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362 results about "Digital image correlation" patented technology

Digital image correlation and tracking is an optical method that employs tracking and image registration techniques for accurate 2D and 3D measurements of changes in images. This method is often used to measure full-field displacement and strains, and it is widely applied in many areas of science and engineering, with new applications being found all the time. Compared to strain gages and extensometers, the amount of information gathered about the fine details of deformation during mechanical tests is increased due to the ability to provide both local and average data using digital image correlation.

High-low temperature dynamic cold-hot circulation thermodynamic test system

The invention discloses a high-low temperature dynamic cold-hot circulation thermodynamic test system suitable for mechanics performance testing under a high-low temperature environment. A test box adopts a design of an inner cavity and an outer cavity; inner and outer cavity baffles are provided with four air outlets from top down and air suction holes in the center; the test box further comprises an optical strain observation window, a defrosting air heater and a multi-point direct-current illumination source; and in addition, the test system further comprises a dual-output PID (Proportion Integration Differentiation) controller, a DIC (Digital Image Correlation) full strain measurement instrument and an automatic switchover liquid nitrogen refrigerating system. According to the high-low temperature dynamic cold-hot circulation thermodynamic test system, the defects that the conventional thermal steady state test system has no thermal transient state and thermal circulation functions and liquid nitrogen cannot be fed without interruption due to limitation of liquid nitrogen container volume on low-temperature refrigeration are solved, and the technical problems of interference and the like of high-temperature hot wave impact and low-temperature frost fog on full strain measurement are solved at the same time, so that the purposes of obtaining the mechanical performance of a test material under the high-low temperature environment in the processes of thermal steady state, thermal transient state, cold-hot circulation and the like and synchronously measuring a sample strain field are achieved.
Owner:TSINGHUA UNIV

System and method for measuring residual stress in real time

InactiveCN102072877AReal-time online drilling non-contact full-field measurementEasy to operateUsing mechanical meansMaterial analysisElectric machineryEngineering
The invention relates to a system and a method for measuring residual stress in real time. The method comprises the following steps of: performing three-dimensional surface coordinate reconstruction on a test piece by three-dimensional digital image correlation, performing related research on a speckle image at the periphery of a hole before and after drilling the test piece, and calculating a three-dimensional displacement field before and after drilling; automatically feeding an electric spindle precisely through control over a stepping motor by a stepping motor controller and the translation of a worm gear and worm mechanism according to the drilling depth of the test piece; and calculating the residual stress of the test piece according to planar assumption of a drilling area of a curved surface by combining a theoretical formula for measuring the residual stress during drilling. The system can drill the hole precisely in real time, and measures the residual stress of the test piece with depth change in a stepping mode. The system and the method for measuring the residual stress have the advantages of real-time property, high precision, non-contact, whole-field displacement measurement, flexibility and convenience of operation, and the like.
Owner:TSINGHUA UNIV

Stress micro mechanical test cell, device, system and methods

The invention provides a stress micro mechanical system for measuring stress and strain in micro- and nano-fibers tubes, and wires as well as for measuring the interface adhesion force and stress in nanofibers and nanotubes embedded in a polymer matrix. A preferred system of the invention has a substrate for supporting a MEMS fabrication. The MEMS fabrication includes freestanding sample attachment points that are movable in a translation direction relative to one another when the substrate is moved and a sample is attached between the sample attachment points. An optical microscope images surfaces of the MEMS fabrication. Software conducts digital image correlation on obtained images to determine the movement of the surfaces at a resolution much greater than the hardware resolution of the optical microscope. A preferred method for measuring stress and strain in micro- and nano-fibers, tubes, and wires, and/or measuring the force required to pull-out individual micro- and nano-fibers, tubes, and wires from a polymer matrix and to therefore measure interfacial adhesion is also provided. In the method a sample is attached between freestanding platforms in a MEMS device. Relative translational movement between the platforms is created and motion of the platforms is imaged with an optical microscope. Mechanical and adhesion properties of the sample are determined by applying a digital image correlation algorithm to the image data.
Owner:THE BOARD OF TRUSTEES OF THE UNIV OF ILLINOIS

Optical method based high-speed aircraft hot surface full-field deformation measuring device

InactiveCN103558243ARealize deformation measurementGood test resultsUsing optical meansMaterial thermal analysisEngineeringRadiant heat
The invention provides an optical method based high-speed aircraft hot surface full-field deformation measuring device. The optical method based high-speed aircraft hot surface full-field deformation measuring device comprises a double-layer quartz lamp heating array, a thin-wall high-speed aircraft shell, a square transparent window, speckle particles, a thermocouple sensor, a signal amplifier, a temperature control computer, a driving power supply, a CMOS (Complementary Metal Oxide Semiconductor) camera, a lens, a narrow-band-pass optical filter and an image processing computer. In order to solve the problem of signal blockage caused by a high temperature radiant heat source between the CMOS camera and the surface of the high-speed aircraft shell, the vertical double-layer quartz lamp heating array is designed and the square transparent window with small area is formed, so that the optical camera lens can obtain images of the hot surface of the high-speed aircraft through the transparent window. The interference light ray of the quartz lamp heating array is shielded by selecting the narrow-band-pass optical filter with specific wave length, so that speckle images with high quality and no degeneration on the hot surface of the high-speed aircraft is obtained; a digital image correlation method is utilized for analyzing the speckle images under different temperatures to realize full measurement on the displacement field and the strain field of the hot surface of the high-speed aircraft in a high temperature environment.
Owner:BEIHANG UNIV

Mechanical property damage change measurement system and method for fragile materials under high-temperature and low-temperature load

InactiveCN105277428ACollection method is simpleHigh precisionStrength propertiesOriginal dataEngineering
The invention provides a mechanical property damage change measurement system and a mechanical property damage change measurement method for fragile materials under high-temperature and low-temperature load and belongs to fragile material measurement system and method. According to the system, a temperature stress coupling and loading device, an acoustic emission signal acquisition device and an image acquisition device are additionally arranged; the temperature stress coupling and loading device is utilized, and an experiment environment is relatively close to an actual environment, such as an environment of deep rocks, so that an experiment research result has a relatively good reference value; the image acquisition device is combined with a digital image correlation technology to obtain a partial displacement field and a strain field of a test piece in a testing process; and the measurement method has the advantages of non-contact and full-field measurement, wide application, high precision, simple acquisition manner on original data, low requirements on measurement environments, and convenience for realizing automation of the whole system. The acoustic emission signal acquisition device is used for detecting the formation and evolution of cracks through measuring cracking energy, so that the damages and attenuation of the fragile materials, such as the rocks, can be described macroscopically and microcosmically under a loading environment.
Owner:CHINA UNIV OF MINING & TECH

Ultrahigh temperature multi-dimensional multi-functional strain measurement system based on ultraviolet imaging DIC and measurement method

The invention relates to an ultrahigh temperature multi-dimensional multi-functional strain measurement system based on an ultraviolet imaging digital-image-correlation(DIC) method and measurement method. The strain measurement system comprises ultraviolet cameras (1,5), coaxial long-working distance microscopic lenses (7,15), a monochromatic source (2), narrowband pass filters (6,16) having wavelengths corresponding to that of the monochromatic source, and high temperature speckles or friction scratch spots on a surface of a test piece. A high temperature image observation furnace and a matched high temperature mechanical testing device are used to apply force and thermal load on the test piece having a rectangular cross section or a cylindrical surface. A coaxial ultraviolet light active illumination test piece is adopted, and the ultrahigh temperature multi-dimensional multi-functional strain measurement system based on the ultraviolet imaging digital-image-correlation(DIC) method is used to acquire the surface image of the test piece. By adopting the DIC method, the two-dimensional or three-dimensional measurement of the high-precision real-time millimeter to micron-level visual field of the strain of the surface of the test piece is carried out. A principle is simple, and a structure is compact. By adopting cooperation between a high temperature image furnace and a high temperature stretching device, the real-time, high-precision measurement of the deformation of the surface of the test piece and the mechanical performance of the test piece in environment at a temperature in a range from indoor temperature to ultrahigh temperature of 2000 DEGC is carried out.
Owner:BEIHANG UNIV

Mechanical sealing end surface deformation measurement system based on binocular vision DIC and measurement method thereof

InactiveCN104634266ARealize full-field measurementAvoid the downside of measuring in pointsMaterial strength using tensile/compressive forcesUsing optical meansFull fieldThree dimensional shape
The invention discloses a mechanical sealing end surface deformation measurement system based on binocular vision DIC and a measurement method thereof. The system comprises a mechanical sealing test device, high-speed digital cameras, lenses, acquisition cards, a light source, a calibration plate, a support system, and a server for digital image acquisition and correlation analysis and processing. The measurement method altogether comprises eight steps. A speckle image on the surface of a mechanical sealing static ring in an operation condition can be acquired, the image can be analyzed and processed by directly using the binocular vision digital image correlation method, and thus, a three-dimensional shape on the surface of the mechanical sealing static ring, and a three-dimensional deformation field under effects of force and thermal load can be acquired. According to the method, the use is convenient, the measurement precision is high, the full-filed measurement problem of surface deformation under effects of force and thermal load of mechanical sealing can be effectively solve4d, and foundation is laid for making a research on key factors influencing mechanical sealing deformation and exploring measures for reducing deformation.
Owner:NANJING COLLEGE OF CHEM TECH

Method for measuring J integration of cracks on basis of digital-image correlation

The invention discloses a method for measuring the J integration of cracks on the basis of digital-image correlation, belongs to the field of fracture mechanics and engineering application and relates to the method for measuring the J integration of cracks on the basis of digital-image correlation. The method comprises the following steps: by a digital-image correlation technology, measuring and calculating a displacement field and a strain field under different loads on the surface containing crack defects, acquiring information of the displacement field and the strain field, and storing into an Excel; writing an MATLAB program, calling data information in the Excel, carrying out numerical-integration calculation and further obtaining the J integration value of the cracks. The method disclosed by the invention has the advantages that the digital-image correlation, an MATLAB technology and J-integration calculation are combined, the strain of a test piece with the cracks is acquired by the digital-image correlation technology, a calculation result of digital-image correlation is extracted by MATLAB, and numerical integration is calculated; the method has the advantages of high efficiency and strong practicability, is suitable for calculating various test pieces which contain micro-deformation cracks and have elasticity and small-range yield, and is strong in universality.
Owner:DALIAN UNIV OF TECH
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