EFFECT OF COMPOSITE STRUCTURE ON STRAIN AND FAILURE OF LAMINAR AND WAFER COMPOSITES

Abstract

The effect of composite structure on the distribution of strain and failure modes in wood laminar and wafer composites was investigated. Mechanical testing was performed using bending tests of solid wood, plywood, and oriented strandboard specimens (OSB) in accordance with ASTM D143-83, Standard Methods of Testing Small Clear Specimens of Timber [1], and ASTM D3043-83, Standard Method of Testing Structural Panels in Flexure [2], The strain distributions were measured using a new technique, the digital image correlation technique Strain distributions from bending tests on small, clear specimens of solid wood indicated close agreement with conventional beam theory and exact correlation with the failure patterns oflht specimens. The layered annual ring structure of the solid wood controlled the path of the tension cracks. Neither composite board followed conventional beam theory entirely. Of the two composites investigated in this study, the laminated veneer board exhibited behavior closer to conventional theory and exhibited the least correlation with composite structure. The wafer composite exhibited strain patterns most closely related to the arrangement of the composite strands.