PSI - Issue 81

Dmytro Y. Kysliuk et al. / Procedia Structural Integrity 81 (2026) 430–433

432

3. Results and discussion During full-scale tests, the deformation and failure characteristics of modified and unmodified softwood species (pine, larch, and spruce) were determined. Fig. 3 shows specimens of untreated wood with a moisture content of 12% after testing. It indicates that the failure of untreated samples occurs according to different patterns.

a

b

c

Fig. 3. Untreated wood specimens with 12% moisture content after testing: (a) pine; (b) larch; (c) spruce.

Fig. 4 presents the results of tests on wood specimens modified with epoxy resin.

a

b

c

Fig.4. Untreated wood specimens with 12% moisture content after testing: (a) pine; (b) larch; (c) spruce.

Analysis of the results presented in Fig. 4, suggests that the failure pattern of epoxy-modified pine and larch specimens is generally similar, whereas spruce specimens demonstrate a somewhat different failure mechanism. This may be attributed to differences in anatomical structure and density among the studied softwood species. Based on the full-scale experiments, compressive strength values were determined for both modified and unmodified pine, larch, and spruce specimens. For untreated samples, the compressive strength along the grain was 45.7 MPa for pine, 59.6 MPa for larch, and 40.2 MPa for spruce. After autoclave modification using epoxy resin, a significant increase in strength was observed: up to 59.1 MPa for pine, 72.0 MPa for larch, and 54.8 MPa for spruce. As a result, the application of autoclave modification increased wood strength by 1.29 for pine, 1.21 for larch, and 1.36 for spruce, confirming the effectiveness of this method in improving the mechanical properties of wood. 4. Conclusions Technological approaches to modifying softwood species with epoxy resins have been improved. The methodology for