In this paper a distributed intelligent system for civil engineering structures on-line measurement, remote monitoring,
and data archiving is presented. The system consists of a set of full-field optical displacement sensors connected to
a controlling server. The server conducts measurements according to a list of scheduled tasks and stores the primary data
or initial results in a remote centralized database. The description of an exemplary set of full-field sensors including IP
and thermovision camera, 2D and 3D digital image correlation systems, and grating interferometry based extensometers
is provided. Three different measurement tasks performed by means of this systems are presented in details.
In this paper a distributed intelligent system for civil engineering structures on-line measurement, remote monitoring,
and data archiving is presented. The system consists of a set of optical, full-field displacement sensors connected to a
controlling server. The server conducts measurements according to a list of scheduled tasks and stores the primary data
or initial results in a remote centralized database. Simultaneously the server performs checks, ordered by the operator,
which may in turn result with an alert or a specific action.
The structure of whole system is analyzed along with the discussion on possible fields of application and the ways to
provide a relevant security during data transport. Finally, a working implementation consisting of a fringe projection,
geometrical moiré, digital image correlation and grating interferometry sensors and Oracle XE database is presented.
The results from database utilized for on-line monitoring of a threshold value of strain for an exemplary area of interest
at the engineering structure are presented and discussed.
The paper deals with design and implementation of an optical extensometer based on grating (moire) interferometry, for
large engineering construction monitoring. The paper presents the principles of the grating interferometry and the
construction of miniaturized and portable version of grating interferometer and its implementation for out-door
measurement directly at civil engineering structures. The paper presents also a concept of the low-cost full-field optical
extensometer.
Current design, analysis and control engineering applications require effective experimental methodologies and tools
for determination of displacement and strain fields as well as material characterization. One of the most important
problem in engineering objects is proper design and quality of joints between elements in the form of welds, glued
and riveted joints and many others. Specificly the fatigue and fracture mechanics problems in joints are difficult
to analyze numerically, therefore they need experimental support. In the paper we present the results of static, dynamic
and fatigue experiments performed by grating (moire) interferometry systems. These full-field optical extensometers
provide information about in-plane displacement field (u,v) and strain fields (εx, εy, γxy) in the region of a joint subjected
to various modes of loads. It is shown that proper design of full-field extensometer (insensitivity to vibration, good
quality of interferogram, automatic analysis of long series of interferograms) allows to use it efficiently directly at
conventional loading machine in workshop environment and for long term fatigue tests.
In the paper we present results of studies of: conventional laser welds (static, fatigue tests), friction stir weld (static tests),
riveted joint (static, fatigue tests). The methodology of determination of local material constants in different zones
of a joint (inc. Poisson ratio, Young’s modulus) is given. The future trends in hybrid experimental-numerical analysis
of joints in conventional and novel material are discussed.
The principles of operation and optomechanical design of novel optical extensometer OPEX for tensile testing machines is presented. The system provider on-line strain measurements performed at an arbitrary measurement base. OPEX is integrated with a tensile loading machine so it can be used for active controlling of the machine setup. The applicability of the system is demonstrated by determination of elongation of various mechanical samples subjected to uniaxial tensile tests.
Results on extended studies on mechanical properties of polarimetric fiber-optic smart structures are presented. The smart structure consists of highly birefringent fiber embedded in an epoxy cylinder.
In the paper the concept of interactive implementation of grating interferometry and FEM is proposed in order to provide additional information to properly design and control both numerical and experimental procedures. At first the information from global FEM approximate model is used to design interferogram and adjust experimental setup. Having the best fitted experimental conditions, the measurement is performed. The results are used to improve the FEM parameters e.g. size and shape of FEM grid and fit local experimental data to modified FEM model. To provide the proper experimental tool, grating interferometry with two-channel acquisition module (for instantaneous u and v displacement measurement) is applied. The concept is tested on the examples of analysis of bending ceramic-to-metal joint and laser beam weldment under tensile semiaxial load.
Electronic speckle pattern shearing interferometry (ESPSI) allows for the measurement of displacement derivative maps. To monitor the stress/strain state of an object surface and its material properties, it is necessary to measure more than one displacement derivative map. The conventional configuration of ESPSI has been modified by parallel adaptation of Michelson shearing interferometers and an optoelectronic/image processing head with the capability of simultaneous capturing of 2 images. The automatic analysis of speckle fields is performed by temporal phase stepping method with the separation of the information by orthogonal polarization states. In the paper the opto-mechanical and electronic configuration of the system is presented. The experimental results obtained in the modified ESPIS system, when applied to determination of shear strain in a tensile loaded aluminium specimen are also presented.
High sensitivity, grating interferometry system (AGI) with automatic fringe pattern analyzer is shown as the effective experimental tool for material macro and micro structure studies (the smallest grains which behavior may be monitored in this system reach 20 micrometers ). The applications of AGI system for non-homogeneous plastic strain studies of bicrystal and polycrystalline aluminum and steel materials are presented and discussed.
The paper introduces an optoelectronic/image processing module, OIMP, which enables more convenient implementation of full-field optical methods of testing into industry. OIMP consist of two miniature CCD cameras and optical wavefront modification system which recombines the beams produced by opto-mechanical measurement system and images fringe patterns on the CCD matrices. The modules makes possible simultaneous registration of there monochromatic images as R,G,B components of color video signal by means of signal frame grabber or by VCR on video tape. This enables convenient and inexpensive storage of large quantities of data which may be analyzed by spatial carrier phase shifting method of automatic fringe pattern analysis. THe usefulness of OIMP is shown by two examples: u and v in-plane displacement simultaneous analysis in grating interferometry system and complex shape determination by fringe projection systems.
High-sensitivity, automatic grating interferometry (AGI) system is shown as the effective experimental tool for the material microstructure studies. Two interferometers, laboratory AGI for static and portable AGI for dynamic loading of the specimen are presented. The full methodology of a sample preparation, measurement and data analysis process with special attention paid to combining the information about grain borders and displacement/strain fields distribution is described. The experimental displacement fields obtained at the borders between grains in bicrystal, tricrystal, and polycrystal aluminum alloy are presented. The strain maps of tricrystal sample are presented and discussed.
The portable, grating interferometer for automatic u- and v- displacement measurements is presented. The interferometer modifications, including registration of interferograms by CCD camera and implementing the phase shifting device, are described. The method for fringe pattern analysis using video recorder and spatial carrier phase stepping algorithm is introduced and discussed. The examples of modified interferometer application in fracture mechanics are given.
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