| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥2,000,000 (Direct Cost: ¥2,000,000)
|
|---|
| Research Abstract |
From the investigation on the deformational and fractural behaviors of structural particleboard, the main results were summarized as follows;
(1) The shearing action at some glue layers between strands reduces the the strength of oriented strandboard, having the internal structure in which the butt joints are interspersed at small distance. Furthermore, the deformational recovery action of the strands deformed fixedly in various curves or collapses reduces the strength of oriented strandboard in which the lapped joints are interspersed at small distance.
(2) In each fatigue of three-layer particleboard and oriented strandboard, a 3-parameter Weibull function can be adopted for the model of life distribution, and besides, a single approximate formula can be applicable for the relationship between the rate of cyclic creep and the fatigue life transition N_c, i.e., the critical point of deformation of internal structure.
(3) In the oriented strandboard, both the intermittent shearing fracture from the outmost surface to the interior and various micro-cracks propagates themselves thereby promoting the cyclic relaxation. On the other hand, in the three-layer particleboard the cyclic relaxation during the stable stage is rectilinearly developed, resulting from the propagation of various cracks during the initial stage.
(4) The minimum hysterisis during the fatigue of three-layer particleboard is closely relative to the life, so that the fractographic condition can be presumed. The ratio of energy loss increases during the fatigue of oriented strandboard.
|
