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Complex analysis of uniaxial compressive tests of the Mórágy granitic rock formation (Hungary)

measured by strain gauges, which measures the deformation between 1/4 and 3/4 of the sample’s height. Fifty uniaxial compressive tests were performed in the rock mechanics laboratory at RockStudy Ltd. The NX ( d = 50 mm)-sized cylindrical rock samples having the ratio of L / d = 2/1 (here L and d are the length and diameter of a sample, respectively) were prepared (see Fig. 4 ). Mechanical properties of granitic rock samples are summarised in Table 1 . Figure 4 A prepared sample in the beginning of the UCS test. Table 1 Mechanical properties

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Research on energy absorption properties of open-cell copper foam for current collector of Li-ions

Abstract

Quasi-static uniaxial compressive tests of open-cell copper (Cu) foams (OCCF) were carried out on an in-situ bi-direction tension/compress testing machine (IBTC 2000). The effects of strain rate, porosity and pore size on the energy absorption of open-cell copper foams were investigated to reveal the energy absorption mechanism. The results show that three performance parameters of open-cell copper foams (OCCF), involving compressive strength, Young modulus and yield stress, increase simultaneously with an increase of strain rate and reduce with increasing porosity and pore size. Furthermore, the energy absorption capacity of OCCF increases with an increase of porosity and pore size. However, energy absorption efficiency increases with increasing porosity and decreasing pore size. The finite element simulation results show that the two-dimensional stochastic model can predict the energy absorption performance of the foam during the compressive process. The large permanent plastic deformation at the weak edge hole is the main factor that affects the energy absorption.

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THE INFLUENCE OF THE DE-ICING SALT ON THE DETERIORATION OF ROCK MATERIALS USED IN MONUMENTAL BUILDINGS

Abstract

The de-icing salt has been used for decades to increase safety on the roads and sidewalks. In Poland, mainly the sodium chloride is used in order to maintain the roads in good condition during winter. Like other salts used for surface de-icing, it depresses the freezing point to lower temperatures and has an additional thermal effect by an exothermic reaction. However, this salt causes the accumulation of chlorides in the walls and stone buildings contributing to the deterioration of these facilities.

The paper addresses the issue of the influence of salt solutions on the structure and geomechanical properties of rocks at negative temperatures. The study was conducted on the basis of cyclic tests which simulate complex action of both the negative temperature and the salty environment. The conditions for the tests were chosen so as to reflect the actual conditions of the winter in Poland. During the tests, the longitudinal wave propagation velocity, changes in weights of the samples as well as visual changes were recorded which allowed continuous tracking of occurring changes. At the end of the tests, the rock samples were subjected to uniaxial compressive tests. For this purpose, four lithological types were chosen, representing the sedimentary rocks: clastic and carbonate, widely used in stone constructions.

Open access