Vieroslav Molnár

Finite element analysis of spiral strands with different shapes subjected to axial loads

A new mathematical geometric model of spiral oval wire strands is proposed.Concrete forms of derived parametric geometric equations are presented.Results of FE analyses of four spiral strands with different shapes are presented.Responses of round, triangular and oval strands under axial loads are compared.Result ant stress and/or deformation behaviours are discussed. In this paper a new mathematical geometric model of spiral one or two-layered oval wire strands are proposed and an accurate computational two-layered oval strand 3D solid model, which is used for a finite element analysis, is presented. The three dimensional curve geometry of wires axes in the individual layers of the oval strand consists of straight linear and helical segments. The present geometric model fully considers the spatial configuration of individual wires in the right and left hand lay strand. Derived geometric equations were used for the generation of accurate 3D geometric and computational models for different types of strands. This study develops 3D finite element models of two-layer spiral round, triangular and oval strands subjected to axial loads using ABAQUS/Explicit software. Accurate modelling and understanding of their mechanical behaviour is complicated due to the complex contact interactions and conditions that exist between individual spirally wound wires. Comparisons of predicted responses for the strands with different shapes and constructions are presented. Resultant stress and/or deformation behaviours are discussed.

Using a Software Tool in Forecasting: a Case Study of Sales Forecasting Taking into Account Data Uncertainty

Abstract Forecasting is one of the logistics activities and a sales forecast is the starting point for the elaboration of business plans. Forecast accuracy affects the business outcomes and ultimately may significantly affect the economic stability of the company. The accuracy of the prediction depends on the suitability of the use of forecasting methods, experience, quality of input data, time period and other factors. The input data are usually not deterministic but they are often of random nature. They are affected by uncertainties of the market environment, and many other factors. Taking into account the input data uncertainty, the forecast error can by reduced. This article deals with the use of the software tool for incorporating data uncertainty into forecasting. Proposals are presented of a forecasting approach and simulation of the impact of uncertain input parameters to the target forecasted value by this case study model. The statistical analysis and risk analysis of the forecast results is carried out including sensitivity analysis and variables impact analysis.

The Simulation Model of Experimental Equipment for the Research of Pipe Conveyor Belts Using ABAQUS Software

We can effectively use experimental and simulation approaches for pipe conveyors research. The paper describes a simulation of experimental measurement which was realized by special test device for pipe conveyors research. The simulation model was created by the help of program Abaqus.

Regression Model Design for the Prediction of Pipe Conveyor Belt Contact Forces on Idler Rollers by Experimental Tests

In this paper there is presented a possibility to estimate, with a sufficient accuracy, contact forces on idler rollers of hexagonal idler housing in case of the pipe conveyor belt. This prediction is based on values of tension forces that are measured experimentally. The calculated regressive models are able to predict contact forces in individual positions of idler rollers with suitable correctness. The measurements of tension forces were carried out on a static model of a pipe conveyor. This static model is able to simulate real operational conditions of idler rollers, which guide the conveyor belt. In this way it is very simply possible to determine contact force values in the individual positions of idler rollers. Information about contact forces is useful for designers and for users of the conveyor belts, as well.

Failure analysis of conveyor belt samples under tensile load

This paper is dedicated to investigating the properties of smooth conveyor belts through a tensile loading test, with the aim of examining the behavior of the inner structure of the belt samples. When the belt is subjected to a long-term strain, the belt relaxation effect is observed and changes may occur to the inner structure of the belt. The tensile test at constant velocity determines the load strength limit of the strip samples. The experiment has also shown the phenomenon of relaxation of the samples after the load. Metro-tomographic analysis is used to observe the behavior of the internal structure of the belt sample after the load. The obtained results indicate the initial damage of the inner structure of the conveyor belt occurred at the value of 2157 N. Under this load, the maximum damage size was 4.8 mm. This confirms the suitability of the method for tracking changes in the internal structure.

Analysis of defects in carcass of rubber–textile conveyor belts using metrotomography:

Rubber–textile construction of conveyor belts is widely used in various continuous transport systems. Due to the fact that complex carcass is vulcanised, its observation and analysis are very difficult to perform. The methods used so far have been based on its violent extracting, often accompanied with the formation and existence of defects. Such an analysis does not allow distinguishing between defects caused by operation of the belt or defects caused by the process of extracting itself. This paper aims to verify a new approach to examining the inner carcass of rubber–textile conveyor belts with a focus on the possibility to obtain information about its condition. This has not been possible with the methods used so far. The main focus is on the measurement of distance between the individual fibres in the warp and weft of the carcass, and simple size analysis of the identified defects. Presented results prove that the method of industrial tomography clearly identifies the defects in the conveyor belt carcass. The method enables the identification of single fibres, punctures and separation of individual layers.

Test Equipment for Analysis of Samples Rubber – Textile Conveyor Belts by Help Industrial Metrotomographs

The test equipment of samples for analysis of rubber-textile conveyor belts is a device designed to create tension and tracking the deformation in different cross sections of conveyor belts in one axis X. This construction is designed tensioning device, which allows the development of automatic tensioning force in one axis X-tensioning force F is exerted screw the nut with a torque wrench and a controlled strain-gauge sensor. Measured sample-textile conveyor belt is clamped in two adjustable clamping jaws ribbed belts for different thicknesses. Ribbed clamping jaws on one side of the tensioning device is attached to the frame and on the other hand are attached to the runner associated with the movable tensioning screw.

Possibilities of Experiments and of Using Experimental Results Obtained from the Test Equipment for Measuring Properties of Conveyor Belts Pipe Conveyor

The publication deals with the test equipment for measuring properties of conveyor belts of pipe conveyor. The device was designed with the aim of setting tension force and measuring the contact forces at positions which correspond to positions of idlers at hexagonal idler housing of pipe conveyor. Contribution gives an overview of experimentally obtained statistics, relations and relationships. Presented several results of analyses focused on potential context between the information brought by experiments and practical application.

Assessment of the Production Reducer for Clamping the Drilling Tools

The article deals with the evaluation of the production of the reduction clamping mandrel on the milling machine. The reducer is designed to clamp the drill tool with a 16 mm diameter cylindrical shank so that it can be clamped into the clamping head of the drill with a maximum diameter of 13 mm. The clamping tool itself is secured with two screws. The billets of the reducer are selected from the available manufactured steel parts, allowing it to be maximally fast and meet the production criteria. The material of the joined parts guarantees guaranteed weldability. The technological process, the method of clamping and setting of the tooling was chosen so as to achieve the desired deviations of co-ordination of the two coupled cylindrical components. Measurement of the produced diameter of the reducer and evaluation of co-ordination was done on the THOME 3D measuring instrument. It has been measured the diameter and the deviation of the co-ordinates of the produced cylindrical surfaces with a maximum value of 0.0053 mm, with a maximum quadratic error of 0.003543 mm. The produced reducer clamp was tested for the production of cylindrical holes by a 25 mm diameter drill. By measuring, stamping and practical application of the clamping mandrel, the possibility of replacing turning operations at the CNC milling center was confirmed.

Restoration of Worn Movable Bridge Props with Use of Bronze Claddings

This article examined the possibility of using CuSn6P claddings in sliding bearing renovation of movable pontoon bridge props. The bronze layer was welded on cylinders of the high-strength steel S355J0WP EN 10155-93, in an inert atmosphere using an automated welding method (gas tungsten arc welding). Pulsed arc welding was used to minimize the effects of heat on the cladding area, while also accounting for the differences in the physical properties of the joined metals. The sliding bearing was created in two layers. The quality of the cladding layer was evaluated by nondestructive and/or destructive tests. The quality of the surface was assessed by visual inspection (visual testing) in accordance with the EN ISO 17637 standard. The quality of the claddings was evaluated by metallographic analysis, performed using light microscopy. The microhardness values of a few weld areas were determined by Vickers tests, performed according to the EN ISO 9015–2 standard. The analyses confirmed that the welding parameters and filler material used resulted in high-quality weld joints with no internal (subsurface) or metallurgical defects.