Modulus of elasticity MOE of LVL

54 Figure 31 MOE values of LVL from pih to bark made of unboiled and boiled sengon a and jabon b

4.6.3.2 Modulus of Rupture MOR of LVL

The same with glue bond strength and MOE, MOR values also increased from pith to bark for LVL made of unboiled and boiled veneers of sengon and jabon Figure 32a-b. The average MOR of unboiled and boiled sengon type I and type II were 36.2, 40.2, 40.2 and 42.9 MPa, respectively Figure 32a. The average MOR of jabon were 50.7 MPa unboiled jabon type I, 54.9 MPa boiled jabon type I, 54.3 MPa unboiled jabon type II, and 59.8 MPa boiled jabon type II Figure 32b Figure 32 MOR values of LVL from pih to bark made from unboiled and boiled sengon a and jabon b The MOE and MOR were influenced by the lathe check Figure 33 and 34. This suggested that the lathe checks may cause a great deal of local stresses on tensile side of the bending specimen, and determine the bending failure of LVL when the lathe checks were situated under the maximum bending moment. The lack of proper connection among the fiber elements was the reason of the frequent rupture on the tensile side. The frequency of lathe check had a statistically significant, negative correlation to bending strength of sengon and jabon, and its 4000 6000 8000 10000 1 2 3 4 5 6 7 8 MOE Mp a Segmented rings from pith to bark Unboiled sengon type I Boiled sengon type I Unboiled sengon type II Boiled sengon type II a 4000 6000 8000 10000 12000 14000 1 2 3 4 5 6 7 8 MO E MP a Segmented rings from pith to bark Unboiled jabon type I Boiled jabon type I Unboiled jabon type II Boiled jabon type II b 20 40 60 80 1 2 3 4 5 6 7 8 MO R Mp a Segmented rings from pith to bark Unboiled sengon type I Boiled sengon type I Unboiled sengon type II Boiled sengon type II a 20 40 60 80 1 2 3 4 5 6 7 8 MO R MP a Segmented rings from pith to bark Unboiled jabon type I Boiled jabon type I Unboiled jabon type II Boiled jabon type II b 55 correlation coefficients according to the lines in Figure 33 and 34 are summarized in Table 11 for MOE and Table 12 for MOR. Figure 33 The effect of lathe check frequency on the MOE LVL of unboiled and boiled sengon a and jabon b Figure 34 The effect of lathe check frequency on the MOR LVL of unboiled and boiled sengon a and jabon b Table 11 Linear regression equation and determination coefficients according to Figure 33 Y = MOE, X = frequency of lathe check, R 2 = determination coefficient Linear regression R 2 Unboiled sengon type I Y = 6791.5 – 329.3X 0.88 Boiled sengon type I Y = 7151.2 – 419.81X 0.90 Unboiled sengon type II Y = 7916.7 – 453.9X 0.83 Boiled sengon type II Y = 8365.8 – 696.88X 0.91 Unboiled jabon type I Y = 11783 – 841.9 X 0.68 Boiled jabon type I Y = 12732 – 1246.5X 0.84 Unboiled jabon type II Y = 10894 – 844.17X 0.82 Boiled jabon type II Y = 14388 – 1495.9X 0.82 5000 10000 15000 1 2 3 4 5 6 7 MO E MP a Frequency of lathe check per cm veneer length Unboiled sengon type I Boiled sengon type I Unboiled sengon type II Boiled sengon type II 5000 10000 15000 1 2 3 4 5 6 7 MO E MP a Frequency of lathe check per cm veneer length Unboiled jabon type I Boiled jabon type I Unboiled jabon type II Boiled jabon type II 20 40 60 80 1 2 3 4 5 6 7 MO R MP a Frequency of lathe check per cm veneer length Unboiled sengon type I Boiled sengon type I Unboiled sengn type II Boiled sengon type II 20 40 60 80 1 2 3 4 5 6 7 MO R Mp a Frequency of lathe check per cm veneer length Unboiled jabon type I Boiled jabon type I Unboiled jabon type II Boiled jabon type II b a b a