Predicted Model of Section Stress Distribution and Bending Strength of Fiberboard Based on Vertical Density Profile

Abstract:

To study the impact of VDP on the bending process of fiberboard, this paper deeply researched into the dynamic changes of section stress distribution of fiberboard during the process of loading and bending and built a static bending strength predicting model, which is based on the piecewise function by simulating fiberboard VDP, theory of elasticity and plasticity, lamella inter-bedded theory and VDP model. The results show: The bending process of fiberboard can be divided into two stages which are elasticity period and elasticity-plasticity period. The latter includes both elasticity region and plasticity region, and compression region comes to elasticity bending before pulling region. The curve of bending section stress distribution is nonlinear and affected by loads and VDP. Critical section stress distribution of bending breakage and breakage load can be predicted by VDP with other condition unchanged. The value of static bending strength predicted by model is basically consistent with testing data. And the static bending strength is closely related to qualification factors of VDP. Fiberboard with high average density doesn’t always contain high static bending strength. VDP is a significant physical parameter which has impact on the bending process and performance of fiberboard, so it must be optimized and controlled in production according to for specific purpose. Key words: fiberboard, vertical density profile, section stress distribution, bending strength, predicting model

• Periodical: Materials Science Forum (Volumes 704-705)
• Pages: 424-433
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.704-705.424
• Online since: December 2011
• Authors: Yang Zhang, Zhi Ming Yu
• Keywords: Bending Strength, Fiberboard, Predicting Model, Section Stress Distribution, Vertical Density Profile

References

[1] Ee Ding Wong. 1999. Formation of the density profile and its effects on the properties of particleboard．Wood Science and Technology 33: 327–340.

[2] Zhang Yang, YU ZM, Ma Jun. 2009. Forecasting model of MOR of fiberboard. Journal of Beijing Forestry University 31: 127–131.

[3] State Bureau of Technical Supervision. 2005. GB/T 17657—1999 Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels, Standards Press of China, Beijing, p.23–35.

[4] Tang ZR. 2006. Wood performance testing. China Forestry Publishing House, p.15–17.

[5] Wang XS. 2007. Test and analysis on mechanical behavior of materials. Tsinghua University Press, Beijing, pp.127-129.

[6] Wang SQ, Winistorfer PM. 2004. Fundamentals of vertical density profile formation in wood composites. Part III. MDF density formation during hot-pressing. Wood and Fiber Science J 36: 17–25.

[7] Wei X. Influence of vertical density distribution on bending modulus of elasticity of wood composites panels: A theoretical consideration. Wood and Fiber Science 31: 277–282.

[8] Winistorfer PM. 2000. Fundamentals of vertical density profile formation in wood composites (Ⅰ): In-situ density measurement of the consolidation process. Wood and Fiber Science 32: 209–219.

[9] Wu ZK, Zhou DG. 2001. Review on studies for vertical density profile of wood composites. China Wood Industry 15: 3–5.

[10] Beijing University of Science and Technology Beijing, 1997. Northeastern University. Engineering mechanics. Higher Education Press, Beijing, pp.127-129.