基于径向基函数的高精度变形测量方法研究

发布时间：2018-07-03 15:31

本文选题：径向基函数 + 电子散斑干涉法　；参考：《东南大学》2016年博士论文

【摘要】：电子散斑干涉方法和数字图像相关方法是较为常用的两种进行物体表面变形测量的现代光测方法。电子散斑干涉法是以条纹图来表现物体的变形形式,通过位相计算得到待测物理量的。数字图像相关方法是一种基于数字图像匹配的方法,通过分析材料或结构变形前后物体表面的数字图像获得被测物体表面的变形信息。这两种方法具有非接触、可实现全场测量的特点,但是其在变形测量精度和应变测量精度上存在一些不足。本文分别对电子散斑干涉方法和数字图像相关方法进行了研究,提出了基于径向基函数的高精度变形测量方法,主要研究成果有三个方面：一、将径向基插值方法与电子散斑干涉法相结合,提出了两种基于径向基函数的条纹滤波方法——预滤波径向基函数方法和基于局部数据的移动径向基函数方法,并讨论了主要参数的选择问题。同时发展了基于径向基函数的位相滤波方法,对采样间隔的选择作了研究。二、将径向基函数与数字图像相关方法相结合,提出了两种应变计算方法：第一种是偏导径向基方法,第二种是径向基函数与局部最小二乘相结合的方法。同时给出了一种新的形状参数选取方法。此外还发展了一种基于梯度熵的径向基函数方法,对计算时原始数据的选取作了研究。三、采用基于径向基函数的高精度变形测量方法对多种材料和结构件进行了实验研究。1、采用振幅波动电子散斑干涉方法和预滤波径向基函数方法对不带缺陷和不同位置带预制裂缝的蜂窝夹芯板的振动特性进行了研究,分析了裂缝对振动特性的影响规律。2、采用电子散斑干涉法对带预制裂缝的三点弯曲梁裂缝尖端应变场进行测量,将径向基函数与位相测量相结合获得了高精度的应变信息。3、提出了一种基于应变变化率的起裂载荷确定方法。通过数字图像相关方法计算出位移,经径向基函数方法滤波处理后采用局部最小二乘方法得到应变场,依据应变随时间的变化率确定出起裂载荷。此外,进一步发展了双K断裂准则。利用应变场信息计算出不同载荷等级时的裂纹扩展长度,依据双K准则对结构的承载力进行了预测。
[Abstract]:Electronic speckle interferometry (ESPI) and digital image correlation (DIA) are two common methods for measuring the surface deformation of objects. The electronic speckle interferometry (ESPI) is used to represent the deformation of an object by using a fringe pattern, and the physical quantities to be measured are obtained by phase calculation. Digital image correlation is a method based on digital image matching, which obtains the deformation information of the measured object surface by analyzing the digital image of the object surface before and after the material or structure is deformed. These two methods have the characteristics of non-contact and can realize full-field measurement, but there are some shortcomings in the accuracy of deformation measurement and strain measurement. In this paper, the ESPI method and the digital image correlation method are studied, and a high precision deformation measurement method based on radial basis function is proposed. The main research results are as follows: 1. By combining radial basis function interpolation method with electronic speckle interferometry, two fringe filtering methods based on radial basis function (RBF), namely, pre-filtering radial basis function (RBF) and moving radial basis function (RBF) based on local data, are proposed. The selection of main parameters is discussed. At the same time, the phase filtering method based on radial basis function is developed, and the selection of sampling interval is studied. Secondly, combining radial basis function with digital image correlation method, two kinds of strain calculation methods are proposed: the first is partial derivative radial basis method, the second is the combination of radial basis function and local least squares. At the same time, a new method of shape parameter selection is given. In addition, a radial basis function method based on gradient entropy is developed, and the selection of original data is studied. III. The high precision deformation measurement method based on radial basis function (RBF) was used to study many kinds of materials and structures experimentally. The amplitude wave electron speckle interferometry (ESPI) and the prefiltered radial basis function (RBF) were used to detect the defects and different bits. The vibration characteristics of honeycomb sandwich panels with prefabricated cracks are studied. The influence of cracks on vibration characteristics is analyzed. The strain field at the crack tip of three-point bending beam with prefabricated cracks is measured by ESPI. The radial basis function is combined with phase measurement to obtain high precision strain information. 3. A method for determining the initial crack load based on strain change rate is proposed. The displacement is calculated by the digital image correlation method, and the strain field is obtained by using the local least square method after filtered by the radial basis function method, and the initial crack load is determined according to the rate of variation of the strain with time. In addition, the double K fracture criterion is further developed. According to the strain field information, the crack propagation length of the structure with different load levels is calculated, and the bearing capacity of the structure is predicted according to the double K criterion.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O348.1

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