PSI - Issue 36

Petro Yasniy et al. / Procedia Structural Integrity 36 (2022) 211–216 Yasniy Petro et al./ Structural Integrity Procedia 00 (2021) 000 – 000

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E*10 3 , МPа

20

15

10

Birch Alder Ash

5

η

0

0

0,2

0,4

0,6

0,8

1

Fig. 3. Diagrams «Е – η» (secant modulus – stress level) of composite materials based on different hardwood species and polymer composite ‘ silor ’ under the surface modification

Therefore, the following indicators of the initial modulus of elasticity of new formed composite materials on the basis of hardwood were obtained (Fig.3): birch wood E 0 = 17900 MPa (45.6% more), alder wood E 0 = 18800 MPa (55.4% more), ash wood E 0 = 19700 MPa (23.1% more). We come to the conclusion that the initial modulus of elasticity of the studied samples is higher by 23.1 – 55.4% in comparison with the 60 year old ones characteristics at standard moisture of 12%. We analyze the change in strain modulus in the same way as for other twin prisms. There was also a decrease in the value of secant modulus, but in a slightly different range: for birch wood by 20.9%; alder wood by 30.6%; ash wood by 37.8%. The main parameters and statistics of correlation equations of modified hardwood regression are given in Table 2.

Table 2. Main parameters and statistics correlation equations of regression of modified hardwood Wood species Correlation equation r m r r/m r V,% Birch E =17,884  (1-0,070  η) 0,768 0,070 18 3,80 Alder Ash E =18,837  (1-0,106  η) E =19,658  (1-0,099  η) 0,786 0,844 0,106 0,099 5 8 4,81 4,63

Hence, we come to the conclusion that due to the modification of solid hardwood with a polymer composition ‘ silor ’ the main strength and deformability indicators significantly improve. 4. Conclusions The experimental study of the strength and deformability characteristics of modified hardwood (birch, alder, ash) for compression along the fibers under rigid load was carried out and complete ‘ stress σ c - deformation u c ’ diagrams from the beginning of loading until fracture (rising and falling branches) have been constructed. A new composite material based on solid wood and polymer composition ‘ silor ’ under surface modification was obtained. With surface modification of solid hardwood, the maximum stresses increase by 12 – 22% in comparison with solid 60 year old wood with a moisture content of 12%. Deformability decreases within 17 – 25%. The initial modulus of elasticity of the studied samples is higher by 21 – 38%. References ANSI/AF&PA: 2012. National design specification for wood construction. American Forest and Paper Association.