混合光载波法分离动静态主应力

本文将等差载波位相调制原理与夹层全息术结合形成的混合光载波法,可同时获得等差载波条纹图与混合载波条纹图.对混合载波纹图进行光学付里叶变换,利用空间滤波技术可将等和载波条纹从中分离出来.利用图象处理技术实现了对两种载波条纹图从预处理到应力计算的自动化处理.将混合光载波法应用于动态全息光弹性,分离了动态主应力. 文中还提出了一个经济实用的大尺寸载波片制作技术.     

光载波条纹图的锁相处理

本文提出了光载波条纹图的锁相处理方法,以对光载波条纹图作精确定位。给出了适合于计算机处理的离散递归实现步骤。在非线性模型下对定位精确度作了详细分析。实验结果表明,当暂态影响衰减后,能对条纹图进行精确定位而无稳态误差,对断裂条纹的大范围补偿也取得了较好的效果。     

光弹性贴片载波法

本文提出了一种提高测量灵敏度的光弹性贴片法。通过高频条纹调制获取载波条纹图。使贴片的等差效应所反映的力学信息规范化。运用计算机图象处理技术,对载波图自动采集、处理和解调,以获得全场条纹级数。编制了专用软件并以实例说明实验过程。     

载波条纹图的处理及应用

本文提出一种载波条纹的处理方法，将变形前、后的载波条纹图分别经过条纹细化、抽取中心、级数编码、全场拟合等处理，首先求出全场每个像素点上的条纹级数，然后再对应相减，以得到仅仅由于变形引起的干涉条纹的全场分布，文中应用该方法分析处理了差分干涉条纹图，测量了水平热管周围的温度场、温度梯度场及壁面换热系数。     

剪切散斑中新的相移技术及其在泵体上的应用研究

本文实现了一种新的剪切散斑干涉技术的载波方法.其特点是通过移动剪切棱镜,而产生载波条纹来调制变形条纹.然后,利用傅立叶变换法解调出变形条纹,获得全场位相图.本文介绍了这种载波相移技术的原理,并且对该载波技术的原理进行了推导.最后将该方法运用到舰用主泵体的离面位移导数(应变)测量上.     

干涉云纹光学倍增方法研究

本文提出一种干涉云纹的光学倍增方法。通过给由试件变形引起的云纹图施加一定频率的载波条纹，用具有高分辨率的记录介质记录这一附加有载波的云纹图，经处理后，记录介质相当于一个频率较低的转移变形试件栅，把它放到云纹干涉光路系统中作为试件栅，当对称入射的双光束在其上形成的虚参考栅频率为原载波条纹频率的２ｎ倍时，就可以得到倍增为２ｎ倍后的载荷条纹，使相应的测量灵敏度提高２ｎ倍。文中对这一方法进行了理论分析和实验验证。     

文献摘要

量测挠度的全息干涉图的数字化Gilbert,J.A.,Dudderar,T.D.,Mattys,DR.,Chern.J.H.,Digitization of HolograpicInterferograms for Deflection Measurement.Procedings of The SEM Spring Conferenceon Experimental Mechanios.294—301.本文讨论自动采集和分析全息干涉数据所需的载波条纹技术的基本原理.一个监视二维实时立即处理图片的实用方法.收集载波条纹的背景强度以及变形/载波条纹图,一个高分辨率的电视摄象机/电子组件使得所得的二维光强分布数字化和一个用来快速数据换算和整理的计算机.该系统明     

扫描云纹法中的光载波解调问题研究

本文提出一种新型的光载波技术,扫描云纹被使用为空间相位的探测器,可以用来实时地复原原始条纹.全场条纹级数可以得到快速而精确地自动识别.文中对调制度的概念及应用的充要条件进行了讨论.     

密集载波条纹的数字错位

本文提出一种用数字图像处理系统对密集的载波条纹进行错位得到偏导数场条纹的方法.该方法错位方向及大小灵活可调,对于由于刚体位移等因素造成的载波条纹调制的条纹处理有较好的适用性.     

云纹干涉法同时测定三维位移场(U_0,U_(45),U_(90),ω)

本文介绍了用云纹干涉法同时获得三维位移场——面内位移(U_0,U_(45),U_(90))和离面位移(w)的两种方法:实时观测法和加载波条纹的差载法.前者可一次加载,分别观测各个位移分量条纹图;后者可用一张底板同时记录全部三维位移信息,通过光学滤波分离出各位移分量条纹图。测试方法和计算都很简便,不仅能测静荷,同时也可测动荷,文中还介绍了实验用的仪器,给出了实验结果。     

导航系统白噪声误差特性的在线统计估计

本文提出了一种无需参考系统，对3个以上导航系统同时进行白噪声误差特性在线统计估计的方法，并进行了仿真实验和实航数据分析。     

Further applications of holography to photoelasticity

A holographic method for reconstructing the polarization of light emitted by a photoelastic model is presented. Isochromatic and the entire family of isoclinic fringe patterns may be obtained by examining the holographic image, a posteriori. This is accomplished by using two orthogonally polarized reference beams so arranged that the reconstructed crosstalk images do not overlap. An analysis is preseted crosstalk images do not overlap. An analysis is presented which shows that, to reconstruct polarization, the phase relationship between the two reference beams must be maintained. This requirement is more stringent than that normally required in holography. Experimental verification is presented.The use of double-exposure holography to obtain isopachic-isochromatic fringe patterns in the reconstructed image is discussed. An analytic treatment of the method is presented. Expressions relating the isopachic-isochromatic fringe pattern in the reconstructed virtual image to the principal stresses are developed. Differences between this analysis and that presented in a recent paper are discussed. Experimental results are obtained and compared to theory and to other experimental results with good agreement.Paper was presented at 1969 SESA Spring Meeting held in Philadelphia, Pa., on May 13–16.The study reported herein was supported in part by NASA Grant No. NsG-401.     

A semi-numerical method for solving inverse heat conduction problems

A semi-numerical method is presented for solving the inverse heat conduction problems in homogeneous and composite bodies. The presented solution does not require both the initial temperature distribution in the body and the whole temperature-time history at the temperature sensor locations. Sample calculations confirm that this approach produces stable and accurate results for both exact and noisy data. The extension of the method presented to two or three dimensions is straightforward.     

Shear modulus of transversely isotropic materials

A new and simple method is presented to determine the inde-pendent shear modulus of transversely isotropic material.Mathematical formulation,derivation and solution are given,and test apparatus and results are presented.The method wastested on one of such materials-Green River Formation oilshale.Comparisons wich other approximate results and acou-stical methods are made.Confirmation of the test methodwith materials having known shear moduli is also presented.     

Advanced response surface method for mechanical reliability analysis

Based on the classical response surface method (RSM), a novel RSM using improved experimental points (EPs) is presented for reliability analysis. Two novel points are included in the presented method. One is the use of linear interpolation, from which the total EPs for determining the RS are selected to be closer to the actual failure surface; the other is the application of sequential linear interpolation to control the distance between the surrounding EPs and the center EP, by which the presented method can ensure that the RS fits the actual failure surface in the region of maximum likelihood as the center EPs converge to the actual most probable point (MPP). Since the fitting precision of the RS to the actual failure surface in the vicinity of the MPP, which has significant contribution to the probability of the failure surface being exceeded, is increased by the presented method, the precision of the failure probability calculated by RS is increased as well. Numerical examples illustrate the accuracy and efficiency of the presented method.     

Fault Detection and Diagnosis of Components of the Vehicle Vertical Dynamics

In this paper, model and signal-based methods for supervision ofsuspension elements of a car are presented. A model-based approach usingparameter estimation is used to determine the current parameters of avehicle suspension. Exploiting the analytical redundancy, different faults,like weak dampers or sensor faults, can be distinguished. For faultdetection the use of parity equations is shown. In addition, a signal-basedapproach is presented which makes a detection of tire pressure losspossible. All presented results were drawn from a test rig or from a drivingcar.     

Modeling, numerical analysis and application of triple physical pendulum with rigid limiters of motion

The mathematical model of a triple physical pendulum harmonically forced with rigid limiters of motion is presented together with the model of stability based on the Aizerman–Gantmakher theory. Some examples of numerical simulations are given for the system of three coupled rods with a horizontal barrier. The system behavior near the grazing incidence is presented; in particular the spectra of Lyapunov exponents are calculated using the presented model of stability.     

An Accurate Solution of the Poisson Equation by the Finite Difference-Chebyshev-Tau Method

ＩｎｔｒｏｄｕｃｔｉｏｎＭａｎｙｓｃｈｏｌｏｒｓｈａｖｅｄｉｓｃｕｓｓｅｄｔｈｅｓｏｌｕｔｉｏｎｏｆｔｈｅｔｗｏ＿ｄｉｍｅｎｓｉｏｎａｌＰｏｉｓｓｏｎｅｑｕａｔｉｏｎ .ＡｍａｔｒｉｘｄｉａｇｏｎａｌｉｚａｔｉｏｎｍｅｔｈｏｄｗａｓｄｅｖｅｌｏｐｅｄｂｙＨａｉｄｖｏｇｅｌａｎｄＺａｎｇ[1]ｆｏｒｔｈｅｓｏｌｕｔｉｏｎｏｆｔｈｅｔｗｏ＿ｄｉｍｅｎｓｉｏｎａｌＰｏｉｓｓｏｎｅｑｕａｔｉｏｎ .Ｔｈｉｓｍｅｔｈｏｄｉｓｅｆｆｉｃｉｅｎｔｂｕｔｒｅｑｕｉｒｅｓａｐｒｅｐｒｏｃｅｓｓｉｎｇｃａｌｃｕｌａｔｉｏ…     

High-order methods for differential equations with large first-derivative terms

A method is developed to solve elliptic singular perturbation problems. Examples are presented in one and two dimensions for both linear and non-linear problems. In particular, examples are presented for fluid flow problems with boundary layers. In the one-dimensional case an approximating equation is developed using just three points. The method first presented is a fourth-order approximation but is extended to become a higher-order method. Results are included for the fourth-, sixth-, eighth- and tenth-order methods. The results are first compared with results found by Segal in an article about elliptic singular perturbation problems. The elliptic singular perturbation problems are compared with a method by Il'in and also with central and backward difference schemes from Segal's article. There was only one case where the results in Segal's paper were as accurate as the results presented in this paper. However, in this case the method used by Segal did not give accurate values for a second problem presented. The results are also compared with results given by Spalding and by Christie. The method of this paper was also tested on the solution of some non-linear diffusion equations with concentration-dependent diffusion coefficients. The results were superior to results presented by Lee and by Schultz. Finally, the method is extended to several two-dimensional problems. The method developed in this paper is accurate, easy to use and can be generalized to other problems.     

Effect of curvature on the turbulence of a two-dimensional jet

An experimental study is presented which details the turbulence characteristics of a two dimensional offset jet. A single offset ratio (height of the nozzle above the solid parallel wall by nozzle width) of seven is used with a nozzle Reynolds number of 15,000. Measurements are presented in the preattachment jet region made with a dual frequency shifted laser Doppler anemometer. The relative strain rates resulting from curvature on the upper and lower sides of the jet are determined and their effects on the r. m. s. fluctuating velocity components are presented.This paper was presented at the Ninth Symposium on Turbulence, University of Missouri-Rolla, October 1–3, 1984