This paper describes a problem related to a casting bridge crane with a combined load of 200/50/12.5 t and a span of 18.6 m, working in a heavy metallurgical operation. Due to the specific stress of the structure after its long-term operation, longitudinal fillet welds between the upper flange and the web of the main box beam on the rail side of the 200 t trolley were irreparably damaged. As a result, the cross-section of the main beam had opened, thereby substantially reducing its strength and stiffness. This resulted in a disproportionate increase and undesirable redistribution of stresses in the beam and, at the same time, an increase in the probability of acute fatigue or the loss of stability of the elastic beam shape. Therefore, the rectification of the damaged load-bearing structure was carried out by specific structural modifications. Critical load-bearing elements were subjected to complicated strength and fatigue life analyses before and after rectification. These analyses were supported by experimental measurements. The applied modifications resulted in a partial strengthening of the lifting device with the possibility of its further operation, but only in a limited mode, with a limited period of operation with a time limit of 2 years and a reduced total load capacity of 150 t. The applied methods are also applicable for the fatigue analysis of load-bearing elements and equipment for bridge, gantry and tower cranes, crane tracks, road and railway bridges and support structures under machinery and other devices with a dominant transverse and rotating effect.

In technical practice, problems associated with material fatigue often arise. These problems can be caused by errors in the stages of design, production or use of the structure, e.g., by incorrect determination of service life, incorrect dimensioning of construction details, incorrect welds, etc. In the case of welds, such issues may be caused due to the fact that the base material is not welded through or due to the presence of a fistula inside the weld, the presence of slags or cracks inside the weld, etc. The task of the designer is to design a technological unit that meets all the requirements of future users. Components have to be designed for fatigue so that there is an acceptable level of probability that their operation will be satisfactory during their operation life. One of the most common causes of failure of welded joints is fatigue. Fatigue design life is understood to be the reference period of time during which the structure is required to serve safely and not to fail with an acceptable probability. This article deals with the assessment of service life of a welded supporting structure of technological equipment. The structure was subjected to strength analysis. The obtained FEA results were needed to plot the extreme amplitudes of the stresses. Based on the obtained stress vibrations and the welds used, the service life of the structure was assessed by means of the standard.

The paper deal with quantification of residual stresses by the drilling method and design of the methodology of using optical device LF/Z-2 for their verification. The optical methods have been used for strain analysis for years, but with the continuous development of new and more accurate measuring instruments and devices, are solved the possibilities of creating new application methodologies. For using the Optical PhotoStress method for quantifying residual stresses, has been designed an accurate positioning device to analyse the released deformations around the drilled hole in multiple steps as considering by ASTM E837-13a for drilling methods.

This paper deals with modal analysis through 3 different approaches, namely: analytically, numerically and experimentally. The investigated mechanical structure in this case will be a beam, which is characterized by three parameters, one of which is significantly larger than the other two. The beam is a structural element designed to transmit forces, mostly external ones. Modal analysis of the beam will be performed in 2 versions of its fixation, as a free structure and a one-sided embedded fixation. Modal parameters obtained by 3 different approaches will be compared with each other, which will determine whether the method of calculation was chosen correctly or whether the experiment was performed correctly.

Slovakia has become one of the leading automobile manufacturers in Central Europe, mainly due to the presence of three global automakers-Volkswagen (Bratislava), PSA Peugeot Citroën (Trnava) and Kia Motors (Žilina). There is the automotive industry necessary for the development of the Slovak economy as decisive industry. Many businesses work right for the automotive industry. A substantial part of these companies is engaged in plastic products, such as the production of large-size plastic mouldings such as dashboard, car door trim and the like. These mouldings are produced on large-size injection moulding machines, with massive injection moulds. One of the problems of these companies is the handling of these massive forms, which can weigh tens of tons. The article is devoted to the design of the transport device, which is designed for the transport of this type of moulds, which is able to easily and safely secure moulds of various dimensions and transport them from the press to the mould warehouse, or vice versa from the mould warehouse to the injection press. There is the strength calculation of the structure is solved using FEM in conclusion.