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It is known that experiments with intensive dynamic influences and high-speed deformation of specimens under tension are important in the analysis of deformations and strength of structures and their elements. The most reasonable and widely used method for obtaining dynamic stressstrain curves, characteristics of ultimate strength and deformations is the modified Kolsky method. It should be noted a small number of publications on the analysis of the influence of fillets and the length of the working part of the specimen on the most important mechanical characteristics obtained by this method. This work is aimed at increasing knowledge in this area. By numerical and experimental analysis it was established that when the working part of the specimen has a length of 5 mm, then the uniformity and one-dimensionality of the stressed state are seriously violated. When choosing the length of the specimen in the Kolsky method, there are important limitations: the length of the specimen must be much smaller than the length of the loading pulse. Therefore, in this study, two specimen lengths of 10 and 15 mm were analyzed. In this paper, we give experimental and calculated diagrams and their comparison with each other. It was shown, that for the above-mentioned lengths, the homogeneity and one-dimensionality of the stressed state is substantially improved.

The combined experimental and theoretical approach was applied to the study of high-speed deformation and fracture of the 1810 stainless steel. The material tests were performed using a split Hopkinson pressure bar to determine dynamic stress-strain curves, strain rate histories, plastic properties and fracture in the strain rate range of 102 ÷ 104 s-1. A scheme has been realized for obtaining a direct tensile load in the SHPB, using a tubular striker and a gas gun of a simple design. The parameters of the Johnson-Cook material model were identified using the experimental results obtained. Using a series of verification experiments under various types of stress-strain state, the degree of reliability of the identified mathematical model of the behavior of the material studied was determined.

A description of experimental complexes, methodological and hardware means for determining the mechanical properties of materials under high-speed deformation and fracture is given in the report. Determination of mechanical properties in the strain rate range 5•102÷103 s-1 is the first direction of work in the laboratory of “Dynamic Materials Testing”. These tests are done using automated complexes based on the Kolsky method and its modifications for compression, tension and shearing. It is also possible to determine the fracture toughness, the characteristics of dynamic crack resistance, as well as to obtain stressstrain curves of low-density materials under uniaxial strain. Original gas guns with a caliber of 10, 20 and 57 mm are used for creation a dynamic load. The study of the behavior of materials at strain rates of 105 s-1 and higher is the second direction of work. In this case, the methods of a planewave shock experiment based on gas guns of 57 and 85 mm caliber are used. Manganine and dielectric pressure sensors, as well as laser interferometry are used for measuring the parameters of elastoplastic waves and for determining such important characteristics as impact compressibility, Hugoniot yield strength, spall strength.

The objective of this study was to investigate the compression behaviour of the UHPFRC and its matrix (UHPC) under high strain rate. Two experimental set-ups were used for compression testing: a traditional Split Hopkinson Pressure Bars and a compression version of the Modified Hopkinson Bar. The tests were conducted, in the range of 100–500 s −1 on cylindrical specimens with both diameter and height of 20 mm. Results show significant increases in peak strength and dissipated energy.

A study of the strength and deformation properties of freshwater ice under compression, tension and shear in a wide range of strain rates (10−4 − 3 ⋅ 103 s−1 ) and temperatures of − 5∘ C, − 20∘ C, − 40∘ C and − 60∘ C was performed. Static stress-strain curves of ice under compression were obtained on which the identified strength properties of ice as well as compressive modulus. To determine the mechanical properties of ice at high-speed loading the Kolsky method was used with various embodiments of split Hopkinson bar. The deformation curves were obtained at various loading conditions. Thereon breaking points were defined as well as their dependence on the strain rate and temperature. Also static and dynamic strength properties of ice at splitting and circular shear were defined. Increase in the dynamic strength properties upon the static ones for all loading conditions was marked.

The paper presents the dynamic characterization in tension and compression of three rocks, Carrara marble, Onsernone gneiss and Peccia Marble, at high strain-rates. Two versions of a Split Hopkinson Bar have been used. The version for direct tension tests is installed at the DynaMat Laboratory of the University of Applied Sciences of Southern Switzerland, while the traditional version in compression is installed at the Laboratory of Dynamic Investigation of Materials of Lobachevsky State University. Results of the tests show a significantly strain-rate sensitive behaviour, exhibiting dynamic strength increasing with strain-rate. The experimental research has been developed in the frame of the Swiss-Russian Joint Research Program.

In the present work the combined experimental and theoretical approach has been ap- plied to study high strain rate behavior and failure of titanium alloy Ti-6Al-4V. For modeling con- stitutive material response it has been suggested to use the modified Gurson's plasticity model which takes into account a dependence on the type of loading. Rate dependency effects have been added to the initial constitutive equations. Compressive and tensile tests were carried out by means of Split Hopkinson Pressure Bar for determination of dynamic stress-strain curves, strain rate histories, plasticity and failure properties for strain rate range 10 2 -10 4 s x1 . Parameters of the material model were determined using the obtained experimental results. High strain rate tensile tests of cylindrical V-cut specimens and three point bending (Charpy) experiments were carried out for validation of the model. The numerical simulation of dynamic material response was conducted with implementa- tion of the developed material model for the last test schemes.

High-porosity materials, such as chamotte and mullite, possess a heat of fusion. Owing to their properties, these materials can be used with success as damping materials in containers for airplane, automobile, etc. transportation of radioactive or highly toxic materials. Experimental studies of the dynamic properties have been executed with using some original modifications of the Kolsky method. These modified experiments have allowed studying the dynamic compressibility of high-porosity chamotte at deformations up to 80% and amplitudes up to 50 MPa. The equations of the mathematical model describing shock compacting of chamotte as a highly porous, fragile, collapsing material are presented. Deformation of high-porous materials at non-stationary loadings is usually accompanied by fragile destruction of interpore partitions as observed in other porous ceramic materials. Comparison of numerical and experimental results has shown their good conformity.

The seed beetle genus Ctenocolum Kingsolver & Whitehead is peculiar because its preferred host Lonchocharpus Kunth (Fabaceae) is not preyed upon by other bruchine species. This study investigates the phylogenetic relationships and evolution of this genus and of its species groups, while providing the description of three new species and of the male of C. biolleyi Kingsolver & Whitehead. To infer phylogenetic relationships, a character matrix of 40 morphological characters was assembled and analysed using both parsimony and Bayesian inference. Ancestral state estimations of host plant use and biogeography analyses were also performed. A total of 22 species were examined: 16 Ctenocolum species (including the three new ones) and six outgroup bruchine species (from genera Caryedes Hummel, Meibomeus Bridwell, Pygiopachymerus Pic and Pachymerus Thunberg). All resulting trees support the monophyly of the genus Ctenocolum. Three synapomorphies characterize the genus: (i) head with frontal carina enlarged at base, (ii) male pygidium truncated apically, and (iii) lateral lobes of tegmen with dorsal process. The two known species groups are also recovered monophyletic in the parsimony analyses. The following three species are described: Ctenocolum inmaculatus Manfio & Ribeiro-Costa sp. nov. (Type locality: Venezuela, Guarico), which belongs to the group tuberculatum; Ctenocolum nigronotus Manfio & Ribeiro-Costa sp. nov. (Type locality: Porto Rico, Mayaguez) and C. pallidus Manfio & Ribeiro-Costa sp. nov. (Type locality: Republic of Guyana), which belong to the group podagricus. Finally, we present colored illustrations of dorsal patterns and male genitalia for these three new species and C. biolleyi in addition to an updated key for the genus Ctenocolum.