【作者】 许斌；

【导师】 张齐生； Robert Wellwood；

【作者基本信息】 南京林业大学 ， 木材科学与技术， 2008， 博士

【摘要】 定向刨花板-单板复合集装箱底板(OSBVCCF)是利用具有高抗剪强度的定向刨花板(OSB)芯层和较高力学性能的单板制成的多层结构用人造板,作为集装箱的主要承载配件——底板,要求具有足够的刚度、强度、耐老化性、抗疲劳性能,来保证集装箱承运货物的安全性以及必要的使用寿命。本论文以OSBVCCF为研究对象,运用断面密度仪、Pressman、激光测角仪、喷蒸压机等先进的仪器设备来进行定向刨花板和复合集装箱底板的热压工艺研究,同时综合运用VBA编程、弹(塑)性力学、正交各向异性复合材料层板理论、损伤力学、模型模拟方法,重点分析了OSBVCCF的宏观力学性能和细观结构(微薄层)之间的相互关系,建立了单板在热、压力、胶粘剂等作用下弹性模量和静曲强度与密度预测模型,进而建立了OSB弹性模量预测模型和OSBVCCF的弹性模量和静曲强度预测模型,并从理论上论证了复合底板的芯层抗剪性能优于传统的克隆底板。1.对板的热压工艺表明:1)采用一次热压成型的OSBVCCF能满足集装箱底板的要求,总的热压时间为27分;2)采用喷蒸预热工艺,可以将OSB的热压时间缩短到常规热压时间的一半(7分钟),且压出的板的芯层抗剪切强度提高35%。3)对工厂生产出的OSB进行分析,施胶量10%比7.5%只有在芯层剪切强度上有显著差异(分别为3.4MPa、3.1MPa),其它性能无显著性差异;4)在芯板上二次覆贴单板的热压时间以24～27分种为佳。2.分析了构成OSBVCCF的定向刨花板芯层和表层单板的材料特性。建立了各种材料的宏观力学性能与其结构参数及其它物理量之间的关系模型。分析认为OSBVCCF是由各向异性的OSB和单板组成的具有对称结构的正交各向异性层合板。3.根据复合材料层板的刚度理论,推导了复合集装箱底板的刚度矩阵,弹性常数之间的耦合效应和交叉效应可以忽略不计。在此基础上,推导出OSBVCCF的弹性模量的理论模型,形成了弹性模量预测的理论基础。4.采用层板的刚度理论,将定向刨花板细分为96薄层,根据激光测量的刨花分布角,并依据每薄层对应的密度,推断出每薄层对应的弹性模量,用VBA编程来计算出定向刨花板的弹性模量。5.基于纤维增强复合材料的混合模型和层合板刚度理论,构建单板涂胶和压力浸胶热压后的弹性模量的物理模型和数学模型。研究结果表明:1)随着胶粘剂的固化和单板的压密实,横向弹性模量也将升高,可将单板的横向弹性模量提高三倍。2)随着密度的增加,单板涂胶和压力浸胶热压后的纵向弹性模量的增加幅度不及单板无胶热压后的增加幅度。6.依据各向异性层合板的强度理论,分析了OSBVCCF分别基于线弹性应力-应变关系和弹塑性应力-应变关系的应力分布,并推导了因考虑上表某些纵向层的产生压缩屈服时中性轴的偏离量的估算公式。根据损伤力学原理和最弱环(Weakest-link)破坏理论,提出了OSBVCCF的弯曲破坏模式。构建了OSBVCCF在不同破坏模式下的静曲强度预测的理论模型。为简化计算,基于木材破坏形式,建立了复合集装箱底板与表背层相同木材的静曲强度之间的预测模型;并建立了不同跨距下底板的静曲强度预测的关系模型。更多还原

【Abstract】 Oriented strand board (OSB)-veneer composite container flooring (OSBVCCF) is a multi-layer composite board manufactured with OSB as the core and the veneer as the face. It is used as container flooring to bear the freight loads. Therefore it must have high stiffness and strength, aging-resistant and fatigue resistant to ensure the safety of freight and have essential service-life.This paper researches mainly on the OSBVCCF. Use modern machines such as DENSE LAB X, PRESSMAN, LASER TEST ANGLE and STEAM INJECTION HOT-PRESS and so on. At the same time the theories of elastic and elastic-plastic mechanics, anisotropic laminate, damage mechanics and model simulation were used to analysis the mechanical properties of OSBVCCF. The study is mainly on the constitutive relationship between macro mechanical properties and micro structure (thin layer). First establish the model of density and MOR & MOE of the veneers, which were treated with heat, pressure and resin, then get the model prediction system of MOR and MOE of the OSBVCCF. The high shear of OSB can be proved by theory.1. Researches on hot-press can get: 1) The mechanic properties of one hot-press OSBVCCF can meet the request of container flooring. 2) The time of steam injection hot-press is only half (7 minutes) time of the ordinary hot-press, and the shear strength increases 35%. 3)Analysis the mechanical properties of the OSB manufactured by the mill with the resin 7.5% and 10%, The significant difference only exists on the shear strength(3.41MPa and 3.1MPa separately). 4) The optimization time of veneer over-layered are 24~27minutes.2. Analyze the composite characteristics of OSB and the veneer of OSBVCCF. Formulate a series of models indicating the relationship between macro properties and micro structure parameter and other physical parameter. The OSBVCCF can be treated as an orthotropic laminate with symmetrical structure configures by the macro even OSB and veneers.3. Derive the stiffness matrix of OSBVCCF in reference to the stiffness theory of composite laminate, and the coupling effect have been neglected according to this assumption, derive the theoretical prediction models of MOE of OSBVCCF.4. In reference to the stiffness theory of laminate, divide the OSB into 96 thin-layers, and use laser to test the distribute angle of strands, then according to the density tested by the DENSE LAB X, and derive the MOE of the thin-layers. According to these data, use Visual Basic for Applications to compute the MOE of the OSB.5. Formulate the MOE model of veneers which were treated with heat, pressure and resin on the basis of mixture mode of fiber reinforced composite and stiffness theory of laminate respectively. It shows: 1) The veneer treated with heat, pressure and resin can get 3 times MOE on perpendicular diction than the veneer without treated. 2) The MOE of veneer spread and impregnated with pressure will be increased with the density, and their increasing speed is lower than that of the compressed veneer.6) According to the theory of anisotropic laminate, study the stress distribution of the OSBVCCF with the linear elastic stress-strain and elastic-plastic stress-strain relation. Derive the evaluating formulation of central axis offset considering the compression yield of upper longitudinal layers. Presume theoretical bending rupture mode of OSBVCCF. On the basis of the damage mechanics principles of MOR of OSBVCCF according with different rupture model. Establish theoretical prediction relationship models of MOR of OSBVCCF with different span. In order to compute the MOR easily. Formulate a MOR model of OSBVCCF according to the MOR of same wood as the surface veneer of the OSBVCCF.更多还原