A stress sensor for similar simulation experiments and its use method

Abstract

The present invention discloses a method for making and using a stress sensor for similar simulation experiments, belonging to the field of sensor technology, and comprising the following steps: S1, material preparation; S2, fixing a strain gauge terminal assembly and packaging materials; S3, pasting the strain gauge terminal assembly; S4, testing the strain gauge terminal assembly; S5, curing the strain gauge surface of the strain gauge terminal assembly; S6, sealing and packaging the strain gauge terminal assembly; S7, sensor integrity inspection. The stiffness of the sensor of the present invention matches the geotechnical material and has little effect on the geotechnical mechanics experiment and the stability of its structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a method for manufacturing a stress sensor used in similar simulation experiments and a method for using the same. Background Art

[0002] Similarity simulation testing is a testing method based on similarity theory. It constructs a model similar to an actual engineering or physical phenomenon and conducts experiments on the model to study the mechanical behavior, physical processes, and other characteristics of the prototype. It utilizes the similarities between the model and the prototype in terms of geometry, physical properties, boundary conditions, and initial conditions, transforming the study of the prototype into the study of the model.

[0003] The following three similarity theorems need to be followed: The first similarity theorem (positive theorem) states that similar phenomena have a similarity index equal to 1, or the numerical values ​​of their similarity criteria are equal; the second similarity theorem (theorem) states that a physical phenomenon can be represented by a functional relationship of one or more similarity criteria. This means that when designing similarity simulation experiments, it is necessary to determine all similarity criteria related to the research object and establish a functional relationship between them in order to accurately simulate the physical process; the third similarity theorem (converse theorem) states that for the same type of physical phenomena, if the single-valued conditions (geometric conditions, physical conditions, boundary conditions, and initial conditions) are similar and the similarity criteria composed of the single-valued conditions are numerically equal, then these phenomena are similar. This provides specific guiding principles for model design and experimental condition setting for similarity simulation experiments.

[0004] In similar simulation tests, the materials used have similar physical and mechanical properties to actual engineering materials. Stress sensors need to be compatible with these similar materials to accurately reflect the stress state. For example, in geotechnical simulation tests, studying the impact of underground excavation on the stress of the surrounding rock and soil requires precise measurement of stress changes within a very small range. This is because the mechanical properties of rock and soil are complex, and even slight changes in stress can alter their deformation characteristics and stability. Furthermore, if the sensor's mechanical parameters, such as the elastic modulus, are low or its stiffness is too high, this can alter the stress distribution of the material itself. Therefore, it is necessary to develop stress sensors that match the stiffness and other properties of similar materials.

[0005] The metal shell of the traditional earth pressure box stress sensor has a greater stiffness than that of the geotechnical material. At the same time, its heavy weight will affect the accuracy of the experiment. Therefore, in order to ensure that the stiffness of the sensor matches the geotechnical material and does not affect the stability of the geotechnical mechanics experiment and its structure as much as possible, a stress sensor that is both lightweight and has a stiffness that matches that of the geotechnical material is proposed. The sensor is used to simulate the test using physically similar materials and its use method is proposed. Summary of the Invention

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A stress sensor fabrication method for similar simulation experiments includes the following steps:

[0008] S1. Material preparation: Prepare strain gauge terminal assembly, welding pen, instant adhesive, room temperature vulcanized silicone rubber, waterproof glass glue, PVC transparent plastic sheet, small clips, scissors, ruler, and multimeter;

[0009] S2. Fixing and packaging materials for the strain gauge terminal assembly: Cut the PVC transparent plastic sheet into appropriate square pieces with scissors, then fold it in half once, and repeatedly clean the location where the strain gauge terminal assembly is to be attached.

[0010] S3. Paste the strain gauge terminal assembly: Paste the strain gauge terminal assembly with instant adhesive onto the prepared PVC transparent plastic plate.

[0011] S4. Inspection of strain gauge terminal assembly: After the strain gauge terminal assembly is firmly attached and the instant adhesive is completely hardened, use a multimeter to check whether the circuit connection is intact;

[0012] S5. Cure the strain gauge surface of the strain gauge terminal assembly. After the instant adhesive is completely hardened, apply room temperature vulcanized silicone rubber to the upper surface of the strain gauge. After the room temperature vulcanized silicone rubber is completely cured, use a multimeter to check whether the circuit connection is intact.

[0013] S6. Seal and package the strain gauge terminal assembly. After the room temperature vulcanized silicone rubber is completely cured, apply waterproof glass glue to the strain gauge terminal assembly. Then fold the transparent PVC plastic sheet in half along the crease and secure it with small clips. Leave it in a ventilated and cool place to ensure that the waterproof glass glue is completely solidified.

[0014] S7. Sensor integrity inspection: After completing the above steps, the sensor manufacturing process is completed, and use a multimeter to check whether the circuit connection is intact to ensure that the resistance value is within the normal value, and record the resistance value at the same time.

[0015] Furthermore, the strain gauge terminal assembly in step S1 uses a strain gauge with terminals and wires.

[0016] Furthermore, in step S1, the strain gauge terminal assembly includes a strain gauge, a terminal and a single-core multi-strand copper core electronic wire, wherein the strain gauge and the single-core multi-strand copper core electronic wire are respectively welded to both ends of the terminal, and a multimeter is used to detect whether the circuit connection is intact.

[0017] Furthermore, in step S3, the strain gauge and terminal in the strain gauge terminal assembly are adhered to the PVC transparent plastic plate through instant adhesive, wherein the strain gauge and terminal of the strain gauge terminal assembly are covered with a transparent plastic film, and pressed with a finger. After the strain gauge and the PVC transparent plastic plate are firmly adhered, the finger is released. During the pressing process, care is taken to protect the wires connecting the strain gauge and the terminal.

[0018] A method for using the stress sensor for a similar simulation experiment as described above comprises the following steps:

[0019] S01. Sensor range test: Connect the sensor to the strain gauge and use the strain gauge to test the working status of the sensor to ensure that the sensor value is within the strain gauge range;

[0020] S02. Similar simulation material ratio: According to the material ratio determined by the similar simulation experiment, measure the similar simulation experiment aggregate and cementitious material, and mix them thoroughly;

[0021] S03. Sample preparation: Pour the mixed similar simulation test material into the sample preparation mold, place the sensor in the middle of the similar simulation test material, remove the mold after compaction, and use a strain gauge to test to ensure that the sensor value is within the strain gauge range;

[0022] S04. Dry the specimens. Based on the similar simulation test cycle and laboratory climate conditions, place the specimens in the same scenario as the similar simulation test for natural drying. The placement time is the same as the time from the completion of paving to the excavation of the similar simulation model.

[0023] S05. Sensor calibration: Place the dried specimen on a press to conduct a uniaxial compression test, obtain the stress-strain curve and the sensor value curve, obtain the relationship curve between specimen pressure and sensor strain, and calculate the linear phase slope of the two to clarify the transformation relationship between sensor strain and stress;

[0024] S06. Arrange sensors according to a similar simulation experiment plan.

[0025] Furthermore, in step S03, half of the mixed similar simulation test material is poured into the sample preparation mold, leveled and compacted; the stress sensor is placed in the middle of the mold, and the wire is smoothly led out from the edge. The remaining similar simulation test material is poured into the mold, leveled and compacted. After standing for 24 hours, the mold is removed and tested with a strain gauge to ensure that the sensor value is within the strain gauge range.

[0026] Beneficial effects:

[0027] The stiffness of the sensor of the present invention matches that of rock and soil materials, and has little influence on rock and soil mechanics experiments and the stability of its structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the sensor of the present invention;

[0029] Figure 2 This is a schematic diagram of a finished product of the sensor of the present invention;

[0030] Figure 3 A test piece for calibrating the sensor of the present invention;

[0031] Figure 4 The press data acquisition system of the present invention;

[0032] Figure 5 The strain gauge data acquisition system of the present invention;

[0033] Figure 6 Calibrate the sensor of the present invention;

[0034] Figure 7 is the stress-strain curve of the present invention;

[0035] Explanation of the reference numerals 1 - strain gauge, 2 - room temperature vulcanized silicone rubber, 3 - terminal, 4 - waterproof glass glue, 5 - single-core multi-strand copper core electronic wire, 6 - PVC plastic board. DETAILED DESCRIPTION

[0036] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0037] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0038] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0039] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0040] Example 1

[0041] refer to Figure 1-Figure 2 , a stress sensor fabrication for similar simulation experiments includes the following steps:

[0042] S1. Material preparation: Prepare strain gauge terminal assembly, welding pen, instant adhesive, room temperature vulcanized silicone rubber 2, waterproof glass glue 4, PVC transparent plastic sheet 6, small clips, scissors, ruler, multimeter;

[0043] S2. Strain gauge terminal assembly fixing and packaging materials: Cut the PVC transparent plastic sheet 6 into appropriate square pieces with scissors, then fold it in half once, and repeatedly clean the location where the strain gauge terminal assembly is to be attached;

[0044] In this embodiment, the PVC transparent plastic plate 6 is cut into small pieces of 5 cm×5 cm with scissors; the cleaning position is 5 mm away from the fold and 15 mm away from the edge of the small piece and is repeatedly cleaned.

[0045] S3, pasting the strain gauge terminal assembly: Paste the strain gauge terminal assembly with instant adhesive onto the prepared PVC transparent plastic plate 6;

[0046] In this embodiment, the instant adhesive is 502 adhesive.

[0047] S4. Inspection of strain gauge terminal assembly: After the strain gauge terminal assembly is firmly attached and the instant adhesive is completely hardened, use a multimeter to check whether the circuit connection is intact;

[0048] In this embodiment, the strain gauge terminal assembly is pasted and left for about 1 hour.

[0049] S5. The strain gauge surface of the strain gauge terminal assembly is cured. After the instant adhesive is completely cured, apply room temperature vulcanized silicone rubber 2 to the upper surface of the strain gauge. After the room temperature vulcanized silicone rubber 2 is completely cured, use a multimeter to check whether the circuit connection is intact.

[0050] In this embodiment, the room temperature vulcanized silicone rubber 2 is 703 glue, and the room temperature vulcanized silicone rubber 2 is applied to a thickness of 0.5 mm and left for about 24 hours.

[0051] S6. Seal and encapsulate the strain gauge terminal assembly. After the room temperature vulcanized silicone rubber 2 is completely cured, apply waterproof glass glue 4 to the strain gauge terminal assembly. Then fold the transparent PVC plastic sheet 6 in half along the crease. Finally, secure it with small clips. Leave it in a ventilated and cool place to ensure that the waterproof glass glue is completely solidified.

[0052] In this embodiment, the waterproof glass glue 4 is applied to a thickness of 3 mm, fixed on all sides with small clips, and then left to stand in a ventilated and cool place for about 7-14 days to ensure that the waterproof glass glue is completely solidified.

[0053] S7. Sensor integrity inspection: After completing the above steps, the sensor manufacturing process is completed, and use a multimeter to check whether the circuit connection is intact to ensure that the resistance value is within the normal value, and record the resistance value at the same time.

[0054] Preferably, the strain gauge terminal assembly in step S1 includes a strain gauge 1, a terminal 3 and a single-core multi-strand copper core electronic wire 5, wherein the strain gauge and the single-core multi-strand copper core electronic wire 5 are respectively welded to the two ends of the terminal 3, and a multimeter is used to detect whether the circuit connection is intact.

[0055] In this embodiment, the strain gauge is a 120-3AA foil strain gauge with a resistance of 120 ohms, a sensitive grid length of 3 mm, and a sensitive grid structure of a quarter bridge.

[0056] In other embodiments, the strain gauge terminal assembly in step S1 uses a strain gauge with a terminal 3 and a wire.

[0057] Preferably, in step S3, after the strain gauge 1 and the terminal 3 in the strain gauge terminal assembly are adhered to the PVC transparent plastic plate 6 through instant adhesive, the strain gauge 1 and the terminal 3 of the strain gauge terminal assembly are covered with a transparent plastic film, and pressed with a finger. After the strain gauge 1 and the PVC transparent plastic plate 6 are firmly adhered, the finger is released. During the pressing process, care is taken to protect the wire connecting the strain gauge 1 and the terminal 3.

[0058] Example 2

[0059] refer to Figure 3-Figure 7 This embodiment is a method for using the stress sensor for a similar simulation experiment described in Example 1, comprising the following steps:

[0060] S01. Sensor range test: Connect the sensor to the strain gauge and use the strain gauge to test the working status of the sensor to ensure that the sensor value is within the strain gauge range;

[0061] S02. Similar simulation material ratio: According to the material ratio determined by the similar simulation experiment, measure the similar simulation experiment aggregate and cementitious material, and mix them thoroughly;

[0062] S03. Sample preparation: Pour the mixed similar simulation test material into the sample preparation mold, place the sensor in the middle of the similar simulation test material, remove the mold after compaction, and use a strain gauge to test to ensure that the sensor value is within the strain gauge range;

[0063] S04. Dry the specimens. Based on the similar simulation test cycle and laboratory climate conditions, place the specimens in the same scenario as the similar simulation test for natural drying. The placement time is the same as the time from the completion of paving to the excavation of the similar simulation model.

[0064] S05. Sensor calibration: Place the dried specimen on a press to conduct a uniaxial compression test, obtain the stress-strain curve and the sensor value curve, obtain the relationship curve between specimen pressure and sensor strain, and calculate the linear phase slope of the two to clarify the transformation relationship between sensor strain and stress;

[0065] S06. Arrange sensors according to a similar simulation experiment plan.

[0066] Preferably, in step S03, half of the mixed similar simulation test material is poured into the sample preparation mold, leveled and compacted; the stress sensor is placed in the middle of the mold, and the wire is smoothly led out from the edge. The remaining similar simulation test material is poured into the mold, leveled and compacted, and after standing for 24 hours, the mold is removed and tested with a strain gauge to ensure that the sensor value is within the strain gauge range.

[0067] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A stress sensor for similar simulation experiments, characterized in that: The following steps are involved: S1. Material preparation: Prepare strain gauge terminal assembly, welding pen, instant adhesive, room temperature vulcanized silicone rubber, waterproof glass glue, PVC transparent plastic sheet, small clips, scissors, ruler, and multimeter; S2. Fixing and packaging materials for the strain gauge terminal assembly: Cut the PVC transparent plastic sheet into appropriate square pieces with scissors, then fold it in half once, and repeatedly clean the location where the strain gauge terminal assembly is to be attached. S3. Paste the strain gauge terminal assembly: Paste the strain gauge terminal assembly with instant adhesive onto the prepared PVC transparent plastic plate. S4. Inspection of strain gauge terminal assembly: After the strain gauge terminal assembly is firmly attached and the instant adhesive is completely hardened, use a multimeter to check whether the circuit connection is intact; S5. Cure the strain gauge surface of the strain gauge terminal assembly. After the instant adhesive is completely hardened, apply room temperature vulcanized silicone rubber to the upper surface of the strain gauge. After the room temperature vulcanized silicone rubber is completely cured, use a multimeter to check whether the circuit connection is intact. S6. Seal and package the strain gauge terminal assembly. After the room temperature vulcanized silicone rubber is completely cured, apply waterproof glass glue to the strain gauge terminal assembly. Then fold the transparent PVC plastic sheet in half along the crease and secure it with small clips. Leave it in a ventilated and cool place to ensure that the waterproof glass glue is completely solidified. S7. Sensor integrity inspection: After completing the above steps, the sensor manufacturing process is completed, and use a multimeter to check whether the circuit connection is intact to ensure that the resistance value is within the normal value, and record the resistance value at the same time.

2. The stress sensor fabrication method for similar simulation experiments according to claim 1 is characterized in that: The strain gauge terminal assembly in step S1 uses a strain gauge with terminals and wires.

3. The stress sensor fabrication method for similar simulation experiments according to claim 1, characterized in that: In step S1, the strain gauge terminal assembly includes a strain gauge, a terminal, and a single-core multi-strand copper core electronic wire. The strain gauge and the single-core multi-strand copper core electronic wire are respectively welded to both ends of the terminal, and a multimeter is used to check whether the circuit connection is intact.

4. The stress sensor fabrication method for similar simulation experiments according to claim 1, characterized in that: In step S3, the strain gauge and terminal in the strain gauge terminal assembly are adhered to the PVC transparent plastic plate with instant adhesive, wherein the strain gauge and terminal of the strain gauge terminal assembly are covered with a transparent plastic film and pressed with a finger. After the strain gauge and the PVC transparent plastic plate are firmly adhered, release the finger. During the pressing process, pay attention to protecting the wires connecting the strain gauge and the terminal.

5. A method for using a stress sensor for a similar simulation experiment as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S01. Sensor range test: Connect the sensor to the strain gauge and use the strain gauge to test the working status of the sensor to ensure that the sensor value is within the strain gauge range; S02. Similar simulation material ratio: According to the material ratio determined by the similar simulation experiment, measure the similar simulation experiment aggregate and cementitious material, and mix them thoroughly; S03. Sample preparation: Pour the mixed similar simulation test material into the sample preparation mold, place the sensor in the middle of the similar simulation test material, remove the mold after compaction, and use a strain gauge to test to ensure that the sensor value is within the strain gauge range; S04. Dry the specimens. Based on the similar simulation test cycle and laboratory climate conditions, place the specimens in the same scenario as the similar simulation test for natural drying. The placement time is the same as the time from the completion of paving to the excavation of the similar simulation model. S05. Sensor calibration: Place the dried specimen on a press to conduct a uniaxial compression test, obtain the stress-strain curve and the sensor value curve, obtain the relationship curve between specimen pressure and sensor strain, and calculate the linear phase slope of the two to clarify the transformation relationship between sensor strain and stress; S06. Arrange sensors according to a similar simulation experiment plan.

6. The method for using a stress sensor for similar simulation experiments according to claim 5, characterized in that: In step S03, half of the mixed similar simulation test material is poured into the sample preparation mold, and then leveled and compacted; Place the stress sensor in the middle of the mold, and lead the wire smoothly from the edge. Pour the remaining similar simulated test material into the mold, compact it evenly, and let it stand for 24 hours. Then remove the mold and use a strain gauge to test to ensure that the sensor value is within the strain gauge range.

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