Stress monitoring device based on strain gauge

Abstract

The utility model discloses a stress monitoring device based on a strain gauge. The stress monitoring device comprises the strain gauge, a steel sheet and rubber, the two steel sheets are respectively arranged on two sides of the strain gauge, and rubber is arranged between each steel sheet and the strain gauge; during measurement, the device is placed between a steel hoop and a concrete single-column pier, the steel hoop tightly holds a concrete column to generate pressure stress and extrudes the device at the same time, and when the steel sheet and the rubber of the device are extruded, tensile deformation is generated, so that the strain gauge is elongated, the sensitive grid in the strain gauge is deformed, and the resistance of the sensitive grid is changed; the resistance change is measured by a special instrument and is converted into the strain value of the device, and the strain value can be converted into the corresponding pressure stress through the corresponding conversion relation between the strain and the pressure stress; during measurement, the steel sheet serves as a carrier and can quickly and uniformly transmit stress to the strain gauge, so that accurate measurement of the stress is realized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to civil engineering stress monitoring technical field, concretely relates to a stress monitoring device based on strain gauge for monitoring the stress between glue injection steel hoop and single column pier. BACKGROUND

[0002] At present, the reinforcement method of adding steel hoop is mostly used in the maintenance and reinforcement of single column pier of bridge in China. The research on steel hoop reinforced single column pier is relatively in-depth, but in the existing research on steel hoop reinforced single column pier, the common scheme for improving the bearing capacity is to install anchor bolt between steel hoop and single column pier, which will cause damage to single column pier. Therefore, in order to avoid damage to single column pier, the combination of hoop and bridge main body can be improved by glue injection, so as to improve the overall stability; the research on glue injection steel hoop is gradually applied from theory to practice, and in the experimental process, in order to understand the stress distribution between steel hoop and single column pier, the stress between glue injection steel hoop and single column pier needs to be measured.

[0003] At present, strain gauge is directly used to measure the stress between glue injection steel hoop and single column pier, and the strain gauge is placed in the glue layer at the contact position of steel hoop and single column pier during measurement. When the steel hoop is stressed, the stress is transmitted to the strain gauge through the glue layer, the strain gauge deforms to cause the resistance to change, and then the resistance change is converted into stress value.

[0004] However, the thickness and hardness of the glue layer between the steel hoop and the single column pier are not uniform, which causes the stress transmitted to the strain gauge to be not uniform, so there will be measurement error when directly using the strain gauge to measure the stress between the glue injection steel hoop and the single column pier. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a stress monitoring device based on strain gauge, which solves the problem of measurement error when directly measuring the stress between glue injection steel hoop and single column pier by using strain gauge.

[0006] The utility model adopts the technical scheme, a stress monitoring device based on strain gauge, comprising:

[0007] Strain gauge, the lead wire of strain gauge is connected with strain gauge;

[0008] Two steel sheets are arranged on the two sides of strain gauge respectively, and the two steel sheets cover the outside of strain gauge. When measuring stress, the whole composed of steel sheet and strain gauge is placed in the glue layer between steel hoop and single column pier, and the steel sheet acts as carrier to uniformly transmit stress to strain gauge, so as to realize accurate measurement of stress.

[0009] Rubber is further arranged between each steel sheet and strain gauge.

[0010] The rubber is nitrile rubber.

[0011] The thickness of the rubber is less than or equal to 0.5 mm.

[0012] The rubber is bonded with the strain gauge and the steel sheet through structural adhesive.

[0013] The two ends of the two leads of the strain gauge are respectively wrapped with first heat shrink tubes, and the rubber and the steel sheet extend to the outside of the first heat shrink tubes.

[0014] The welding position of the two leads when connected with the strain gauge is wrapped with a second heat shrink tube.

[0015] The beneficial effects of the present application are as follows:

[0016] The stress monitoring device provided by the present application comprises two steel sheets and a rubber, wherein the two steel sheets are arranged on the two sides of a strain gauge, and the two steel sheets cover the outside of the strain gauge. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The strain gauge provided by the present application is shown in the figure;

[0018] Figure 2 The heat shrink tube is tightly bonded with the lead, as shown in the figure;

[0019] Figure 3 The 0.5 mm nitrile rubber is bonded with the strain gauge, as shown in the figure;

[0020] Figure 4 The main body of the stress monitoring device provided by the present application is shown in the figure;

[0021] Figure 5 The insulation treatment of the lead and the welding point of the lead is shown in the figure.

[0022] In the figure, 1 is a strain gauge, 2 is a steel sheet, 3 is a rubber, 4 is a first heat shrink tube, and 5 is a second heat shrink tube. DETAILED DESCRIPTION

[0023] The present application will be described in detail below in combination with the drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and cannot be used to limit the protection scheme of the present application.

[0024] At present, the method of adding steel hoop is mostly used in the maintenance and reinforcement of single-column pier in China. The research on the steel hoop reinforced single-column pier has been relatively in-depth, but in order to improve the bearing capacity, the common scheme in the existing research on the steel hoop reinforced single-column pier is to install anchor bolts between the steel hoop and the single-column pier, which will cause damage to the single-column pier. Therefore, in order to avoid damage to the single-column pier, the bonding force between the steel hoop and the bridge body can be improved by means of glue injection, so as to improve the overall stability; the research on the glue injection steel hoop is gradually proceeding from theory to practice. In the experimental process, in order to understand the stress distribution between the steel hoop and the single-column pier, the stress between the glue injection steel hoop and the single-column pier needs to be measured.

[0025] At present, when measuring the stress between the glue injection steel hoop and the single-column pier, strain gauges are directly used for measurement. When measuring, the strain gauges are placed in the glue layer at the contact position between the steel hoop and the single-column pier. When the steel hoop is stressed, the stress is transmitted to the strain gauges through the glue layer. The strain gauges produce deformation, which leads to changes in resistance. Then the resistance changes are converted into stress values.

[0026] However, for the stress between the glue injection steel hoop and the single-column pier, because the thickness and hardness of the glue layer between the steel hoop and the single-column pier are not uniform, the stress transmitted to the strain gauges is also not uniform. Therefore, when directly using strain gauges to measure the stress between the glue injection steel hoop and the single-column pier, measurement errors will exist.

[0027] The utility model discloses a stress monitoring device based on strain gauge, as shown in Figure 1 Figure 5 The utility model discloses a stress monitoring device based on strain gauge, as shown in

[0028] Each steel sheet 2 and strain gauge 1 still be provided with rubber 3, and the rubber 3 adopts nitrile rubber. Nitrile rubber can be used as an isolation layer, which can prevent the strain gauges 1 from directly contacting the steel sheets 2, reduce the influence of the surface roughness or unevenness of the steel sheets 2 on the strain gauges 1, and protect the strain gauges 1 from damage. Nitrile rubber has certain elasticity and flexibility, which can buffer and absorb the impact and stress peak caused by external load or vibration, thereby protecting the strain gauges 1 from excessive force. In addition, the rubber layer can also help to transmit the stress on the steel sheets 2 more evenly to the strain gauges 1, reduce local stress concentration, and improve the accuracy of measurement. Nitrile rubber also has good sealing performance, which can prevent moisture, oil stains and other harmful substances from penetrating between the strain gauges and the steel sheets, and protect the strain gauges 1 from environmental influences. ​

[0029] The thickness of rubber 3 is less than or equal to 0.5 mm to avoid the rubber being too thick and affecting the stress measurement of the strain gauge.

[0030] The rubber 3 is bonded to both the strain gauge 1 and the steel plate 2 using structural adhesive. The adhesive can firmly fix the rubber between the steel plate 2 and the strain gauge 1, ensuring that the strain gauge 1 will not move during the measurement process, thereby guaranteeing the accuracy of the measurement results.

[0031] The two leads of strain gauge 1 are respectively wrapped with first heat shrink tubing 4 at the ends closest to the strain gauge. Rubber 3 and steel sheet 2 both extend to the outside of the first heat shrink tubing 4. The first heat shrink tubing 4 can provide good insulation performance to prevent the leads from contacting other metals or conductive materials, thereby avoiding short circuits or leakage. At the same time, the first heat shrink tubing 4 can reduce mutual interference between leads, especially when multiple leads are arranged in parallel, which helps to maintain signal stability.

[0032] A second heat shrink tubing 5 is wrapped around the welding point where the two leads are connected to the strain gauge. Both the first heat shrink tubing 4 and the second heat shrink tubing 5 are high-temperature resistant rubber hoses, and both are made of polypropylene. The second heat shrink tubing 5 provides good insulation protection, preventing the welding point from contacting other metal parts and avoiding short circuits. In addition, the second heat shrink tubing 5 can protect the welding point from external physical damage, such as friction and impact. Furthermore, the second heat shrink tubing 5 can resist the corrosion of the welding point by environmental factors such as moisture, oil, and chemicals, extending the service life of the connection. After shrinking, the second heat shrink tubing 5 can tightly wrap around the leads and welding point, playing a fixing role and preventing the leads from loosening due to vibration.

[0033] The method for manufacturing a strain gauge-based stress monitoring device disclosed in this utility model includes the following steps:

[0034] Step 1, as follows Figure 1 As shown, select and inspect strain gauge 1. The inspection method is as follows: measure the resistance of the strain gauge, check whether the structure of the strain gauge is intact, and check whether the leads are secure.

[0035] Step 2, as follows Figure 2 As shown, cut two first heat shrink tubes 4 and wrap them around the two leads of the strain gauge for insulation and protection, leaving 3mm-6mm of leads for welding and connecting the strain gauge wires;

[0036] Step 3: As Figure 3 As shown, two sheets of 0.5mm thick nitrile rubber are selected, and the strain gauge 1 and the lead wire wrapped by the first heat shrink tube 4 near the strain gauge are tightly bonded together with structural adhesive to form a plastic-sealed strain gauge structure (a square with a side length of 10mm-12mm).

[0037] Step 4: AsFigure 4 As shown, two steel sheets 2 with smooth surfaces of equal size are selected, and are adhered to both sides of the plastic-encapsulated strain gauge structure by structural adhesive to form the main body (a square with a side length of 10mm-12mm) of the stress monitoring device;

[0038] Step 5: the exposed lead wires are cut to a size that can be welded, and the two lead wires are welded and butt-connected to the lead wires, and the surface of the butt-connection is smooth, and there is no protrusion visually and by hand;

[0039] Step 6: the welding site is fixed by a second heat shrink tube 5, and the diameter of the second heat shrink tube 5 used is 4mm;

[0040] Step 7: the lead wires are fixed and resistance detection is performed, that is, the stress monitoring device is completed.

[0041] When the stress monitoring device disclosed in the utility model is used to measure the stress between a steel hoop and a single-column pier, the stress monitoring device is preliminarily fixed by being adhered to the connection between the steel hoop and the single-column pier by structural adhesive, and then the two sides of the stress monitoring device are pressed to be attached to the steel hoop and the single-column pier respectively, so that the stress can be detected.

[0042] The measurement principle of the stress monitoring device disclosed in the utility model is as follows: when the device is placed between a steel hoop and a concrete column for stress measurement, a pre-tightening force is applied through a high-strength bolt, the steel hoop tightly holds the concrete single-column pier, a compressive stress is generated, and the stress is transmitted to the device and the device is extruded, the steel sheet 2 and the rubber 3 of the device are extruded to generate tensile deformation, and then the strain gauge 1 is elongated, the sensitive grid in the strain gauge 1 is deformed to change the resistance, the change in the resistance is measured by a special instrument, and the strain value of the device is converted, and through the corresponding conversion relationship between the strain and the compressive stress, the corresponding compressive stress can be converted.

[0043] The stress monitoring device disclosed in the utility model has the following advantages: 1. the device can be directly used for measuring the stress between a glue-injection steel hoop and a single-column pier, the nitrile rubber outside the strain gauge can avoid the structure of the strain gauge 1 from being damaged before use due to the direct contact between the strain gauge 1 and the two steel sheets 2, and the 0.5mm rubber does not affect the measurement of the strain gauge; 2. the lead wires and the lead wire welding points of the stress monitoring device are fixed and insulated by heat shrink tubes, so that the lead wires are protected from being damaged; 3. the lead wires of the strain gauge 1 are welded to the lead wires of the strain gauge in advance, so that live-line operation and high-temperature operation on site are avoided, safety hazards are reduced, and engineering time is saved.

[0044] The above-described embodiments are merely preferred specific embodiments of the present application, and the protection scope of the present application is not limited thereto, and any simple change or equivalent replacement of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present application shall all fall within the protection scope of the present application.

Claims

1. A strain gauge based stress monitoring device, characterized by, The utility model relates to a strain gauge, which comprises: a strain gauge (1) whose lead wires are connected to a strain meter; two steel sheets (2) arranged on the two sides of the strain gauge (1) respectively, which cover the outside of the strain gauge (1) and are placed in the glue layer between the steel hoop and the single column pier when measuring stress, and the steel sheets (2) serve as carriers to transmit stress to the strain gauge (1) uniformly, thus realizing accurate measurement of stress.

2. A strain gauge based stress monitoring device according to claim 1, wherein, A rubber (3) is arranged between each steel sheet (2) and the strain gauge (1).

3. A strain gauge based stress monitoring device according to claim 2, wherein, The rubber (3) is made of nitrile rubber.

4. A strain gauge based stress monitoring device as claimed in claim 2, wherein, The thickness of the rubber (3) is less than or equal to 0.5 mm.

5. A strain gauge based stress monitoring device as claimed in claim 2, wherein, The rubber (3) is bonded to the strain gauge (1) and the steel sheet (2) by structural adhesive.

6. A strain gauge based stress monitoring device as claimed in claim 2, wherein, The two lead wires of the strain gauge (1) are wrapped with first heat-shrinkable tubes (4) near the ends connected to the strain meter.

7. A strain gauge based stress monitoring device according to claim 6, wherein, The two lead wires are wrapped with second heat-shrinkable tubes (5) at the welding positions connected to the strain meter.

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