A QGIS Based Workflow for Optimized Cable Road Layout Planning

Cable-based technologies have been a backbone for harvesting on steep slopes. The planning of a cable road is a complex task. It essentially comprises the definition of the start and end points of a cable road, as well as the intermediate supports. It must be ensured that the permissible forces (in particular, skyline tensile forces) are not exceeded, that there is a sufficient clearance between the load path and the ground, that suitable anchor trees are found, and that at the same time the number of intermediate supports is minimized as far as possible. On the other hand, for ergonomic and silvicultural reasons (work safety, damages to the forest), the skyline should be as high as possible. In practice, the search for a solution is often iterative; especially with long lines, several attempts may be necessary until a good line is found. The presented QGIS (free and open-source cross-platform desktop geographic information system) plugin searches automatically for the optimal cable road layout, so the planning process can be considerably simplified and obtained solutions are more cost-efficient. The plugin is designed for Central European conditions and assumes a standing skyline (fixed anchored skyline at both ends). For the calculation of the mechanical properties of the skyline, a close to catenary method is used (Zweifel 1960). When testing the feasibility of the cable line, care is taken that (1) the maximum permissible stresses in the skyline are not exceeded, (2) there is a minimum distance between the load path and the ground, and (3) when using a gravitational system, there is a minimum inclination in the load path. The newly developed method calculates the load path curve and the forces occurring in it more accurately than other tools available on the market. We further present a method to identify potential support and anchor trees directly from remote sensing data, which we aim to integrate in a further plugin. This ensures that there are effectively trees at the proposed intermediate positions and that the solution can be implemented in practice.

DEVELOPMENT OF UNIFORM STRENGTH DESIGN OF CABLE-NET MID-WATER TRAWL

The article implements the previously outlined proposal [1] on the feasibility of calculating the diameters of cables and threads of the cable-net part of a mid-water trawl based on ensuring their strength is equal to the cables in the first net piece. The case study was carried out regarding a commonly used trawl “Atlantic-1920 m, Nizin” developed by the company “Fishering Service”. The calculation algorithm is described which includes determination of resistance forces of the cable-net part and tensions in the cables and threads of net pieces. The safety factor is determined on the basis of the permissible stresses for the respective materials of which cables and threads are manufactured. After that, the values of diameters for cables and threads are calculated so as to ensure that the safety factor in the net pieces is equal to the cables in the first net piece. As a result, the formula is derived, which is able to calculate the diameters of cables and threads of the cable-net part of a mid-water trawl based on ensuring their strength is equal to the cables in the first net piece.

RESERVE CAPACITY OF LONGITUDINAL BEAM OF WAGON TRUCK UNDER THE ACTION OF UNIFORMLY DISTRIBUTED LOADING

Priority directions and measures among the main branches of urban electric transport are resource saving in the subway transportation system during its operation. First of all, this problem must be solved by scientific support, that is, at the stage of designing parts and components of vehicles. One of the main tasks that are solved at the design stage is to increase the load-bearing capacity of the parts by analyzing their stress-strain state. The article is devoted to the calculation of the load capacity reserve of the longitudinal beam of the front subway trolley under the action of evenly distributed over the entire length of the load without taking into account the transverse forces. The priority of the research topic is substantiated, the purpose and tasks are formulated. Two approaches to the power calculation of the bearing capacity of the longitudinal beam are introduced: the calculation of the permissible stresses and the limit state. In both cases elastic models of beams are considered. In the case of calculation on the limit state, the mechanics of the occurrence of plastic hinges at the places of rigid fixing of the ends of the beam are first substantiated. The beam still retains its load capacity. With the further growth of the external load, the emergence of a plastic hinge is justified even in the middle of the beam with the simultaneous loss of the beam of the bearing capacity. To simulate the behavior of the beam according to its characteristics, including the stress and the degradation condition of its load capacity, the mathematical formulation of the problem of calculating the load capacity of the longitudinal beam when calculating the permissible stresses and the limit state without taking into account the transverse force. The load-bearing capacity of the longitudinal beam in the calculation of permissible stresses and the limit state is analyzed. The analysis of the obtained results allows us to judge the effectiveness of the proposed mathematical model as a whole. The obtained equations for the maximum allowable load when calculating the limit state and the allowable stresses allow us to reliably estimate the bearing capacity of the longitudinal beam in both cases. The increase in the bearing capacity of the beam in the case of calculation on the limit is three times. The conclusions about the adequacy of the analysis of the bearing capacity of the longitudinal beam bearing capacity were made. Keywords: resource saving, beam, bearing capacity, allowable stresses, limit state.

Determination of Permissible Stresses along the Stiffened Hole Outline in Designs of Anisotropic Composite Materials

Technique of determination of permissible compressive stresses in products made of anisotropic composite materials with holes in joints “parent sheet - stiffening element” is introduced. Besides, physical-mechanical properties and material load factor are taken into account. Finite-element model to determine stress strain behavior along the hole outline and in the ”field” points of composite material has been developed.

Designs of low frictional coefficients for joint bearings by inlaying graphites and liquid spraying of MoS2

PurposeThe purpose of this paper is to solve the problem of joint bearings that cannot work in high temperature because of their high frictional coefficients.Design/methodology/approachTwo methods of inlaying graphites and liquid spraying of MoS2are designed. The arrangement of graphites is shown and its frictional coefficients (COFs) are discussed. MoS2coating is deposited by liquid spraying. The ingredients of liquid spraying of MoS2are illustrated. Stresses, structure deformations and fatigue life are analyzed by finite element analysis.FindingsResults show that both two designed methods can decrease COFs effectively. All stresses are in the limit of the maximum permissible stresses. The new designed bearings can be safety worked in sealed and high temperature environment which are proved by fatigue analyses.Practical implicationsTwo new designs can help joint bearings work in nuclear plants because of their low COFs and litter wear. The new designs can improve bearings life.Originality/valueTwo methods of decreasing COFs of joint bearings are designed in this paper. The technologies are illustrated. The proper scopes of applications of two designed methods are discussed.

Determining strength of rubble masonry of bridges’ supports being in operation

The purpose of this article is to create a methodology for determining the design strength of rubble masonry of bridge supports meeting the modern safety requirements for transport structures. The article contains data on the use of the rubble masonry in solid supports of railway bridges. Development of methodology of determining the permissible stresses on the rubble masonry, and the practice of applying the design strength of the rubble masonry in regulatory documents are considered. Analysis of the research works is carried out, according to which the design strength of the rubble masonry of solid supports is determined when calculating the load-bearing capacity. The experimental data of European scientists in the field of determining the strength characteristics of stone masonries are considered. A domestic method for determining the design values of strength characteristics for building materials used in transport construction is presented. The main deficiencies of the existing method for determining the design strength of rubble masonry are defined and suggestions are made for its clarification. The article concludes with the formulation of tasks required to be solved for clarification of strength characteristics of the operated railway supports made of rubble masonry.

Interactive graphics tool for the calculation and serviceability limit state stress check of bonded post-tensioned concrete beams according to brazilian codes via Autodesk Robot Structural Analysis Professional(r)

This work presents an interactive graphics computational tool for the verification of prestressed concrete beams with post-tensioned bonded tendons to the serviceability limit state (SLS) stress check according to the Brazilian code NBR 6118:2014. The tool is an add-in for Autodesk Robot Structural Analysis Professional(r), which serves as a structural modeling platform. With data supplied by the user through a graphics user interface, the program here developed calculates all relevant prestress losses that occur throughout the structure's life-cycle, along with the prestress' equivalent loads during this period. The traditional calculation methods, obtained in the NBR 6118, are presented along with the modifications which had to be implemented in order to allow for incremental loss calculations. Usage examples and results are presented, validating the adopted methodology. At the end of the software's calculation, the user receives two outputs: the prestress' equivalent loads in the Robot model and an Excel spreadsheet. The spreadsheet contains the resultant stresses in the beam and warns whether these are greater than the permissible stresses in the SLS stress check. The loads may then be used in other calculations, such as shear reinforcement.