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154 results about "Residual strain" patented technology

Residual strain is the permanent deformation that remains after removing the stress from a test sample. This deformation can be important for product design and material selection. Standard mechanical test procedures do not take into account the condition of the specimen after stress has been removed.

Fiber grating monitoring method for curing residual strain of composite materials

The invention provides a fiber grating monitoring method for the curing residual strain of composite materials. The method comprises the following steps: (1) manufacturing a sensor string comprising grating temperature sensors and grating temperature strain sensors; (2) embedding fiber grating sensors in to-be-monitored parts of a composite material in the process of layering the composite material; (3) reasonably selecting a molding process for the composite material, such as hot-pressing reactor, compression molding and the like; (4) cooling the composite material to room temperature after curing molding is performed and using a grating demodulation instrument to monitor the wavelength value of the highest reflection peak of a reflection spectrum of a fiber grating; and (5) utilizing epsilon=1/k epsilon((delta lambda B1/lambda B1)-(Delta lambda B2/lambda B2)) to calculate the curing residual strain of the composite material. The method can realize the measurement of the residual strain of key parts of the structure of the composite material on the premise of not destroying the structure, and has the advantages of stable reliable measured values and good repeatability; in addition, the embedded grating can continue to play a role in monitoring the structure health of the composite material. The method organically combines the digital manufacturing and the health monitoring of the composite material, thereby realizing the on-line monitoring for the manufacturing process of the composite material.
Owner:SHENYANG INST OF AERONAUTICAL ENG +1

Residual strain based after-damage bearing capacity estimation method of concrete beam bridge

ActiveCN106485029AResidual strain solutionAvoid nonlinear damage process analysisDesign optimisation/simulationSpecial data processing applicationsResidual strainEstimation methods
The invention provides a residual strain based after-damage bearing capacity estimation method of a concrete beam bridge. The method is characterized in that the residual strain ep of concrete in a stressed area of the concrete beam bridge which does not meet the requirement by assessing in a static load test according to the concrete damage elasticity modulus Er in the stressed area; the real strain and stress state of a section can be obtained according to the section load balance and plane surface deformation; the standard extreme bearing bending moment Mjj and design bearing bending moment Mdc are obtained according to the actually-measured concrete strength and section size; the damage degree can be determined according to the concrete residual strain, and thus the actual extreme bearing bending moment Mzj and the bending moment Mzc for normal use can be obtained. With the adoption of the method, the technical problems that the assessment of the bearing capacity of an existing concrete beam bridge is highly influenced by subjective factors, only the bridge performance under test load is assessed in the traditional static load test, and the real working state and bearing capacity of the concrete beam bridge cannot be obtained, can be solved.
Owner:BEIJING MUNICIPAL ENG RES INST

Device and method for measuring three-dimensional distribution of residual stress in metal microstructure

The invention discloses a device for measuring three-dimensional distribution of residual stress in a metal microstructure, which comprises an X-ray generating system, a microdiffraction and light path guide system, a work system, a detection system, a computer and a control system; the X-ray generating system generates X-rays with short wavelengths; the X-rays irradiate on points to be measured on a metal microstructural sample to be measured in the work system through the microdiffraction and light path guide system; then the X-rays enter the detection system through the microdiffraction and light path guide system after being subjected to diffraction by the sample; the detection system receives the X-rays entering the detection system for detection and sends obtained detection data to the computer; the computer takes analysis process on the received detection data to obtain residual strain and residual stress data of the point to be measured of the metal microstructral sample and take error analysis and parameter amendment; and after the test for the current point is finished, the computer sends a command to the control system for changing the detection point of the sample. According to the invention, the three-dimensional distribution of the residual strain and the residual stress in the penetrating range of the X-ray in a metal microstructure can be measured automatically and factually in a lossless way; therefore, the device provided by the invention is efficient and lossless and is convenient to operate.
Owner:SUZHOU UNIV OF SCI & TECH

Method for measuring residual stress on surface of metal sample based on micro indentation

The invention discloses a method for measuring residual stress on surface of a metal sample based on micro indentation. The method comprises the following steps: performing a micro indentation test on the surface of the sample by utilizing a Vickers microhardness tester, recording the indentation morphology by adopting a scanning electron microscope, and obtaining the nominal projection area and actual projection area of the indentation on the surface of the sample through calculation for diagonal length and side length of the micro indentation; obtaining a strength coefficient and strain hardening index of the material through a standard tensile test; and obtaining a theoretical formula for measuring the residual stress through an indentation method and containing the ratio of the actual projection area to the nominal projection area of the micro indentation, the strength coefficient and strain hardening index based on the hypothesis for the two-dimension isometric residual stress field on the surface of the sample, and further obtaining the residual strain and residual stress on the surface of the sample. The measurement method belongs to basically nondestructive or micro-damage measurement and has the advantages of low measurement cost, simplicity and convenience in operation and high measurement efficiency. If being combined with a portable high-power optical microscope with a distance measurement function, the method can be popularized and applied in the field of engineering.
Owner:UNIV OF SCI & TECH BEIJING

Rolling reduction acquisition method and device for upper-row rollers of roller-type stretch bend straightening machine

The invention discloses a rolling reduction acquisition method and device for upper-row rollers of a roller-type stretch bend straightening machine. The method is characterized in that relational expressions between residual strains of interlayers of strip steel during stretch bending and the relative bending curvatures of the strip steel at all straightening rollers, as well as between the residual strains of the interlayers of the strip steel during stretch bending and the relative tensile stresses of strip steel at all the straightening rollers are established through theoretical analysis; then the residual strains of the strip steel at all the straightening rollers are calculated according to given roller-type stretch bend straightening process parameters, and accumulated to work out the ductility of the strip steel, and the calculated ductility values and the actual ductility values are compared to realize optimal calculation of the rolling reduction of upper-row rollers of the roller-type stretch bend straightening machine. The rolling reduction acquisition method is definite and clear in principle, and simple and quick in calculation; the calculated results and the field measured values are identical; the rolling reduction of the upper-row rollers can be accurately matched with the speed difference between an inlet tension roller set and an outlet tension roller set, so that the ductility of the strip steel, which can be provided by the roller-type stretch bend straightening machine, conforms to the actual ductility, and accordingly, the strip steel is prevented from sliding.
Owner:WISDRI ENG & RES INC LTD +1
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