WO2020211007A1 - 一种面向航空航天薄壳结构的形位偏差特征库建立方法 - Google Patents
一种面向航空航天薄壳结构的形位偏差特征库建立方法 Download PDFInfo
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- the invention belongs to the technical field of design of main bearing members of aerospace structures, and relates to a method for establishing a shape and position deviation feature library for aerospace thin-shell structures.
- the thin shell structure has high specific stiffness and high specific strength, so it is widely used in the main bearing members of aerospace structures.
- the main bearing thin-shell structure mainly bears axial load, and the main mode of failure is buckling instability. Therefore, the ultimate load-bearing capacity of the thin-shell structure under axial compression is a key evaluation index in the design of aerospace structures.
- the buckling load obtained by the test is usually only 20%-60% solved by the classical theory, and the experimental results have huge dispersion and difference. After decades of research, it has been discovered that the existence of initial geometric defects is one of the main reasons for the huge difference between experimental and theoretical results.
- Geometric defects are inevitable in the process of manufacturing, transportation and assembly, service, etc. Therefore, how to accurately consider different types of shape and position deviations (processing and manufacturing geometric defects) is to accurately estimate the ultimate bearing capacity of thin-shell structures and carry out refined design
- the European Union adopts the method of the European Steel Shell Specification to evaluate and classify the processed thin shell structure based on the initial defects. This method is considered to be the authoritative specification for the stability design of cylindrical shells.
- the US NASA uses experimental equipment to measure the complete initial geometric defects of the cylindrical shell skin and establish an initial geometric defect database to guide the design of aerospace thin shell structures.
- the main bearing structure of China’s launch vehicle adopts the grid-reinforced shell structure.
- the establishment of a numerical model that can fully consider the different types of shape and position deviations in the reinforced thin shell structure is an effective way to accurately predict the actual bearing capacity of the thin-walled cylindrical shell structure. It is also the basis for the lightweight design of the simplified cylindrical shell structure of China's launch vehicle, and the establishment of a feature library of shape and position deviation of the aerospace thin shell structure with China's independent intellectual property rights is also a solid foundation for China's heavy launch vehicle and large aircraft manufacturing.
- Aerospace main bearing thin shell structures generally include cylindrical shell structures, cone shell structures, spherical shell structures and complex heterogeneous curved thin shells.
- a finite element numerical model that can reflect the geometric defects of different types and positions is established, and then the ultimate bearing capacity of the cylindrical shell structure is accurately analyzed and calculated as the main bearing structure of the aerospace.
- the main shape and position deviations include the deviation of the outer surface of the shell, the flatness of the end face, the radial depression of the skin, the width and height of the weld, the unevenness of the rib thickness and other manufacturing geometric defects .
- the present invention mainly solves the problems that the existing numerical analysis model of aerospace thin shell structure is difficult to fully consider different types of shape and position deviations, and it is difficult to perform fine modeling and effective collection and analysis of shape and position deviations.
- a method for establishing a shape and position deviation feature library for aerospace thin-shell structures is proposed.
- the information on the shape and position deviation of the manufacturing features is summarized and combed by filling in the shell quality inspection card.
- interpolation is used with the method of probability estimation, the coordinates of the nodes in the finite element model are adjusted, and then refined finite element models considering different types of shape and position deviations are obtained, so as to achieve refined modeling and effectively sort out manufacturing features to guide the optimization design.
- This method is easy to use, can realize the feature combing of various shape and position deviations and effectively reflect them in the numerical model, and can complete the establishment of the shape and position deviation feature library of aerospace thin shell structures, and provide specifications and designs for the subsequent design of multiple models Foundation, shorten the design cycle.
- a method for establishing a shape and position deviation feature library for aerospace thin shell structures including the following steps:
- the first step is to build a feature library for the shape and position deviation of aerospace thin-shell structures, provide a data basis for the fine modeling of aerospace main bearing thin-shell structures, establish design specifications for aerospace thin-shell structures, and design suitable sites Workers measure the shell quality inspection card, take point measurements and fill in the shell quality inspection card to obtain key structural parameters and shape and position deviation characteristic data of the shell. Specifically:
- the key structural parameters of the shell include shell diameter, height, skin thickness, rib height and thickness, tightening type, welding type and other structural parameters and descriptions.
- the characteristic data of the shape and position deviation includes the deviation of the outer surface of the shell, the flatness of the end face, the radial depression of the skin, the width and height of the weld, the unevenness of the rib thickness, etc., and various methods for measuring the shape and position deviation data As follows: (1) The offset value of the busbar on the outer surface of the shell: Take a measurement line on the outer surface of the shell at a certain angle along the circumferential direction. The measurement line should avoid the longitudinal welding seam as much as possible and form several measurement points equally along the length of the measurement line.
- the proposed shell quality inspection card template plays a role of standard demonstration.
- the second step is to carry out the feature combing and mathematical description of the shape and position deviation data obtained in the first step, and perform the defect component analysis. Specifically:
- the data interpolation method or data fitting method is used for mathematical modeling for the busbar offset value and end surface flatness of the outer surface of the shell.
- the data interpolation and data fitting methods include bilinear, nearest, cubic spline , Polynomial, Fourier and other different forms of interpolation and function fitting methods.
- the mathematical description function of the depression is used for the radial depression of the skin.
- mathematical probability statistics are used to describe the degree of size dispersion mathematically.
- the most effective method for the offset value of the outer surface of the shell and the flatness of the end face is to use Fourier series to fit the data, and expand the shape and position deviation in the spatial frequency domain of half-wave cosine or half-wave sine
- the double Fourier series is an efficient and accurate three-dimensional characterization method.
- the double Fourier series of Fourier half-wave cosine and half-wave sine are expressed as follows:
- Equation (1) is transformed into a generalized multivariate linear fitting problem, and then the least square method is used to solve the coefficients.
- the methods of the first and second steps are used to collect and analyze the shape and position deviation data of multiple typical aerospace thin-walled structures, and establish the shape and position deviation feature database of the aerospace thin-walled structure. Specifically:
- the shell quality inspection card obtained in the first step is used to collect the shape and position deviation data of multiple groups of typical thin shell structures.
- the second step method is used to comb the characteristics of the shape and position deviation and mathematical description, and analyze the defect components. Based on the key geometric parameters and shape deviation characteristics of the thin shell structure, data grouping and classification, dimensionless processing, and data storage are carried out to complete the establishment of aerospace thin shell structure shape and position deviation feature database. Based on the shape and position deviation feature library of aerospace thin-shell structures, the quality rating and defect sensitivity analysis of thin-shell structures can be carried out, so as to establish design specifications for different forms of thin-shell structures, which will lay a solid foundation for my country's future heavy launch vehicle and large aircraft manufacturing basis.
- the fourth step is to establish a finite element numerical model that fully considers the shape and position deviation based on the shape and position deviation feature database of the aerospace thin shell structure established in the third step. Specifically:
- the interpolation method is used to modify the overall or local node coordinates of the three-dimensional finite element model of the perfect structure or select the cross-sectional geometric dimensions for the welds and ribs based on the probability distribution function of geometric parameters to achieve the introduction of different real manufacturing geometric defects into the perfect structure
- the purpose of the three-dimensional finite element model is to obtain a refined finite element model that fully considers manufacturing geometric defects.
- the shell quality inspection card suitable for on-site workers' measurement described in the first step is also suitable for cone shells, spherical shells and other structural forms.
- This template can serve to build shape and position deviation feature libraries of different structural forms. It plays an important role in establishing refined and authentic numerical models and establishing industry standards.
- the present invention is difficult to consider the different types of shape and position deviations generated in the manufacturing process for the existing aerospace thin shell structure numerical analysis model, and is to build a shape and position deviation feature library of the aerospace thin shell structure.
- Established a refined thin-shell structure numerical model and performed refined numerical analysis gave a shell quality inspection card suitable for on-site workers measurement, built a shape and position deviation feature library for aerospace thin-shell structure, and gave considerations for establishment Various methods of refined finite element model of shape and position deviation.
- the feature information of the main manufacturing geometric defects of the shell can be collected by point-by-point measurement, including: the offset value of the outer surface of the shell, the flatness of the end face, the radial depression of the skin, the width and height of the weld, and the thickness of the rib. Evenness.
- the shape and position deviation feature library of the aerospace thin shell structure is established.
- the perfect finite element model can be modified by moving the finite element model nodes. In this way, a refined finite element numerical model considering a variety of manufacturing geometric defects is obtained.
- the shape and position deviation feature library of the aerospace thin shell structure established by the invention can make full use of the real shape and position deviation information embodied by the experimental components, establish a refined numerical analysis model considering different types of manufacturing geometric defects, and enhance the finite element prediction model The authenticity of the finite element prediction further improves the accuracy of the finite element prediction.
- the establishment of the shape and position deviation feature library of aerospace thin-shell structures with my country's independent intellectual property rights can effectively serve the development of my country's aerospace equipment, shorten the design cycle, and provide guidance and design specifications for the main load-bearing thin-shell structures.
- Figure 1 is a flowchart of the implementation of the method for establishing a shape and position deviation feature library for aerospace thin shell structures provided by the present invention
- Figure 2 is a schematic diagram of typical shape and position deviation;
- Figure 2(a) shows the deviation of the outer surface of the shell,
- Figure 2(b) shows the flatness of the end surface,
- Figure 2(c) shows the radial depression of the skin, and
- Figure 2(d) ) Represents the width and thickness of the weld;
- Figure 3(a) is a schematic diagram of the effect of combing and mathematical description of the shape and position deviation of the busbar offset on the outer surface of the shell;
- Figure 3(b) is a schematic diagram of the feature combing and mathematical description of the flatness of the end face
- Figure 3(c) is a schematic diagram of the effect of combing and mathematical description of the thickness, shape and position deviation of the weld
- Figure 3(d) is a schematic diagram of the effect of combing the characteristics of rib thickness and position deviation and mathematical description
- Figure 4 is an enlarged and visualized schematic diagram of the shape and position deviation of the axial compression cylinder shell structure.
- Fig. 1 is an implementation flow chart of a method for establishing a shape and position deviation feature library for aerospace thin shell structures provided by an example of the present invention.
- a method for establishing a shape and position deviation feature library for aerospace thin shell structures provided by an embodiment of the present invention includes:
- the first step is to provide a shell quality inspection card suitable for on-site workers to measure, take point measurements and fill in the shell quality inspection card to obtain key structural parameters and shape and position deviation characteristic data of the shell.
- the main shape and position deviation data of 29 stiffened cylindrical shells with a diameter of about 2 meters are measured and statistics, and the shell quality inspection card is filled in to obtain the key geometry of the grid stiffened cylindrical shell structure test piece Parameter and form and position deviation data.
- the measured shape and position deviation mainly include: the offset value of the outer surface of the shell, the flatness of the end face, the radial depression of the skin, the width and height of the weld, and the unevenness of the rib thickness.
- Figure 2 is a schematic diagram of a typical shape and position deviation measured.
- the shell quality inspection card template used here is shown in Table 1(a) and Table 1(b) below.
- the second step is to carry out the feature combing and mathematical description of the shape and position deviation data obtained in the first step, and perform the defect component analysis.
- Use mathematical methods such as data fitting, probability distribution, and data interpolation to analyze the shape and position deviation characteristics (manufacturing geometric characteristics) data collected in the shell quality inspection card, and establish appropriate mathematical models for different types of shape and position deviation data.
- Complete the feature combing and description of manufacturing geometric features For the example of the present invention, the offset value of the outer surface of the shell uses spline curve interpolation; the flatness of the end face uses Fourier function fitting; the width and height of the weld seam and the unevenness of the rib thickness use mathematical probability statistics to determine the size The degree of dispersion is described mathematically.
- Figure 3 is a schematic diagram of the effect of defect feature combing and mathematical description.
- the third step is to use the first and second steps to collect and analyze the shape and position deviation data of multiple typical aerospace thin-walled structures, and establish the shape and position deviation feature library of the aerospace thin-walled structure.
- the shell quality inspection card obtained in the first step to collect the shape and position deviation data of multiple groups of typical thin shell structures, and use the second step to carry out the feature combing and mathematical description of the shape and position deviation, and perform the defect component analysis.
- data grouping and classification, dimensionless processing, and data storage are carried out to complete the establishment of aerospace thin shell structure shape and position deviation feature database.
- the fourth step is to establish a finite element numerical model that fully considers the shape and position deviation based on the shape and position deviation feature library of the aerospace thin shell structure.
- the finite element analysis software ABAQUS is used to establish a perfect three-dimensional finite element model for a specific thin shell structure, which is a perfect three-dimensional finite element model without manufacturing geometric defects.
- search for the shape and position deviation feature data that has the same structure and similar geometric dimensions as the specified model; based on the mathematical feature description of the shape and position deviation, the shape and position deviation defects are reasonable Scaled to fit the specified structure size.
- the interpolation method is used to modify the overall or local node coordinates of the three-dimensional finite element model of the perfect structure or select the cross-sectional geometric dimensions for the welds and ribs based on the probability distribution function of geometric parameters to achieve the introduction of different real manufacturing geometric defects into the perfect structure
- the purpose of the three-dimensional finite element model is to obtain a refined finite element model that fully considers manufacturing geometric defects.
- the radial depression of the skin can calculate the offset of the node coordinates through an accurate mathematical function.
- the spatial scatter data obtained by interpolation based on the offset data of the outer surface of the shell is difficult to correspond to the finite element grid one by one.
- the skin node coordinates are adjusted one by one based on the point-by-point interpolation of the grid nodes. It can be realized by the method of amplifying the defect amplitude, and the visualization of the form and position deviation data (as shown in Figure 4, the form and position deviation defect data method is 200 times), which provides a reference for designers.
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Abstract
提供一种面向航空航天薄壳结构的形位偏差特征库建立方法，属于航空航天结构主承力构件设计技术领域，包括以下步骤：1）给出适合现场工人测量的壳体质量检测卡，采点测量并填写壳体质量检测卡，获取壳体关键结构参数和形位偏差特征数据；2）对第一步得到的形位偏差数据，进行形位偏差的特征梳理和数学描述，进行缺陷成分分析；3)使用第一步和第二步对于多个典型航空航天薄壁结构的形位偏差数据进行收集和分析，建立航空航天薄壳结构形位偏差特征库。该方法有助于建立拥有过我国自主知识产权的航空航天薄壳结构形位偏差特征库，能够有效服务于我国航空航天装备的研制，缩短设计周期，为主要承力薄壳结构提供指导和设计规范。
Description
本发明属于航空航天结构主承力构件设计技术领域，涉及一种面向航空航天薄壳结构的形位偏差特征库建立方法。
薄壳结构具有高比刚度和高比强度，因此被广泛应用于航空航天结构的主承力构件中。航空航天中主承力薄壳结构主要承受轴压载荷，破坏的主要模式为屈曲失稳，因此薄壳结构在轴压工况下的极限承载能力是航空航天结构设计过程中的关键考核指标。然而通过大量轴压圆柱壳试验发现，试验结果和经典理论存在巨大的差异，试验得到的屈曲载荷往往只有经典理论解得20％-60％，并且实验结果存在巨大的分散和差异性。经过数十年的研究发现，初始几何缺陷的存在是试验结果和理论结果存在巨大差异的主要原因之一。而几何缺陷是加工制造、运输装配、服役等过程中不可避免的，因此如何精确地考虑不同种类的形位偏差(加工制造几何缺陷)是准确预估薄壳结构极限承载力并进行精细化设计的有效途径之一。欧盟采用欧洲钢壳规范的方法，根据初始缺陷的情况对已加工薄壳结构进行评估分级，该方法被认为是圆柱壳稳定设计方面的权威性规范。美国NASA使用实验设备测量圆柱壳蒙皮的完整初始几何缺陷并建立初始几何缺陷数据库，为航天薄壳结构设计起到指导作用。我国运载火箭主承力结构采用网格加筋壳结构形式，建立能够充分考虑加筋薄壳结构中不同种类形位偏差的数值模型，是准确预测薄壁筒壳结构实际承载力的有效途径，也是我国运载火箭简体筒壳结构轻量化设计的基础，建立拥有我国自主知识产权的航空航天薄壳结构形位偏差特征库，更是我国重型运载火箭和大型飞机制造的坚实基础。
航天航空主承力薄壳结构一般包括筒壳结构，锥壳结构，球壳结构和复杂异性曲面薄壳等结构形式。随着有限元等数值分析方法的快速发展，充分考虑形位偏差，建立能够体现不同种类和位置制造几何缺陷的有限元数值模型，进而精确分析计算筒壳结构极限承载能力是航天主承力结构精细化分析与设计的必要途径之一。针对网格加筋薄壳结构，主要的形位偏差包括壳体外表面母线偏移值、端面平整度、蒙皮径向凹陷、焊缝宽度和高度、筋条厚度不均匀度等制造几何缺陷形式。工程中一般采用较为保守的折减因子方法预估薄壳结构的极限承载力，这样限制了航空航天主承力结构的精细化和轻量化设计。因此，亟需建立一种能充分考虑不同种类形位偏差，实现精细化模型的建立方法，并开展一种面向航空航天薄壳结构的形位偏差特征库建立方法，为我国未来重型运载火箭和大型飞机制造提供指导和规范。
发明内容
本发明主要解决现有航空航天薄壳结构数值分析模型难以充分考虑不同类型形位偏差， 难以精细化建模并针对形位偏差进行有效收集和分析的问题。提出一种面向航空航天薄壳结构的形位偏差特征库建立方法，通过填写壳体质量检测卡完成制造特征形位偏差的信息汇总和梳理，在完美有限元网格模型的基础上，采用插值和概率估计的方法对有限元模型中节点坐标进行修调，进而获得考虑不同种类形位偏差的精细化有限元模型，达到精细化建模并有效梳理制造特征，指导优化设计的目的。这种方法方便使用，可实现多种形位偏差的特征梳理并在数值模型中有效体现，并且可以完成航空航天薄壳结构形位偏差特征库的建立，为后续多种型号设计提供规范和设计基础，缩短设计周期。
为了达到上述目的，本发明的技术方案为：
一种面向航空航天薄壳结构的形位偏差特征库建立方法，包括以下步骤：
第一步，为搭建航空航天薄壳结构形位偏差特征库，为航空航天主承力薄壳结构的精细化建模提供数据基础，建立航空航天薄壳结构的设计规范，设计给出适合现场工人测量的壳体质量检测卡，采点测量并填写壳体质量检测卡，获取壳体关键结构参数和形位偏差特征数据。具体为：
针对网格加筋筒壳结构，所述的壳体关键结构参数包括壳体直径、高度、蒙皮厚度，筋条高度及厚度、加紧类型、焊接类型等结构参数和描述。所述的形位偏差特征数据包括壳体外表面母线偏移值、端面平整度、蒙皮径向凹陷、焊缝宽度和高度、筋条厚度不均匀度等形式，各种形位偏差数据测量方法如下：(1)壳体外表面母线偏移值：沿环向每隔一定角度在壳体外表面取一条测量线，测量线尽量避开纵向焊缝，沿测量线长度方向等分形成若干个测量点，利用靠尺测量并记录其径向偏移值，其中内凹为正，外凸为负。(2)端面平整度：沿环向每隔一定角度，利用塞尺测量下端面与地面间的距离Z
下，翻转壳体，按照同样环向位置，利用塞尺测量上端面与地面间的距离Z
上。(3)蒙皮径向凹陷：通过目测，将蒙皮凹陷由大到小依次排序，测量并记录每个凹陷的位置(轴向坐标和环向角度)、幅值(凹陷深度)。其中内凹为正，外凸为负。(4)焊缝宽度和高度：对每个焊缝，沿轴向或环向等分若干个点，作为测量点，测量并记录每个测量点处的焊缝宽度和高度。(5)筋条厚度不均匀度：沿环向每隔一定角度取一条纵向筋条(或有纵向分量)，沿纵向筋条的长度方向等分形成若干个测量点，利用游标卡尺测量并记录其厚度，并统计其不均匀度。需要说明，这些形位偏差数据类型和测量方法同样适用于锥壳、球壳、异性薄壳等其他薄壁结构形式。
通过对单一构件形位偏差数据的统计分析，可以用于实际结构的精细化数值分析，而数据的积累可实现航空航天薄壳结构形位偏差特征库的搭建，服务于我国火箭主承力构件精细化分析和设计，为火箭的进一步减重起到重要作用。所提出的壳体质量检测卡模板起到标准示范作用。
第二步，对第一步得到的形位偏差数据，进行形位偏差的特征梳理和数学描述，进行缺陷成分分析。具体为：
采用数据拟合、概率分布、数据插值等数学方法对壳体质量检测卡中收集的形位偏差特征(制造几何特征)数据进行分析，针对不同类型的形位偏差数据分别建立合适的数学模型，完成制造几何特征的特征梳理和描述。具体为：对于壳体外表面母线偏移值和端面平整度采用数据插值方法或数据拟合方法进行数学建模，所述的数据插值和数据拟合方法包括双线性、最临近、三次样条、多项式、傅里叶等不同形式的插值和函数拟合方法。对于蒙皮径向凹陷，采用凹陷形式的数学描述函数。对于焊缝宽度和高度、筋条厚度不均匀度采用数学概率统计的方法对尺寸的离散程度进行数学描述。
进一步的，对于壳体外表面母线偏移值和端面平整度，最有效的方法是使用傅里叶级数进行数据拟合，将形位偏差在空间频域范围内展开半波余弦或半波正弦的双重傅里叶级数是一种高效准确的三维形貌表征方法。所述的傅里叶半波余弦和半波正弦的双重傅里叶级数分别表示如下：
其中，
为无量纲离面位移，x为形位偏差环向坐标，y为形位偏差轴向坐标；L和R为柱壳的名义高度和名义半径；A
kl、B
kl为半波余弦傅里叶级数的系数；C
kl、D
kl为半波正弦傅里叶级数的系数；k和l为傅里叶级数系数的编号，n1和n2为傅里叶系数的个数。将式(1)转化为广义多变元线性拟合问题，然后使用最小二乘法进行系数的求解。
第三步，采用第一步和第二步的方法对于多个典型航空航天薄壁结构的形位偏差数据进行收集和分析，建立航空航天薄壳结构形位偏差特征库。具体为：
采用第一步获得的壳体质量检测卡对多组典型薄壳结构进行形位偏差数据收集，采用第二步的方法进行形位偏差的特征梳理和数学描述，进行缺陷成分分析。基于薄壳结构的关键几何参数和形位偏差特征进行数据分组归类、无量纲处理、数据存储，完成航空航天薄壳结构形位偏差特征库的建立。基于航空航天薄壳结构形位偏差特征库，可进行薄壳结构的质量评级和缺陷敏感性分析，从而建立不同形式薄壳结构的设计规范，为我国未来重型运载火箭和大飞机制造打下坚实的基础。
第四步，基于第三步建立的航空航天薄壳结构形位偏差特征库，建立充分考虑形位偏差的有限元数值模型。具体为：
首先，采用有限元分析软件ANSYS、ABAQUS或MSC.Patran，针对特定的薄壳结构建立完美的三维有限元模型，该模型为不含有制造几何缺陷的完美三维有限元模型。然后，在航空航天薄壳结构形位偏差特征库中搜索与指定模型具有相同结构形式和相近几何尺寸的形位偏差特征数据；基于该形位偏差的数学特征描述，对形位偏差缺陷进行合理的放缩以适应指定的结构尺寸。最后，采用插值方法对完美结构三维有限元模型整体或局部的节点坐标进行修调或者基于几何参数的概率分布函数为焊缝和筋条选取截面几何尺寸，达到将不同真实制造几何缺陷引入完美结构三维有限元模型的目的，进而获得充分考虑制造几何缺陷的精细化有限元模型。通过对缺陷幅值放大的方法可实现形位偏差数据的可视化，为设计人员提供参考。
另外，第一步中所述的适合现场工人测量的壳体质量检测卡，该模板同样适用于锥壳、球壳等结构形式，该模板可服务于搭建不同结构形式的形位偏差特征库，为建立精细化、真实化数值模型和建立行业规范起到重要作用。
本发明的有益效果为：本发明针对现有的航空航天薄壳结构数值分析模型难以考虑加工制造过程中产生的不同类型形位偏差问题，为搭建航空航天薄壳结构的形位偏差特征库，建立精细化薄壳结构数值模型并进行精细化数值分析，给出了适合现场工人测量使用的壳体质量检测卡，搭建了航空航天薄壳结构的形位偏差特征库，并给出了建立考虑多种形位偏差的精细化有限元模型的方法。可以通过逐点测量的方式对筒壳主要的制造几何缺陷特征信息进行采集，包括：壳体外表面母线偏移值、端面平整度、蒙皮径向凹陷、焊缝宽度和高度、筋条厚度不均匀度。通过对壳体质量检测卡所测量制造几何缺陷的特征梳理和数学描述，建立航空航天薄壳结构的形位偏差特征库，可以通过移动有限元模型节点的方式对完美有限元模型进行修调，从而获得考虑多种制造几何缺陷的精细化有限元数值模型。本发明所建立的航空航天薄壳结构的形位偏差特征库能够充分利用实验构件所体现的真实形位偏差信息，建立考虑不同种类制造几何缺陷的精细化数值分析模型，增强了有限元预测模型的真实性，进一步提高了有限元预测的准确性。建立拥有过我国自主知识产权的航空航天薄壳结构形位偏差特征库能够有效服务于我国航空航天装备的研制，缩短设计周期，为主要承力薄壳结构提供指导和设计规范。
图1为本发明提供的面向航空航天薄壳结构的形位偏差特征库建立方法的实现流程图；
图2为典型形位偏差示意图；其中，图2(a)表示壳体外表面母线偏移，图2(b)表示端面平整度，图2(c)表示蒙皮径向凹陷，图2(d)表示焊缝宽度和厚度；
图3(a)为壳体外表面母线偏移形位偏差特征梳理和数学描述效果示意图；
图3(b)为端面平整度形位偏差特征梳理和数学描述效果示意图；
图3(c)为焊缝厚度形位偏差特征梳理和数学描述效果示意图；
图3(d)为筋条厚度形位偏差特征梳理和数学描述效果示意图；
图4为轴压筒壳结构的形位偏差放大可视化示意图。
为使本发明解决的方法问题、采用的方法方案和达到的方法效果更加清楚，下面结合附图和实施例对本发明作进一步的详细说明。可以理解的是，此处所描述的具体实施例仅仅用于解释本发明，而非对本发明的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与本发明相关的部分而非全部内容。
图1为本发明实例提供的一种面向航空航天薄壳结构的形位偏差特征库建立方法的实现流程图。如图1所示，本发明实施例提供的一种面向航空航天薄壳结构的形位偏差特征库建立方法包括：
第一步，给出适合现场工人测量的壳体质量检测卡，采点测量并填写壳体质量检测卡，获取壳体关键结构参数和形位偏差特征数据。采用逐点测量的方式，对直径2米左右的29个加筋筒壳的主要形位偏差数据进行测量统计，并填写壳体质量检测卡，获得网格加筋筒壳结构试验件的关键几何参数和形位偏差数据。测量的形位偏差主要包括：壳体外表面母线偏移值、端面平整度、蒙皮径向凹陷、焊缝宽度和高度、筋条厚度不均匀度。图2为测量的典型形位偏差示意图。这里采用的壳体质量检测卡模板如下表1(a)、表1(b)所示。
表1：壳体质量检测卡模板(a)
表1：壳体质量检测卡模板(b)
第二步，对第一步得到的形位偏差数据，进行形位偏差的特征梳理和数学描述，进行缺陷成分分析。使用数据拟合，概率分布，数据插值等数学方法对壳体质量检测卡中收集的形位偏差特征(制造几何特征)数据进行分析，针对不同类型的形位偏差数据分别建立合适的数学模型，完成制造几何特征的特征梳理和描述。对于本发明实例，壳体外表面母线偏移值使用样条曲线插值；端面平整度使用傅里叶函数拟合；焊缝宽度和高度和筋条厚度不均匀度使用数学概率统计的方法对尺寸的离散程度进行数学描述。图3为缺陷特征梳理和数学描述的效果示意图。
第三步，使用第一步和第二步对于多个典型航空航天薄壁结构的形位偏差数据进行收集和分析，建立航空航天薄壳结构形位偏差特征库。
使用第一步获得的壳体质量检测卡对多组典型薄壳结构进行形位偏差数据收集，使用第二步进行形位偏差的特征梳理和数学描述，进行缺陷成分分析。基于薄壳结构的关键几何参数和形位偏差特征进行数据分组归类、无量纲处理、数据存储，完成航空航天薄壳结构形位偏差特征库的建立。
第四步，基于航空航天薄壳结构形位偏差特征库，建立充分考虑形位偏差的有限元数值模型。首先，采用有限元分析软件ABAQUS针对特定的薄壳结构建立完美的三维有限元模型，该模型为不含有制造几何缺陷的完美三维有限元模型。然后，在航空航天薄壳结构形位偏差特征库中搜索与指定模型具有相同结构形式和相近几何尺寸的形位偏差特征数据；基于该形位偏差的数学特征描述，对形位偏差缺陷进行合理的放缩以适应指定的结构尺寸。最后，采用插值方法对完美结构三维有限元模型整体或局部的节点坐标进行修调或者基于几何参数的概率分布函数为焊缝和筋条选取截面几何尺寸，达到将不同真实制造几何缺陷引入完美结构三维有限元模型的目的，进而获得充分考虑制造几何缺陷的精细化有限元模型。对于端面平整度，蒙皮径向凹陷可通过准确的数学函数计算节点坐标的偏移量。基于壳体外表面母线偏移值数据插值获得的空间散点数据很难与有限元网格逐一对应，这里采用基于网格节点逐点插值的方法逐一修调蒙皮节点坐标。通过对缺陷幅值放大的方法可实现，形位偏差数据的可视化(如图4，形位偏差缺陷数据方法200倍)，为设计人员提供参考。
最后应说明的是：以上各实施例仅用以说明本发明的方法方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通方法人员应当理解：其对前述各实施例所记载的方法方案进行修改，或者对其中部分或者全部方法特征进行等同替换，并不使相应方法方案的本质脱离本发明各实施例方法方案的范围。
Claims (5)
- 一种面向航空航天薄壳结构的形位偏差特征库建立方法，其特征在于，所述的形位偏差特征库建立方法包括以下步骤：第一步，设计给出适合现场工人测量的壳体质量检测卡，采点测量并填写壳体质量检测卡，获取壳体关键结构参数和形位偏差特征数据，形位偏差特征数据包括壳体外表面母线偏移值、端面平整度、蒙皮径向凹陷、焊缝宽度和高度、筋条厚度不均匀度；第二步，对第一步得到的形位偏差数据，进行形位偏差的特征梳理和数学描述，进行缺陷成分分析；采用数学方法对壳体质量检测卡中收集的形位偏差特征数据进行分析，针对不同类型的形位偏差数据分别建立合适的数学模型，完成形位偏差特征的特征梳理和描述：对于壳体外表面母线偏移值和端面平整度采用数据插值方法或数据拟合方法进行数学建模；对于蒙皮径向凹陷，采用凹陷形式的数学描述函数；对于焊缝宽度和高度、筋条厚度不均匀度采用数学概率统计的方法对尺寸的离散程度进行数学描述；第三步，采用第一步和第二步的方法对于多个典型航空航天薄壁结构的形位偏差数据进行收集和分析，建立航空航天薄壳结构形位偏差特征库；采用第一步获得的壳体质量检测卡对多组典型薄壳结构进行形位偏差数据收集，采用第二步的方法进行形位偏差的特征梳理和数学描述，进行缺陷成分分析；基于薄壳结构的关键几何参数和形位偏差特征进行数据分组归类、无量纲处理、数据存储，完成航空航天薄壳结构形位偏差特征库的建立；基于航空航天薄壳结构形位偏差特征库，进行薄壳结构的质量评级和缺陷敏感性分析，建立不同形式薄壳结构的设计规范；第四步，基于第三步建立的航空航天薄壳结构形位偏差特征库，建立充分考虑形位偏差的有限元数值模型；首先，针对特定的薄壳结构建立完美的三维有限元模型，该模型为不含有制造几何缺陷的完美三维有限元模型；然后，在航空航天薄壳结构形位偏差特征库中搜索与指定模型具有相同结构形式和相近几何尺寸的形位偏差特征数据；基于该形位偏差的数学特征描述，对形位偏差缺陷进行合理的放缩以适应指定的结构尺寸；最后，采用插值方法对完美结构三维有限元模型整体或局部的节点坐标进行修调或者基于几何参数的概率分布函数为焊缝和筋条选取截面几何尺寸，达到将不同真实制造几何缺陷引入完美结构三维有限元模型的目的，进而获得充分考虑制造几何缺陷的精细化有限元模型；通过对缺陷幅值放大的方法可实现形位偏差数据的可视化，为设计人员提供参考。
- 根据权利要求1所述的一种面向航空航天薄壳结构的形位偏差特征库建立方法，其特征在于，第一步中所述的适合现场工人测量的壳体质量检测卡，形位偏差数据类型和测量方法同 样适用于锥壳、球壳、异性薄壳或其他薄壁结构形式，用于搭建不同结构形式的形位偏差特征库，为建立精细化、真实化数值模型和建立行业规范起到重要作用。
- 根据权利要求1或2所述的一种面向航空航天薄壳结构的形位偏差特征库建立方法，其特征在于，第一步中所述都形位偏差数据测量方法如下：(1)壳体外表面母线偏移值：沿环向每隔一定角度在壳体外表面取一条测量线，测量线避开纵向焊缝，沿测量线长度方向等分形成若干个测量点，利用靠尺测量并记录其径向偏移值，其中内凹为正，外凸为负；(2)端面平整度：沿环向每隔一定角度，利用塞尺测量下端面与地面间的距离Z 下，翻转壳体，按照同样环向位置，利用塞尺测量上端面与地面间的距离Z 上；(3)蒙皮径向凹陷：通过目测，将蒙皮凹陷由大到小依次排序，测量并记录每个凹陷的位置、幅值；其中内凹为正，外凸为负；(4)焊缝宽度和高度：对每个焊缝，沿轴向或环向等分若干个点，作为测量点，测量并记录每个测量点处的焊缝宽度和高度；(5)筋条厚度不均匀度：沿环向每隔一定角度取一条纵向筋条，沿纵向筋条的长度方向等分形成若干个测量点，利用游标卡尺测量并记录其厚度，并统计其不均匀度。
- 根据权利要求1或2所述的一种面向航空航天薄壳结构的形位偏差特征库建立方法，其特征在于，第二步中，对于壳体外表面母线偏移值和端面平整度，优选采用傅里叶级数进行数据拟合，将形位偏差在空间频域范围内展开半波余弦或半波正弦的双重傅里叶级数是一种高效准确的三维形貌表征方法；所述的傅里叶半波余弦和半波正弦的双重傅里叶级数分别表示如下：
其中，为无量纲离面位移，x为形位偏差环向坐标，y为形位偏差轴向坐标；L和R为柱壳的名义高度和名义半径；A kl、B kl为半波余弦傅里叶级数的系数；C kl、D kl为半波正弦傅里叶级数的系数；k和l为傅里叶级数系数的编号，n1和n2为傅里叶系数的个数；
将公式(1)转化为广义多变元线性拟合问题，采用最小二乘法求解系数。 - 根据权利要求3所述的一种面向航空航天薄壳结构的形位偏差特征库建立方法，其特征在于，第二步中，对于壳体外表面母线偏移值和端面平整度，优选采用傅里叶级数进行数据拟合，将形位偏差在空间频域范围内展开半波余弦或半波正弦的双重傅里叶级数是一种高效准 确的三维形貌表征方法；所述的傅里叶半波余弦和半波正弦的双重傅里叶级数分别表示如下：
其中，为无量纲离面位移，x为形位偏差环向坐标，y为形位偏差轴向坐标；L和R为柱壳的名义高度和名义半径；A kl、B kl为半波余弦傅里叶级数的系数；C kl、D kl为半波正弦傅里叶级数的系数；k和l为傅里叶级数系数的编号，n1和n2为傅里叶系数的个数；
将公式(1)转化为广义多变元线性拟合问题，采用最小二乘法求解系数。
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2019/083019 WO2020211007A1 (zh) | 2019-04-17 | 2019-04-17 | 一种面向航空航天薄壳结构的形位偏差特征库建立方法 |
| US16/754,672 US20210056243A1 (en) | 2019-04-17 | 2019-04-17 | Method for establishing the geometrical imperfection database for the aerospace thin-walled structure |
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| PCT/CN2019/083019 WO2020211007A1 (zh) | 2019-04-17 | 2019-04-17 | 一种面向航空航天薄壳结构的形位偏差特征库建立方法 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112307673A (zh) * | 2020-11-02 | 2021-02-02 | 中国空气动力研究与发展中心计算空气动力研究所 | 一种基于深度学习的网格面质量检测方法 |
| CN112668220A (zh) * | 2020-12-23 | 2021-04-16 | 天津大学 | 一种基于有限元分析的航天装置结构三维热变形测量方法 |
| CN112926147A (zh) * | 2021-01-27 | 2021-06-08 | 合肥工业大学 | 含缺陷加筋柱壳的后验优化设计方法 |
| CN113049339A (zh) * | 2021-04-01 | 2021-06-29 | 西北工业大学 | 用于在薄壳结构外表面产生特定局部几何初始缺陷的装置 |
| CN113158597A (zh) * | 2021-04-25 | 2021-07-23 | 中国电建集团贵阳勘测设计研究院有限公司 | 一种基于catia计算的水闸应力稳定分析方法 |
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| CN112307673A (zh) * | 2020-11-02 | 2021-02-02 | 中国空气动力研究与发展中心计算空气动力研究所 | 一种基于深度学习的网格面质量检测方法 |
| CN112668220A (zh) * | 2020-12-23 | 2021-04-16 | 天津大学 | 一种基于有限元分析的航天装置结构三维热变形测量方法 |
| CN112926147A (zh) * | 2021-01-27 | 2021-06-08 | 合肥工业大学 | 含缺陷加筋柱壳的后验优化设计方法 |
| CN112926147B (zh) * | 2021-01-27 | 2023-11-03 | 合肥工业大学 | 含缺陷加筋柱壳的后验优化设计方法 |
| CN113049339A (zh) * | 2021-04-01 | 2021-06-29 | 西北工业大学 | 用于在薄壳结构外表面产生特定局部几何初始缺陷的装置 |
| CN113049339B (zh) * | 2021-04-01 | 2024-01-16 | 西北工业大学 | 用于在薄壳结构外表面产生特定局部几何初始缺陷的装置 |
| CN113158597A (zh) * | 2021-04-25 | 2021-07-23 | 中国电建集团贵阳勘测设计研究院有限公司 | 一种基于catia计算的水闸应力稳定分析方法 |
| CN113158597B (zh) * | 2021-04-25 | 2022-08-19 | 中国电建集团贵阳勘测设计研究院有限公司 | 一种基于catia计算的水闸应力稳定分析方法 |
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