木/竹复合客车底板性能研究及弹性模量预测

【作者】 罗江丽；

【导师】 杨家富；

【作者基本信息】 南京林业大学 ， 机械设计及理论， 2006， 硕士

【摘要】 为了考察木／竹复合城市客车底板的静态力学性能，本论文利用单向拉伸法、电测法和三点弯曲试验法对组分材料——杨木单板、竹片以及木／竹复合城市客车底板的弹性模量和强度等进行了综合研究。 在三种名义厚度的杨木单板的静态性能研究中，研究了常态、常态受压以及浸渍塑化情况下，杨木单板的弹性模量、强度和泊松系数，并将不同压力情况下的弹性模量值和强度值进行了比较分析。在木／竹复合城市客车底板的静态特性的研究中，研究了跨距对木／竹复合城市客车底板的弯曲弹性模量的影响并分析了原因；同时研究了经过整车疲劳试验的木／竹复合城市客车底板不同跨距下的静曲模量和静曲强度，并将其与未经过整车疲劳试验的木／竹复合城市客车底板相应跨距下的静曲模量和静曲强度进行了分析比较。在竹片静态特性的研究中，研究了4MPa浸渍塑化竹片的顺纹拉伸弹性模量、泊松系数以及静曲模量和静曲强度。最后利用经典层合板理论构建了木／竹复合城市客车底板弹性模量的预测模型。 本研究的结果归纳如下： 常态下，杨木单板的顺纹拉伸弹性模量值的变化范围在4000MPa～5000MPa之间；而拉伸强度值的变化范围在40MPa～70MPa之间。 经过PF树脂浸渍塑化处理的杨木单板的顺纹拉伸性能较常态时的各项性能都有较大的提高。 名义厚度为1.1mm、1.4mm和1.7mm的塑化杨木单板在1MPa和4MPa压力时的面内泊松系数分别为0.22、0.35、0.40和0.21、0.28、0.35；4MPa浸渍塑化竹片的面内泊松系数为0.33。 1MPa和4MPa浸渍塑化杨木单板的横纹拉伸弹性模量的变化范围分别在230MPa～410MPa、550MPa～850MPa；横纹弯曲弹性模量值的变化范围分别是240MPa～385MPa、560MPa～650MPa；而横纹拉伸强度值和弯曲强度值均较小，说明杨木单板的横纹抗拉、抗弯性能差。 杨木单板的弹性模量与塑化压力间呈非线性关系，随塑化压力的增大，弹性模量甚至有减小的趋势，说明此时单板已被压溃。 密度不同的木／竹复合城市客车底板，顺纹拉伸弹性模量值大于横纹且密度大的其弹性模量值较大；但无论密度的大小，其泊松系数均是顺纹大于横纹。 随跨距增大，木／竹复合城市客车底板的弯曲弹性模量和弯曲强度有增大趋势。这说明随跨距增大，剪切效应的影响减小。更多还原

【Abstract】 In order to investigate the static mechanic properties of wood-bamboo composite city bus- floor, elastic modulus and strength of component materials——poplar veneer, bamboo shoot and wood-bamboo composite city bus-floor were measured by uniaxial tension, electrometry and three-point bending.For normal poplar veneer, normal press poplar veneer and adhesive-soaking poplar veneer, elastic modulus, strength and Poisson’s ratio were investigated. The effects of pressure on elastic modulus and strength were analyzed. For wood-bamboo composite city bus floor, the effects of span on Modulus of elasticity(MOE) and Modulus of rupture(MOR) were investigated and analyzed. At the same time, for wood-bamboo composite city bus floor after fatigued, Modulus of elasticity(MOE) and Modulus of rupture(MOR) were investigated when different length of spans and compared with the result of wood-bamboo composite city bus floor before fatigue test. For adhesive-soaking bamboo shoot by 4MPa pressure, tension elastic modulus along the grain, Poisson’s ratio, MOE and MOR were investigated. Finally, the prediction model of elastic modulus is found by using classical laminate theory.The results were summarized as follows:For normal poplar veneer, the range of elastic modulus along the grain is 4000MPa～5000MPa and the range of tension strength along the grain is 40MPa～70MPa.When poplar veneer was soaked with PF adhesive, tension properties along the grain compare favourably with tension properties along the grain of normal poplar veneer.For adhesive-soaking poplar veneer of 1.1mm, 1.4mm and 1.7mm, when pressure are 1MPa and 4MPa, Poisson’s ratio are respective 0.22, 0.35, 0.40 And 0.21,0.28,0.35; Poisson’s ratio of adhesive-soaking bamboo shoot by 4MPa pressure is 0.33.For adhesive-soaking poplar veneer of 1MPa and 4MPa, the range of tension elastic modulus tangential elastic module are respective 230MPa～410MPa, and 550MPa～850MPa; the range of tangential Modulus of elasticity(MOE) are respective 240MPa～385MPa and 560MPa～650MPa. As result of tension strength and tangential Modulus of rupture(MOR) are very small, it indicates that the properties of tension and bending are very bad.The relationship between elastic modulus and adhesive pressure is non-linear. With the increase of the adhesive pressure, elastic modulus reduce. It indicates that poplar veneer was squished.更多还原