Performance And Structure Optimization And Reliability Analysis Of Typical Biomass Composites

In this paper, the research objects included the wood particleboard, OSB, rice straw particleboard, wood lamination, glulam, Ⅰ-joist and wood composites with lattice structures. The performance and structure optimization of several typical biomass composites were studied, such as the coir fiber was used to improve the properties of rice straw particleboard and the structure of wood engineering composites was optimized with lattice structures. The properties of new material and new structure were analyzed using related performance characterization methods. The reliability of new material or structure and several typical biomass composites was also investigated using AFOSM and Monte-Carlo methods.Firstly, the production technologies of particleboard manufactured with the homemade rice straw particles or wood particles were optimized. The optimum process parameters were determined by orthogonal experiments, such as the process parameters of rice straw particles alkali treatment and the production parameters of particleboards (hot pressing temperature, hot pressing time and adhesive spread).Secondly, the coir fiber was used to improve the bonding strength and dimensional stability of rice straw particleboard. The effects of the mass ratio of rice straw and coir fiber (R/C ratio), the mat structure (hybrid or sandwich) and the MDI on the rice straw-coir fiber composites (RC composites) properties were studied. The conclusion was that the best R/C ratio was6/4. The particleboard manufactured with the best ratio and without MDI also had excellent performance to meet the requirements for load-bearing boards used in dry conditions. The hybrid structure was the optimum form that could give full play to the hybrid effect. The R/C ratios and structural forms also had different effects on the impact toughness and vibration damping ratios of particleboard. So the RC composites should be manufactured with a graduated structure. The performance prediction of RC composites with different methods was studied, and it was found that the most convenient and efficient method was the NDT method which could be used in real-time online testing.The reliability of particleboard materials, such as RC particleboard, wood particleboard and OSB, were analyzed. The statistical properties of three particleboards were studied; it was found that every property basically accorded with normal distribution. The correlation relationships between density and properties were very significance. The properties discretization of particleboards was analyzed resulting from the nonuniform of adhesive application and mat forming, which resulted in the fluctuation of density and properties. Meanwhile, the reliability of three particleboard materials was analyzed based on AFOSM and Monte-Carlo methods under three different working conditions. It was found that the particleboard materials can meet the reliability requirements of bearing strength limit state. But the RC particleboard and wood particleboard easily occour large bending deformation and exceeds the set maximum allowable deflection. The mechanical properties predicted values obtained using dynamic Young’s moduli of NDT, and the reliability of predicted values was also analyzed. It was found that the failure probability using the predicted values was smaller than the actual failure probability. So in actual use, the failure probability based on NDT predicted values should be appropriate amplification, in order to improve the accuracy of safety assessment for using the material or component.The structure of wood engineering composites such as glulam and Ⅰ-joist was optimized. And the wood composites with two different lattice structures were manufactured. The properties comparation between glulam, Ⅰ-joist and wood composites with lattice structure were analyzed. It was found that the wood composites with lattice structure had very superior performance in weight, strength, modulus, damping and toughness. Meanwhile, the reliability of five wood engineering materials was analyzed based on AFOSM and Monte-Carlo methods under three different conditions. It was found that the wood lamination with small thickness should not be used as the wooden beam. The materials such as glulam, Ⅰ-joist and wood composites with lattice structure could meet the reliability requirements of bearing strength limit state under the appropriate load conditions. But the wood composites with lattice structure easily had large bending deformation under larger load, because of the samller stiffness and larger toughness of these materials; and the large bending deformation usually occured before the structural broke, which was a reminder of the danger level of this structure for giving more time to escape.Finally, when using biomass engineering composites such as particleboard, glulam, Ⅰ-joist and wood composites with lattice structure, the bending strength and toughness of materials must be comprehensive consideration, the span and thickness of components should be reasonable selected, the restraint and load also should be reasonable arrangement.