Tadeusz Smolnicki

Superelement-based modeling of load distribution in large-size slewing bearings

The supporting structures in large-size slewing bearings are highly flexible. In order to choose the proper bearing and shape the load-carrying structure one must estimate the distribution of forces among the individual rolling elements. Advanced numerical models are needed for this. An original method of modeling the rolling element-track system is presented and its usefulness for modeling large-size bearings is demonstrated. The results of an exemplary analysis are presented in the form of graphs and figures. The superelement-based discrete bearing models are so far most comprehensive and take into account all the phenomena involved in the bearing-supporting structures system. The application of the finite-element method and the models based on the track-rolling element-track superelement made it possible to determine the effect of the deformability of the supporting structures and the nonuniformity of their flexibility on the loading of the rolling elements in the two-row bearing. The use of formulas which do not take into account the flexibility of the supporting structures to determine the distribution of the load among the rolling elements is unacceptable.

Degradation of a geared bearing of a stacker

Large size rolling-element bearings used for turning of upper body of machines used in open-pit mining are made in form of single-row or double-row ball bearings. Section diameter of those bearings may be as large as 20 m and rolling elements have diameters of 100 to 250 mm, while they are under eccentric axial load from few to tens of MN. Due to low stiffness of supportive elements and its non-uniform presence all over the circumference of the bearing, the load upon rolling elements is rather unequal in those bearings. The flow of load stream concentrates in points which are in the areas with highest stiffness. This may be achieved using modern computer-assisted design tools. The specificity of these custom made machines makes obtaining credible data for numeric models possible only by applying analyses of the already existing bearings and their support structures which had been in operation for many years. Was introduced applied to opinion of effect of long-lasting exploitation on change of parameters of bearing.

Multicaterpillar Track Chassis of Big Machines - Identification of Loads

Multicaterpillar track chassis are used in the biggest machines. This kind of chassis is commonly used in open cast mines for mobile transfer conveyor or for bucket wheel excavators. In each machine the chassis consist of 6 to 12 caterpillar tracks, which some are steered. Existing models used for analytical calculations are based on simplified relations taken from quasistatic equations of stability and geometrical connections. The complex research was conducted on mobile transfer conveyor, which is used in open cast mine. The aim of measurements was to identify the value of force that acts on elements of chassis during the steering and driving the machine. The measurements were taken during the drive in different directions, with different positions of center of gravity. The strain gauges were used to measure the deformation on each caterpillar track, trusses and drawbar.

Determination of Centre of Gravity of Machines with the Rail Undercarriage

Determination of centre of gravity of rotational handling machines with the rail undercarriage can be conducted by the measurement of rails strains induced by the wheels of driving machine. At the properly selected combination of superstructure locations with respect to undercarriage, it is possible to eliminate the systematic measurement failures. Determination of centre of gravity is necessary for proper weighing of the machine and selection counterweight. Otherwise it can cause the loss of stability or fast degradation of superstructure rotation bearing.

The Model of Estimating the Loss of Maintenance Potential the High Mobility Wheeled Vehicle

In the paper, the model of estimating the loss of maintenance potential of high mobility wheeled vehicles within proving ground tests is presented. This problem is up-to-date, especially important for military vehicles. The authors have analysed the selected requirements directed to this class of vehicles. In the main body of the paper, some model that could be applied in on-line system of prognostic Health and Usage Monitoring System (pHUMS) was presented. This model can be used to analyse information about the maintenance process of vehicle before some maintenance decision would be made.

Identification of Internal Stresses in Bolted Flanged Joints

In bolted flange joints of flexible constructional elements, bolts are subjected not only to tension and torsion but also to bending loads. Identification of straining of each bolt is only possible by means of numerical methods e.g. the finite element method. In the case of large objects, the calculation problem is faithful projection of the phenomena occurring in direct zone of the contact of screw-nut pair. The application of global equivalent models of the whole joint is necessary in order to make it possible to precisely determine internal loads in individual bolts and then local models to establish stress fields necessary to assign durability. Calculation methodology based on the construction of two coherent models has been described: global - for the entire flange joint, and local - for a single bolt joint. The elaborated methodology was applied to evaluate a flange joint in a heat exchanger with rotating heating surfaces that was subject to damage. The causes of damage of the flange joint were determined.

Modeling of dispersion effects in elliptical core highly birefringet fibers

The results of modeling spectral characteristics of modal birefringence and its sensitivity to temperature using different approaches for calculation the residual thermal stress are presented. The modeling was carried out using the modified perturbation approach first proposed by Kumar.