Video Extensometer System with Reflective Back Screen

Abstract

The present disclosure describes systems and methods for making deformation (e.g., elongation and / or strain) measurements based on characteristics of a specimen using light originating from a single side of the specimen. A light source and an imaging device are arranged on a single side of the specimen relative to a rear screen, with the light source illuminating both the front surface and the rear screen of the specimen. The rear screen reflects the light to produce an outline of the specimen. The imaging device captures an image of one or more markers on the front surface of the specimen and measures the position of the markers during a test process. The imaging device also measures relative changes in the position of an edge of the specimen during a test process by analyzing the edges of the outline image produced by the reflective rear screen.

Description

[0001] Cross-reference to related applications

[0002] This application is a non-provisional patent application that claims priority to U.S. Provisional Patent Application No. 62 / 866,379, filed on June 25, 2019, entitled “Video Extensometer System with Reflective Rear Screen,” the contents of which are incorporated herein by reference in their entirety. Background Art

[0003] Camera-based vision systems have been implemented as part of materials testing systems to measure sample strain. These systems collect one or more images of the specimen, which are synchronized with other signals of interest (e.g., sample load, machine actuator / crosshead displacement, etc.). The images of the specimen can be analyzed to locate and track specific features of the specimen as the test progresses. This change in feature position allows calculation of localized sample deformation, and thus sample strain.

[0004] Conventional systems use backlit screens and / or multiple light sources to direct light onto multiple surfaces and / or sides of a specimen. Such systems require complex arrangements of lights and cameras, as well as one or more specialized backlit screens to locate and track features on the specimen. This increases cost, introduces errors in system setup, and requires intensive computing resources. Therefore, a more straightforward system for measuring the specimen under test is needed. Summary of the Invention

[0005] Disclosed herein are systems and methods for measuring deformation (e.g., elongation and / or strain) based on characteristics of a specimen using light originating from a defined viewpoint (e.g., a single side of the specimen). In some examples, a light source is disposed on a single side of the specimen relative to a rear screen, but is configured to illuminate both the front surface of the specimen and the rear screen, which is configured to reflect light from the light source to produce an outline of the specimen.

[0006] This technique allows the width of the specimen to be measured at multiple axial positions, offering the advantages of a "single-line" measurement technique. In some examples, a rear screen is used in conjunction with a single light source to define the outline of the specimen as viewed from an imaging device positioned on the same side of the specimen as the light source.

[0007] In disclosed examples, a single imaging device or camera captures images of one or more markers on the front surface of a specimen and measures the position of the markers during the test process. In some examples, the imaging device also measures the relative change in position of the specimen's edge during the test process by analyzing the edges of a silhouette image generated by a reflective rear screen. Furthermore, one or more image processing algorithms can be implemented to measure the specimen's width by identifying the specimen's transition edge, which appears as a dark outline in front of the illuminated rear screen.

[0008] It is therefore an object of the present disclosure to investigate further improvements in extensometer systems that employ light originating from a defined viewpoint and a single imaging device to capture light reflected from one or more markers and / or a reflective rear screen.

[0009] These and other features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the appended claims.

[0010] [Claims to be added by MHM] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The benefits and advantages of the present invention will become more apparent to those skilled in the relevant art after reviewing the following detailed description and accompanying drawings, in which:

[0012] Figure 1 is a block diagram of an example extensometer system according to aspects of the present disclosure.

[0013] Figure 2 According to aspects of the present disclosure, Figure 1 Example specimens measured in the extensometer system.

[0014] Figure 3A and Figure 3B According to various aspects of the present disclosure Figure 1

[0046] An alternative implementation of an example extensometer system.

[0015] Figure 4 yes Figure 1 A block diagram of an example implementation of an extensometer system.

[0016] The accompanying drawings are not necessarily drawn to scale. Where appropriate, similar or identical reference numerals are used to designate similar or identical components. DETAILED DESCRIPTION

[0017] The present disclosure describes systems and methods for performing deformation (e.g., elongation and / or strain) measurements based on characteristics of a specimen using light originating from a defined viewpoint (e.g., a single side of the sample). In some examples, a light source is disposed on a single side of the specimen relative to a rear screen, but is configured to illuminate both the front surface of the specimen and the rear screen, with the rear screen configured to reflect light from the light source to produce an outline of the specimen. In the disclosed examples, the light source can be employed to provide front and rear illumination for image capture of specimen features when combined with a vision-based camera to perform deformation measurements. In the disclosed examples, the features can include the size, shape, and / or absolute or relative position of markers and / or specimen edges.

[0018] As described herein, material testing systems, including those that apply tension, compression, and / or torsion, include one or more components that cause displacement and / or bear weight to apply and / or measure stress on a specimen. In some examples, a video extensometer system is employed in sample strain testing, which may include one or more of: collecting high-resolution images, providing the images to an image processor, analyzing the images to identify one or more sample characteristics corresponding to deformation, displacement, or strain values, and generating an output corresponding to the characteristics. In the disclosed examples, features identified from one or more collected images are compared to one or more sources, such as a threshold list, a comparison of features from previously collected images (i.e., before the test). In some examples, the values ​​of the identified characteristics may be applied to one or more algorithms to generate an output corresponding to the deformation, displacement, or strain value associated with the specimen.

[0019] Video processing with an extensometer may include an external machine vision imaging device connected to a processing system or computing platform and / or video processing hardware and using software and / or hardware to convert the data from the camera into electrical signals or having a software interface that is compatible with the materials testing system.

[0020] As disclosed herein, a camera-based image capture (e.g., visual or video) system is implemented in a materials testing system for measuring strain on a specimen. Such a system collects multiple images of the specimen being tested (e.g., during a test process), where the images are synchronized with other signals of interest for the test (such as specimen load, machine actuator and / or crosshead displacement, etc.). The sample images are analyzed by an algorithm (e.g., in real time and / or after the test) to locate and track specific sample features as the test proceeds. For example, changes in the position, size, shape, etc. of such features allow calculation of specimen deformation, which in turn leads to analysis and calculation of specimen strain.

[0021] The sample features can correspond to markers and / or patterns applied to the surface of the specimen facing the imaging device. For example, image analysis can be performed by the extensometer system (e.g., via one or more processors) to determine a first or initial position of the markers, thereby tracking the markers as they move (e.g., relative to each other) while the test is conducted. Multiple markers can be applied to the surface of the specimen facing the imaging device. For example, relative motion of paired groups is used to measure length-based strain measurements (i.e., axial markers, lateral markers, etc.). Similar tracking and analysis techniques can also be applied to quasi-random speckle patterns of markers (e.g., by digital image correlation (DIC) techniques).

[0022] As explained here, conventional systems employ dedicated and precisely controlled backlighting, which involves creating a uniformly illuminated background directly behind the specimen when viewed by the extensometer system imaging device (e.g., using an actively illuminated back screen). The specimen then appears as a silhouette against the bright background, and the camera is now able to see a clear delineation of the specimen edge using algorithms applied to make accurate specimen width measurements, and thus calculate lateral specimen width deformation during testing.

[0023] The invention described in the following sections provides an active illumination solution that enables establishing appropriate illumination conditions for the front and background of a sample using a single active illumination element.

[0024] Conventional video extensometers used to track and measure markers on a sample surface can use polarizing filters between the front light and the sample, and between the sample and the imaging lens. This arrangement makes the marker appear bright against the dark specimen surface. Such systems use image processing algorithms to determine the marker's position on the front of the sample, thereby calculating the instantaneous sample gauge length and the change in sample gauge length relative to its value at the start of the test (i.e., axial and / or lateral deformation).

[0025] Conventional video extensometers can also track and measure the edges of a sample. For example, the specimen is outlined against a brightly illuminated background, appearing dark to the camera. Image processing algorithms then determine the sample's edges and calculate the sample's width and the tracked change in width compared to its initial width at the start of the test (i.e., lateral deformation).

[0026] As described herein, conventional video extensometers that measure specimen width require precisely controlled background lighting conditions. This is achieved by including an active backlight system (with its associated cost, installation requirements, and cable management system). In the case of video extensometers that will be used to measure features from the front sample surface (e.g., axial strain markers) as well as sample width (e.g., strain based on a transverse sample edge), the current limitation is the need for two light sources: one to illuminate the front face of the specimen and one to generate the necessary background illumination to provide a dark sample outline for edge detection.

[0027] The present disclosure provides improvements over conventional systems by using light from a single direction and / or a single light source to illuminate the specimen and provide a background for the specimen. The disclosed video extensometer system also employs an imaging device to capture images of the specimen during the test process to measure one or both of the specimen's front surface (e.g., one or more markers and / or patterns to calculate axial and / or transverse strain and / or generate a strain map) and edge-based measurements (e.g., calculating strain based on changes in specimen width).

[0028] In some examples, a single light source (or multiple light sources arranged on a single side of the specimen relative to the back screen) is used to perform two distinct lighting tasks within the testing system. The light source provides uniform illumination to the surface of the specimen facing the light source. In some examples, the light source provides light sufficient to illuminate both the surface of the specimen and the back screen directly to the surface (e.g., at a 90-degree angle to the surface) of the specimen. In this way, the markings and / or patterns applied to the surface are directly illuminated by the light source. In addition, the light source provides illumination for the reflective (i.e., passive) back screen, which in turn provides a bright background against which the sample is outlined and contrasted.

[0029] In some examples, the light source is arranged at a non-orthogonal angle to one or both of the specimen and the back screen. In such examples, the material and / or surface of one or both of the marker, pattern, or back screen can be configured to reflect incident light to the image capture system. For example, the image capture system can be arranged co-linearly with the light source and / or at an angle complementary to the light source (i.e., relative to the angle of incidence on one or both of the specimen or back screen).

[0030] The arrangement of components in the disclosed extensometer system utilizes a single active illumination source to capture both front- and back-illuminated specimen features. Backlighting sufficient to produce a dark outline of the specimen is achieved by adding a simple, low-cost, passive rear screen. This offers advantages over conventional designs that require a costly second active backlight source.

[0031] Furthermore, by adjusting the absolute position and angular orientation of the camera, light source, specimen, and / or rear screen, lighting variations and relative front-to-back brightness levels can be balanced.

[0032] Advantageously, accurate and consistent tracking of such markers / patterns is achieved by using a unique arrangement of components, without the need for dedicated and precisely controlled light sources for each sample and screen as required in conventional systems. Similarly, determination of lateral sample strain is achieved by identifying and tracking the edges of the specimen during testing.

[0033] In a disclosed example, an extensometer system for measuring deformation on a specimen includes one or more light sources for directing light onto a surface of the specimen and a screen, wherein the specimen is disposed between the one or more light sources and the screen; and an imaging device for capturing an image of the specimen when subjected to a stress-induced force via a testing system, the imaging device being configured to transmit the image to a processor for calculating the deformation of the specimen as a result of the stress-induced force.

[0034] In some examples, the processor is configured to receive two or more images of the specimen from the imaging device; and compare the first image to the second image to determine a change in a property of the specimen as a result of the stress-induced force.

[0035] In some examples, the specimen further includes one or more markers disposed on a surface of the specimen. In an example, the characteristic is one of the size, shape, or position of the one or more markers. In an example, the characteristic is one of the size, shape, or position of an edge of the specimen.

[0036] In some examples, deformation is determined in two orthogonal directions. In an example, deformation is determined in an axial direction and a transverse direction.

[0037] In some examples, the light source emits polarized light or infrared light. In some examples, the imaging device is configured to capture the polarized light or infrared light reflected from the screen or the specimen, wherein the markers reflect light from the light source to the imaging device, and the screen reflects the light to produce a dark outline of the specimen for edge analysis.

[0038] In an example, the light source or the imaging device further includes a filter.

[0039] In some examples, a connector input in communication with the auxiliary camera is used to receive an image of the specimen subjected to the stress-induced load. In an example, the processor includes a field programmable gate array. In an example, the processor and the field programmable gate array are located on a single circuit board.

[0040] In a disclosed example, an extensometer system for measuring deformation on a specimen includes: a testing system that subjects the specimen to one or more forces; one or more light sources for directing light onto a surface of the specimen and a screen, wherein the specimen is disposed between the one or more light sources and the screen; and an imaging device for capturing an image of the specimen while subjected to stress-induced forces via the testing system, the imaging device being configured to transmit the image to a processor for calculating deformation of the specimen as a result of the stress-induced forces.

[0041] In some examples, the screen further includes a collimating filter. In some examples, the collimating filter includes a first collimating filter and a second collimating filter, the first collimating filter being arranged on the screen in a first orientation, the second collimating filter being arranged on the screen in a second orientation different from the first orientation. In some examples, the screen further includes a reflective filter.

[0042] In a disclosed example, an extensometer system for measuring deformation on a specimen includes: a screen comprising a reflective surface; one or more light sources for directing light onto a surface of the specimen and the reflective surface of the screen, wherein the specimen is disposed between the one or more light sources and the screen; and an imaging device for capturing an image of the specimen when subjected to a stress-induced force via the testing system, wherein the image is generated by light reflected from one or more markers on the specimen, or by light reflected from the screen, to form an outline of the specimen.

[0043] In some examples, the imaging device is configured to transmit the images to a processor to calculate deformation on the reflective filter specimen as a result of the stress-induced forces. In an example, the testing system subjects the specimen to one or more forces to provide the stress-induced forces.

[0044] As used herein, "crosshead" refers to a component of a materials testing system that applies directional (axial) and / or rotational forces to a sample. A materials testing system can have one or more crossheads, and the crosshead can be located in any suitable position and / or orientation in the materials testing system.

[0045] Referring now to the accompanying drawings, Figure 1 1 is an example extensometer system 10 for measuring changes in one or more properties of a specimen 16 undergoing mechanical property testing. The example extensometer system 10 can be connected to, for example, a testing system 33 capable of performing mechanical testing on the specimen 16. The extensometer system 10 can measure and / or calculate changes in the specimen 16 undergoing, for example, a compression strength test, a tensile strength test, a shear strength test, a bending strength test, a flexural strength test, a tear strength test, a peel strength test (e.g., adhesive strength), a torsional strength test, and / or any other compression and / or tension test. Additionally or alternatively, the material extensometer system 10 can perform dynamic testing.

[0046] According to the disclosed example, the extensometer system 10 may include a testing system 33 for manipulating and testing the specimen 16, and / or a computing device or processing system 32 communicatively coupled to the testing system 33, a light source, and / or an imaging device, such as Figure 4 As further shown, the testing system 33 applies a load to the specimen 16 and measures a mechanical characteristic of the test, such as the displacement of the specimen 16 and / or the force applied to the specimen 16 .

[0047] The extensometer system 10 includes a remote and / or integrated light source 14 (eg, an LED array) to illuminate the specimen 16 and / or the reflective back screen 18. The extensometer system 10 includes a processing system 32 (see also Figure 4) and a camera or imaging device 12. In some examples, the light source 14 and the imaging device 12 are configured to transmit and receive infrared (IR) wavelengths; however, other wavelengths are also suitable. In some examples, one or both of the light source 14 or the imaging device 12 include one or more filters (e.g., polarization filters), one or more lenses. In some examples, a calibration routine (e.g., a two-dimensional calibration routine) is performed to identify one or more features of the specimen 16, and one or more markers 20 (including patterns of markers) are also used.

[0048] In some examples, rear screen 18 is configured to reflect light from light source 14 back toward imaging device 12. For example, the surface of rear screen 18 can be configured with properties that enhance reflection and / or direct reflected light toward the imaging device. Properties can include the shape of rear screen 18 (e.g., a parabolic configuration), and / or treatments that increase reflection (e.g., application of cube corner reflectors, reflective materials, etc.). Additionally or alternatively, a filter 30 can be arranged and / or applied to the surface to increase the amount of reflection and / or direct the reflected light in a desired direction and / or wavelength.

[0049] In some examples, filter 30 is configured as a collimating filter to direct as much reflected light as possible toward imaging device 12 and away from other nearby components. For example, the collimating filter directs light toward imaging device 12 regardless of the angle of incidence of light from light source 14 on specimen 16 and / or rear screen 18. In some examples, light source 14 and imaging device 12 are arranged on a single side of specimen 16 and / or rear screen 18. Thus, reflected light can be reflected off the screen at an angle away from imaging device 12. The use of a collimating filter concentrates the reflected light in a desired direction (e.g., toward the imaging device). In some examples, the collimating filter includes two or more collimating filters, wherein a first collimating filter is arranged on rear screen 18 in a first orientation and a second collimating filter is arranged on rear screen 18 in a second orientation (e.g., orthogonal to the first orientation).

[0050] In the disclosed example, the computing device 32 can be used to configure the test system 33, control the test system 33 and / or receive measurement data (e.g., transducer measurements such as force and displacement) and / or test results (e.g., peak force, fracture displacement, etc.) from the test system 33 for processing, display, reporting and / or any other desired purpose. The extensometer system 10 connects to the test system 33 and software using standard interfaces including Ethernet, analog, encoder, or SPI. This allows the device to be plugged into and used by existing systems without the need for specialized integration software or hardware. The extensometer system 10 provides axial and lateral encoder or analog information to the material testing machine 33 in real time. The real-time video extensometer 10 and the material testing machine 190 exchange real-time test data, including deformation, elongation, and / or strain data, with the external computer 32, which can be configured via wired and / or wireless communication channels. The extensometer system 10 provides measurement and / or calculation of deformation, elongation, and / or strain data captured from a specimen 16 undergoing testing in a materials testing machine 33 , which in turn provides stress and deformation, elongation, and / or strain data to a processor 32 .

[0051] As disclosed herein, the captured images are input from the imaging device to a processor 32 where one or more algorithms and / or lookup tables are used to calculate multiple axes of deformation, elongation, and / or strain values ​​for the specimen 16 (i.e., such as by monitoring the calculated change or percentage change in target spacing from images of markers 20 attached to the specimen 16). Following calculation, the data may be stored in memory or output to a network and / or one or more display devices, I / O devices, etc. (see also FIG. Figure 4 ).

[0052] Figure 2 is used in Figure 1 Example specimen 16 measured in the extensometer system 10 of FIG. For example, one or more markers are applied to the surface 28 facing the light source 14 and the imaging device 12. The fixture segment 26 is configured to be placed within the fixture of the testing system 33 (see also FIG. Figure 4 ) and applies a force to the specimen 16. For example, a cross member loader applies a force to the specimen 16 under test while the fixture grasps the specimen 16 or otherwise couples the specimen to the testing system 33. As indicated by double arrow 34, a force applicator, such as a motor, moves the crosshead relative to the frame to apply the force to the specimen 16. The force 34 pulling the fixture segments 26 apart from each other can cause the specimen 16 to stretch, causing the marker to move from the first position 20A to the second position 20B. Additionally or alternatively, the marker can change shape or size, which can also be measured by the processing system 32 based on the captured image. The force 34 can also cause an edge of the specimen to move from the first position 22A to the second position 22B. For example, in the first or initial position, the edge has a width 24A, which is reduced to a width 24B when the force 34 is applied.

[0053] Based on the captured images, the processing system 33 is configured to implement deformation, elongation, and / or strain during the measurement process. For example, to detect deformation, elongation, and / or strain on the specimen 16, the processing system 33 monitors the image provided by the imaging device 12. When the processing system 33 identifies a change in the relative position between two or more markers and / or the edge of the specimen 16 (e.g., compared to the initial position at the beginning of the crosshead movement), the processing system 33 measures the amount of change to calculate the amount of deformation, elongation, and / or strain on the specimen 16. As disclosed herein, the markers are configured to reflect light from a light source to the camera, and the screen then reflects the light to form a dark outline for edge analysis.

[0054] Figure 3A and Figure 3B An arrangement is shown for use with a video extensometer system 10 to measure one or both of axial deformation (based on changes in the markers 20 and / or marker pattern on the front surface 28 of the specimen 16) and lateral deformation (calculated from changes in the width of the specimen 16). The components of the video extensometer system 10 are shown in FIG. Figure 3A Shown in side perspective, Figure 3B 1 is shown in a top perspective view illustrating the general position of each component relative to the other components. As shown, these components include an imaging device 12 (e.g., a camera) configured to capture one or more images of a specimen 16 during a physical test (e.g., at regular intervals, continuously, and / or based on one or more thresholds associated with time, force, or other suitable test characteristics).

[0055] One or more light sources 14 emit light 36 to illuminate the surface 28 of the specimen 16 and the screen 18, which is arranged to face the rear surface of the specimen 16 opposite the light sources 14. Figure 3A As shown, light 36 incident on the marker 20 is reflected back as light 38 directed toward the imaging device 12. The reflected light 38 is captured by the imaging device 12 and provided to the processing system 33 to allow analysis of changes in the characteristics of the marker 20 during the testing process. In some examples, the light source 14 is arranged to direct light off-axis (e.g., at Figure 3B , and is angled to illuminate the front surface 28 of the specimen 16 and the rear screen 18.

[0056] As shown, a passive (i.e., lacking an active illumination source) rear screen 18 is positioned behind the specimen 16 and is designed to have reflective properties and is sized to present a uniformly illuminated background to the video extensometer imaging device 12. Figure 3BAs shown, light 36 incident on rear screen 18 is reflected back as light 40 directed toward imaging device 12. The reflected light creates a darkened outline of specimen 16, allowing imaging device 12 to capture images of edge 22 and changes thereto during the testing process.

[0057] The specimen 16 is positioned between the imaging device 12 and the rear screen 18. The specimen 16 has suitable markers 20 on the front surface 28 of the specimen 16. One or more images associated with the video extensometer system 10 are analyzed by a processing system 32 to execute a recognition algorithm that allows the markers 20 and specimen edge 22 of the specimen 16 to be continuously tracked and measured during testing.

[0058] Figure 4 yes Figure 1 A block diagram of an example extensometer system 10 is shown. Figure 1 As shown, the extensometer system 10 includes a testing system 33 and a computing device 32. The example computing device 32 may be a general purpose computer, a laptop computer, a tablet computer, a mobile device, a server, an all-in-one computer, and / or any other type of computing device. Figure 4 The computing device 32 includes a processor 202, which can be a general-purpose central processing unit (CPU). In some examples, the processor 202 can include one or more specialized processing units, such as an FPGA, a RISC processor with an ARM core, a graphics processing unit, a digital signal processor, and / or a system on a chip (SoC). The processor 202 executes machine-readable instructions 204, which can be stored locally at the processor (e.g., in an internal cache or SoC), in random access memory 206 (or other volatile memory), in read-only memory 208 (or other non-volatile memory, such as flash memory), and / or in a mass storage device 210. Example mass storage devices 210 can be hard drives, solid-state storage drives, hybrid drives, RAID arrays, and / or any other mass data storage devices. A bus 212 enables communication between the processor 202, RAM 206, ROM 208, the mass storage device 210, a network interface 214, and / or an input / output interface 216.

[0059] An example network interface 214 includes hardware, firmware, and / or software that connects the computing device 201 to a communication network 218, such as the Internet. For example, the network interface 214 may include IEEE 202.x compliant wireless and / or wired communication hardware for transmitting and / or receiving communication data.

[0060] Figure 4The example I / O interface 216 includes hardware, firmware, and / or software that connects one or more input / output devices 220 to the processor 202 for providing input to and / or output from the processor 202. For example, the I / O interface 216 may include a graphics processing unit for interfacing with a display device, a universal serial bus port for interfacing with one or more USB-compatible devices, FireWire, a Fieldbus, and / or any other type of interface. The example extensometer system 10 includes a display device 224 (e.g., an LCD screen) connected to the I / O interface 216. Other example I / O devices 220 may include a keyboard, a keypad, a mouse, a trackball, a pointing device, a microphone, an audio speaker, a display device, an optical media drive, a multi-touch screen, a gesture recognition interface, a magnetic media drive, and / or any other type of input and / or output device.

[0061] Computing device 32 may access non-transitory machine-readable media 222 via I / O interface 216 and / or I / O device 220 . Figure 4 Examples of machine-readable media 222 include optical discs (e.g., compact discs (CDs), digital versatile / video discs (DVDs), Blu-ray discs, etc.), magnetic media (e.g., floppy disks), portable storage media (e.g., portable flash drives, secure digital (SD) cards, etc.), and / or any other type of removable and / or mounted machine-readable media.

[0062] The extensometer system 10 also includes a testing system 33 coupled to the computing device 32. Figure 4 In some examples, test system 33 is coupled to a computing device via I / O interface 216, such as via a USB port, a Thunderbolt port, a FireWire (IEEE 1394) port, and / or any other type of serial or parallel data port. In some examples, test system 33 is coupled to network interface 214 and / or I / O interface 216 directly or via network 218 via a wired or wireless connection (e.g., Ethernet, Wi-Fi, etc.).

[0063] The testing system 33 includes a frame 228, a load cell 230, a displacement transducer 232, a cross-member loader 234, a material gripping device 236, and a control processor 238. The frame 228 provides rigid structural support for the other components of the testing system 33 that perform the test. The load cell 230 measures the force applied to the material under test by the cross-member loader 234 through the clamp 236. The cross-member loader 234 applies force to the material under test, while the material gripping device 236 (also referred to as a clamp) grips or otherwise couples the material under test to the cross-member loader 234. The exemplary cross-member loader 234 includes a motor 242 (or other actuator) and a crosshead 244. The crosshead 244 couples the material gripping device 236 to the frame 228, and the motor 242 moves the crosshead relative to the frame to position the material gripping device 236 and / or apply force to the material under test. Example actuators that may be used to provide force and / or motion to components of the extensometer system 10 include electric motors, pneumatic actuators, hydraulic actuators, piezoelectric actuators, relays, and / or switches.

[0064] While the example test system 33 uses a motor 242, such as a servo or direct drive linear motor, other systems may use different types of actuators. For example, hydraulic actuators, pneumatic actuators, and / or any other type of actuator may be used based on the requirements of the system.

[0065] Depending on the mechanical property being tested and / or the material being tested, example fixtures 236 include platens, clamps, or other types of clamping devices. The fixtures 236 can be manually configured, controlled by manual input, and / or automatically controlled by a control processor 238. The crosshead 244 and the fixtures 236 are operator-accessible components.

[0066] The extensometer system 10 may also include one or more control panels 250 including one or more mode switches 252. The mode switches 252 may include buttons, switches, and / or other input devices located on an operator control panel. For example, the mode switches 252 may include buttons that control the motor 242 to move (e.g., position) the crosshead 244 in small increments at a specific location on the frame 228, switches (e.g., foot switches) that control the grip actuator 246 to close or open the pneumatic grips 248, and / or any other input device that controls the operation of the test system 33.

[0067] An example control processor 238 communicates with the computing device 32 to, for example, receive test parameters from the computing device 32 and / or report measurements and / or other results to the computing device 32. For example, the control processor 238 may include one or more communication or I / O interfaces to enable communication with the computing device 32. The control processor 238 may control the cross-member loader 234 to increase or decrease the applied force, control the clamping device 236 to grasp or release the material under test, and / or receive measurements from the displacement transducer 232, the load cell 230, and / or other transducers.

[0068] The example control processor 238 is configured to implement a deformation, elongation, and / or strain measurement process while the specimen 16 is being tested in the testing system 33. For example, to detect deformation, elongation, and / or strain on the specimen 16, the control processor 238 monitors images provided by the imaging device 12. When the control processor 238 identifies a change in the relative position between two or more markers 20 and / or the edge 22 of the specimen 16 (e.g., compared to the initial position when the crosshead 244 begins moving), the control processor 238 measures the change to calculate the amount of elongation and / or strain on the specimen 16. For example, the real-time video provided by the imaging device 12 captures the absolute position of the markers 20 and / or edge 22 and monitors their relative movement over the course of several images to calculate the deformation, elongation, and / or strain in real time. Stress data and deformation, elongation, and / or strain data are exchanged between the real-time video extensometer 10, the testing system 33, and the processing system 32, and are typically organized and displayed via the display device 224.

[0069] The present method and system can be implemented with hardware, software or a combination of hardware and software. The method and / or system of the present invention can be implemented in a centralized manner in at least one computing system, or in a distributed manner in which different elements are distributed among several interconnected computing systems. Any type of computing system or other device suitable for executing the method described herein is suitable. A typical combination of hardware and software can include a general-purpose computing system with a program or other code that controls the computing system when loaded and executed so that it executes the method described herein. Another typical implementation can include a dedicated integrated circuit or chip. Some implementations can include a non-transitory machine-readable (e.g., computer-readable) medium (e.g., a flash drive, an optical disc, a magnetic storage disk, etc.) having one or more lines of code that can be executed by a machine stored thereon, so that the machine executes the process as described herein. As used herein, the term "non-transitory machine-readable medium" is defined to include all types of machine-readable storage media and excludes propagation signals.

[0070] As used herein, the terms "circuit" and "circuitry" refer to physical electronic components (i.e., hardware) and any software and / or firmware ("code") that can configure, be executed by, or otherwise be associated with the hardware. As used herein, for example, a particular processor and memory may constitute a first "circuit" when executing a first one or more lines of code, and a second "circuit" when executing a second one or more lines of code. As used herein, "and / or" means any one or more of a plurality of items in a list connected by "and / or". As an example, "x and / or y" means any element in the three-element set {(x), (y), (x, y)}. In other words, "x and / or y" means "one or both of x and y". As another example, "x, y and / or z" means any element in the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" means "one or more of x, y and z". As used herein, the term "exemplary" means serving as a non-limiting example, instance, or illustration. As used herein, the terms "for example" and "such as" provide a list of one or more non-limiting examples, instances, or illustrations. As used herein, whenever a circuit system includes the necessary hardware and code (if necessary) to perform a function, the circuit system is "operable" to perform the function, regardless of whether performance of the function is disabled (e.g., by a user-configurable setting, a factory trim, etc.).

[0071] Although the present method and / or system has been described with reference to specific implementations, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present method and / or system. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the present disclosure without departing from the scope of the present disclosure. For example, the systems, frames and / or other components of the disclosed examples may be combined, divided, rearranged and / or modified in other ways. Therefore, the present method and / or system is not limited to the specific implementations disclosed. On the contrary, the present method and / or system will include all implementations that fall within the scope of the appended claims, both literally and under the doctrine of equivalents.

Claims

1. An extensometer system for measuring deformation on a specimen, comprising: one or more infrared light sources for directing infrared light onto a surface of a specimen and a screen comprising a collimating filter, wherein the specimen is disposed between the one or more infrared light sources and the screen; as well as an imaging device for capturing an infrared light image of the specimen when subjected to a stress-induced force via a testing system, the imaging device being configured to transmit the infrared light image to a processor for calculating a deformation of the specimen as a result of the stress-induced force; The collimating filter is configured to direct infrared light reflected from the surface of the sample toward the imaging device.

2. The extensometer system of claim 1 , further comprising a processor configured to: receiving two or more images of the specimen from the imaging device; and The first image is compared to the second image to determine changes in properties of the specimen as a result of the stress-induced forces.

3. The extensometer system of claim 2, wherein the specimen further comprises one or more markers disposed on a surface of the specimen.

4. The extensometer system of claim 3, wherein the characteristic is one of a size, a shape, or a position of the one or more markers.

5. The extensometer system of claim 2, wherein the characteristic is one of a size, a shape, or a position of an edge of the specimen.

6. The extensometer system of claim 1 , wherein the deformation is determined in two orthogonal directions.

7. The extensometer system of claim 3 , wherein the imaging device is configured to capture infrared light reflected from the screen or the specimen, wherein the marker reflects light from the light source to the imaging device and the screen reflects light to produce a dark outline of the specimen for edge analysis.

8. The extensometer system of claim 1, wherein the infrared light source or the imaging device further comprises a filter.

9. The extensometer system of claim 1 further comprising a connector input in communication with an auxiliary camera for receiving an image of a specimen subjected to a stress-induced load.

10. The extensometer system of claim 1, wherein the processor comprises a field programmable gate array.

11. The extensometer system of claim 1 , wherein the processor and field programmable gate array are located on a single circuit board.

12. An extensometer system for measuring deformation elongation / strain on a specimen, comprising: a testing system that subjects the specimen to one or more forces; one or more infrared light sources for directing infrared light onto a surface of the specimen and a screen comprising a collimating filter, wherein the specimen is disposed between the one or more infrared light sources and the screen; as well as an imaging device for capturing an infrared light image of the specimen when subjected to a stress-induced force via a testing system, the imaging device being configured to transmit the infrared light image to a processor for calculating a deformation of the specimen as a result of the stress-induced force; The collimating filter is configured to direct infrared light reflected from the surface of the sample toward the imaging device.

13. The extensometer system of claim 12, wherein the collimating filter comprises a first collimating filter and a second collimating filter, the first collimating filter being arranged on the screen in a first orientation, the second collimating filter being arranged on the screen in a second orientation different from the first orientation.

14. The extensometer system of claim 12, wherein the screen further comprises a reflective filter.

15. An extensometer system for measuring deformation on a specimen, comprising: screens including reflective surfaces; one or more light sources for directing light onto a front surface of the specimen and a reflective surface of the screen, wherein the specimen is disposed between the one or more light sources and the screen, wherein the one or more light sources are arranged to direct light off-axis and at an angle relative to the screen and the specimen to illuminate both the front surface of the specimen and the screen; and An imaging device for capturing an image of a specimen while subjected to a stress-induced force via a testing system, wherein the image is produced by light reflected from one or more markers on the specimen or from a screen to form an outline of the specimen.

16. The extensometer system of claim 15, wherein the imaging device is configured to transmit the image to a processor for calculating deformation on the specimen as a result of the stress-induced force.

17. The extensometer system of claim 15, further comprising a testing system that subjects the specimen to one or more forces to provide the stress-inducing force.

18. An extensometer system comprising any one or any combination of the technical features of claims 1-11.

19. An extensometer system comprising any one or any combination of the technical features of claims 12-14.

20. The extensometer system of claim 15, wherein: The imaging device is arranged at an angle based on the angle of incidence of light on one or both of the specimen or the screen.

Images