A displacement transmission device for overall stiffness measurement of a rod

Abstract

The present application relates to the technical fields of structural mechanics test measurement, in particular to a displacement transmission device for measuring the overall stiffness of a rod, comprising a connecting component arranged at both ends of the rod for connecting and fixing the rod; a measuring component for converting and measuring the overall deformation of the rod and inversely obtaining the overall stiffness of the rod. The connecting component comprises a tool yoke and a pin; the measuring component comprises a first long pin, a second long pin and an adapter block connected thereto respectively. The adapter block is arranged on the upper and lower yokes of the measured rod and is connected and fixed by using an adhesive. Compared with the traditional overall stiffness measurement strategy of the rod, the adapter block is not in contact with the tool yoke and the pin, but is directly connected with the yoke of the measured rod, thereby eliminating the measurement error caused by the deformation of the tool yoke and the pin during the loading process, improving the accuracy of the measurement results and realizing the high-precision measurement of the overall stiffness of the rod.

Description

Technical Field

[0001] This invention relates to the field of structural mechanics testing and measurement technology, and in particular to a displacement transfer device for measuring the overall stiffness of a member. Background Technology

[0002] Axial tension-compression testing of rods is the most direct test method for measuring the axial mechanical properties of rods. In tension-compression tests, the axial deformation of the rod is the core parameter for calculating the overall axial stiffness of the rod structure. Therefore, accurately measuring the axial deformation of the rod structure during loading is extremely important.

[0003] In the existing technology, a common measurement method is to use the LVDT displacement sensor on the universal testing machine to directly read the relative displacement between the upper and lower clamps of the testing machine as the overall displacement response of the rod structure. However, the measurement accuracy is low, and the deformation of the tooling fork lugs and pins is introduced into the measurement results, resulting in a large measurement error.

[0004] Currently, the most common measurement method is to use a displacement extensometer to measure the deformation of the rod. A conventional extensometer measures the displacement between the two cutting edges. When measuring the overall deformation of the rod structure, a displacement transfer device is needed to convert the deformation into a concentrated area between the two cutting edges of the extensometer. Simulation analysis revealed that the deformation of the rod structure is mainly concentrated in the fork lug part. To avoid structural damage, holes are usually drilled in the connecting pins of the fork lug, and the displacement transfer device is installed on the fork lug pins. The relative displacement between the two pins is then measured to represent the overall deformation of the rod. Inevitably, to install the testing fixture, the pins will protrude 20-30mm beyond the surface of the rod. During loading, the fork lug pins bend due to bending and shear loads, introducing deformation errors into the test. Furthermore, in the compression test of the rod structure, due to machining errors and other reasons, the rod will undergo not only axial compression deformation but also bending deformation perpendicular to the axial direction. Typically, a universal testing machine is equipped with only one displacement extensometer, which cannot eliminate the influence of bending deformation by arranging displacement extensometers on both sides of the bending direction of the rod.

[0005] In the overall stiffness measurement of high-stiffness members, due to the very small structural deformation, the deformation errors of pins and forks, as well as the introduction of bending deformation of members, will cause the measurement results to deviate significantly from the actual structural deformation, resulting in poor repeatability and low reliability of the experimental measurement results. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a displacement transmission device for measuring the overall stiffness of a rod. This invention features high coaxiality accuracy between the two long pins, resulting in minimal error in the axial displacement direction between the connected pins and the rod. The displacement transmission device measures the entire rod, eliminating deformation errors caused by the tooling fork and connecting pins. Through the special arrangement of the adapter block, only one knife-edge displacement extensometer is used to reduce measurement errors caused by rod bending deformation, effectively reducing measurement errors and complexity in the overall stiffness measurement test of high-stiffness rods. It offers advantages such as low testing cost, simple operation, and small measurement error.

[0007] Connecting components are located at both ends of the rod and are used to connect and fix the rod.

[0008] A measuring component is located on the side of the rod and is used to convert and measure the overall deformation of the rod.

[0009] Furthermore, the connecting component includes a tooling fork lug and a pin; the measuring component includes a first long pin, a second long pin, and a conversion block connected thereto.

[0010] Furthermore, the adapter block is installed on the fork lugs at both ends of the rod. The adapter block includes an arc segment and a horizontal L-shaped connecting bracket for converting and transmitting the overall deformation displacement of the rod. The width of the arc segment is the same as the thickness of the tooling fork lug. The adapter block has a limiting surface on its side, which is used to assist in the positioning and installation of the adapter block.

[0011] Furthermore, the horizontal L-shaped connecting bracket has a through hole at its end, the center of which is on the axis of the arc segment, for fixing the first long pin and the second long pin.

[0012] Furthermore, the adapter blocks at both ends of the rod are arranged in a reverse mirror shape so that the through holes on the adapter blocks are on the same axis, which is parallel to the central axis of the rod.

[0013] Furthermore, an adhesive is applied to the inner side of the adapter block to tightly bond it to the forks at both ends of the rod, thereby achieving complete measurement of the entire rod and reducing measurement errors caused by the deformation of the tooling forks and pins under load in traditional testing methods.

[0014] Furthermore, the first long pin is a stepped shaft pin that is thin at both ends and thick in the middle. A thread is provided at the end of the thin shaft of the first long pin to facilitate the fixed connection of the first long pin to the adapter block. A protruding pin body is provided at the front end of the short thin shaft for connecting with the second long pin. The outer surface of the thick shaft in the middle is sanded to increase the roughness.

[0015] Furthermore, the second long pin is a stepped shaft pin that is thicker at one end and thinner at the other. A thread is provided at the end of the thin shaft to facilitate the fixed connection of the second long pin to the adapter block. The outer surface of the thick shaft is sanded to increase its roughness. The front end of the thick shaft is in the form of a sleeve for connecting with the first long pin.

[0016] Furthermore, the outer diameter of the protruding pin body at the front end of the short thin shaft of the first long pin is the same as the inner diameter of the front sleeve of the second long pin, so as to achieve splicing with the second long pin.

[0017] Furthermore, the protruding pin and the front sleeve are fitted with a small clearance, and a lubricant is applied to the front sleeve to allow the protruding pin to slide freely within the front sleeve.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] (1) The protruding pin body of the first long pin and the second long pin of the present invention are sleeved together. The pin body can slide freely in the sleeve. Compared with the traditional displacement adapter rod, the two long pins are directly connected and have high coaxiality accuracy.

[0020] (2) The adapter blocks of this invention are arranged on both sides of the bending direction of the rod, and a limiting surface is attached to the side. The limiting installation is achieved by surface-to-surface contact. Compared with traditional adapter blocks, the limiting surface ensures that the axial direction of the first and second long pins is consistent with the axial displacement direction of the rod. The adapter blocks are located on the left and right sides of the bending direction of the rod. After being converted by the horizontal L-shaped connecting bracket, only one knife-edge displacement extensometer is needed to reduce the influence of the bending deformation of the rod during loading on the measurement of the axial deformation of the rod, thereby improving the accuracy of the rod deformation measurement.

[0021] (3) The adapter block of the present invention is also arranged at the upper and lower ends of the fork lug of the rod and is connected and fixed by adhesive. Compared with the traditional overall stiffness measurement strategy of the rod, the adapter block does not connect with the tooling fork lug and the pin, but directly connects with the rod fork lug, which eliminates the measurement error caused by the deformation of the tooling fork lug and the pin during the loading process and improves the accuracy of the measurement results.

[0022] (4) The adapter block, the first long pin and the second long pin of the present invention adopt a separate structure, and the adapter block, the first long pin and the second long pin can be replaced individually according to the size of the rod, without the need for overall reprocessing and production, which reduces the test cost and further expands the application range of the test device. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0024] In the attached diagram:

[0025] Figure 1 This is a schematic diagram of a displacement transmission device for measuring the overall stiffness of a rod according to the present invention.

[0026] Figure 2 This invention relates to a transfer block for a displacement transmission device used for measuring the overall stiffness of a rod.

[0027] Figure 3 This is the first long pin of a displacement transmission device for measuring the overall stiffness of a rod according to the present invention.

[0028] Figure 4 This is the second long pin of a displacement transmission device for measuring the overall stiffness of a rod according to the present invention.

[0029] Figure Labels

[0030] 1: Connection part;

[0031] 11: Tooling fork lug; 12: Pin;

[0032] 2: Rods;

[0033] 3: Measurement section;

[0034] 31: First long pin; 32: Second long pin; 33: Adapter block;

[0035] 4: Extensometer blade edge. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0037] Example 1

[0038] Please see Figure 1-4 The technical solution provided in this embodiment is as follows:

[0039] A displacement transmission device for measuring the overall stiffness of a rod, comprising:

[0040] Connecting component 1 is located at both ends of rod 2 and is used to connect and fix the rod;

[0041] Measuring component 3 is located on the side of rod 2 and is used to convert and measure the overall deformation of rod.

[0042] Specifically, the connecting component 1 includes a tooling fork lug 11 and a pin 12; the measuring component 3 includes a first long pin 31, a second long pin 32 and an adapter block 33 connected thereto.

[0043] Specifically, such as Figure 1-2 As shown, the adapter block 33 is installed on the fork lugs at both ends of the rod 2. The adapter block 33 includes an arc segment and a horizontal L-shaped connecting bracket, which is used to convert and transmit the overall deformation displacement of the rod 2. The width of the arc segment is the same as the thickness of the tooling fork lug 11. The adapter block 33 has a limiting surface on its side, which is used to assist in the positioning and installation of the adapter block 33.

[0044] Specifically, the horizontal L-shaped connecting bracket has a through hole at its end, with the center of the through hole on the axis of the arc segment, for fixing the first long pin 31 and the second long pin 32.

[0045] Specifically, the transition blocks 33 at both ends of the rod 2 are arranged in opposite mirror shapes so that the through holes on the transition blocks 33 are on the same axis, and the axis is parallel to the central axis of the rod 2.

[0046] Specifically, an adhesive is applied to the inner side of the adapter block 33 to tightly bond it to the fork lugs at both ends of the rod 2, so as to achieve complete measurement of the entire rod 2 and reduce the measurement error caused by the loading deformation of the tooling fork lugs 11 and pins 12 in traditional testing methods.

[0047] In this embodiment, the overall thickness of the adapter block 33 is 4mm. The end of the horizontal L-shaped connecting bracket of the adapter block 33 extends 10mm beyond the center of the arc and has a through hole with a diameter of 4mm. The axis of the hole is located on the symmetrical mid-plane of the arc segment. The width of the arc segment of the adapter block 33 is the same as the width of the tooling fork lug 11, and there is a limiting surface on one side. The surface-to-surface contact method is used to assist in the positioning and installation of the adapter block.

[0048] Specifically, such as Figure 3 As shown, the first long pin 31 is a stepped shaft pin that is thin at both ends and thick in the middle. The tail of the long thin shaft of the first long pin 31 is provided with an external thread so that the first long pin 31 can be fixedly connected to the adapter block 33 with a nut. The front end of the short thin shaft is provided with a protruding pin body for splicing with the second long pin 32. The outer surface of the thick shaft in the middle is sanded to increase the roughness.

[0049] In the embodiment, the first long pin 31 used in this invention is made of stainless steel, with a front end protruding 20mm from the pin body, an outer diameter of 4mm, and a 0.5mm chamfer at the front end of the pin body.

[0050] Specifically, such as Figure 4 As shown, the second long pin 32 is a stepped shaft pin that is thick at one end and thin at the other. An external thread is provided at the end of the thin shaft so that the second long pin 32 can be fixedly connected to the adapter block 33 with a nut. The outer surface of the thick shaft is sanded to increase the roughness. The front end of the thick shaft is in the form of a sleeve for connecting with the first long pin 31.

[0051] In this embodiment, the threaded rods at the ends of the first long pin 31 and the second long pin 32 are first screwed into an M4 nut and inserted into the through holes of the two adapter blocks 33 respectively. The diameter of the through holes is 4mm. Then, an M4 nut is screwed into the adapter block 33 to slightly clamp the horizontal L-shaped connecting bracket of the adapter block 33. The two adapter blocks 33 are arranged in opposite mirror surfaces, and the through holes of the two horizontal L-shaped connecting brackets are on the same axis.

[0052] Specifically, the outer diameter of the protruding pin body at the front end of the short thin shaft of the first long pin 31 is the same as the inner diameter of the sleeve at the front end of the second long pin 32, and is used to connect with the second long pin 32.

[0053] In this embodiment, the second long pin 32 is made of titanium alloy, the front sleeve depth is 25mm, the inner diameter is 4mm, and a small clearance fit is adopted. The fit accuracy and coaxiality requirements of the two are high. The pin is not fully inserted into the sleeve, leaving a distance of 10mm.

[0054] Specifically, the protruding pin and the front sleeve are fitted with a small clearance, and lubricant is applied to the front sleeve to allow the protruding pin to slide freely within the front sleeve.

[0055] In this embodiment, the extensometer blade 4 used in this invention has a displacement measurement gauge length of 20 mm and a measurement range of 2 mm.

[0056] Specifically, the two adapter blocks 33 are arranged in a mirror-like, opposite orientation.

[0057] The working principle or process of the displacement transfer device for measuring the overall stiffness of a rod provided by this invention is as follows:

[0058] First, test install the adapter block 33 and the rod 2. Place the rod 2 on the horizontal L-shaped connecting bracket of the adapter block 33, press the limiting surface against the side of the tooling fork lug 11, apply pads under the first long pin 31 and the second long pin 32 to ensure that the first long pin 31 and the second long pin 32 are in the same plane as the axis of the rod 2, tighten the upper and lower nuts of the first long pin 31 and the second long pin 32 to fix the position of the two long pins, apply adhesive to the inside of the adapter block 33, and fix the positioned adapter block 33 to the fork lugs at both ends of the rod 2.

[0059] Furthermore, the tooling fork lug 11 is connected to the rod 2 via the pin 12. The rod 2 can rotate freely around the pin 12 within the tooling fork lug 11, ensuring that the axial force can pass through the axis of the rod 2 during tensile and compressive loading. After the rod 2 is fixed to the testing machine via the tooling fork lug 11, the upper and lower blades of the extensometer blade 4 are fixed to the thick shafts of the first long pin 31 and the second long pin 32 using rubber bands or similar means, completing the fixed installation of the overall tooling.

[0060] In summary, this invention proposes a displacement transfer device for measuring the overall stiffness of a rod. The two long pins of this device have high coaxiality accuracy, and the error between the two long pins and the axial displacement direction of the rod 2 after connection is small. Compared with the traditional measurement method, this device arranges the adapter block 33 on the fork lugs at both ends of the rod 2 to directly measure the deformation of the entire rod 2, eliminating the deformation error of the tooling fork lugs 11 and pins 12, effectively reducing the measurement error and test complexity of the overall stiffness measurement test of the rod 2. It is especially suitable for the overall stiffness measurement of large stiffness rods with small deformation, and has the advantages of low test cost, simple operation, and small measurement error.

[0061] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A displacement transmission device for measuring the overall stiffness of a rod, characterized in that, include: Connecting components are located at both ends of the rod and are used for connecting and fixing the rod. The connecting component includes a tooling fork lug and a pin; the measuring component includes a first long pin, a second long pin, and adapter blocks connected to them respectively. The adapter block is installed on the fork lugs at both ends of the rod. The adapter block includes an arc segment and a horizontal L-shaped connecting bracket, which is used to convert and transmit the overall deformation displacement of the rod. The horizontal L-shaped connecting bracket has a through hole at one end, and the adapter blocks at both ends of the rod are arranged in opposite mirror surfaces so that the through holes on the adapter blocks are on the same axis. The center of the through hole is on the axis of the arc segment, which is used to fix the first long pin and the second long pin. A measuring component is located on the side of the rod and is used to convert and measure the overall deformation of the rod.

2. The displacement transmission device for measuring the overall stiffness of a rod according to claim 1, characterized in that: The width of the arc segment is the same as the thickness of the tooling fork lug, and the side of the adapter block is provided with a limiting surface, which is used to assist the adapter block in positioning and installation.

3. The displacement transmission device for measuring the overall stiffness of a rod according to claim 2, characterized in that: The axis is parallel to the central axis of the rod.

4. The displacement transmission device for measuring the overall stiffness of a rod according to claim 3, characterized in that: The inner side of the adapter block is coated with adhesive to bond it tightly to the rod, thereby enabling complete measurement of the entire rod and reducing measurement errors caused by the deformation of the tooling fork and the pin under load in traditional testing methods.

5. The displacement transmission device for measuring the overall stiffness of a rod according to claim 2, characterized in that: The first long pin is a stepped shaft pin that is thin at both ends and thick in the middle. The tail of the thin shaft of the first long pin is threaded to facilitate the fixed connection of the first long pin to the adapter block. The front end of the short thin shaft is provided with a protruding pin body for connecting with the second long pin. The outer surface of the thick shaft in the middle is sanded to increase the roughness.

6. The displacement transmission device for measuring the overall stiffness of a rod according to claim 2, characterized in that: The second long pin is a stepped shaft pin that is thicker at one end and thinner at the other. A thread is provided at the end of the thin shaft to facilitate the fixed connection of the second long pin to the adapter block. The outer surface of the thick shaft is sanded to increase its roughness. The front end of the thick shaft is in the form of a sleeve for connecting with the first long pin.

7. The displacement transmission device for measuring the overall stiffness of a rod according to claim 1, characterized in that: The outer diameter of the protruding pin body at the front end of the short thin shaft of the first long pin is the same as the inner diameter of the front end sleeve of the second long pin, so as to achieve the connection with the second long pin.

8. The displacement transmission device for measuring the overall stiffness of a rod according to claim 7, characterized in that: The protruding pin and the front sleeve are fitted with a small clearance. Lubricant is applied to the front sleeve to allow the protruding pin to slide freely within the front sleeve.

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