PSI - Issue 81

Oleksandr Svyrydiuk et al. / Procedia Structural Integrity 81 (2026) 504–508

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investigations. Only specimens with a moisture content within the range of 11 – 13% were allowed for testing. This corresponds to the standard operating conditions for wood-based materials and ensures the accuracy of the obtained results. The geometric parameters of the specimens were measured before testing. These included height, width, and length. A visual inspection of the surface was also carried out according to DSTU EN 518:2003. During the inspection, any defects or damage that could affect the test results were recorded. Specimens with defects or damage were not allowed for testing. The deviation of actual dimensions from nominal values was limited to 1 mm for height, width, and length. The total number of tested specimens was five. 3. Results and discussion Based on the results of experimental tests of composite samples made from wood veneer, an average stress – strain diagram ( σ с u c ) was constructed (Fig. 2). The diagram was developed using the averaged values obtained from five tested prisms. This approach provided a more representative description of the material’s mechanical behavior.

σ c , М P а

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Fig. 2. Average deformation diagram of a composite sample based on wood veneer (averaged values for 5 prisms)

The diagram (Fig. 2) shows changes in the material’s stress from the initial applied load to the point of failure. It illustrates both the pre-critical and post-critical stages of deformation. This makes it possible to evaluate the elastic and plastic properties of the composite material, as well as its ability to ensure the joint performance of veneer layers under axial compression. The main strength and deformation characteristics were determined in the pre-critical and post- critical stages of the material’s behavior in accordance with (Homon et al. (2023)). The ultimate tensile strength, as well as the relative critical and residual strains, were determined. (Table 1). Table 1. Strength and deformation characteristics of composite samples based on wood veneer in the pre-critical and post-critical stages of behavior Prism number Cross-section of the samples, mm f c,0,d, MPa u c,0,d, mm/mm u c,fin , mm/mm Р -1 45х45х150 62.8 0.00501 0.4012 Р -2 45х45х150 59.6 0.00472 0.3791 Р -3 45х45х150 69.3 0.00568 0.4183 Р -4 45х45х150 64.2 0.00520 0.4098 Р -5 45х45х150 66.1 0.00539 0.4391 Averaged indicators Р 45х45х150 64.4 0.00520 0.4095 The features of behavior and the failure pattern of composite prisms made of wood veneer are shown in Fig. 3. Analyzing Fig. 3 shows a gradual change in the stress – strain state during axial compression. This process includes both the pre-critical and post critical stages of the material’s behavior. At the initial loading stage, the deformations were mainly elastic, while the structure remained intact and the veneer layers worked together. As the load increased, the material entered the elastic – plastic stage. This