1413 results about "Strain measurement" patented technology

The present invention is directed toward a fiber optic position and shape sensing device and the method of use. The device comprises an optical fiber means. The optical fiber means comprises either at least two single core optical fibers or a multicore optical fiber having at least two fiber cores. In either case, the fiber cores are spaced apart such that mode coupling between the fiber cores is minimized. An array of fiber Bragg gratings are disposed within each fiber core. A broadband reference reflector is positioned in an operable relationship to each fiber Bragg grating wherein an optical path length is established for each reflector/grating relationship. A frequency domain reflectometer is positioned in an operable relationship to the optical fiber means. In use, the device is affixed to an object. Strain on the optical fiber is measured and the strain measurements correlated to local bend measurements. Local bend measurements are integrated to determine position or shape of the object.

A tissue ablation device has a handle and an ablation head coupled to the handle. The ablation head has a first jaw, a second jaw, and an ablative element coupled to at least one of the first and second jaws. A thickness measurement device may be coupled to the ablation device to indicate the distance separating the first and second jaws. Further, a force measurement device may be coupled to the ablation device to measure the force being applied by the first and second jaws to a piece of tissue. Further, a strain measurement device may be coupled to the ablation device to indicate the strain resulting in a piece of tissue disposed between the first and second jaws when a stress is applied to the tissue.

The present invention is directed toward a fiber optic position and shape sensing device and the method of use. The device comprises an optical fiber means. The optical fiber means comprises either at least two single core optical fibers or a multicore optical fiber having at least two fiber cores. In either case, the fiber cores are spaced apart such that mode coupling between the fiber cores is minimized. An array of fiber Bragg gratings are disposed within each fiber core and a frequency domain reflectometer is positioned in an operable relationship to the optical fiber means. In use, the device is affixed to an object. Strain on the optical fiber is measured and the strain measurements correlated to local bend measurements. Local bend measurements are integrated to determine position and/or shape of the object.

Methods for evaluating motion of a cardiac tissue location, e.g., heart wall, are provided. In the subject methods, timing of a signal obtain from a strain gauge stably associated with the tissue location of interest is employed to evaluate movement of the cardiac tissue location. Also provided are systems, devices and related compositions for practicing the subject methods. The subject methods and devices find use in a variety of different applications, including cardiac resynchronization therapy.

A disc opener unit for an agricultural implement has a down pressure adjustment device that automatically adjusts the amount of down pressure applied on a furrowing disc based on strain measurements taken by a strain gauge or load cell. The strain gauge, which may be mounted to an arm that is used to set the position of a depth setting gauge wheel, provides feedback to a processor that in turn controls the amount of hydraulic fluid in a hydraulic cylinder to adjust the down force applied on the disc. The amount of down pressure is therefore adjusted in substantially real-time in response to changes in field conditions, which improves furrow depth consistency and reduces wear on the gauge wheel and its components.

Strain gauges are mounted on each crank arm of the bicycle and provide a measure of the torque applied to each crank arm. In a preferred embodiment, strain gauges are mounted on opposite edges of each crank arm, which includes a self-contained power, electrical circuitry, and a wireless transmitter for transmitting the strain measurement information to a main controller. The main controller includes a wireless transceiver for transmitting and receiving data from both the left and right crank arms and external devices. Memory is also included for storing such data for subsequent analysis to determine the individual leg performance of a cyclist during a race or training session.

A monitoring system is provided, which may include a structural component configured to undergo mechanical loading and a wireless node attached to the structural component. The node may include a strain sensing device configured to measure strain experienced by the structural component at the location of the node. The node may also include a processor configured to predict, based on the strain measurements, fatigue life of the structural component.

The invention discloses a graphene-based strain measuring or motion sensing device. The device is formed by the following steps: a layer or a plurality of layers of graphene film layers are combined on a flexibly insulating substrate; two ends of the graphene film layer are led out through electrodes and connected with ohmmeters, wherein the device is closely combined on the surface of an object to be detected, or a plurality of the devices are closely combined on the surface of the object to be detected, so that the strain variation measurement or motion monitoring can be realized. The device disclosed by the invention has the advantages of simple manufacturing method and capabilities of being suitable for large-scale production such as surface mounting and the like, and being applied to various types of environments and deformed surfaces; especially, the influence on the object to be detected is small, so that contactless measurement can be realized, and the device is suitable for monitoring biological motion. The invention further discloses a manufacturing method and a measuring method for the device.

The invention discloses a three-dimensional speckle strain measurement method, comprising: (1) speckle preparation; (2) camera calibration; (3) state information acquisition; (4) computational domaindesignation; (5) initial point setting; (6) speckle matching; (7) three-dimensional reconstruction; and (8) strain computation. By the above operation steps, the invention provides a three-dimensionalspeckle strain measurement method, which can effectively obtain high preciseness measurement results in measurements of material characteristic parameters such as full-field vibration measurement, dynamic strain measurement, high speed deformation measurement, fracture mechanics, impact excitation and dynamic material experiments. The invention has the characteristics of convenient measurement operation, high automation degree, exact and reliable results, high efficiency and non-contact measurement.

A bolt with a function of measuring strain, comprising a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, a translate circuit that amplifies a signal from the Wheatstone bridge circuit to convert the same into a digital signal, a transmitting circuit that transmits the digital signal outside the bolt, and a power circuit, by which electromagnetic wave energy received from outside the bolt is supplied as a power source for at least any one of the circuits.

The invention relates to an oil/gas well cement sheath sealing integrity testing device. The testing device comprises a pressure kettle and a simulation wellbore located in the pressure kettle. The testing device further comprises a pressure control system, a temperature control system, a fluid channeling detection system, a strain measuring system and a mud cake simulation system. The simulation wellbore comprises a casing pipe and a core located on the periphery of the casing pipe. An annular gap is formed between the sleeve and the core, and a cement sheath is formed in the annular gap. The upper ends and the lower ends of the casing pipe and the core are provided with an upper end cover and a lower end cover respectively. The temperature borne by the cement sheath under different downhole working conditions and complex loads from the casing pipe and a stratum can be truly simulated, and the process range covers well cementation at the oil/gas well drilling and completion stage and pressure tests, producing tests, circulating injection production, fracturing and other improvement working conditions in the production process. The influence rule of the cement sheath sealing integrity can be evaluated by changing the thickness of the cement sheath, the character of mud cakes, the maintenance temperature and other factors.

A reinforcement element, comprises at least one sensor fiber adapted for strain measurements based on stimulated Brillouin scattering within said sensor fiber. Furthermore, a system for monitoring strain within a structure comprises a reinforcement element comprising at least one sensor fiber adapted for strain measurements based on stimulated Brillouin scattering within said sensor fiber, a pump laser for coupling in laser radiation of a pump frequency into said at least one sensor fiber, a Stokes laser for coupling in laser radiation of a Stokes laser radiation into said at least one sensor fiber, wherein the pump frequency and the Stokes frequency are different from one another and wherein the frequency difference between the pump and Stokes frequencies is within the range of acoustical phonons within said sensor fiber, a sensor adapted to obtain a stimulated Brillouin backscattering signal, and a network analyzer adapted for determining the complex transfer function of the sensor fiber to determine a spatially resolved strain measurement.

A high sensitivity strain sensor that utilizes a micro-scale cavity built in a multi-layer structure, with a pair of interdigitalized capacitor incorporated on one of the layers, is described in this document. The device's capacitance changes produced by unattended deformations of the cavity can be used to measure the associated strain without using any movable electrodes. The sensor can be remotely energized from a radio frequency wave sent by a reader antenna to construct a battery-free wireless instrument. Changes on the sensor's resonant frequency are remotely detected so that a strain level is measured from fluctuations in the received signal. This detection method provides a simple, reliable and sensitive technique to measure small strain changes down to the pico-scale. Materials with a highly strain-dependant permittivity are integrated in the sensor to enhance its sensitivity. The proposed sensor consists of a simple planar structure. It can be used as the main component on low-cost, accurate and highly stable strain measuring instruments capable of monitoring very small strain levels. Furthermore, the sensor is passive, may be operated wirelessly, and can, thus, be used for remote long-term embedded strain detection.

The invention discloses a high-strength bolt axial force measuring device and measuring method. The measuring device comprises a pull rod, an axial force sensor, a force providing part and a support; the close end of the pull rod is provided with a connecting part for being connected with a high-strength bolt thread end, and the close and far ends of the pull rod are provided with a first match part and a second match part respectively; the first match part is in match contact with the close end face of the axial force sensor, the second match part and the far end of the force providing part act in a match mode, the far end of the support is mounted between the force providing part and the axial force sensor, and the close end of the support is used for being supported on a part connected with a high-strength bolt; and the high-strength bolt axial force measuring device also comprises a strain measuring part arranged on a nut. The measuring method comprises the steps of (1) mounting the strain measuring part on the axial outer face of the nut; 2, connecting the pull rod with the thread end of the high-strength bolt in the match mode; and 3 starting the force providing part to read the value of the axial force sensor at proper time according to the changing condition of the stain measuring part. The high-strength bolt axial force measuring device and method are accurate in measuring by directly measuring the axial force of the high-strength bolt.

A method of measuring strain in a test specimen comprises the steps of placing a pattern of marks on a surface of the test specimen, wherein the pattern of marks includes a plurality of target marks and a plurality of sets of coded marks, using the sets of coded marks to identify locations of at least two of the target marks, and using a change in distance between at least two of the marks to determine strain in the test specimen. An apparatus that performs the method is also provided.

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.

A method, apparatus and computer-readable medium for determining a deformation strain distribution of a member corresponding to a selected deformation mode is disclosed. Strain measurements are obtained at a plurality of sensors, wherein each strain measurement is related to a strain at a location of the member. A component of the strain related to a selected deformation mode for the obtained strain measurements is determined and a principal strain component and a secondary strain component for each of the determined components of the strain is determined. The determined principal strain component and secondary strain component are mapped to a surface of the member to determine the deformation strain distribution.

The invention discloses a method for determining the long-period strength of rock through a multistage stress staged loading creep mechanic test. The method comprises the following steps that the in-site sampling is carried out, and a rock core test piece is manufactured; the test piece is arranged into a rock three-axis rheological mechanic test instrument, and an axial stress and annular stress system is regulated to an initial value; the test piece is subjected to multistage stress staged loading creep mechanic test in a stress load control mode until a specimen is damaged, and in the process, the change of the axial compression stress and the annular volume expanding stress along with the time in the whole test process under the effects of different stress is measured; the change of the size of the test piece along with the time is calculated; a rock creep curve is drawn, and the weakening creeping stage and the steady-state creep stage of the creep curve under the effect of each stage stress load are judged; the steady-state creep speed under the effect of each stage of stress load is calculated, the relationship curve of the change of the axial, annular and size steady-state creep speed along with the stress level is drawn, a crossing point is determined, and the stress corresponding to the crossing point is the long-period intensity of the rock.

The invention researches the substantive characteristics of material deformation to aim at the practical problem of measuring real stress-real strain and discloses a real stress-real strain calculating model and a practical testing system: 1, based on the analysis on the deformation of a tension specimen, taking a unit body the special part of which is provided with characteristics as the object for the stress-strain analysis, building a unique full-deformation unit model, firstly solving the theory analysis problem of real stress-real strain, establishing a theory foundation and building a novel real stress-real strain calculating formula: Sigma i is equal to 4Fi/Pi d<2>I and Epsilon is equal to (d<2>0/d<2>i) minus 1; 2, adopting a machine visual technology and an image processing method to develop a practical software system and a practical hardware system that are compatible with the machine visual technology and the image processing method, and realizing the direct non-contact real stress-real strain measuring in real meaning; 3, the testing system includes a light source (1), CCD camera (2), an image acquisition card (3), a data acquisition card (4) and a material testing machine (5); 4,the software includes image capturing program, load data acquisition program and comprehensive calculation analysis program.

The invention provides a packaging method for a fiber grating sensitivity-increasing/decreasing strain sensor, belonging to the sensing technology field, which comprises a sensitivity-increasing/decreasing theory for the fiber grating strain sensor, a formula for sensitivity-increasing/decreasing coefficients, a sensor structure and a packaging method. The packaging method for a fiber grating strain sensor not only effectively protects the bare fiber grating, but also can change the strain sensitivity of the fiber grating; the sensitivity-increasing/decreasing coefficients can be customized according to the dimensions of the packaging materials in order to meet the requirements of different measurement. The invention has the advantages of that the fiber grating strain sensor based on the packaging method provides the monitoring means of large strain range and high measurement accuracy for the surface and internal strain measurement of large engineering structures.