FATIGUE LIFE AND DESIGN STRESSES FOR WOOD COMPOSITES USED IN FURNITURE

Medium density fiberboard (MDF), oriented strandboard (OSB), and particleboard beams were tested on edge in order to determine their resistance to fatigue. Tests were carried out at selected stress levels that corresponded to specific percentages of the material's ultimate strength (modulus of rupture (MOR)). The relationship between level of stress and fatigue life was regular and, as anticipated, fatigue life decreased as levels of stress increased. Fatigue life amounted to over 1 million cycles when the stress level was 30 percent of MOR and decreased to 405 cycles for MDF and 10,887 cycles for OSB ata stress level of 70 percent. Results of the tests suggest that allowable design stresses for the composite materials included in the study could likely be derived from a consideration of their fatigue resistance at various load levels.