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Effect of decay on strength and frac...

Akande, Adebayo John.

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Effect of decay on strength and fracture morphology of Populus tremuloides Michx.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Effect of decay on strength and fracture morphology of Populus tremuloides Michx./
Author:	Akande, Adebayo John.
Description:	196 p.
Notes:	Major Professor: G. H. Kyanka.
Contained By:	Dissertation Abstracts International50-04B.
Subject:	Agriculture, Wood Technology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8911453

Effect of decay on strength and fracture morphology of Populus tremuloides Michx.
Akande, Adebayo John.

Effect of decay on strength and fracture morphology of Populus tremuloides Michx. - 196 p.

Major Professor: G. H. Kyanka.

Thesis (Ph.D.)--State University of New York College of Environmental Science and Forestry, 1988.

To relate fungal decay to strength losses and associated wood failures, weight and strength losses in Populus tremuloides were monitored following exposure to three decay fungi viz., Trametes versicolor (a simultaneous white rotter), Bjerkandera adusta (a selective white rotter), and Gloeophyllum trabeum (a brown rotter). Test specimens were subjected to tension parallel to grain and toughness tests, after which the macroscopic and ultrastructural details of fracture surfaces were studied. Results showed that decay fungi produced strength losses which positively correlated with weight losses in wood. Decay also affected fracture development. Decayed woods ($>Subjects--Topical Terms:

1031154
Agriculture, Wood Technology.

Effect of decay on strength and fracture morphology of Populus tremuloides Michx.
LDR:03537nam 2200253 a 45 001 973105
005 20110928
008 110928s1988 eng d
035 $a (UMI)AAI8911453
035 $a AAI8911453
040 $a UMI $c UMI
100 1 $a Akande, Adebayo John. $3 1297064
245 1 0 $a Effect of decay on strength and fracture morphology of Populus tremuloides Michx.
300 $a 196 p.
500 $a Major Professor: G. H. Kyanka.
500 $a Source: Dissertation Abstracts International, Volume: 50-04, Section: B, page: 1190.
502 $a Thesis (Ph.D.)--State University of New York College of Environmental Science and Forestry, 1988.
520 $a To relate fungal decay to strength losses and associated wood failures, weight and strength losses in Populus tremuloides were monitored following exposure to three decay fungi viz., Trametes versicolor (a simultaneous white rotter), Bjerkandera adusta (a selective white rotter), and Gloeophyllum trabeum (a brown rotter). Test specimens were subjected to tension parallel to grain and toughness tests, after which the macroscopic and ultrastructural details of fracture surfaces were studied. Results showed that decay fungi produced strength losses which positively correlated with weight losses in wood. Decay also affected fracture development. Decayed woods ($> $2 % weight loss) failed differently from sound wood. High energy fracturing like splintering and production of rough shear planes typified the failure characteristics up to 2% weight loss. The associated fractographic features included transwall failures of fibres at angles close to the S2 microfibrillar orientation, intrawall failures at the S1/S2 interfaces, and "cellular unwinding" due to a pull out of the S2 wall layer from the whole fibre. These features diminished gradually as weight loss increased. At $\geq $1 0% weight loss, failures were often brash and characterized by abrupt transwall failures of fibres along the transverse plane. Abrupt transverse fibre failures were recognized in specimens decayed by all the test fungi. The S2 microfibrillar angle did not influence the fibre failure angles in decayed cells. Smooth split fractures occurred from longitudinal transwall failures through the parenchyma cells. This type of failure was unique to the white rot fungi and it occurred at weight losses below that required to produce middle lamella separation. Strength gradients were found in decayed wood. As a result, the fractographic features related to fungal decay occurred more frequently near the specimen exterior. A correlation drawn between the fractographic features and fracture resistance shows that smoother fracture planes denote lower energy of fracture. Fracture toughness (${\bf K}\sb{\rm Ic}$) progressively attenuates with increasing decay. Using the average distance between rays as the critical flaw dimension, loss of ${\bf K}\sb{\rm Ic}\sp{\rm LR}$ was found to be more pronounced with the brown rot fungus when compared to the white rot fungi. This trend is generally similar to that existing in the ratio of strength loss/weight loss by these groups of fungi. It is concluded that decay affects the morphology of wood fracture surfaces and that the nature of the fracture surface is an indication of the degree of degradation of wood cells.
590 $a School code: 0213.
650 4 $a Agriculture, Wood Technology. $3 1031154
690 $a 0746
710 2 0 $a State University of New York College of Environmental Science and Forestry. $3 1017822
773 0 $t Dissertation Abstracts International $g 50-04B.
790 $a 0213
790 1 0 $a Kyanka, G. H., $e advisor
791 $a Ph.D.
792 $a 1988
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8911453