially designed specimen, is commonly used for materials at medium to high strain rates. Klepaczko [14] modified the double-notch shear specimen and directly impacted it with the striker, which shortened the rising time of the incident wave, and the strain rate reached 105 s−1. By analyzing the deficiencies in the existing TSHB experimental technique, several issues worthy of research and exploration are proposed
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