Manufacturing and using method of stress sensor for similar simulation experiment

Abstract

The invention discloses a method for manufacturing and using a stress sensor for an analog simulation experiment, and belongs to the technical field of sensors, and the method comprises the following steps: S1, preparing materials; s2, fixing a strain gauge wiring terminal assembly and packaging a material; s3, pasting a strain gauge wiring terminal assembly; s4, detecting a strain gauge wiring terminal assembly; s5, curing the surface of the strain gauge of the strain gauge wiring terminal assembly; s6, sealing and packaging the strain gauge wiring terminal assembly; s7, checking the integrity of the sensor; the rigidity of the sensor is matched with that of a geotechnical material, and the influence on the stability of a geotechnical mechanics experiment and a structure thereof is small.

Description

Technical Field

[0001] The 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 stress sensor. Background Art

[0002] Similarity simulation test is an experimental method based on similarity theory. It constructs a model similar to the actual engineering or physical phenomenon and conducts experiments on the model to study the mechanical behavior, physical process and other characteristics of the prototype. It uses the similarity between the model and the prototype in terms of geometric shape, physical properties, boundary conditions and initial conditions to transform 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 similarity indexes equal to 1 or have the same numerical values ​​of similarity criteria; the second similarity theorem (theorem) states that a physical phenomenon can be represented by a functional relationship of one or more similarity criteria, which means that when designing similar 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 (inverse 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 the model design and experimental condition setting of similar simulation experiments.

[0004] In similar simulation tests, the materials used have similar proportional relationships with actual engineering materials in terms of physical and mechanical properties, and stress sensors need to match these similar materials to correctly reflect the stress state. For example, in geotechnical similar simulation tests, the study of the impact of underground engineering excavation on the stress of the surrounding rock and soil requires precision to a very small range of stress changes, because the mechanical properties of the rock and soil itself are complex, and a slight change in stress may cause changes in its deformation characteristics and stability. In addition, if the mechanical parameters such as the elastic modulus of the sensor are low, if the stiffness of the sensor is too large, it will change the stress distribution of the material itself, so it is necessary to develop a stress sensor that is compatible with the stiffness and other characteristics 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 lightweight and has a stiffness that matches that of the geotechnical material and is used to simulate the test using physically similar materials and a method for its use is proposed. Summary of the invention

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The fabrication of a stress sensor for similarity simulation experiments includes the following steps:

[0008] S1. Material preparation: Prepare a strain gauge wiring terminal assembly, an electric soldering pen, instant glue, room temperature vulcanizing silicone rubber, waterproof glass glue, PVC transparent plastic sheet, small clips, scissors, a ruler, and a multimeter;

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

[0010] S3. Pasting the strain gauge wiring terminal assembly: Paste the strain gauge wiring terminal assembly with instant glue dropped on it onto the prepared PVC transparent plastic sheet;

[0011] S4. Detecting the strain gauge wiring terminal assembly: After the strain gauge wiring terminal assembly is firmly pasted and the instant glue is completely hardened, use a multimeter to detect whether the circuit connection is intact;

[0012] S5. Curing the surface of the strain gauge of the strain gauge wiring terminal assembly: After the instant glue is completely hardened, apply room temperature vulcanizing silicone rubber on the upper surface of the strain gauge. After the room temperature vulcanizing silicone rubber is completely cured, use a multimeter to detect whether the circuit connection is intact;

[0013] S6. Sealing and encapsulating the strain gauge wiring terminal assembly: After the room temperature vulcanizing silicone rubber is completely cured, apply waterproof glass glue on the strain gauge wiring terminal assembly, then fold the PVC transparent plastic sheet along the crease, and finally fix its four sides with small clips, and let it stand in a ventilated and shady place to ensure that the waterproof glass glue is completely solidified;

[0014] S7. Inspection of the integrity of the sensor: Completing the above steps completes the fabrication process of the sensor, and use a multimeter to detect whether the circuit connection is intact, ensure that the resistance value is within the normal value, and record the resistance value at the same time.

[0015] Further, the strain gauge wiring terminal assembly in step S1 adopts a strain gauge with terminals and wires.

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

[0017] Furthermore, in step S3, after the strain gauge and the terminal in the strain gauge terminal assembly are adhered to the PVC transparent plastic plate by means of instant adhesive, the strain gauge and the terminal of the strain gauge terminal assembly are covered with a transparent plastic film, and pressed with fingers, and the fingers are released after the strain gauge and the PVC transparent plastic plate are firmly adhered, and attention is paid to protecting the wires connecting the strain gauge and the terminals during the pressing process.

[0018] A method for using the stress sensor for similar simulation experiments 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 detect the working state of the sensor to ensure that the sensor value is within the range of the strain gauge;

[0020] S02. Proportion of similar simulation materials: according to the material proportion determined by the similar simulation experiment, measure the aggregate and cementitious material of the similar simulation experiment and mix them thoroughly;

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

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

[0023] S05, sensor calibration; place the dried specimen on a press to carry out a uniaxial compression test, obtain the stress-strain curve and the sensor numerical curve, obtain the specimen pressure and sensor strain relationship curve, obtain the linear stage slope of the two, and clarify the sensor strain and stress conversion relationship;

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

[0025] Furthermore, in step S03, half of the mixed similar simulation test materials are 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 materials are 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.

[0026] Beneficial effects:

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

[0028] Figure 1 This is the structural schematic diagram of the sensor of the present invention;

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

[0030] Figure 3 This is the calibration specimen of the sensor of the present invention;

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

[0032] Figure 5 This is the data acquisition system of the strain instrument of the present invention;

[0033] Figure 6 This is the calibration of the sensor of the present invention;

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

[0035] Explanation of 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 implementation manners

[0036] This part will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the drawings. The function of the drawings is to supplement the description in the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the protection scope of the present invention.

[0037] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] In the description of the present invention, the meaning of several is one or more, the meaning of multiple is more than two, greater than, less than, exceeding, etc. are understood as not including the original number, and above, below, within, etc. are understood as including the original number. If the first and second are described, it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0039] In the description of the present invention, unless otherwise clearly defined, terms such as "setting", "installing", "connecting", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0040] Example 1

[0041] Reference Figures 1 - 2 , the fabrication of a stress sensor for similar simulation experiments includes the following steps:

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

[0043] S2. Fixing and encapsulating materials for the strain gauge terminal assembly: Cut the PVC transparent plastic sheet 6 into appropriate square small pieces with scissors, then fold it in half once, and repeatedly clean the position where the strain gauge terminal assembly is to be pasted;

[0044] In this embodiment, the PVC transparent plastic sheet 6 is cut into small pieces with a size of 5 cm × 5 cm with scissors; the cleaning position is 5 mm from the crease and 15 mm from the edge of the small piece for repeated cleaning.

[0045] S3. Pasting the strain gauge terminal assembly: Paste the strain gauge terminal assembly with instant glue dropped onto the prepared PVC transparent plastic sheet 6;

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

[0047] S4. Detecting the strain gauge terminal assembly: After the strain gauge terminal assembly is firmly pasted and the instant glue is completely hardened, use a multimeter to detect whether the circuit connection is intact;

[0048] In this embodiment, after the strain gauge terminal assembly is pasted, it is placed for about 1 hour.

[0049] S5. Curing the surface of the strain gauge of the strain gauge terminal assembly: After the instant glue is completely hardened, apply room temperature vulcanized silicone rubber 2 on the upper surface of the strain gauge. After the room temperature vulcanized silicone rubber 2 is completely cured, use a multimeter to detect whether the circuit connection is intact;

[0050] In this embodiment, the room temperature vulcanized silicone rubber 2 is 703 glue, and the coating thickness of the room temperature vulcanized silicone rubber 2 is 0.5 mm, and it is placed for about 24 hours.

[0051] S6, sealing and encapsulating the strain gauge terminal assembly; after the room temperature vulcanized silicone rubber 2 is completely cured, apply waterproof glass glue 4 on the strain gauge terminal assembly, then fold the PVC transparent plastic plate 6 in half along the crease, and finally fix it around with a small clip, and 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 with 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 a multimeter is used to check whether the circuit connection is intact to ensure that the resistance value is within the normal value, and the resistance value is recorded at the same time.

[0054] Preferably, in step S1, the strain gauge terminal assembly 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 both 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, the resistance is 120 ohms, the sensitive gate length is 3 mm, and the sensitive gate structure is 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 by means of 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 fingers, and the fingers are released after the strain gauge 1 and the PVC transparent plastic plate 6 are firmly adhered. During the pressing process, care is taken to protect the wires connecting the strain gauge 1 and the terminal 3.

[0058] Example 2

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

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

[0061] S02. Proportion of similar simulation materials: according to the material proportion determined by the similar simulation experiment, measure the aggregate and cementitious material of the similar simulation experiment and mix them thoroughly;

[0062] S03, Specimen preparation: Pour the mixed similar simulation test materials into the specimen-making mold, place the sensor in the middle of the similar simulation test materials, demold after compaction, and use a strain gauge to detect to ensure that the sensor value is within the range of the strain gauge.

[0063] S04, Specimen air-drying: According to the similar simulation test cycle and laboratory climate conditions, place the specimen in the same scene of the similar simulation test for natural air-drying, and the placement time is the same as the time from the completion of the laying of the similar simulation model to the excavation.

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

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

[0066] Preferably, in step S03, pour half of the mixed similar simulation test materials into the specimen-making mold, level and compact them; place the stress sensor in the middle of the mold, lead the wire out smoothly from the edge, pour the remaining similar simulation test materials into the mold, level and compact them, and after standing for 24 hours, demold and use a strain gauge to detect to ensure that the sensor value is within the range of the strain gauge.

[0067] The above is only 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 according to the technical essence of the present invention still belong to the scope of the technical solution of the present invention.

Claims

1. Fabrication of a stress sensor for similarity simulation experiments, characterized in that, The following steps are involved: S1. Material preparation: prepare strain gauge terminal assembly, welding pen, instant glue, room temperature vulcanized silicone rubber, waterproof glass glue, PVC transparent plastic plate, small clips, scissors, ruler, and multimeter; S2, Strain gauge terminal assembly fixing and packaging materials; Cut the PVC transparent plastic sheet into suitable square pieces with scissors, then fold it in half once, and repeatedly clean the position where the strain gauge terminal assembly is to be pasted; S3, pasting 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 pasted and the instant adhesive is completely hardened, use a multimeter to check whether the circuit connection is intact; S5. The strain gauge surface of the strain gauge terminal assembly is cured; after the instant adhesive is completely hardened, room temperature vulcanized silicone rubber is applied 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 on the strain gauge terminal assembly, then fold the PVC transparent plastic sheet in half along the crease, and finally fix it with a small clip. 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 a multimeter is used to check whether the circuit connection is intact to ensure that the resistance value is within the normal value, and the resistance value is recorded at the same time.

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

3. The fabrication of a stress sensor for similarity 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, wherein the strain gauge and the single-core multi-strand copper core electronic wire are respectively welded to two ends of the terminal, and a multimeter is used to detect whether the circuit connection is intact.

4. The fabrication of a stress sensor for similarity simulation experiments according to claim 1, characterized in that, In step S3, the strain gauge and the terminal in the strain gauge terminal assembly are adhered to the PVC transparent plastic plate by means of instant adhesive, wherein the strain gauge and the terminal of the strain gauge terminal assembly are covered with a transparent plastic film, and pressed with fingers, and the fingers are released after the strain gauge and the PVC transparent plastic plate are firmly adhered, and attention is paid to protecting the wires connecting the strain gauge and the terminal during the pressing process.

5. A method for using a stress sensor for similarity simulation experiments as described in any one of claims 1-4, 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 detect the working state of the sensor to ensure that the sensor value is within the range of the strain gauge; S02. Proportion of similar simulation materials: according to the material proportion determined by the similar simulation experiment, measure the aggregate and cementitious material of the similar simulation experiment and mix them thoroughly; S03, sample preparation: pour the mixed similar simulation test materials into the sample preparation mold, place the sensor in the middle of the similar simulation test materials, remove the mold after compaction, and use the strain gauge to detect to ensure that the sensor value is within the strain gauge range; S04. Dry the specimens. According to the similar simulation test cycle and laboratory climate conditions, place the specimens in the same scene of the similar simulation test for natural drying. The placement time is the same as the time from the completion of the paving of the similar simulation model to the excavation. S05. Sensor calibration: Place the dried test piece on a press to conduct a uniaxial compression test, obtain the stress-strain curve and the sensor numerical curve, acquire the curve of the relationship between the pressure of the test piece and the sensor strain, calculate the slope of the linear stage of the two, and clarify the conversion relationship between the sensor strain and the stress. S06. Arrange sensors according to the similar simulation experiment plan.

6. The method for using a stress sensor for similarity simulation experiments according to claim 5, characterized in that, In step S03, pour half of the mixed similar simulation test materials into the sample preparation mold, level and compact them after leveling. Place the stress sensor in the middle of the mold, lead the wire out smoothly from the edge, pour the remaining similar simulation test materials into the mold, level and compact them, and after standing for 24 hours, remove the mold and use a strain gauge to detect to ensure that the sensor value is within the range of the strain gauge.

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