PSI - Issue 6

A.M. Bragov et al. / Procedia Structural Integrity 6 (2017) 161–167 Author name / Structural Integrity Procedia 00 (2017) 000–000

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dynamic exploitation loading. The solution of this problem is especially important for critical structures, such as atomic power engineering facilities, unique hydro-engineering structures, high-rise buildings, facilities of aviation infrastructure, subway, etc. Emergencies resulting from technogenic or natural disasters, as well as acts of terrorism at such facilities can lead to irreplaceable damage in human and material resources. The solution of the problem in question is based on the investigation of properties of structural materials under pulsed-wave effects changing in time. In this connection. The report presents a review of experimental and theoretical results obtained by the team of the authors as a result of long-term work in this field.

Nomenclature Е

elastic modulus of measuring bars cross-section area of measuring bars sonic velocity in measuring bars cross-section area of cylindrical specimen

А

с

A 0 L 0 D 0 H 0 B 0

height of cylindrical specimen diameter of cylindrical specimen

height of specimen in the form of a rectangular parallelepiped side of cross-section of specimen in the form of a rectangular parallelepiped

ε R (t) ε Т (t)

reflected strain pulse registered at the loading bar transmitted strain pulse registered at the supporting bar

σ cr comp static compression strength of material σ cr tens tensile strength of material τ incubation failure time

2. Experimental investigations

Tested in the experiments were samples (Table 1) of fine-grain and fiber-reinforced concrete, ceramic brick, as well as of several rocks (gabbro-diabase and limestone) by Bragov et al. (2013), Bragov et al. (2017), Smirnov et al. (2016). To obtain dynamic deformation diagrams for compression, the fundamental Kolsky method with split Hopkinson pressure bar (SHPB) was used, which currently is the most widely used method of studying the behavior of various materials under pulsed loading, both in this country and abroad. Stress, strain and strain rate in the specimen are computed from strain pulses registered at cross-sections of loading and supporting measuring bars according to the following formulas: ( ) ( ) 0 n compressio t A t EA T ε σ ⋅ = , ∫ ⋅ = − t R dt t L t C 0 0 n compressio ( ) ( ) 2 ε ε , ( ) ( ) 2 0 n compressio t L t C R ε ε ⋅ = − & . where Е, А, с are elastic modulus, cross-section area and sonic velocity in the measuring bars, respectively; A 0 , L 0 are specimen cross-section area and length, respectively; ε R (t), ε Т (t) are reflected and transmitted strain pulses, registered at the cross-sections of the loading and supporting bars, respectively.