【作者】 张伍连；

【导师】 丁辛；

【作者基本信息】 东华大学 ， 纺织工程， 2011， 博士

【摘要】 随着膜结构建筑的发展与膜材料的广泛应用,建筑膜材料的力学性能愈来愈受到关注。由平纹或方平组织为基布的机织建筑膜材料,因织造工艺简单、价格适中等优点倍受青睐。机织建筑膜材料不同于一般性的其它建筑材料,它是一种基布处于中间、而两侧进行涂层所组成的柔性复合材料,其拉伸力学性能具有自身独特的特点。而膜材料在膜结构的建筑中需要依据其在特定的张拉形状来承受载荷或变形,因此,充分理解与把握膜材料在拉伸时和随后的使用过程中的力学性能,对指导膜结构的设计与构建十分必要。本课题将围绕机织建筑膜材料经纬向在拉伸时的非线性粘弹塑性能进行研究。通过对机织建筑膜材料经纬向在拉伸时的非线性粘弹塑性能的研究,以期达到如下的目标：(1)给出膜材料在不同应力与不同作用时间条件下出现塑性变形的合理模型；(2)给出膜材料在蠕变条件下合理的非线性粘弹塑元件模型；(3)给出膜材料在不同应变与不现作用时间条件下出现塑性变形的合理模型；(4)给出膜材料在应力松弛条件下合理的非线性粘弹塑元件模型；(5)在考虑塑性变形的基础上给出膜材料合理的非线性粘弹塑性单积分模型。在蠕变条件下,通过选择不同的作用应力与不同的作用时间,对机织建筑膜材料经纬向的塑性变形进行了试验,从中找出,开始出现塑性变形的临界值,并将机织建筑膜材料经纬向的塑性变形看成是：应力差(应力值-应力临界值)的幂函数与作用时间幂函数的乘积,对试验数据进行了多元回归分析,结果发现：该模型可以很好地预测出材料的塑性变形量,进而再利用该模型对塑性变形中的瞬时塑性与推迟塑性进行的分析,结果显示：开始阶段的瞬时塑性变形明显高于在随后的推迟塑性变形,而就推迟塑性变形而言,在先前时间段的塑性变形量又高于随后时间段的塑性变形量,即：推迟塑性变形量随作用时间的增加而较大幅度的减少。论文给出了机织建筑膜材料经纬向各自五种不同应力9,000s的蠕变试验,利用四个线性粘弹性模型,包括：四参数Burgers流体模型、三参数固体模型、五参数广义Kelvin-Voigt固体模型与七参数广义Kelvin-Voigt固体模型,对试验数据进行了拟合,从中发现：七参数广义Kelvin-Voigt线性粘弹性固体模型具有最好的拟合效果,且对于同类同方向膜材料而言,各个不同应力间与三个推迟时间相关的三个参数保持不变,以此为基础,将该线性粘弹性模型修改为七参数非线性粘弹性模型与十四参数非线性粘弹塑型模型,同时,将十四参数非线性粘弹塑元件模型中的六个与推迟时间相关的参数合并为三个,其它与应力大小相关的八个参数合并为四个,再假定修改后的两种非线性蠕变元件模型中与推迟时间相关的三个参数与七参数线性粘弹性广义Kelvin-Voigt固体模型中的三个与推迟时间的参数保持相同,将建筑膜材料的非线性原因看成仅来自于与应力相关的四个不同的参数,假定这些参数与不同的应力之间满足四阶多项式函数,借助上述五种不同应力条件下蠕变试验的数据对四阶多项式函数进行了拟合,并将拟合后的函数与机织建筑膜材料经纬向的三种不同的其它应力、作用时间为1,200s的蠕变试验进行了比较,结果发现：该方法可以很好地预测不同应力间的蠕变特性。在应力松弛条件下,通过选择不同的应变与不同的作用时间,对机织建筑膜材料经纬向的塑性变形进行了试验,从中找出,开始出现塑性变形的临界值,并将机织建筑膜材料经纬向的塑性变形看成是：应变差(应变值-应变临界值)的幂函数与作用时间幂函数的乘积,对试验数据进行了多元回归分析,结果发现：该模型可以很好的预测出材料的塑性变形量,进而再利用该模型对塑性变形中的瞬时塑性与松弛塑性进行的分析,结果显示：开始阶段的瞬时塑性变形明显高于在随后的松弛塑性变形,而就松弛塑性变形而言,在先前时间段的塑性变形量又高于随后时间段的塑性变形量,即：松弛塑性变形量随作用时间的增加而较大幅度的减少。论文给出了机织建筑膜材料经纬向各自五种不同应变9,000s的应力松弛试验,利用四个线性粘弹性模型,包括：三参数固体模型、三参数广义Maxwell模型、五参数广义Maxwell模型与七参数广义Maxwell模型,对试验数据进行了拟合,从中发现：七参数广义Maxwell线性粘弹性模型具有最好的拟合效果,且对于同类同方向膜材料而言,各个不同应变间与三个松弛时间相关的三个参数保持不变,以此为基础,将该线性粘弹性模型修改为七参数非线性粘弹性模型与十四参数非线性粘弹塑型模型,同时,将十四参数非线性粘弹塑元件模型中的六个与松弛时间相关的参数合并为三个,其它与应变大小相关的八个参数合并为四个,再假定修改后的两种非线性应力松弛元件模型中与松弛时间相关的三个参数与七参数线性粘弹性广义Maxwell模型中的三个与松弛时间相关的参数保持相同,将建筑膜材料的非线性原因看成仅来自于与应变相关的四个不同的参数,假定这些参数与不同的应变之间满足四阶多项式函数,借助上述五种不同应力条件下应力松弛试验的数据对四阶多项式函数进行了拟合,并将拟合后的函数与机织建筑膜材料经纬向的三种不同的其它应变、作用时间为1,500s的应力松弛试验进行了比较,结果发现：该方法可以很好地预测不同应变间的应力松弛特性。论文给出了机织建筑膜材料经纬向六种不同的应力与作用时间分别为9,000s的蠕变试验与回复试验,在考虑机织建筑膜材料在蠕变条件下可能产生的瞬时塑性与推迟塑性变形,将塑性变形叠加到Schapery非线性粘弹性单积分本构方程上,利用试验数据对修改后的非线性粘弹塑型单积分模型中的材料常数与非线性应力依赖参数进行了求解,并将这些求解后的材料常数与非线性应力依赖参数代入蠕变与回复方程中,结果发现：该方法可以较好地预测出蠕变试验与回复试验的试验数据。更多还原

【Abstract】 Along with membrane structure construction development and membrane material widespread application, the mechanical performance of architectural membrane material is more and more emphasized. Because of simple technology and moderate prices, the architectural woven membrane material composed of plain or panama fabric is very popular. The architectural woven membrane material differs from general architectural material, it is a flexible composite material which is made up of fabric in the middle and coating on both sides, its mechanical performance has its own distinguishing features. The membrane material needs to sustain load or defonnation depending on a specific tensile shape in construction, therefore, on the sufficient understanding and grasping mechanical performance of membrane material in tension or in the course of using is important to instruct the membrane structure the design. This study focuses on tensile nonlinear visco-elastic-plastic performance of woven membrane material.Through the tensile nonlinear visco-elastic-plastic performance study of woven membrane material in warp and weft direction, the objectives of the study are as follows:(1) to present rational plastic model under the conditions of different stresses and time; (2) to present rational nonlinear visco-elastic-plastic element model under creep conditions; (3) to present rational plastic model under the conditions of different strain and time; (4) to present rational nonlinear visco-elastic-plastic element model under stress relaxation conditions; (5) on the basis of considering plastic defonnation, to present rational nonlinear visco-elastic-plastic integral model.The creep tests are carried out on the architectural woven membrane material along the warp and weft direction at different stresses and time, stress critical value of plastic deformation is found. According to a function of several variables from the product of both the stress difference (stress-stress critical value) power function and the time power function, the experiment datum are studied by using a multiple regression analysis. It is concluded that the model has better fitting results. Then the instantaneous and transient parts of the plastic deformation are analyzed by using this model, it is showed that the instantaneous plastic deformation is higher than transient part, as far as the transient plastic deformation is concerned, the plastic deformation at an initial stage is higher than the one at a later stage, namely:the increment of the transient plastic strain will be a significant decrease.The creep tests for architectural woven membrane material are carried out along the warp and weft directions at five different stresses. By mean of four linear viscoelastic element models:Burgers fluid one with four parameters, a solid one with three parameters, a generalized Kelvin-Voigt solid one with five parameters and a generalized Kelvin-Voigt solid one with seven parameters, the experimental datum are analyzed. The results revealed that there is better fitting effect for the generalized Kelvin-Voigt solid model with seven parameters, and as far as the membrane material of the same kind and direction is concerned, three parameters of or relating to retarded time keep unchanged at various stresses. Based on these properties, the linear viscoelastic element model with seven parameters was modified into a nonlinear viscoelastic element one with seven parameters and a nonlinear visco-elastic-plastic element one with fourteen parameters. Then six parameters of or relating to retarded time are amalgamated into three ones and eight parameters of or relating to stress are amalgamated into four ones for the nonlinear viscoelastic element model with fourteen parameters. Considering that the three retarded time of the two nonlinear models were the same as the linear model, that the nonlinear factors are come from four parameters of or relating to stress, to assume between the four parameters of or relating to stress and different stresses meets 4th degree polynomial function, the creep test datum at five different stresses are fitted and then the fitted polynomial function is compared to a creep test at three other stresses and 1,200s.It is concluded that this method can predict the creep performance of different stresses well.The stress relaxed tests are carried out on the architectural woven membrane material along the warp and weft direction at different strain and time, strain critical value of plastic deformation is found. According to a function of several variables from the product of both the strain difference (strain- strain critical value) power function and the time power function, the experiment datum are studied by using a multiple regression analysis. It is concluded that the model has better fitting results. Then the instantaneous and relaxed parts of the plastic deformation are analyzed by using this model, it is showed that the instantaneous plastic deformation is higher than relaxed part, as far as the relaxed plastic deformation is concerned, the plastic deformation at an initial stage is higher than the one at a later stage, namely:the increment of the relaxed plastic strain will be a significant decrease. The stress relaxed tests for architectural woven membrane material are carried out along the warp and weft directions at five different strain. By mean of four linear viscoelastic element models:a solid one with there parameters, a generalized Maxwell one with three parameters, a generalized Maxwell one with five parameters and a generalized Maxwell one with seven parameters, the experimental datum are analyzed. The results revealed that there is better fitting effect for the generalized Maxwell model with seven parameters, and as far as the membrane material of the same kind and direction is concerned, three parameters of or relating to relaxed time keep unchanged at various strain. Based on these properties, the linear viscoelastic element model with seven parameters was modified into a nonlinear viscoelastic element one with seven parameters and a nonlinear visco-elastic-plastic element one with fourteen parameters. Then six parameters of or relating to relaxed time are amalgamated into three ones and eight parameters of or relating to strain are amalgamated into four ones for the nonlinear viscoelastic element model with fourteen parameters. Considering that the three relaxed time of the two nonlinear models are the same as the linear model, that the nonlinear factors are come from four parameters of or relating to strain, to assume between the four parameters of or relating to strain and different strain meets 4th degree polynomial function, the stress relaxed test datum at five different strain are fitted and then the fitted polynomial function is compared to a stress relaxed test at three other strain and 1,500s.It is concluded that this method can predict the stress relaxed performance of different strain well.The creep and recovery tests for architectural woven membrane material are carried out along the warp and weft directions at six different stresses and respective 9,000s. Considering possible instantaneous and transient plastic deformation under the condition of creep, the plastic deformation is combined into nonlinear viscoelastic integral Schapery’s constitutive equation. The material constants and nonlinear stress depended parameters of the new model are solved with the aid of test datum, and these constants and parameters substitute the creep and recovery equation. It is found that this method can predict the creep and recovery datum well.更多还原