Item View
Publication: Forest Products Journal
Authors: Hoyle R J Jr
Reference ID: 18(4):87-97
Publish Year: 1968
Member Download Price: $0.00
Member Physical Price: $0.00
Title: Background to Machine Stress Grading
Description:
This is a review article in which data and discussion from 41 references are used to develop grading standards for six species of western woods. Modulus of elasticity in increments of 0.2 x 106 psi in the range 1.0 to 2.6 x 106 psi) is related to allowable working stresses following a statistically rigorous treatment of test data. It, is clearly shown that visual grading for stress purposes and upgrading of product are possible by use of calibrated, high speed MOE sensing machines. The author presents a convincing case for the use of machines to measure modulus of elasticity as a means of grading structural lumber. The results of work by western lumber producers show the method by which modulus of rupture, ultimate compression strength, and ultimate tensile strength were related to MOE so that single grading standards could be applied to all species. From these data, allowable working stresses were selected to provide reasonable safety factors. Machine calibration and effects of wood anatomy are related through analysis of the controlling factors; the machine grading takes all ""defects"" into account as it measures effective MOE. Compression perpendicular-to-grain and horizontal shear require separation according to species because ASTM methods use only clear specimens.
This is a review article in which data and discussion from 41 references are used to develop grading standards for six species of western woods. Modulus of elasticity in increments of 0.2 x 106 psi in the range 1.0 to 2.6 x 106 psi) is related to allowable working stresses following a statistically rigorous treatment of test data. It, is clearly shown that visual grading for stress purposes and upgrading of product are possible by use of calibrated, high speed MOE sensing machines. The author presents a convincing case for the use of machines to measure modulus of elasticity as a means of grading structural lumber. The results of work by western lumber producers show the method by which modulus of rupture, ultimate compression strength, and ultimate tensile strength were related to MOE so that single grading standards could be applied to all species. From these data, allowable working stresses were selected to provide reasonable safety factors. Machine calibration and effects of wood anatomy are related through analysis of the controlling factors; the machine grading takes all ""defects"" into account as it measures effective MOE. Compression perpendicular-to-grain and horizontal shear require separation according to species because ASTM methods use only clear specimens.
You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member