PSI - Issue 81

Oleksiy Petrenko et al. / Procedia Structural Integrity 81 (2026) 292–296

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after one, two, three, four. and five years of use. For this, one pallet was selected from the batch with the specified service life. The number of tests was from 30 to 60. a b

Fig. 1. Design (a) and appearance (b) of a wooden technological pallet for forming concrete products by the vibro-press method/

3. Results and discussion Visual inspection of newly manufactured pallets revealed that the layered working surface of individual elements - boards with a width of 80 to 150 mm and a thickness of 53 mm, a total of 722 boards, is oriented radially in 265 boards (36.7%), tangentially in 305 boards (42.2%). The results obtained do not provide a reasonable basis to consider the tangential or radial orientation of the working surface layers as predominant. Based on the experimental studies conducted, the hardness in the tangential section was determined to be 0.88 J/cm2 and in the radial section to be 0.96 J/cm 2 . Considering the chaotic orientation of individual boards in the pallet, and sometimes the impossibility of establishing a specific orientation of the working surface layer, the integral value of the hardness was taken as the arithmetic mean value of the tangential and radial values - 0.92 J/cm 2 . Based on the analysis and chronometric studies of the daily and annual operation mode of the pallet, it was established that it is affected by a number of adverse factors. During the formation of concrete products, mechanical static and dynamic (vibrational) loads act. When the concrete gains strength, the technological pallet is affected by the difference in air humidity from 60% to 95% and temperature in the cold period from +10 0 С to +25 0 С, in the warm period from +15 0 С to +50 0 С. According to the analytical and chronometric study of the operation mode, it was established that during one year of operation of the technological pallet, there are 250 production cycles. Within the framework of the scientific and practical task, it has been established that the hardness of wood of a newly manufactured technological pallet which has not been in operation is 0.92 J/cm2 at a moisture content of 8…14%. According to the test results after 3, 6, 12 months, 2, 3, 4, and 5 years of operation, the dependence of hardness on the duration of operation has three characteristic sections:

1) decrease in hardness during the first three months from 0.92 to 0.73 J/cm²; 2) partial increase in hardness over the next nine months from 0.73 to 0.81 J/cm²; 3) gradual decrease in hardness during the following four years of operation from 0.81 to 0.45 J/cm².