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Numerical modelling of uniaxial compressive strength laboratory tests

Nguyen Phu Minh Vuong, Walentek Andrzej, Waclawik Petr, Souček Kamil, Antoniuk Michał

Journal of Sustainable Mining

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2023

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Vol. 22. iss. 4

280--294

EN

In the last decades, numerical modelling has been widely used to simulate rock mass behaviour in geo-engineering issues. The only disadvantage of numerical modelling is the reliability of required input data (e.g. mechanical parameters), which is not always fully provided due to the complexity of rock mass, project budget, available test methods or human errors. On the other hand, it was proven in many cases that numerical modelling is a helpful tool for solving such complex problems, especially when coupled with the results of laboratory and in-situ tests. This paper presents an attempt to determine the proper numerical constitutive model of rock and its mechanical parameters for further simulating rock mass response based on the outcomes of laboratory testing. For this purpose, the available constitutive models, including mechanical parameters, were taken into account. The simulation performance with the selected constitutive models is demonstrated by matching the numerical modelling results with the uniaxial compressive strength laboratory tests of rock samples from the Bogdanka coal mine. All numerical simulations were carried out using the finite difference method software FLAC3D.

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A study of molybdenum addition on W-Ni-Fe based heavy alloys sintered with spark plasma sintering

Prasad B. S. L., Annamalai R.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2019

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Vol. 67, nr 2

167--172

EN

Tungsten heavy alloys comprising tungsten, nickel and ferrous were modified, where molybdenum was added in varying weight proportions keeping the ratio of Ni: Fe (8:2) constant. The powders were mixed in a high-energy ball mill and were further fabricated using the spark plasma sintering (SPS) method at a peak temperature of 1000°C with heating rate of 100°C/min. The details of the microstructure and mechanical properties of these various alloy compositions were studied. With the increasing weight composition of the Mo in the alloy, the relative density of the alloy increased with a significant improvement in all the mechanical properties. The yield strength (YS), ultimate tensile strength (UTS) and hardness improved significantly with increase in the proportion of Mo; however, a reduction in elongation percentage was observed. The maximum strength of 1250 MPa UTS was observed in the alloy with a Mo proportion of 24%. The heavy alloy unmixed with Mo has shown distinct white and grey regions, where white (W) grain is due to tungsten and grey region is a combinatorial effect of Ni and Fe. Upon addition of Mo, the white and gray phase differences started to minimize resulting in deep gray and black ‘C’-phase structures because of homogenization of the alloy. The main fracture mode found during this investigation in the alloys was inter-granular mode.

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Effect of the shielding gas flow rate on mechanical properties and microstructure of structural steel (IS2062) welds

Rizvi S. A., Tewari S. P.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 4

971--984

EN

Structural steel is frequently used for industrial purpose as it is more economical as compared to other steels .In the present research article an attempt has been made to find, how the mechanical properties and microstructure properties of the IS2062 structural steel are affected by the different welding parameters such as shielding gas flow rate, voltage, wire feed speed and welding current. In this research work 75%Ar+25%CO2, is used as shielding gas because it is a best shielding gas mixture for getting a good quality mechanical properties and micro structural properties of welded joint. For study of fracture mode of tensile fracture, SEM test carried out which help to understand the factor influence the microstructure and it is found that the Fractures of tensile samples are brittle in nature which shows the low ductility and brittle fracture. Micro hardness values change throughout weld metal varying by shielding gas flow rate.