Quantification Analysis of Geometric Characteristics of Micro Crack Network On Fault Rock Surface

Fault is a common water conduit in coal mine, and the cracks of fault rock will greatly affect its permeability. In this study, three fault samples obtained in the mining area in Southwest Shandong of China was tested and observed by SEM, XRD and plane-polarized light microscope. The geometric characteristics, including crack density, fractal dimension and crack connectivity, of the crack network on the sample surface were calculated. Combined with the mineral content obtained by XRD, the nonuniformity coefficient of mineral composition in rock is defined. The results show that the crack geometric characteristics of the three samples are quite different and the above geometric parameters of crack network on three fault rock samples are correlated. The optical photomicrographs and SEM images show that the crack network is developed most in the fault rock samples with the least clay content. The study suggests that the nonuniformity coefficient of rock samples is positively correlated with the geometric characteristic of crack network. The difference in the crack network of fault rock samples is related to the coefficient of friction of clay.

Анализ суперкаверн, формируемых при высокоскоростном движении в воде группой ударников

The analysis of supercavities formed during the high-speed motion in water of two closely spaced supercavitating strikers is performed. By comparing of geometric characteristics of supercavities, the possibility of qualitative assessment of the degree of influence of closely spaced strikers is shown. By the example of two strikers, the characteristic distance between them was determined, at which the minimum mutual influence of the strikers on each other is observed.

Method for the influence design assessment of a wheeled agricultural vehicle on the soil

The impact of a wheeled agricultural vehicle on the deformable support surface determines the vehicle's ability to move, as well as soil compaction, which is not desirable in agriculture. The agricultural machine must not cause more pressure on the ground than is permissible. Therefore, in the tasks of design numerical modelling of the agricultural vehicle movement or trailer, it is required to calculate the specified parameter. It is impossible to calculate without knowledge of the geometric characteristics of the contact spot associated with the normal deformation of the tire under normal load. To calculate these characteristics, it is necessary to have universal dependencies for determining the normal stiffness of the tire. These are available for tires of various purposes. The elastic properties of ultra-low pressure tires are insufficiently studied. Experimental studies of the elastic properties of these tires have been carried out with the authors participation. However, there are currently no dependencies to describe them. This does not provide the possibility of a correct design calculation of the influence of such tires on the soil. The purpose of the work: to develop a universal method for calculating the influence on the soil of agricultural vehicle. A universal method for calculating the impact of a wheeled agricultural machine on the ground has been developed. Universal design-experimental dependence for determining the normal stiffness of ultra-low pressure tires is obtained. It takes into account tire pressure, normal load under specific conditions and geometric characteristics.

INFLUENCE OF OBJECT TECHNOLOGICAL PHANTOM’S TRANSFORMATIONS OF THE PRODUCTION’S QUALITY

The article states that the relevance of modeling processes, followed by analysis of the features of the transformation of the technological phantom of the real object, in particular precision instrumentation products, which affects the accuracy of shaping the formation of this object in automated production. The main purpose of this study was to substantiate analytical models of transformations of the technological phantom of the object, taking into account the type of coordinate systems, which can be observed transformation of some coordinates into others. These features of the transformations significantly affect the accuracy of the formation of this object. The main analytical models that determine the features of the formation of the technological phantom and the need to combine the technological phantom with the mass of the object, which provides opportunities to take into account the problems of manufacturing surface elements, determine the features of shaping the accuracy of reproduction of objects From the analytical models obtained in our work, we have the opportunity to say that for any object the technological phantom has a geometric construction, and the shape of this construction is the main factor influencing the accuracy of object formation. The research substantiates the analytical model of transformations of the technological phantom of the object, which determines the dependence of the geometric characteristics of the formation of the precision object, which is made using certain additive or destructive (with decreasing mass of the real object) technological processes. In further research, the model of shaping technological objects in space requires modeling of the peculiarities of mass representation in view of the energy connections of the technological phantom of the object in a certain volume, which has the task of determining and improving manufacturing accuracy.

MACH’S PRINCIPLE AND SOME PROMISING NEW RESULTS IN FIVE-DIMENSIONAL FIELD THEORY

The further development of the five-dimensional field theory is considered and it is shown that it contains even more new and very promising possibilities that relate to the influence of the dimension of our Universe and its geometry on the physical and geometric characteristics available in it, as well as the identification of the connection between the field equations of this theory and various old and new problems of modern physics, astrophysics and cosmology.

BUCKLE PROPAGATION OF SANDWICH PIPES UNDER EXTERNAL PRESSURE

Buckle propagation of local collapse appearing in the damaged pipes is one of the failure modes that are of particular interest for deepwater application. The local collapse can propagate along the pipeline for long distances in both directions when the external pressure magnitude is up to the propagation pressure. In this paper, the buckle propagation pressure of sandwich pipes (SP) with different material properties and geometric characteristics is investigated by numerical simulation using Python programming language based on general finite element code. The results of the pressure history data obtained are verified by comparing those published previously. The effect of material properties, geometric characteristics and adhesion conditions on the propagation pressure are analyzed.

Experimental study of the resistance to the movement of trimaran vessels

The aim of the work is to develop a method for finding the resistance of a trimaran ship at the initial stages of design, depending on the geometric characteristics of the central hull, outriggers and their mutual position. The program of model tests in the experimental tank is characterized. Based on the analysis of the experimentally obtained data, the graphs of the resistance dependence on the Froude number for the trimaran ship model with the fore, central and stern arrangement of outriggers are presented. A graph of the outriggers’ location influence along the vessel length on its hydrodynamic resistance is also shown. A method for calculating the hydrodynamic resistance for a trimaran vessel at the stages of research design is proposed, which is an adjustment of a single-hull vessel model tests’ recalculation classical principle. One of the developed graphs of the residual drag coefficient dependence on the relative speed according to the Froude number for various central hull geometric characteristics of the vessel, outriggers and their relative position is presented. The analysis of serial model tests made it possible to establish the dependence of the trimaran ship resistance on the geometric characteristics of the central hull and outriggers, and their relative position relative to each other in this study. The method proposed in this work will make it possible to substantiate the best layout of outriggers when solving the problem of optimizing the design elements and characteristics of a trimaran at the research design stage.