PSI - Issue 59

O. Fomin et al. / Procedia Structural Integrity 59 (2024) 636–641 O. Fomin, S. Kara, D. Turovets, S. Shevchenko, Y. Polupan / Structural Integrity Procedia 00 (2023) 000 – 000

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longitudinal beams of the car. The test facility, consisting of a 13-9004M platform car with a device for transporting semi-trailers and a loaded semi-trailer installed on it, is shown on Fig.1.

Fig. 1. Platform car model 13-9004M with a device installed on it for transporting semi-trailers and a loaded semi-trailer.

Today, the device is made of steel. However, in the future, it is expedient to direct scientific and engineering research to find the possibility of manufacturing this device from modern composite materials. At the same time, it is necessary to consider the following features. The location of deconcentration in composite materials is of primary importance. With the correct location, the deconcentrators direct the power lines and turn off the areas adjacent to the voltage concentrator from the power flow. The arrangement is incorrect, which increases the distortion of the lines of force and, therefore, causes additional stress concentration. The stress concentration caused by the form is practically exacerbated by the fact that areas, where concentrators are located, are almost always weakened for technological reasons. In parts subject to mechanical processing, the weakening in the transition areas occurs due to the cutting of fibers obtained during the preliminary hot processing of the workpiece by pressure. In cast parts, transition areas are usually weakened by casting defects caused by structural disturbances during the crystallization of the material and cooling of the casting. In these areas, looseness, porosity, microcracks are usually concentrated, and internal stresses arise. In stamped parts, the transition areas have reduced strength due to material extrusion in these areas. Accordingly, geometric concentrators (form concentrators) and technological concentrators are distinguished. Stress concentration can be caused by the shape of the part and the action of connected parts. In addition to representing complex honeycomb shapes, geometries with smooth lines will likely have less stress concentration than angular geometries with faces. With these considerations in mind, smooth lines should be used in the shapes to model the device, making the geometry prone to better stress distribution on its walls than conventional shapes. In accordance with the test program according to the layout of tensor resistors shown in Fig. 2 and 3, strain gauges were installed on the elements of the device for transporting semi-trailers on the platform wagon and on the carriage of the platform wagon model 13-9004M and their connection into a Wheatstone half-bridge circuit with one active and compensating strain gauge. Such a scheme provides a measuring channel, supplemented by a strain gauge module NI 9237, which performs scaling of instantaneous values of the input voltage and analog-digital conversion into a digital signal. After connecting and checking the performance of the measuring equipment, stress measurements were made in the elements of the device for transporting semi-trailers on the 13-9004M platform car during impact tests and experimental trips in a loaded state at speeds up to 90 km/h to evaluate the strength indicators and natural frequencies of oscillations. Processing of the test results was performed on a computer using specialized mathematical software for statistical processing of the primary results obtained during the experimental trip. The measuring complex for diagnostics and testing of rolling stock consists of a software-hardware automatic recorder, a set of communication cables, a