This paper deals with the investigation of crack strength of nuclear reactor cooling system wedge valve body. The main fracture mechanics expressions linking stress intensity factor with cracklike defect length are presented in the introduction. Analytical equations for reliability function evaluation are obtained, fracture toughness and stress intensity factor are viewed as Gaussian random values in the second part of the paper. The statistical linearization method is used to determine the distribution parameters (mean value, dispersion). The stress intensity was estimated by the finite element method with the use of SolidWorks Simulation system. Calculations are done for different types of cracks: throughwall, edge and semielliptic. It is shown that the presence of cracklike defects, even of small length, rather reduces the level of reliability function.

Keywords: fracture toughness, stress intensity factor, survival function

The paper deals with the investigation of exploitation technological efficiency of metall-cutting machine tools. The main goal of this study is to determine more advanced way of choice of equipment and to organize metall-cutting machine tools rational maintenance. Classification of basic and optional evaluative measures is presented in the first part of the paper. The research methodology provides the estimation of exploitation technological efficiency by calculation of the complex evaluative measure. The results of comparative estimation of two metall-cutting machine tools (Okuma LB 4000 EX, CTX Gamma 2000) are presented in the last part of the paper. According to evaluation result, Okuma LB 4000 EX stands at a higher level of exploitation technological efficiency.

Keywords: exploitation technological efficiency, comparative estimation, complex evaluative measure, methodology, data analysis

This article deals with the way of increasing the energy absorption capacity of forest machine cabin roll-over protective structure. The ability to absorb certain amount of potential energy during deformation is the one of basic requirements to cabin of a forest machine. The risk of injures to the operator is reduced by using two-way energy-absorbing cab support in the construction of roll-over protective structure. The protective effect is attained by plastic strain of cab support elements, that provides operator’s protection during an accidental roll-over. The article presents the design of the cab support, describes its functional principle in the event of an emergency.

Keywords: roll-over protective structure, forest machine, energy-absorbing support, construction, plastic strain

This paper deals with the application of main fracture mechanics equations for estimation of cracklike defects influence over forest machine roll-over protective structure survival. The definition of breaking points in protective structure was done by finite elements method. Stress intensity factor was defined as the estimation criterion. It relate the local mechanical state near the crack tip to macroscopic characteristics such as the geometry of a body and loading, and enable to give simple description of crack growth process. The stress intensity was estimated by finite element method. Breaking lengths were calculated for different types of cracks: through, edge and semielliptic. As shown, the presence of cracklike defects, even small length, rather reduces the level of breakdown load.

Keywords: fracture mechanics, cracklike defect, finite element method, roll-over protective structure, breakdown load