Assessment of the possibility of using mobile bridges to overcome man-made structures by specialized multi–axle wheeled vehicles

The article provides general information about double-support mobile bridges designed for contactless movement of heavily loaded specialized multi-axle wheeled vehicles on top of man–made structures. Also, recommendations are given on substantiating the possibility of their use for solving specific problems. These recommendations contain expressions obtained by the methods of structural mechanics, on the basis of which it is possible to determine not only the required (minimum) camber of the mobile bridge, which is necessary to ensure the normal passage of the vehicle, but also to assess the stress state of the mobile bridge, as well as to determine the nature of the deformation of the mobile bridge when vehicle moves along it. The presented recommendations allow, at a first approximation, to assess the suitability of the available solutions of a mobile bridge for the passage of specialized multi-axle vehicles over mane–made structures, depending on the required span of the mobile bridge and the load from the vehicle on the mobile bridge. The article also provides an example of solving a specific problem on the basis of these recommendations, in accordance with which, when a mobile bridge is spanned 23.4 m and a working load from one axis of the vehicle is equal to 33.5 tons, the required camber is 400 mm, and the highest equivalent stresses will be about 380 MPa.

Ein Kommentar zum mehrachsigen Spannungszustand im reibungsfrei überrollten Kontakt elastischer Körper und zur Anwendung von Vergleichsspannungshypothesen

For the assessment of a rolling contact, knowledge about the inhomogeneous multi-axial stress state as well as the limitations of available equivalent stress hypotheses are important. Therefore, this paper examines the multi-axial stress state using the example of the HERTZian contact ball/plane in order to derive the stress history for the frictionless rolling contact. Finally, the oppor tunities and limitations of the use of equivalent stresses are shown using the maximum distortion criterion as an example.

The numerical parametric study of the stress-strain state of I-beams having versatile corrugated webs

Introduction. The numerical parametric study of the stress-strain state of I-beams, having versatile corrugated walls, was carried out in the ANSYS Mechanical APDL software package. Numerical results are obtained for displacements, equivalent stresses and stability coefficients depending on the change in the inclination angle of web corrugations for trapezoidal, wavy and triangular profiles. The obtained results can help to design and substantiate the design solutions applicable to bending elements. Materials and methods. The parametric study involved a series of numerical experiments conducted using the finite element method in the ANSYS Mechanical APDL software package. APDL parametric language was used to develop the software that was built into the software package. It allowed to perform a parametric reconstruction of the numerical model depending on varied parameters of the corrugated wall, and the reconstruction was followed by the numerical solution and post-processing of the calculation results. The calculations were made with the help of the model whose overall dimensions and material were identical to those of a standard I-beam having a solid wall exposed to a uniformly distributed transverse load. Results. The parametric study enabled the co-authors to identify the main features of the stress-strain state of the beams that had different types of corrugated walls. A parametric numerical model was compiled to determine maximum displacements, equivalent stresses and stability coefficients for various types of corrugated walls and various parameters of the corrugation angle. Isofields of equivalent stresses and buckling modes are provided for characteristic parameters and types of corrugations. The reliability of the obtained results was confirmed by the verification of the numerical model using the method of the strength of materials and corrugation inclination angle α = 0, which was the initial point of simulation for all types of corrugations. Conclusions. The results, obtained in the course of parametric studies, have identified the main features of the stress-strain state of beams having corrugated walls; they allow to substantiate their effectiveness as design solutions applied to bending elements.

STUDY OF LOADING OF THE LOAD-BEARING STRUCTURE OF HOPPER WAGONS ON Y25 BOGIES

To increase the efficiency of using railway transport, the possibility of using new designs of bogies, for example, Y25 under "wide gauge" wagons was considered. In order to substantiate the proposed solution, mathematical modeling of the dynamic loading of the hopper wagon Y25 bogies was carried out. A hopper wagon for the transportation of pellets and hot sinter model 20-9749 built by the State Enterprise "Ukrspetsvagon" (Ukraine) was chosen as a prototype. The simulation results showed that the use of Y25 bogies for hopper wagons allows to reduce the acceleration of its load-bearing structure, in comparison with the use of conventional 18100 bogies, by 36 %. Other performance indicators are also significantly improved. The use of Y25 bogies for hopper wagons with actual parameters allows to reduce the acceleration of its load-bearing structure, in comparison with the use of conventional 18100 bogies, by 28 %. The determination of the main indicators of the strength of the bearing structure of the hopper wagon Y25 bogie was carried out. The calculation was carried out in the SolidWorks Simulation software package (CosmosWorks), (France), which implements the finite element method. The calculations showed that the maximum equivalent stresses in the load-bearing structure of a hopper wagon with nominal parameters are 17 % lower than the stress acting in the load-bearing structure of a wagon on bogies 18–100 V of the load-bearing structure of a hopper wagon with actual parameters, the maximum equivalent stresses are 12 % lower per voltage in the load-bearing structure on bogies 18100. The conducted research will help to reduce the load on the load-bearing structures of hopper wagons in operation, improve the dynamics and strength indicators, as well as their service life

Design Improvement of Cutting Part in Tunneling Shield

The article presents a variant for improving the design of a working body of a tunneling shield, its cutting part to be more precise. The working body of the tunneling shield has been improved with the changes in the design of a rotor working surface. The theoretical studies aimed at determining the strength characteristics of the proposed rotor design have been carried out. The proposed rotor model has been visualized with the use of the T-Flex CAD software. On the basis of the results obtained in the course of the theoretical research, a comparative analysis of the strength characteristics of the main and improved model of the cutting working body of the tunneling shield have been made. The studies carried out at T-Flex CAD confirmed the working capacity of the improved design of the tunneling shield working body. The strength of the rotor has been determined as a result of the studies carried out. The maximum values of the displacement module is 2.875E-05 m, the equivalent stresses are 29.47 MPa, a reserve coefficient on equivalent stresses is 9.446E 06.

A NEW FASTENER TO ENSURE THE RELIABILITY OF A PASSENGER CAR BODY ON A TRAIN FERRY

To ensure the strength of the passenger car bodies during transportation on train ferries, it is proposed to mount fastening elements of chain binders on the body bolster beams. The principle of such an element is based on the hydraulic damper operation. The mathematic modelling was conducted in order to determine the dynamic loading on a passenger car body during sea transportation. The study established that the improvements mentioned made it possible to reduce the dynamic loading on the body during sea transportation by 30% in a comparison with that of a typical fastening scheme. The strength of an improved passenger car body was calculated. The maximum equivalent stresses in the body structure accounted for about 120MPa, i.e., they did not exceed the admissible values. The conducted research may contribute to ensuring the required strength of passenger car bodies during train ferry transportation, thus leading to a higher operational efficiency of train ferry transportation within the international transportation.

Assessment of the Impact of Shot-Peening on the Fatigue Life of a Compressor Blade Subjected to Resonance Vibrations

This publication presents an assessment of the influence of a surface treatment such as shot-peening on the fatigue life of a compressor blade exposed to resonant vibrations. As part of the work, a geometric model of the blade was developed, and a numerical modal and fatigue analysis were performed. The fatigue analysis was based on the Manson–Coffin–Basquin and Ramberg–Osgood models. Additionally, the location of the highest equivalent stresses was established. Based on the results of the strength analysis, two points were identified where a fatigue crack may potentially occur. As part of the work, the influence of different values of residual stresses on the results of the fatigue life was determined. The obtained results were compared to the literature values of fatigue life for this blade. A secondary objective of the study was to determine the size of the grains at various points of the blade, as well as the thickness of the layer plasticized as a result of peening. The relationship between the location of the highest values of the equivalent stresses and the thickness of the plasticized layer was determined. An explanation of the effect of shot-peening on the increase in the fatigue life of the blade was proposed.

Stress-strain state of metal in deformation zone during production of steel section billets on the unit of combined continuous casting and deformation. Report 2

Stress state of metal in deformation zone during introduction of the separating collars of the grooved die into continuously casted steel slab was calculated for production of section billets on the unit of combined continuous casting and deformation. Calculation of axial, tangential and equivalent stresses arising in deformation zone of metal was made in four sections of deformation zone and its results are presented in specific points and lines. View of the section of deformation zone and location of specific points are provided. The stress state of metal in zone of cyclic deformation at formation of three steel section billets from continuously cast slab by separating collars of grooved die on the unit of combined continuous casting and deformation was determined by solving extensive problem of elasticity with the finite element method using the ANSYS package. The results of calculation of axial, tangential and equivalent stresses according to Mises in deformation zone are given in form of graphs and tables for working surfaces in four cross sections. The values and regularities of distribution of these stresses along the length and width of deformation zone were determined. The character of axial stresses distribution by characteristic lines located along the length of deformation zone is shown. Values of the highest compressive and tensile axial stresses arising in deformation zone during introduction of separating collars of grooved were obtained for the unit of combined continuous casting and deformation.

Assessment of the Impact of Shot Peening on the Fatigue Life of a Compressor Blade Subjected to Resonance Vibrations

The publication presents the assessment of the influence of surface treatment such as shot-peening on the fatigue life of a compressor blade exposed to resonant vibrations. As part of the work, a geometric model of the blade was developed and a numerical modal and fatigue analysis were performed. The fatigue analysis was based on the Manson-Coffin-Basquin and Ramberg-Osgood models. As part of the work, the influence of different values of residual stresses on the results of fatigue life was determined. Additionally, the location of the highest equivalent stresses was established. The obtained results of the numerical analyzes were compared with the results presented in the scientific literature. An additional aim of the study was to determine the size of the grains at various points of the blade as well as the thickness of the layer plasticized as a result of peening. The obtained results are presented in the form of tables and charts. The relationship between the location of the highest values of equivalent stresses and the thickness of the plasticized layer was determined. The explanation of the effect of shot peening on the increase in fatigue life of the blade was proposed.