There are several measuring techniques for determining residual stress which can be divided according to the created damage in to the construction in non-destructive, semi-destructive and destructive ones. One of the most common is semi-destructive hole-drilling method. This paper deals about Ring-Core method which is based on the similar principles. Today, there is no standard for the Ring-Core method, thus it is important to consider various influential factors. One of them are the dimensions of specimen. Calibration coefficients are determined by finite element (FE) analysis using the commercial software Solidworks. These coefficients are used for residual stress evaluation by incremental method used in Ring-Core method. The influence of different specimen dimensions on the accuracy of the evaluated residual stresses is considered.

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The article deals with the issue of use of geometric mechanics tools in modelling nonholonomic systems. The introductory part of the article contains fiber bundle theory that we use at creating mathematical model of nonholonomic locomotion system with undulatory movement. Further the determination of general mathematical model for n-link snake-like robot is presented, where we used nonholonomic constraints. The relation between changes of shape and position variables was expressed using the local connection that was used to analyze and control system movement by vector fields. The effect of links number of snake-like robot on its mathematical model was investigated. The last part of this article consists of detailed description of modeling reconstruction equation for four-and five-link snake-like robot.

Abstract. The evaluation of residual stresses using Ring-Core method requires complex analysis of the acquired strain values. The development is based on ASTM Standard E837-08 for hole-drilling method, but the specific approach for Ring-Core is needed. The input data sets obtained from strain gage rosette are categorized by proposed uniformity test. The influence of geometric parameters of the specimen on this test and subsequently on the both uniform and nonuniform calculations is considered.