Calibration device for DIC system

Abstract

The utility model discloses a calibration device for a DIC system, which comprises a force standard machine and a strain standard plate used for non-contact three-dimensional strain measurement of the DIC system, and two ends of the strain standard plate are connected between an upper chuck and a lower chuck of the force standard machine through a universal hinge mechanism. The strain standard plate is provided with a double-optical-path laser interference system used for linear measurement and rotation angle measurement, and the double-optical-path laser interference system comprises a double-optical-path laser interferometer, and a spectroscope group and a reflector group which are vertically installed at the upper end and the lower end of the strain standard plate in an opposite manner. A measurement area is formed between the spectroscope group and the reflector group; and the double-light-path laser interferometer is used for carrying out linear measurement and rotation angle measurement between the spectroscope group and the reflector group. The calibration device has the advantages of being reasonable in structural design, convenient to operate and use, capable of calibrating the DIC measurement system and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to detection technical field, especially a kind of calibration device for DIC system. BACKGROUND

[0002] Non-contact three-dimensional strain measurement system (DIC system) is a kind of optical non-contact measurement object strain field image analysis method, it has wide measurement range, low to measurement environment (vibration isolation, light) requirement, non-contact and other characteristics.As a convenient and fast plate three-dimensional mechanics measurement analysis means, it has attracted more and more scholars at home and abroad, but, currently, the measurement result quantity accuracy and traceability of non-contact three-dimensional strain measurement system still lack related systematic calibration method and traceability system, so that the strain analysis means is often used for trend analysis.DIC system measurement error includes correlation algorithm, displacement characterization mode and other calculation principle errors, and measurement errors, among them, calculation principle error can be corrected by optimizing calculation algorithm, and measurement error needs to be calibrated by calibration device, therefore, it is urgent to design a calibration device for DIC measurement system calibration. SUMMARY

[0003] In view of the above technical problems, the technical problem to be solved by the utility model is: how to provide a DIC system calibration device with reasonable structure design, convenient operation and use, and capable of calibrating DIC measurement system.

[0004] In order to solve the above technical problems, the utility model adopts the following technical scheme:

[0005] A kind of calibration device for DIC system, including force standard machine, the strain standard plate for DIC system to carry out non-contact three-dimensional strain measurement, the two ends of the strain standard plate are connected between the upper and lower chuck of the force standard machine by universal hinge mechanism;Linear measurement and corner measurement are carried out on the strain standard plate Double optical path laser interference system is provided, and the double optical path laser interference system includes double optical path laser interferometer, and the light splitter group and mirror group vertically opposite and installed on the upper and lower ends of the strain standard plate, measurement area is formed between the light splitter group and mirror group;Double optical path laser interferometer is used to carry out linear measurement and corner measurement between the light splitter group and mirror group.

[0006] When in use, the DIC system to be calibrated measures the measurement area of the standard strain plate, at the same time, a double light path laser interferometer measures the measurement area between the mirror group and the beam splitter group, and a standard strain value is obtained, and the measurement results of the two are compared to obtain a calibration equation or a calibration coefficient, so as to correct the measurement value of the DIC system.

[0007] Further, the force standard machine comprises fixedly arranged upper and lower cross beams, one rotatably arranged lead screw is connected to each end of the upper and lower cross beams; a parallel arranged middle cross beam is further arranged between the upper and lower cross beams, and the middle cross beam is matched with the lead screws through lead screw nuts at both ends; and the ends of the two lead screws are connected with a lead screw driving mechanism.

[0008] Further, the lead screw driving mechanism comprises a servo motor and a planetary gear reducer, the input end of the planetary gear reducer is connected with the output end of the servo motor, the output end of the planetary gear reducer is provided with a driving synchronous pulley, the input end of the lead screw is provided with a driven synchronous pulley, and the driving synchronous pulley and the driven synchronous pulley are connected with a synchronous belt.

[0009] Further, the universal hinge mechanism comprises a hinge support fixedly installed on the upper cross beam or the lower cross beam through a flange seat, the hinge support is provided with two side-by-side arranged first lugs, and a connecting head is hingedly connected between the two first lugs through a hinge shaft, and a joint bearing is arranged at the connection between the connecting head and the hinge shaft.

[0010] In this way, the joint bearing between the connecting head and the hinge support can realize the universal connection between the connecting head and the hinge support.

[0011] Further, double lug joints are installed at both ends of the standard strain plate, one end of the double lug joint is provided with two side-by-side arranged second lugs, the standard strain plate is located between the two second lugs and is hingedly connected to the two second lugs through a penetrating bolt.

[0012] Further, the two sides of the standard strain plate are provided with gaskets sleeved on the bolts, so that the standard strain plate is located in the middle of the two second lugs.

[0013] In this way, the gasket can avoid the sliding of the standard strain plate on the bolt, so as to ensure the stability of the system.

[0014] Further, the second lug is provided with a through threaded hole and an inwardly arranged centering screw, and the two centering screws abut against the two sides of the standard strain plate.

[0015] In this way, by using two centering screws to abut against the strain gauge plate from both sides, the strain gauge plate can always be positioned in the exact center of the two second lugs, thereby improving the stability and reliability of the system.

[0016] Furthermore, an S-shaped force sensor is connected between the lower connector and the corresponding double-ear connector, and the upper connector is connected to the corresponding double-ear connector by threads.

[0017] In summary, this utility model has the advantages of reasonable structural design, convenient operation and use, and the ability to calibrate DIC measurement systems. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of this embodiment.

[0019] Figure 2 This is a schematic diagram of the stress standard plate.

[0020] Figure 3 This is a schematic diagram of the lower end connection structure of the stress standard plate.

[0021] Figure 4 This is a schematic diagram of the upper connection structure of the stress standard plate.

[0022] Figure 5 This is a calibration diagram. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the embodiments.

[0024] In practical implementation: such as Figures 1-4 As shown, a calibration device for a DIC system includes a force standard machine 1 and a strain standard plate 2 for non-contact three-dimensional strain measurement of the DIC system. The two ends of the strain standard plate 2 are connected between the upper and lower clamps of the force standard machine 1 via a universal hinge mechanism 3. A dual-path laser interferometry system 4 for linear and angular measurements is provided on the strain standard plate 2. The dual-path laser interferometry system 4 includes a dual-path laser interferometer 41 and a beam splitter group 42 and a reflector group 43 vertically mounted opposite each other at the upper and lower ends of the strain standard plate 2, forming a measurement area between the beam splitter group 42 and the reflector group 43. The dual-path laser interferometer 41 is used to perform linear and angular measurements between the beam splitter group 42 and the reflector group 43.

[0025] The force standard machine 1 comprises a fixedly arranged upper cross beam 11 and lower cross beam 12, both ends of the upper cross beam 11 and lower cross beam 12 are connected with a rotatably arranged screw rod 13; the upper cross beam 11 and lower cross beam 12 further have a parallel arranged middle cross beam 14, both ends of the middle cross beam 14 are connected with the screw rod 13 through screw rod nuts; the ends of the two screw rods 13 are connected with a screw rod driving mechanism. The screw rod driving mechanism comprises a servo motor 15 and a planetary gear reducer 16, the input end of the planetary gear reducer 16 is connected with the output end of the servo motor 15, the output end of the planetary gear reducer 16 is provided with a driving synchronous pulley 17, the input end of the screw rod 13 is provided with a driven synchronous pulley 18, the driving synchronous pulley 17 and the driven synchronous pulley 18 are connected with a synchronous belt.

[0026] As shown in Figure 3 and Figure 4 The universal hinge mechanism 3 comprises a hinge support 31 fixedly installed on the upper cross beam 11 or lower cross beam 12 through a flange seat, the hinge support 31 has two first lugs arranged side by side, a connecting head 32 is hingedly connected between the two first lugs through a hinge shaft, and a joint bearing is arranged at the connection between the connecting head 32 and the hinge shaft. Through the joint bearing between the connecting head and the hinge support, the universal connection between the connecting head and the hinge support can be realized.

[0027] Both ends of the strain standard plate 2 are provided with double lug connectors 5, one end of the double lug connector 5 has two second lugs arranged side by side, the strain standard plate 2 is located between the two second lugs and is hingedly connected to the two second lugs through bolts arranged in a penetrating manner. The strain standard plate 2 has gaskets 51 arranged on the bolts on both sides, so that the strain standard plate 2 is located in the middle of the two second lugs. In this way, the strain standard plate can be prevented from sliding on the bolts through the gaskets, thereby ensuring the stability of the system.

[0028] The second lug has a threaded hole arranged in a penetrating manner and has two centering screws 52 arranged inwardly, and the two centering screws 52 abut against both sides of the strain standard plate 2. In this way, the strain standard plate is abutted from both sides by the two centering screws, so that the strain standard plate is always located in the middle of the two second lugs, thereby improving the stability and reliability of the system. Meanwhile, the connecting head 32 located at the lower end is connected with the corresponding double lug connector 5 through an S-shaped force sensor 6, and the connecting head 32 located at the upper end is connected with the corresponding double lug connector 5 through threads.

[0029] In use, as shown in Figure 5The DIC system to be calibrated is used to measure the measurement area of the strain standard plate, and a double light path laser interferometer is used to measure the measurement area between the mirror group and the beam splitter group, so that the standard strain value is obtained, the measurement results of the two are compared, the calibration equation or the calibration coefficient is obtained, and the measurement value of the DIC system is corrected.

[0030] The measurement principle design of the DIC system calibration device is as follows:

[0031] The device generates single-axis tensile load by driving the moving beam through high-precision ball screws, universal hinge devices are arranged at the upper and lower ends of the strain standard plate, so that the strain standard plate is only subjected to axial force and is not subjected to additional torque. Figure 2 The laser source is installed below the strain standard plate, and the laser light path passes through the beam splitter and the interferometer installed on the positioning hanging plate.

[0032] The calculation formula is as follows:

[0033] The distance between the two positioning hanging plate top pins; The displacement change of the two positioning hanging plates under the axial load; The distance from the optical center point of the measurement mirror group to the middle surface of the strain standard plate; The relative angular displacement of the horizontal section of the two positioning hanging plates.

[0034] The calibration principle of the DIC system calibration device is as follows:

[0035] The measurement accuracy of the DIC system is affected by the calculation efficiency, the correlation algorithm and the displacement representation mode, the material surface speckle quality, the digital speckle imaging distortion, the perspective error and the off-plane displacement, the synchronization error of the two CCD cameras, the environment and the like.

[0036] The accuracy of the measurement result needs to be judged by comprehensively considering various influence factors of the DIC system, and the most direct comprehensive evaluation mode is to use other mature measurement technologies to manufacture a strain field with known characteristic quantity. The calibration device of the utility model is to use the laser interference principle, measure the standard strain value of the strain plate deformation. Then the DIC system measures the same strain field, and compares the measurement results of the two, obtains the calibration equation or calibration coefficient, and corrects the measurement value of the DIC system.

[0037] The above only describes the preferred embodiments of the utility model, and does not limit the utility model, any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A calibration device for a DIC system, characterized in that, The system includes a force standard machine (1), a strain standard plate (2) for non-contact three-dimensional strain measurement of the DIC system, and the two ends of the strain standard plate (2) are connected between the upper and lower clamps of the force standard machine (1) through a universal hinge mechanism (3); the strain standard plate (2) is provided with a dual-beam laser interferometer system (4) for linear measurement and rotation measurement, the dual-beam laser interferometer system (4) includes a dual-beam laser interferometer (41), and a beam splitter group (42) and a reflector group (43) vertically mounted on the upper and lower ends of the strain standard plate (2), forming a measurement area between the beam splitter group (42) and the reflector group (43); the dual-beam laser interferometer (41) is used to perform linear measurement and rotation measurement between the beam splitter group (42) and the reflector group (43).

2. The calibration device for a DIC system as described in claim 1, characterized in that, The force standard machine (1) includes a fixed upper crossbeam (11) and a lower crossbeam (12), and each end of the upper crossbeam (11) and the lower crossbeam (12) is connected to a rotatable lead screw (13); there is also a parallel middle crossbeam (14) between the upper crossbeam (11) and the lower crossbeam (12), and the two ends of the middle crossbeam (14) are respectively engaged with the lead screw (13) through lead screw nuts; the ends of the two lead screws (13) are connected to lead screw drive mechanisms.

3. The calibration device for a DIC system as described in claim 2, characterized in that, The lead screw drive mechanism includes a servo motor (15) and a planetary gear reducer (16). The input end of the planetary gear reducer (16) is connected to the output end of the servo motor (15). The output end of the planetary gear reducer (16) is provided with an active synchronous pulley (17). The input end of the lead screw (13) is provided with a driven synchronous pulley (18). A synchronous belt is connected to the active synchronous pulley (17) and the driven synchronous pulley (18).

4. The calibration device for a DIC system as described in claim 2, characterized in that, The universal joint mechanism (3) includes a hinge support (31) fixedly installed on the upper crossbeam (11) or lower crossbeam (12) via a flange seat. The hinge support (31) has two first lugs arranged side by side. A connector (32) is hinged between the two first lugs via a hinge shaft. A joint bearing is provided at the connection between the connector (32) and the hinge shaft.

5. The calibration device for a DIC system as described in claim 4, characterized in that, The strain standard plate (2) is equipped with a double-ear connector (5) at both ends. One end of the double-ear connector (5) has two second ears arranged side by side. The strain standard plate (2) is located between the two second ears and is hinged to the two second ears by a through bolt.

6. The calibration device for a DIC system as described in claim 5, characterized in that, The strain standard plate (2) has washers (51) on both sides that are fitted onto the bolts, so that the strain standard plate (2) is located between the two second lugs.

7. The calibration device for a DIC system as described in claim 5, characterized in that, The second lug has a through threaded hole and an inwardly facing centering screw (52), the two centering screws (52) abutting against both sides of the strain standard plate (2).

8. The calibration device for a DIC system as described in claim 5, characterized in that, An S-type force sensor (6) is connected between the lower connector (32) and the corresponding double-ear connector (5), and the upper connector (32) and the corresponding double-ear connector (5) are connected by threads.

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