Oskar Ostertag

Methodology of contact stress analysis of gearwheel by means of experimental photoelasticity.

The subject of this paper is the analysis of contact stresses that occur between the teeth of a gear. The analysis was carried out by means of reflection photoelasticity, which is an experimental method rarely used in this field. Contact stresses assessed in the experiment are compared with values assessed through an analytical calculation while using the Airy stress function or Hertzian relations.

Miniature Mobile Bristled In-Pipe Machine

The in-pipe machine locomotes in the pipe on the principle of differential friction between the bristles and the pipe wall during the movement of the bristle forwards and backwards. These bristles are very important construction parts of the in-pipe machine. In order to define the locomotion of movement it is important to know the force situation on the bristles caused by its high deformation in the pipe. The determination of force situation brought us to a non-linear differential equation of the second order and determination of conditions for its solution. By this equation it is possible to describe the outline of large deformations of the construction part and to determine the forces affecting this part.

Methodology and Application of the Kruskal-Wallis Test

This paper describes the methodology and application of the very popular nonparametric test which is a rank based test named as Kruskal-Wallis. This test is useful as a general nonparametric test for comparing more than two independent samples. It can be used to test whether such samples come from the same distribution. This test is powerful alternative to the one-way analysis of variance. Nonparametric ANOVA has no assumption of normality of random error but the independence of random error is required. If the Kruskal-Wallis statistic is significant, the nonparametric multiple comparison tests are useful methods for further analysis. The statistical analysis of the application data in this paper was performed with software MATLAB.

Application of the harmonic star method in photoelastic separation of principal stresses.

This paper deals with automation of an experiment process by means of photoelasticity on the condition that only information which was previously collected by identification of isochromatic fringes is used. The analysis of this issue pointed to Poissons and Laplaces equations. These equations were solved through the harmonic star method. The automation of an experiment was based on the development of a noncommercial program for processing of data which had been collected during photoelastic measurements. In addition, the program was used for verification of these measurements and comparison of measurement outcomes with results which were gained by the finite element method (FEM). Such a program enabled us to measure stresses in a certain point of the examined surface and, at the same time, separate these stresses, that is, determine the magnitude of individual stresses. A data transfer medium-a camera-was used to transfer the picture of isochromatic fringes directly into a computer. The chosen procedure of solving and evaluating the experiment provided us with reliable outcomes comparable to results gained by FEM.

Distorsion of Isochromatic Fringes in the Process of Stress Measurement in Structural Part by Photoelasticimetry

Abstract In the article we show the possibility of distorting the results of the experiment by photoelasticity path, in case the isochromatic fringe patterns are recorded by the camera. The recording of the color spectrum may be distorted by inappropriate selection of the recording medium, which is reflected by different types of aberrations. Transferring a record to a computer allows you to automate the experiment process, thus saving time to work with isochromatic fringes. As an example, we present the experimental determination of the stresses of the rotor with a symmetrical arm. The analysis was performed using software developed by the authors. This software enables full automation of the experiment process. The rotor is investigated by the method of reflection photoelasticity. The experimental solution is realized as a case of periodically repeating dynamic effects, in which a stroboscopic source of white light is needed. The results of the experiment are compared with the numerical solution and their dependence is represented by diagram.

Experimental and Numerical Analysis of the Damage Causes of Rail Traction Vehicles

This paper presents the results of the investigation of the causes of the occurrence and the influence of the dynamic effects in the couplers of the remotely controlled electric shunting locomotives and a set of fully loaded rail cars. These are typical rail-road sets, working at the logistic area of the central ore trans-shipment of large steelworks with heavy rail traffic. The stated effects lead to excessive deterioration of the supporting structure of the locomotives, axle gripping, drive mechanisms and braking systems. To achieve the desired goal, the methods and means of numerical and experimental modelling have been used. Based on the performed numerical and experimental analyses were then specified the recommended design and operational measures to prevent the failures mentioned above.

Analytical and Numerical Solution of Large Actuator Deformation

This paper deals with the possibility of controlled deformation of the actuator of a flexible system. In the solution, large deformations of the actuator have been assumed. The model was made of a material capable of large deformations caused by internal pressure. The internal pressure was let into the cavities located in the actuator. The solution was realized analytically and numerically. The results show the relevance of the stated proposal.

Utilisation Possibilities of PhotoStress Method in Determination of Residual Stresses

The presented paper demonstrates the determination of residual stresses by means of PhotoStress® method. The identification was performed on a drilled and subsequently loaded sample of a split ring. Through drilling and subsequent loading of the sample we were able to simulate residual stresses throughout the surface of the split ring. Using the values of residual stresses, a gradient of residual stresses was specified. The 3 mm thick split ring was laser-cut from a non-alloyed fine-grained structural steel sheet suitable for welding, i.e. steel 11 523. It was coated with 3.125 mm thick photoelastic coating PS-1A with fringe constant.

Application of the Simple Linear Regression Model in the Experiment

The paper presents the results of experiments and measurements of the stress of a pipeline located on a pipe bridge. The experiment was carried out by means of resistance strain gages for two modes, which were the stress changes upon pressure changes in the pipes and at the driving in of sheet pilings in the immediate vicinity of the pipeline. On the basis of measurements, the impact of these changes on the operational safety of the pipeline in the renovation process of old above ground and the realization of new underground pipeline solutions. Polynomial regression models were applied for the prediction and a statistical analysis of residuals was applied for the quality assessment of selected models.

The Experimental and Numerical Analysis of Stress as a Tool for Optimizing the Selected Structural Components of an Injection Device

The improvement of the main monitored technical parameters of the production devices is connected with the optimization of the individual structural components and construction nodes of these devices. Mainly those critical structural nodes of the devices that have a significant impact on the quality of the products manufactured by this device and its service life are studied. This paper briefly presents the results of experimental and numerical analysis of stresses and strains of selected structural components of the injection device, such as the connecting and guiding columns and the adjustable push plate. The relevant analyses of stresses and strains have been connected with the performance of a series of experimental and computer simulations. The results of these simulations then became an important basis for further optimization of selected structural parts of the injection device.