两种竹质工程材料的流变性能研究

发布时间：2018-01-03 04:36

本文关键词：两种竹质工程材料的流变性能研究　出处：《中南林业科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：竹质工程材料是以竹材为原料,经过一系列的机械和化学加工,在一定的温度和压力下,借助胶黏剂的作用,胶合而成的板状材料。近些年来,我国的竹材工业化利用的比重逐年增加,在工程领域的应用也越来越普遍,对竹质工程材料性能的要求也越来越高。目前,竹质工程材料主要包括竹层积材、竹胶合板、竹集成材、竹重组材和竹复合材等。蠕变性能是决定竹质工程材料是否能在工程中应用的一个重要指标。本文以竹集成材和重组竹两种应用较广泛的竹质工程材料为研究对象,首先对其进行了抗弯和抗压的物理力学性能试验。在此基础上测试了其在不同荷载条件下的短期弯曲蠕变,通过拟合建立了蠕变本构模型,获取相应的容许应力值,并由蠕变曲线导出松弛曲线。(1)对重组竹和竹集成材进行了抗弯和抗压力学性能试验,分别得到了它们的抗弯弹性模量、抗弯强度、抗压弹性模量和抗压强度,并分析了两种竹质工程材料的不同破坏情况。结果表明:重组竹的抗弯和抗压力学性能要优于竹集成材;重组竹抗弯破坏表现为脆性破坏,竹集成材则表现出一定的延性特性;竹材的力学性能与其本身材料性能和胶合面的力学性能有关;(2)两种竹质工程材料的普通蠕变变形分为三个阶段:弹性变形、黏弹性变形和黏性变形,不同荷载作用下两种竹材的蠕变曲线规律相似,蠕变总量随着荷载的增大而增加;竹集成材的蠕变容许应力值为最大破坏荷载的14.67%,重组竹的蠕变容许应力值为最大破坏荷载的18.93%;(3)利用Origin软件对竹集成材和重组竹的短期普通蠕变数据进行拟合,得出了 Burgers模型的相关参数,拟合曲线与试验曲线的相关系数均在0.994以上,实测值与模型计算值的误差不超过1%,说明用Burgers流变模型可以较好的模拟两种竹质工程材料蠕变的初始阶段和第二阶段;(4)通过引入参数x,对Burgers流变模型进行改良得到的5-因素流变模型,能够很好的解决Burgers流变模型在蠕变第二阶段蠕变曲线过于线性的问题,且改良模型的拟合曲线与试验曲线相关系数能达到0.999以上,大部分情况下比Burgers流变模型更精确;(5)讨论了蠕变与松弛的等价关系,根据这个等价原理,可由测得的蠕变试验曲线推导其应力松弛曲线。
[Abstract]:Bamboo engineering materials with bamboo as raw material, through a series of mechanical and chemical processing, in a certain temperature and pressure, with the help of adhesive, plate material is glued together. In recent years, China's bamboo industrial utilization ratio increased year by year, and in the field of engineering application more widely and on the properties of bamboo engineering materials are increasingly high requirements. At present, bamboo engineering materials including bamboo laminated wood, bamboo plywood, bamboo timber, bamboo scrimber and bamboo composite material. The creep performance is an important indicator to decide whether bamboo engineering materials can be applied in engineering. In this paper, bamboo gluelam and recombinant bamboo engineering materials of two kinds of bamboo is widely used as the research object, firstly, the physical and mechanical properties of bending and compressive test on the test. Based on the different load conditions of short-term bending creep, By fitting the creep constitutive model is established, and obtain the corresponding allowable stress value, and the creep curve derived relaxation curve. (1) the flexural and compressive mechanical properties of bamboo and bamboo timber set are obtained. Their flexural modulus, flexural strength, compressive elastic modulus and the compressive strength, and analyzes the different damage situations of two kinds of bamboo engineering materials. The results show that the flexural and compressive mechanical properties of bamboo is better than bamboo gluelam; bamboo bending destruction was fragile, bamboo integrated material showed a certain ductility; the mechanical properties of materials and bonding with itself the mechanical properties of bamboo; (2) the common two kinds of bamboo engineering materials creep deformation is divided into three stages: elastic deformation, visco elastic deformation and viscous deformation, creep curves of two kinds of Bamboo under different loads, creep The total increase with the increase of the load; creep bamboo gluelam permissible stress value for the maximum failure load of 14.67% creep Reconstituted Bamboo allowable stress value for the maximum failure load of 18.93%; (3) lumber and restructuring of short-term creep data were fitted by ordinary bamboo to bamboo sets by using Origin software, draw the relevant parameters the Burgers model, the correlation coefficient of the fitting curve and test curve was above 0.994, the measured value and the calculated value of the error is less than 1%, indicating that the Burgers rheological model can simulate two kinds of bamboo engineering materials creep initial stage and the second stage; (4) by introducing the parameter of X, Burgers on the rheological model 5- improved the rheological model of factors, can solve the problem of Burgers rheological model very well in the second stage of creep creep curve is linear, the fitting curve and test curve and the modified model of the phase relationship The number can reach more than 0.999. In most cases, it is more accurate than the Burgers rheological model. (5) the equivalence relation between creep and relaxation is discussed. According to this equivalence principle, the stress relaxation curve can be deduced from the measured creep test curve.

【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU366.1

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