毛竹材径向篾抗拉和抗弯性能研究

  目的  目前对于径向竹篾的相关研究较少，且未有竹节对径向竹篾性能影响方面的研究。研究随高度变化径向竹篾的结构特征、抗弯和抗拉性能变化规律，以及竹节对其力学性能的影响，可为径向竹篾在竹木复合集装箱底板应用中的结构设计和工艺优化提供理论依据以及技术参考。  方法  采用4年生不同高度毛竹制备的径向竹篾，分析不同高度等级的径向竹篾尺寸大小、通直度和竹节等结构特征，并研究其抗拉和抗弯性能随竹筒高度的变化规律以及竹节的影响。  结果  由地面向上沿竹竿方向，上部径向竹篾的结构规整度最差，中部竹篾的通直度高且两端厚度偏差小，下部竹篾的竹节数最多。径向竹篾的抗拉强度和弹性模量随高度的增加而逐渐增大，抗弯强度和模量随高度的增加呈先减小后增加趋势。竹节影响径向竹篾的力学强度，虽然使上、中、下部径向竹篾的抗拉强度分别降低了28.9%、28.4%和10.5%，但却使上、中、下部径向竹篾的抗弯强度分别提高了27.8%、26%和42.4%，这极大提升了集装箱底板的多点负载和抗变形能力。  结论  中部径向竹篾厚度偏差小，通直度高于上、下部竹篾。随高度方向的增加，径向竹篾的抗拉性能逐渐增强，抗弯性能先减小后增大。竹节会影响径向竹篾的结构规整度，虽会降低其抗拉性能，但却能提高其抗弯性能。 

Tensile and bending properties of radial slivers of Moso bamboo

ObjectiveThere are few related research on radial bamboo slivers, and there is no research on the influence of bamboo nodes on the performance of radial bamboo slivers. This paper studies the structural characteristics, bending and tensile properties of radial bamboo slivers varying with height, as well as the influence of bamboo nodes on their mechanical properties was studied, which can provide theoretical basis and technical reference for the structural design and process optimization of radial bamboo slivers in the application of bamboo-wood composite container flooring.MethodIn this paper, radial bamboo slivers prepared by 4-year-old Moso bamboo of different heights were used to analyze the structural characteristics of radial bamboo slivers with different height grades, such as size, straightness and bamboo node, and to study the variation law of tensile and bending properties with the height of bamboo tube and the effect of bamboo node on them. ResultFrom the ground up along the bamboo poles direction, the structural regularity of the top radial bamboo sliver was the worst, the straightness of the middle bamboo sliver was high, the thickness deviation at both ends of the bamboo sliver was small, and the number of bamboo nodes in the bottom bamboo sliver was the most. The tensile strength and elastic modulus of radial bamboo sliver gradually increased with the increase of height, and the bending strength and modulus first decreased and then increased with the increase of height. The bamboo nodes affected the mechanical strength of radial bamboo slivers. Although the tensile strength of top, middle and bottom radial bamboo slivers was reduced by 28.9%, 28.4% and 10.5%, respectively, the bending strength of top, middle and bottom radial bamboo slivers was increased by 27.8%, 26% and 42.4%, respectively, which greatly improved the multi-point load and deformation resistance of container flooring. ConclusionThe thickness deviation of radial bamboo slivers in the middle is small, and the straightness is higher than that of top and bottom bamboo slivers. With the increase of height direction, the tensile property of radial bamboo sliver gradually increases, and the bending property first decreases and then increases. Bamboo node will affect the structural regularity of radial bamboo sliver. Although it will reduce its tensile properties, it can improve its bending properties.