PSI - Issue 59

Sviatoslav Homon et al. / Procedia Structural Integrity 59 (2024) 545–550 Sviatoslav Homon et al. / Structural Integrity Procedia 00 (2019) 000 – 000

547 3

D 143-14: 2014; EN 380: 2008; DSTU 3129: 2015; NDS:2018; Eurocode 5:2004). There were 63 samples in total. The extent of experimental studies is given in Table 1.

Table 1. The volume of experimental research. Wood species Moisture, % Age, years

Loading speed, mm/min

Number of samples, pcs

Larch

12 12 12 12 12 12 12 12 12

60 60 60 40 40 40 20 20 20

1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

9 9 9 6 6 6 6 6 6

Pine Spruce

Larch

Pine

Spruce

Larch

Pine

Spruce

Testing of wood samples was carried out on a universal modern servo-hydraulic testing machine СТМ -100 (Yasniy et al. (2022); Homon et al. (2023)) under short-term axial compression along the fibers according to current standards (ASTM D 143-14: 2014; EN 380: 2008; DSTU 3129: 2015; DSTU EN 380-2008). The rate of deformation was 1.5 mm/min. 3. Results and discussion Complete diagrams of the deformation of larch, pine and spruce wood of different ages at a standard moisture content of 12% were constructed after conducting experimental studies and processing the obtained results (Fig.1a, 1b, 1c). It was established that under a strict test regime, the deformation diagram of solid wood necessarily has two branches, namely, an ascending and a descending one. The samples operate up to the point of critical deformations and pass into the critical stage of the material's operation. In the critical work stage, wood deformability increases rapidly while the stresses decrease. New testing machines under a strict test regime allow precise recording of strain parameters on both ascending and descending branches of the diagram. This makes it possible to obtain unique results from experimental studies and establish a full range of mechanical properties of coniferous wood of different ages.

a σ c , МРа

60

Larch Pine Spruce

50

40

30

20

10

u c

0

0

0,1

0,2

0,3

0,4

0,5