Quality of blast preparation for rock beneficiation influences both on integrity of mineral stock in particular and in economical performances of enterprise operations in general. While rock processing for obtaining of crushed stone the yield of screenings is high, its amounts depend on rock strength properties. Investigation into the influence of drilling and blasting parameters on strength properties of blasted rocks is an urgent research and practical task for mining companies producing building stones. This article discusses results of full-scale experiment aimed at determination of strength of blasted rocks in shotpile with accounting for fracture zones as a function of rock massif saturation with energy of explosive substance.

In the present study, the flexural behavior of concrete beams reinforced with longitudinal rebars made of glass fiber reinforced polymer composites (GFRP), is studied using finite element method. For this purpose, a number of concrete beams with square sections are modeled in ABAQUS. In all of the beams, four GFRP rebars with diameter of 12 mm, and 10 steel rebars with diameter of 8 mm are vertically used to prevent creating shear cracks in the beams. The beam no. 1 is without transverse rebar, beam no. 2 has a row of transverse rebar, which is placed at the bottom and in the plane of vertical rebars. Beam no. 3 has a row of transverse rebars that is placed at the top and in the plane of vertical rebars; and the beam no. 4 has two rows of transverse rebar at the top and bottom of the beam in the plane of vertical rebars. The beams are gradually loaded under up to 6 ton, and the amounts of displacement and strain at the middle of beams are compared together. The obtained results reveal that the force-displacement diagram of reinforced beams with composite rebars are almost linear until ultimate phase, and in all of the beams, adding transverse rebar leads to less deflection in the middle of the beam under an identical loading. Moreover, the load bearing capacity of beams containing transverse rebars, were higher than the other beams.

The present invention provides a modular drilling assembly having a module for contactless power and data transfer over a nonconductive gap between rotating and non-rotating members of a steering module. The gap usually application data contains a non-conductive fluid, such as drilling fluid, or oil for operating hydraulic devices in the down-hole tool. The down-hole tool in one embodiment is a modular drilling assembly wherein a drive shaft is rotated by a down-hole motor to rotate a drill bit attached to the bottom end of the drive shaft. Generally, there are two main sections on mud motor which are bearing section and power section. The power section generally includes a housing which houses a motor stator within which a motor rotor is rotationally mounted. The power section converts hydraulic energy into rotational energy by reverse application of the Moineau pump principle. The stator has a plurality of helical lobes which define a corresponding number of helical cavities. The rotor has a plurality of lobes which number one fewer than the stator lobes and which define a corresponding plurality of helical cavities. Generally, the greater the number of lobes on the rotor and stator, the greater the torque generated by the motor. Fewer lobes will generate less torque but will permit the rotor to rotate at a higher speed. Based on torque and rotate speed, determine the optimum power can be produced by power section configurations.

In recent years, efforts have been made to produce advanced composite materials in order to lessen environmental impact and to extent sustainability. Traditional materials are largely substituted by composites due to their greater properties like flexural strength, low thermal expansion and high strength. Numerous studies are present that show the process of composite materials reinforcement with natural fiber to improve mechanical and thermal properties. The vital aspect of exploitation of natural fiber in composites is associated with biodegradability. An extensive range of different natural fibers has been used for reinforcement till now. In present work, mechanical properties of jute fiber reinforced epoxy and polyester composites manufactured using Taguchi optimization method are investigated, experimentally. It was found that jute reinforced epoxy composite had better mechanical properties than jute polyester composite. Also, Epoxy- jute composite had lower erosion wear rate than polyester jute composites.

The present work summarizes some recent experimental, theoretical and numerical results on brittle fracture of isostatic polycrystalline graphite. The analyses have been carried out on V-notched samples under mixed mode (I+II), torsion and compression loading, considering various combinations of the notch tip radius, opening angle and notch tilt angle. The static strength of the considered specimens is assessed through an approach based on the strain energy density averaged over a control volume. The center of the control volume is located on the notch edge, where the principal stress reaches its maximum value. The correct orientation is obtained by a rigid rotation of the crescent-shaped volume while the size depends on the fracture toughness and the ultimate strength of the material. This methodology has been already used in the literature to analyze U- and V-shaped notches subject to mode I loading with very good results and advantages with respect to classic approaches. The results reported in this new work show, also under mixed mode loading conditions, good agreement between experimental data and theoretical predictions.

This paper presents the effect of vibratory dissimilar TIG (Tungsten Inert Gas) welding process on hardness of welded joins with respect to change of vibratory parameters. In this study, new vibratory setup with two metal engravers is used to give mechanical vibrations to the specimens to be welded. Finally, the effect of mechanical vibrations with the variation of vibration parameters is studied on the hardness at the weld bead and heat effected zone (HAZ) of welded joints.

The article discusses the strength of concrete and other brittle materials in the case of non-uniform biaxial type of compression (σ1 > σ2 > 0) and triaxial compression of σ1 > σ2 = σ3 > 0 type (it was assumed that σ> 0 corresponds to compression). It is noted that, when considering the biaxial loading in the accepted model, probabilistic nature of distribution of stresses along the contour of pores and inclusions, i.e. stress causing formation and propagation of cracks in the material, plays an important role. Moreover, the stress across the circuit pores was regarded as a three-dimensional random field of S(α,β,γ,ω),where ω - is a random argument. Considering the average number of overshoots NR we believed that the random field of S is not homogeneous (not stationary): its expectation is not constant, but is a function of nonrandom arguments Мs = Мs(α;β;γ). External load, corresponding to NR = const (and at the same time constant of level exceedance probability), first increases and then decreases a little. Heating up to 300оС (573K) and 400оС (673K) leads to violations, and long-term load leads to significant changes in the macro- and microstructure of concrete.

Aluminium alloy AlMg4.5Mn has got comprehensive acceptance in the manufacturing of light weight frames, marine structures which require high strength and worthy corrosion revulsion. The present investigation work focuses on friction stir welding process in which influences of operating parameters have been studied on friction stir welded butt joints. The FSWed joints specimens have been produced by experimentation at three levels of tool traverse speed and tool rotational speed keeping input force and tool tilt angle constant. Mechanical properties and microstructure of welded joints have been investigated in the present study. Change in the microstructure at different zones which transforms the mechanical properties of welded joints was due to the asymmetrical flow of material and thermal cycles around the pin. The second phase beta grains are formed as the very high temperature reached due to input parameters combinations. Traverse speed (TS) and tool rotational speed (TRS) are taken in a range of 16-40 mm/min and 500-1400 rpm, respectively. The best combination of parameters results in higher tensile strength which is well supported by the micro-hardness curve and the compact grains microstructure profile. Microstructure at different points and physical properties exhibited by the welded joint are well brought into line to summarize the effects of different parameters.

Two procedures to evaluate fracture resistance of notched components are proposed in this contribution: the Strain Energy Density (SED) over a control volume and the Cohesive Zone Model (CZM). With the aim to simplify the application of the two fracture criteria, the concept of the ‘equivalent local mode I’ is presented. The control volume of the SED criterion and the cohesive crack of the CZM, have been rotated along the notch edge and centered with respect to the point where the elastic principal stress is maximum. Numerical predictions are compared with experimental results from U and V shaped notches under three point bending with notch root radius ranging from 0.2 to 4.0 mm. In parallel the loading conditions vary, from pure mode I to a prevailing mode II. All specimens were made of PMMA and tested at -60°C. The good agreement between theory and experimental results adds further confidence to the proposed fracture criteria.

Application of cooling slope in casting is a relatively simple process with low equipment and processing costs, which is able to produce semi-solid slurries with different parameters such as pouring temperature, length and angle of slope plate, and plate type. In this study, the effect of angle and length of copper made slope plate on the microstructure of A360-Aluminum alloy is investigated. Microstructure study of metallographic samples in different conditions revealed that for 400mm slope length and 60° slope angle the optimum sphierized and homogenized microstructure is achieved. Also, under these conditions, the most hardness (77HB) was obtained, which might be because of suitable solidification conditions namely time and rate of shear stress. After finding the suitable conditions of slope length and angle, the effect of the circulation cooling system was examined; and the method with cooling system was found to result in more homogenized microstructure compared to ordinary method.