【作者】 杨峰；

【导师】 费本华；

【作者基本信息】 中国林业科学研究院 ， 木材科学与技术， 2014， 博士

【摘要】 竹重组材，是将竹材重新组织并加以强化成型的一种竹质新材料，具有原料利用率高、强度高、材质均匀、加工性能好等优点。十年来，我国以毛竹为主要原料的竹重组材产业发展迅猛，产品逐步应用于建筑、工程、结构等高附加值领域。我国杨木等速生木材资源丰富，是制造胶合板、纤维板和刨花板的优等原料，应用十分广泛。本文提出以竹重组材和OSB（定向刨花板）为复合单元制造竹重组材/OSB复合材料的理念，探讨复合材料的设计、工艺、性能和应用，具有良好的发展前景。在毛竹和重组后竹材的基本物理力学性能基础上，比较了两者在微观构造和性能上的差异，研究了毛竹重组材和杨木OSB结构特性和表面性能，基于产业化前景的考虑，从工艺条件和生产成本两方面，分别对热压和冷压生产过程进行分析，研究适合毛竹重组材和杨木OSB材料特性的胶合工艺以及复合形式对复合材性能的影响。在确定竹重组材与OSB复合工艺的基础上，利用经典层合板理论，分别建立了竹木层合板的弹性模量以及静曲强度的预测模型，编制了基于VB的竹木层合板弯曲性能预测程序。采用有限元方法，对竹木层合板弯曲行为进行分析以及厚度优化设计，得出了基于有限元分析的竹木层合材料弯曲性能的预测方法，并用竹重组材/OSB集装箱底板的实例验证。论文的主要研究结论如下：（1）竹材的纤维体积分数Vy沿径向由青向黄侧梯度减小，重组后竹材内部结构发生变化，靠近髓环侧的韧皮纤维变得致密，大部分区域的Vy值在50%上下，但是临近髓环区域的Vy值维持不变。（2）炭化处理对于算数平均偏差（Ra）、微观不平度十点高度（Rz）及轮廓最大高度（Rmax）这三种指标的影响均不显著。随着砂纸目数的增大，砂光后竹重组材表面越光滑，算数平均偏差（Ra）、微观不平度十点高度（Rz）及轮廓最大高度（Rmax）值越小。刨切后表面（BS-B）与100目砂纸砂光后的粗糙度（BS-100）比较接近。总的来说，竹重组材纵纹粗糙度参数远小于横纹，同种测量条件下，前者值不到后者的一半。目数越小砂纸砂光处理的竹重组材表面水接触角相对越小。（3）利用PUR胶冷压制备竹重组材/OSB复合材料，较优的工艺参数为时间1.5min/mm；单面涂胶量200g/m2；压力1.2MPa。（4）对于竹重组材/OSB复合材料，适当增加竹质材料厚度或者纵横组坯，可使复合材整体获得更高的刚度值。铺层方向的变化（纵横组坯），可以改善复合材的尺寸稳定性。对于给定厚度的竹重组材，增加层数并不显著地影响复合材整体的强度值和刚度值。背衬无纺布（纸）可明显降低复合材的尺寸稳定性。（5）在最终产品性能方面，与竹重组材复合，可显著地提升OSB的抗弯性能。位于表层的竹材很好地避免了应力集中引起的结构破坏，验证了三层夹层结构（强-弱-强）是一种合理的结构组合。有限元模型可以较精确地预测层合板弹性区域内的刚度值，且三维模型比二维模型更为精确；但对于强度预测来说，更精准的预测需要进一步改善模型。（6）利用Altair Optistruct结构分析和优化工具，优化后的厚度能满足工程应用的安全需要，该优化方法在工程实际中验证是可行的。对于竹重组材/木质定向刨花板/竹重组材三层结构的层合板类人造板而言，采用优化后的铺层结构对比由传统公式计算出的铺层结构，在木质材料不变的情况下，竹材使用量节省三分之一。更多还原

【Abstract】 Bamboo scrimber is reorganized and reinforced by raw bamboo which is a kind of newbamboo composite. Its advantages include high utilization rate of raw materials, high strength,uniform texture, good processing performance. For a decade, china’s MOSO bamboo scrimberindustry being develop rapidly, products have been used in the field of construction,engineering, strcture etc, gradually. Meanwhile, the poplar, a important fast-growing timberresources in china, is a wonderful substitute resource to manufacture plywood, fiberboard, andparticleboard. In this paper, the idea of bamboo scrimber and OSB composite was proposed,that laminated by bamboo scrimber and OSB has been proved have a broad prospects fordevelopment, and the design construction, process, performance and application of thiscomposite were discussed. Based on the physical and mechanical properties of MOSO naturalbamboo and bamboo scrimber, the differences of micro structure and performance betweenthem were studied. The structure features and surface properties of bamboo scrimber andpoplar OSB were also studied. Based on considerations of industrialization prospect, the hotand cold pressing production processes were analyzed in aspects of process conditions andproduction cost, respectively. The combination technology and the effect of laminate form oncomposite properties were studied and the optimal factors were decided. The classicallaminated plate theory was used to established the MOR and MOE models of bamboo-woodlaminate, and the VB program was coded. The Finite element method (FEM) was used toanalysis and optimize the bending behaviors of bamboo-wood laminate, the prediction methodbased on FEM was finally obtained and the example of bamboo-wood laminate container floorwas used to tested. The main conclusions of this paper are following:(1) Vyis the fiber volume fraction of bamboo composite. The Vyvalue along the radialgradient decreases from outer to inner side. The internal construction was changed afterreforming, the bast fibers become dense near pith ring side, whose Vyvalue around50%in most area, and the value remain constant near the pith ring. After reforming, most of theparenchyma of the pores, the vessels between vascular bundlesand sieve tubes weredisappeared, the circular shape of the vascular bundle also changed to elliptic and theparenchyma were largely removed by rolling process. The density and evenness of wholestructure were improved because of PF adhesive cured as the substrate. Overall, The basicproperties of bamboo scrimber increased with the increased of density, and the magnitude ofbamboo modulus is higher than strength’s. The radial shrinkage rate greater than tangential’sand the bulk shrinkage rate of bamboo scrimber (48%compressive rate) is greater than naturalbamboo.(2) Due to the heating volatilization rate differences and the effects of extraction,carbonized process make the surface of bamboo scrimber become rough. The influence ofarithmetic average deviation (Ra) and the point height of irregularities (Rz) and maximumheight of profile (Rmax) were not significant. With the mesh of sand paper increase, sandedbamboo scrimber surface more smooth and Ra, Rzand Rmaxvalues smaller. The roughnessvalues of surface treated by sliced and100mesh sandpaper are near. In general, thelongitudinal roughness values is far less than transverse grain, the former is half of the latterunder the same measure condition. For UF, PF, EPI, PUR and water, the change rate on theouter surface and contact angle are smaller than the inner’s, the wettability of bamboo joint isweak.(3) Compare to PF heat-press process, the advantages of PUR cold-press process includefree pollution, low cost, low energy consumption and higher efficiency. For annual productionof1million m2of3-layers bamboo scrimber and OSB composite manufacture, the unit cost ofthe cold-press process lower12.52yuan than PF heat-press process. The optimum processconditions are1.5min/mm of press time,200g/m2of single gule content and1.2MPa of press.(4) To make the composite obtained higher stiffness, appropriate increase thickness andcriss-cross lay seen to be the optional way. The change of layer direction could improve thedimensional stability. For a given thickness of bamboo layer, the increase of layer does not influence the properties of composite, significantly. Add of nonwoven fabrics decrease thedimensional stability of composite significantly.(5) In terms of the end product performance, laminating with bamboo scrimber, is a kindof rational way to improve the bending properties. It is proven that the bamboo is a promisingreinforced material. The bamboo located in the surface to support the stress concentration ofthe structure, to verify the three layers of laminated structure (strong-weak-strong) is a kindof rational structure combination. The FE model can accurately predict the stiffness of laminate,and3-D model is proven more accurate than the2-D model. For strength prediction, the furtherimproved model is need.(6) The Altair Optistruct structure analysis and optimization tool are proven feasible,optimized thickness can meet the security needs of the engineering application. For3-layeredbamboo scrimber and OSB composite, compare with traditional structure, the optimized layerstructure save a third of bamboo usage.更多还原