考虑蠕变与环境影响的膜结构受力性能研究
发布时间：2019-02-14 08:18
【摘要】：膜结构因其卓越的建筑表现力日益得到广泛应用,其安全性和耐久性也越来越多地得到人们的重视,它们受到膜材的物理、力学性能的直接影响。目前对于膜材的研究主要集中在膜材的强度指标上,对膜材在实际膜结构中的工作性能研究相对较少。膜结构设计规范中采用安全系数法的目的在于满足一般工程设计,安全系数中各个参数的影响与取值并不明确。此外,考虑到经费及研究周期的局限性,对于膜材以及膜结构的耐久性能的相关研究工作的开展并不充分。为了补充并完善膜材耐久性问题的研究,本文以建筑膜材PTFE、PVC为研究对象,开展了膜材蠕变理论研究、蠕变试验、膜结构受力分析及自然暴露试验研究,建立了膜材的蠕变本构模型,给出了环境影响因子随时间变化的曲线和拟合公式,分析了考虑膜材蠕变的前提下膜结构受力性能的影响因素及影响程度,得出了蠕变影响因子。最后,结合材料蠕变和耐候性能的研究,对膜结构进行了考虑材料时变效应的受力性能分析,为进一步膜结构设计计算提供了理论基础。本文的工作主要包含以下几方面内容:1、建筑膜材的蠕变本构模型及蠕变试验研究。基于复合材料理论、蠕变力学及粘弹性力学,首先对建筑膜材的蠕变特性和机理进行了探讨,并介绍了三种类型的蠕变本构模型;进而,结合PTFE建筑膜材蠕变试验结果确定了膜材本构模型中的相关参数,通过对比分析,提出并建立了两种膜材的蠕变本构模型——改进的时间硬化模型,作为本文膜材及膜结构蠕变分析计算的基础。2、PTFE膜材寒地耐候性能研究。本文进行了在哈尔滨地区为期10年的膜材自然暴露试验研究,通过对暴露1年、2年、4年和7年的膜材试样的拉伸强度和撕裂强度进行逐年测试,基于试验数据,拟合出PTFE膜材环境影响因子的变化规律,以此对膜材力学性能进行预测,并为膜结构设计选材提供了依据。3、考虑膜材蠕变的典型膜结构受力性能研究。基于膜材的蠕变试验和本构模型,采用有限元分析软件对两类典型膜结构——鞍形膜结构和伞形膜结构进行力学性能分析,探讨了各个影响因素对膜结构受力性能的影响;在此基础上,对数值模拟结果进行统计分析,确定了两种膜材考虑蠕变后其蠕变因子对结构受力性能的影响程度及范围,并针对其他膜结构进行了蠕变因子范围适用性的验证。4、基于两种膜材蠕变性能和耐候性能的研究,对膜结构设计计算中膜结构强度安全系数进行了探讨。
[Abstract]:Membrane structures have been widely used because of their excellent architectural performance, and their safety and durability have been paid more and more attention. They are directly affected by the physical and mechanical properties of membrane materials. At present, the research of membrane material is mainly focused on the strength index of membrane material, and the research on the performance of membrane material in actual membrane structure is relatively few. The purpose of adopting the safety factor method in the design code of membrane structure is to satisfy the general engineering design, and the influence and value of each parameter in the safety factor is not clear. In addition, due to the limitation of funding and research cycle, the research work on the durability of membrane materials and structures is not sufficient. In order to supplement and perfect the research on the durability of membrane material, this paper studies the creep theory, creep test, stress analysis of membrane structure and natural exposure test with PTFE,PVC as the research object. The creep constitutive model of membrane material is established, the curve and fitting formula of environmental influence factor changing with time are given, and the influence factors and degree of membrane structure's mechanical properties under the premise of membrane material creep are analyzed, and the creep influence factors are obtained. Finally, combined with the study of creep and weathering properties of the membrane structure, the mechanical properties of the membrane structure considering the time-varying effect of the material are analyzed, which provides a theoretical basis for the further design and calculation of the membrane structure. The work of this paper mainly includes the following aspects: 1. Creep constitutive model of building membrane and creep test. Based on the theory of composite material, creep mechanics and viscoelastic mechanics, the creep characteristics and mechanism of building membrane are discussed, and three kinds of creep constitutive models are introduced. Then, according to the creep test results of PTFE building membrane, the related parameters of the constitutive model of membrane material are determined. Through comparative analysis, two kinds of creep constitutive model of membrane material, an improved time hardening model, is proposed and established. As the basis of creep analysis and calculation of membrane material and membrane structure in this paper. 2 study on weather resistance of PTFE membrane in cold region. In this paper, the natural exposure test of membrane materials was carried out in Harbin area for 10 years. The tensile strength and tear strength of membrane specimens exposed for 1, 2, 4 and 7 years were tested year by year, based on the experimental data. The variation law of environmental influence factors of PTFE membrane materials was fitted to predict the mechanical properties of membrane materials and provide a basis for the design and selection of membrane structures. 3. The mechanical properties of typical membrane structures considering membrane creep were studied. Based on the creep test and constitutive model of membrane material, the mechanical properties of two typical membrane structures, saddle membrane structure and umbrella membrane structure, were analyzed by finite element analysis software, and the effects of various factors on the mechanical properties of membrane structure were discussed. On this basis, the statistical analysis of the numerical simulation results is carried out, and the influence degree and range of creep factor of two kinds of membrane materials on the mechanical properties of the structure after considering creep are determined. The applicability of creep factor range for other membrane structures is verified. 4. Based on the study of creep and weathering properties of two kinds of membrane materials, the strength safety factor of membrane structure is discussed in the design and calculation of membrane structure.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU383
本文编号：2422020
[Abstract]:Membrane structures have been widely used because of their excellent architectural performance, and their safety and durability have been paid more and more attention. They are directly affected by the physical and mechanical properties of membrane materials. At present, the research of membrane material is mainly focused on the strength index of membrane material, and the research on the performance of membrane material in actual membrane structure is relatively few. The purpose of adopting the safety factor method in the design code of membrane structure is to satisfy the general engineering design, and the influence and value of each parameter in the safety factor is not clear. In addition, due to the limitation of funding and research cycle, the research work on the durability of membrane materials and structures is not sufficient. In order to supplement and perfect the research on the durability of membrane material, this paper studies the creep theory, creep test, stress analysis of membrane structure and natural exposure test with PTFE,PVC as the research object. The creep constitutive model of membrane material is established, the curve and fitting formula of environmental influence factor changing with time are given, and the influence factors and degree of membrane structure's mechanical properties under the premise of membrane material creep are analyzed, and the creep influence factors are obtained. Finally, combined with the study of creep and weathering properties of the membrane structure, the mechanical properties of the membrane structure considering the time-varying effect of the material are analyzed, which provides a theoretical basis for the further design and calculation of the membrane structure. The work of this paper mainly includes the following aspects: 1. Creep constitutive model of building membrane and creep test. Based on the theory of composite material, creep mechanics and viscoelastic mechanics, the creep characteristics and mechanism of building membrane are discussed, and three kinds of creep constitutive models are introduced. Then, according to the creep test results of PTFE building membrane, the related parameters of the constitutive model of membrane material are determined. Through comparative analysis, two kinds of creep constitutive model of membrane material, an improved time hardening model, is proposed and established. As the basis of creep analysis and calculation of membrane material and membrane structure in this paper. 2 study on weather resistance of PTFE membrane in cold region. In this paper, the natural exposure test of membrane materials was carried out in Harbin area for 10 years. The tensile strength and tear strength of membrane specimens exposed for 1, 2, 4 and 7 years were tested year by year, based on the experimental data. The variation law of environmental influence factors of PTFE membrane materials was fitted to predict the mechanical properties of membrane materials and provide a basis for the design and selection of membrane structures. 3. The mechanical properties of typical membrane structures considering membrane creep were studied. Based on the creep test and constitutive model of membrane material, the mechanical properties of two typical membrane structures, saddle membrane structure and umbrella membrane structure, were analyzed by finite element analysis software, and the effects of various factors on the mechanical properties of membrane structure were discussed. On this basis, the statistical analysis of the numerical simulation results is carried out, and the influence degree and range of creep factor of two kinds of membrane materials on the mechanical properties of the structure after considering creep are determined. The applicability of creep factor range for other membrane structures is verified. 4. Based on the study of creep and weathering properties of two kinds of membrane materials, the strength safety factor of membrane structure is discussed in the design and calculation of membrane structure.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU383
【参考文献】
相关期刊论文 前3条
1 宋雄彬;;新型建筑材料——膜材[J];广东建材;2006年10期
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3 徐彦;关富玲;管瑜;;充气可展天线精度分析和形面调整[J];空间科学学报;2006年04期
，本文编号：2422020
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