聚氨酯金属屋面板力学性能及其对屋盖结构风振影响研究
发布时间：2018-10-15 11:03
【摘要】：当前的大跨度屋盖结构普遍采用轻型金属屋面系统,但结构设计时通常忽略屋面板对结构受力性能的影响。本文以常用的聚氨酯夹芯金属屋面板作为研究对象,对此类屋面板的刚度和阻尼性能、解析理论以及有限单元模型开展了研究,并进一步考察了屋面板刚度和阻尼性能对屋盖结构风致振动效应的影响。论文主要包括以下五个方面的工作： (1)对屋面板常用聚氨酯夹芯材料的基本力学性能进行了试验测定。发现聚氨酯夹芯的拉伸、压缩性能不同,且不同方向的力学性能也有明显的差异。指出聚氨酯夹芯可以假定为横观各向同性材料,并根据试验数据对其基本力学参数进行了拟合。进一步对聚氨酯夹芯的材料损耗因子进行了测定,给出了损耗因子随温度、频率的变化曲线。 (2)对聚氨酯夹芯金属屋面板的整体阻尼特性进行了研究。分析了聚氨酯夹芯金属屋面板的模态损耗因子随檩距、夹心层厚度及面板厚度的影响,表明屋面板对于外部高频激励具有较高的阻尼耗能能力,聚氨酯夹芯层的阻尼特性对整个屋面板的阻尼特性起着决定性影响。考察了不同刚度、阻尼的屋面板在脉动风荷载作用下的动力反应,发现在风压传递过程中屋面板的有限刚度及夹芯层阻尼都会显著改变风压的脉动特性。 (3)将面层压型金属板等代为正交各向异性的平板,进而将聚氨酯夹芯屋面板简化为上下面层厚度不同、且各层材料均为正交各向异性的夹层板。基于Hoff型夹层板理论,推导了屋面板的静力基本方程,并对该静力方程的解析方法进行了讨论。采用复模量法来表征聚氨酯夹芯的粘弹性特性,进一步推导了考虑夹芯层阻尼的屋面板横向振动的动力基本方程。 (4)基于Hoff型夹层板理论,建立了一种定义在夹芯层中面上的八结点的矩形夹层板单元,每个结点具有5个自由度,3个线位移和2个转角。采用该单元模拟的屋面板在静荷载作用下的变形形式与更精细有限元分析结果相同,变形值基本接近。模态分析求得的基本振型与精细模型相同,自振频率也较接近。表明该夹层板单元能够有效模拟聚氨酯夹芯金属屋面板的静、动力特性。 (5)通过两个算例考察了屋面板刚度和阻尼性能对屋盖结构风振效应的影响。分析结构表明是否考虑屋面板对结构的风振效应的计算结果存在明显的差异。屋面板刚度都是影响结构风致振动效应的主要因素。夹芯层阻尼会对刚度较大屋盖结构的风振效应产生的影响明显,影响程度还与屋面自身刚度相关。
[Abstract]:At present, light metal roof system is widely used in large span roof structure, but the influence of roof slab on structural performance is usually neglected in structural design. In this paper, the stiffness and damping properties, analytical theory and finite element model of common polyurethane sandwich metal roof panels are studied. Furthermore, the effects of roof stiffness and damping on the wind-induced vibration of roof structures are investigated. This paper mainly includes the following five aspects: (1) the basic mechanical properties of common polyurethane sandwich materials for roof panels are tested. It was found that the tensile and compression properties of polyurethane sandwich core were different, and the mechanical properties in different directions were also different. It is pointed out that polyurethane core can be assumed as transversely isotropic material and its basic mechanical parameters are fitted according to the experimental data. Furthermore, the material loss factor of polyurethane sandwich is measured, and the curve of loss factor with temperature and frequency is given. (2) the damping characteristics of polyurethane sandwich metal roof panel are studied. The effects of the distance of purlin, the thickness of sandwich layer and the thickness of panel on the modal loss factor of polyurethane sandwich metal roof plate are analyzed. The results show that the roof plate has a high damping energy dissipation ability to the external high frequency excitation. The damping characteristics of polyurethane sandwich layer play a decisive role in the damping characteristics of the whole roof board. The dynamic responses of roof panels with different stiffness and damping under pulsating wind loads are investigated. It is found that both the finite stiffness of roof slab and the damping of sandwich layer will significantly change the fluctuating characteristics of wind pressure during the process of wind pressure transfer. (3) the plate with orthotropic surface is replaced by metal plate. Then the polyurethane sandwich roof panel is simplified as a sandwich plate with different upper and lower layer thickness and each layer material is orthotropic. Based on the theory of Hoff sandwich plate, the basic static equation of roof plate is derived, and the analytical method of the static equation is discussed. The viscoelastic properties of polyurethane sandwich are characterized by complex modulus method, and the basic dynamic equation of transverse vibration of roof plate considering sandwich layer damping is derived. (4) based on Hoff sandwich plate theory, A rectangular sandwich plate element with eight nodes defined on the middle surface of the sandwich layer is established. Each node has five degrees of freedom, three linear displacements and two rotation angles. The deformation form of the roof slab simulated by this element under static load is the same as that of the finer finite element analysis, and the deformation value is basically close to that of the finite element method. The basic modes obtained by modal analysis are the same as the fine model, and the natural frequencies are close to each other. It is shown that the sandwich plate element can effectively simulate the static and dynamic characteristics of the polyurethane sandwich metal roof panel. (5) the effects of roof stiffness and damping properties on the wind-induced vibration effect of the roof structure are investigated by two numerical examples. The analysis of the structure shows that there are obvious differences between the calculation results of the wind-induced vibration effect of the roof slab and that of the roof slab. The stiffness of roof slab is the main factor that affects the wind-induced vibration effect of structure. The influence of sandwich layer damping on the wind-induced vibration of the roof structure with larger stiffness is obvious, and the influence degree is also related to the roof stiffness.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU311.3
本文编号：2272341
[Abstract]:At present, light metal roof system is widely used in large span roof structure, but the influence of roof slab on structural performance is usually neglected in structural design. In this paper, the stiffness and damping properties, analytical theory and finite element model of common polyurethane sandwich metal roof panels are studied. Furthermore, the effects of roof stiffness and damping on the wind-induced vibration of roof structures are investigated. This paper mainly includes the following five aspects: (1) the basic mechanical properties of common polyurethane sandwich materials for roof panels are tested. It was found that the tensile and compression properties of polyurethane sandwich core were different, and the mechanical properties in different directions were also different. It is pointed out that polyurethane core can be assumed as transversely isotropic material and its basic mechanical parameters are fitted according to the experimental data. Furthermore, the material loss factor of polyurethane sandwich is measured, and the curve of loss factor with temperature and frequency is given. (2) the damping characteristics of polyurethane sandwich metal roof panel are studied. The effects of the distance of purlin, the thickness of sandwich layer and the thickness of panel on the modal loss factor of polyurethane sandwich metal roof plate are analyzed. The results show that the roof plate has a high damping energy dissipation ability to the external high frequency excitation. The damping characteristics of polyurethane sandwich layer play a decisive role in the damping characteristics of the whole roof board. The dynamic responses of roof panels with different stiffness and damping under pulsating wind loads are investigated. It is found that both the finite stiffness of roof slab and the damping of sandwich layer will significantly change the fluctuating characteristics of wind pressure during the process of wind pressure transfer. (3) the plate with orthotropic surface is replaced by metal plate. Then the polyurethane sandwich roof panel is simplified as a sandwich plate with different upper and lower layer thickness and each layer material is orthotropic. Based on the theory of Hoff sandwich plate, the basic static equation of roof plate is derived, and the analytical method of the static equation is discussed. The viscoelastic properties of polyurethane sandwich are characterized by complex modulus method, and the basic dynamic equation of transverse vibration of roof plate considering sandwich layer damping is derived. (4) based on Hoff sandwich plate theory, A rectangular sandwich plate element with eight nodes defined on the middle surface of the sandwich layer is established. Each node has five degrees of freedom, three linear displacements and two rotation angles. The deformation form of the roof slab simulated by this element under static load is the same as that of the finer finite element analysis, and the deformation value is basically close to that of the finite element method. The basic modes obtained by modal analysis are the same as the fine model, and the natural frequencies are close to each other. It is shown that the sandwich plate element can effectively simulate the static and dynamic characteristics of the polyurethane sandwich metal roof panel. (5) the effects of roof stiffness and damping properties on the wind-induced vibration effect of the roof structure are investigated by two numerical examples. The analysis of the structure shows that there are obvious differences between the calculation results of the wind-induced vibration effect of the roof slab and that of the roof slab. The stiffness of roof slab is the main factor that affects the wind-induced vibration effect of structure. The influence of sandwich layer damping on the wind-induced vibration of the roof structure with larger stiffness is obvious, and the influence degree is also related to the roof stiffness.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU311.3
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