Effects of Cross-Section Design and Loading Direction on the Creep and Fatigue Properties of Wood/PVC Composite Beams

The creep and fatigue properties of two wood/poly(vinyl chloride) (WPVC) composite beams were studied under flexural and cyclic deformations. The effects of cross-section design and load direction were the main interests. The weight ratio of the wood and PVC compound used was 1:1, and the composites were produced by using an industrial-scale twin-screw extruder. In creep testing, the changes in WPVC beam displacement for the edgewise and flatwise directions increased with time. The WPVC composite with a greater size (thickness) and number of cores had the higher creep resistance. Testing a WPVC composite in the flatwise direction gave less time-dependence than testing in the edgewise direction. The recommended applied loads for optimum creep resistance of the WPVC specimens were found to be 20 and 30% of the ultimate load to failure, depending on the size and number of cores for the cross-section used. In fatigue testing, the number of cycles to failure for both WPVC composite specimens tested in the flatwise direction was greater than that for testing in the edgewise direction. J. VINYL ADDIT. TECHNOL., 16:42-49, 2010. (C) 2010 Society of Plastics Engineers