CN118168910A - Clamp and method for monitoring prestress loading under multiple working conditions in real time - Google Patents
Clamp and method for monitoring prestress loading under multiple working conditions in real time Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000012544 monitoring process Methods 0.000 title claims abstract description 24
- 230000036316 preload Effects 0.000 claims abstract description 8
- 238000012360 testing method Methods 0.000 claims description 78
- 239000002131 composite material Substances 0.000 claims description 62
- 238000003825 pressing Methods 0.000 claims description 26
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 19
- 229910052739 hydrogen Inorganic materials 0.000 claims description 19
- 239000001257 hydrogen Substances 0.000 claims description 19
- 238000003860 storage Methods 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000002474 experimental method Methods 0.000 claims description 5
- 238000004088 simulation Methods 0.000 claims description 5
- 238000009863 impact test Methods 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 230000002457 bidirectional effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000003733 fiber-reinforced composite Substances 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/04—Chucks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/025—Geometry of the test
- G01N2203/0254—Biaxial, the forces being applied along two normal axes of the specimen
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Abstract
The invention discloses a clamp and a method for monitoring multi-working-condition prestress loading in real time, and belongs to the technical field of tool clamps; the clamp in the existing prestress application impact test has the problems of inaccurate preload, difficulty in monitoring load application, inconvenience in carrying the clamp, time consuming and complex operation and the like.
Description
Technical Field
The invention relates to the technical field of tool clamps, in particular to a clamp and a method for monitoring multi-working-condition prestress loading in real time.
Background
The hydrogen energy automobile is one of the most application potential new energy automobiles at present, and the hydrogen storage cylinder is used as a key energy supply device of the hydrogen energy automobile, metal is mainly adopted as a raw material for production in the early stage, and in order to ensure the structural strength of the cylinder, a designer can only improve the bearing capacity of the cylinder by continuously increasing the thickness, so that the quality of the designed hydrogen storage cylinder is higher, and the endurance mileage of the hydrogen energy automobile is seriously influenced. In recent years, in order to improve the energy utilization rate and mileage of a hydrogen energy automobile, designers adopt a light high-strength carbon fiber composite material as a raw material for preparation, and the overall weight of the hydrogen storage cylinder is greatly reduced. However, the composite material has natural defects, namely the composite material is very sensitive to impact load, and engineering personnel can find out in time relative to high-speed impact, and typical visual invisible damage caused by low-speed impact has serious threat to the performance of a hydrogen storage cylinder of the composite material, so that the low-speed impact behavior and mechanism research of the composite material for the hydrogen energy automobile have important significance for guiding the impact resistance design of the composite material.
The main method currently used to study the impact resistance of composite laminates is the drop hammer impact test. In drop hammer impact test standard ASTM D7136-12, the specified clamping device does not preload the composite laminate. However, in an actual service environment, the composite hydrogen storage cylinder is subjected to a certain load before being subjected to low-speed impact due to the existence of the internal high-pressure gas, for example, the hydrogen storage cylinder is subjected to bidirectional tensile prestress from the internal high-pressure gas during normal running, the shell is subjected to external axial compression and bidirectional tensile-compressive prestress caused by the internal high-pressure gas during rear-end collision of an automobile, and the like, but the pre-load is not considered in the existing simulation test.
Disclosure of Invention
The invention aims to provide a clamp and a method for monitoring multi-working-condition prestress loading in real time, which are used for realizing accurate and monitorable non-cooperative pulling/pressing load on a composite material, are simple and convenient to operate and good in portability, and obtain the corresponding clamp size, clamping area size and the applied prestress application range size used for experiments in a reasonable calculation mode.
In order to achieve the above purpose, the invention provides a clamp for monitoring multi-working-condition prestress loading in real time, which comprises a cross fixing frame, wherein baffle plates are arranged on four end faces of the cross fixing frame, a testing device and a fixed end are respectively arranged on the two baffle plates which are oppositely arranged, the clamp is arranged in the cross fixing frame, two adjacent side faces of the clamp are respectively and fixedly connected with the two fixed ends, and the other two adjacent side faces are respectively and fixedly connected with the two testing devices.
Preferably, the fixture is set to rectangular structure, the hollow position in the middle sets up to the clamping area, the fixture includes four-layer structure, from down up in proper order be the bottom plate layer, slip sheet layer, pad sheet layer and clamp plate layer, the bottom plate layer the slip sheet layer the pad sheet layer with all be provided with a plurality of bolt hole on the clamp plate layer, use the bolt to fix four-layer structure.
Preferably, the top surface of the sliding plate layer and the top surface of the bottom plate layer are arranged in the same horizontal plane, the sliding plate layer comprises a first side sliding block and a second side sliding block, a plurality of sliding convex grooves are formed in the bottoms of the first side sliding block and the second side sliding block, and sliding grooves meshed with the sliding convex grooves are formed in the bottom plate layer at corresponding positions of the sliding convex grooves.
Preferably, the backing plate layer comprises a first fixed side backing plate, a second fixed side backing plate, a first sliding side backing plate and a second sliding side backing plate, the pressing plate layer comprises a first side pressing plate arranged vertically, a second side pressing plate arranged horizontally and an L-shaped pressing plate, and gaps are formed between the backing plate layer and the components of the pressing plate layer.
Preferably, the backing plate layer and the pressing plate layer are both rectangular structures, and the size of the backing plate layer is smaller than that of the pressing plate layer.
Preferably, the testing device comprises a screw rod, the screw rod horizontally penetrates through the baffle plate, one end of the screw rod is provided with a rotary handle, the other end of the screw rod is connected with a force sensor, and the force sensor is connected with the corresponding side pressing plate through a fixing rod.
A clamp using method for monitoring multi-working-condition prestress loading in real time comprises the following steps:
s1: the method comprises the steps of establishing a stress state model of a composite material hydrogen storage cylinder, and calculating main stress, pre-tensioning or pre-pressing load, clamping force range and clamping pressure, wherein the process is as follows:
When the thin-wall cylinder is under the action of the axial force T and the internal water pressure p, the stress state of the pipe wall is expressed as follows:
In the above formula, σ θ is the circumferential main stress, σ z is the axial main stress, τ θz is the shear stress, T is the axial force, R is the average radius of the thin-wall tube, T is the wall thickness of the thin-wall tube, radial stress σ r =0 has the magnitude of p, the shear stresses in different directions are all 0, and stress σ r、σθ、σz is the main stress;
When the stress state of the pipe wall is Τ θz =0, which is divided into the following cases:
when the composite material test piece is subjected to biaxial pre-tensioning load, sigma θ＞0,σz is more than 0, and the load formula is as follows:
When the composite material test piece is subjected to biaxial pre-pressing load, sigma θ＜0,σz is smaller than 0, and the load formula is as follows:
When the composite material test piece is subjected to biaxial asymmetric pretension or ballast load, sigma θσz is less than 0, and the load formula is as follows:
or/>
In the above formula, f y is the pre-tensioning load of the composite material test piece in the y-axis direction, N y is the pre-tensioning load of the composite material test piece in the y-axis direction, f x is the pre-tensioning load of the composite material test piece in the x-axis direction, N x is the pre-tensioning load of the composite material test piece in the x-axis direction, and a, b and c are the length, width and height of the composite material test piece respectively;
When the tensile load state of the test piece is The formula of the clamping force range of the clamp is as follows:
in the above formula, F n(y) is the clamping force of the clamp on the composite material test piece in the y-axis direction, F n(x) is the clamping force of the clamp on the composite material test piece in the x-axis direction, and mu is the friction coefficient of the surface of the composite material test piece;
When the clamping force range of the clamp to the composite material test piece is When the clamping pressure of the clamping force of the clamping part of the base or the sliding block and the pressing plate contacted with the test piece is as follows:
In the above formula, S y is the clamping area of one side of the clamp and the composite material test piece in the y-axis direction, p y is the clamping pressure of the corresponding clamping surface of S y, S x is the clamping area of one side of the clamp and the composite material test piece in the x-axis direction, and p x is the clamping pressure of the corresponding clamping surface of S x;
S2: simulating and calculating the clamping area and the clamping force range of the clamp calculated in the step S1, wherein the specific process is to perform stress field numerical simulation on the composite material test piece under different clamping areas and clamping force ranges based on finite element software, and verifying reasonable clamping area and clamping force range according to stress and strain fields of the test piece under the clamping state by setting different clamping forces and clamping area sizes;
S3: selecting a proper force sensor according to the main stress range in the step S1, and selecting a clamp with proper size according to the clamping area and the clamping force range calculated in the step S2;
S4: installing a composite material test piece into a clamp, and rotating a screw rod to apply a required preload to the test piece clamped by the clamp;
S5: subsequent impact experiments were performed on the clamps to which the preload was applied.
Therefore, the clamp and the method for monitoring the multi-working-condition prestress loading in real time by adopting the method have the following advantages:
(1) According to the invention, the sliding plate is directly connected with the screw rod through the force sensor, so that the accuracy of preloaded load is ensured, and the stress state data of the test piece in the impact test process can be transmitted to the force sensor in real time, thereby facilitating observers to analyze the stress state of the test piece in the impact process and realizing non-contact monitoring. Meanwhile, the method can be applied to other fiber reinforced composite materials, metals, plastics and the like, and is used for evaluating the impact resistance and fracture toughness of the materials when the materials are subjected to impact loads.
(2) According to the invention, the coordination and non-coordination of biaxial prestress application can be realized through the double sliding blocks, the sliding grooves, the force sensor and the screw, and six load loading modes of symmetrical pressure-pressure, symmetrical pull-pressure, symmetrical shearing pull-pressure, asymmetrical pressure-pressure, asymmetrical pull-pressure and asymmetrical shearing pull-pressure can be simulated, so that the actual loaded working condition in the service environment can be simulated more truly.
(3) In the invention, the adopted tool is a fully mechanical part, the occupied area is small, and the tool is convenient for an operator to carry. The fixture is simple in structure, can apply pre-tension or pre-tension quickly, and is simple and quick to operate.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a block diagram of a device in a fixture for monitoring multi-condition pre-stress loading in real time according to the present invention;
FIG. 2 is a block diagram of a base plate layer and a sliding plate layer in a clamp for monitoring multi-condition prestressing loading in real time according to the invention;
FIG. 3 is a block diagram of a shim plate layer and shim plate layer in a fixture for monitoring multi-condition pre-stressing in real time in accordance with the present invention;
FIG. 4 is a schematic illustration of the clamp of the present invention with the clamp removed for monitoring the prestress loading in real time under multiple conditions;
FIG. 5 is a schematic diagram of the tensile and internal water pressure action of a thin-walled cylinder in a clamp and method for monitoring multi-condition prestressing force loading in real time according to the present invention;
Reference numerals
1. A bottom plate layer; 2. a sliding plate layer; 21. a first side slider; 22. a second side slider; 23. sliding convex groove; 24. a sliding groove; 3. a mat layer; 31. a first fixed side bolster; 32. a second fixed side bolster; 33. a first sliding side pad; 34. a second sliding side pad; 4. a lamination layer; 41. a first side platen; 42. a second side platen; 43. an L-shaped pressing plate; 5. a bolt; 6. a baffle; 7. a cross fixing frame; 8. a force sensor.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. The specific model specification needs to be determined by selecting the model according to the actual specification and the like of the device, and the specific model selection calculation method adopts the prior art in the field, so detailed description is omitted.
Examples
As shown in fig. 1-4, the invention discloses a clamp for monitoring multi-working-condition prestress loading in real time, which comprises a cross fixing frame 7, wherein baffle plates 6 are arranged on four end faces of the cross fixing frame 7, a testing device and a fixed end are respectively arranged on two baffle plates 6 which are oppositely arranged, the clamp is arranged in the cross fixing frame 7, two adjacent side faces of the clamp are respectively fixedly connected with the two fixed ends to play a role in fixing furniture, the other two adjacent side faces are respectively fixedly connected with the two testing devices, and the testing devices are responsible for applying prestress and metering the applied prestress.
The anchor clamps set up to rectangular structure, and the hollow position in the middle sets up to the clamping area, sets up dull and stereotyped test piece in the clamping area and carries out the centre gripping, and anchor clamps include four-layer structure, from down upwards being in proper order bottom plate layer 1, slip sheet layer 2, backing plate layer 3 and clamp plate layer 4, all are provided with a plurality of bolt hole on bottom plate layer 1, slip sheet layer 2, backing plate layer 3 and the clamp plate layer 4, from last four-layer structure down fixed through bolt 5 for four-layer structure keeps stable, installs the test piece under clamp plate layer 4 and carries out the centre gripping work, and compresses tightly the sheet layer 4 through bolt 5 and carries out fixed clamp.
The bolts 5 are penetrated from top to bottom to fix the clamp structure, and the connection of the sliding plate layer 2 and the bottom plate layer 1 does not affect the force transmission, because the gap between the screws and the screw holes is larger than the micro-strain generated by the stress of the composite material test piece, and the application of the prestress cannot be affected.
The top surface of slip sheet layer 2 sets up in same horizontal plane with the top surface of bottom plate layer 1, and slip sheet layer 2 includes first side sliding block 21 and second side sliding block 22, and the bottom of first side sliding block 21 and second side sliding block 22 all is provided with a plurality of slip tongue 23, and bottom plate layer 1 is provided with the slip recess 24 with slip tongue 23 meshing in the corresponding position department of slip tongue 23, makes things convenient for the screw rod to exert prestressing force to the test piece of anchor clamps fixed.
The cushion layer 3 and the pressing plate layer 4 are all enclosed into a rectangular structure, the cushion layer 3 comprises a first fixed side cushion plate 31, a second fixed side cushion plate 32, a first sliding side cushion plate 33 and a second sliding side cushion plate 34, the first sliding side cushion plate 33 and the second sliding side cushion plate 34 are arranged above the sliding plate layer 2, the first fixed side cushion plate 31 and the second fixed side cushion plate 32 are arranged above the cushion layer 1, the cushion layer 3 is arranged into four parts, gaps are reserved between parts, when the four cushion plates are arranged to prevent double shafts from exerting pressure, the pressure of the two shafts affect each other, the thickness of the cushion layer 3 is smaller than that of a test piece, the pressure exerted by the pressing plate can be only exerted on the test piece, and other resistance caused by the contact of the pressing plate layer 4 and the cushion layer 3 is avoided.
The platen layer 4 includes the first side clamp plate 41 of vertical setting, the second side clamp plate 42 and the L shape clamp plate 43 of level setting, all is provided with the clearance between the part in backing plate layer 3 and the clamp plate layer 4, sets up the clearance and provides the condition for frictional force's production, still makes the pressure of diaxon or the mutual noninterference in the pulling force transmission process, guarantees the unidirectional transmission of power, can let the test piece have the space of deformation, leads to the mutual conflict between the anchor clamps structure when avoiding exerting prestressing force.
The testing device comprises a screw rod, the screw rod horizontally penetrates through the baffle 6, one end of the screw rod is provided with a rotary handle, the other end of the screw rod is connected with the force sensor 8, the force sensor 8 is connected with a corresponding side pressing plate through a fixed rod, the screw rod is rotated to apply the preload, and the force sensor 8 is used for detecting the load.
A clamp using method for monitoring multi-working-condition prestress loading in real time comprises the following steps:
s1: according to the actual load born by the material used by the hydrogen storage cylinder of the composite material in the service process, calculating the main stress, the pre-stretching or pre-pressing load, the clamping force range and the clamping pressure, as shown in figure 5, calculating the stress born by the interior of the composite material, and thus determining the pre-stress application range of the pre-stress impact clamp;
the actual load born by the composite material hydrogen storage cylinder in the service process can be applied to a stress state model of the thin-wall cylinder under the action of stretching, torsion and internal water pressure, so that the stress state model of the composite material hydrogen storage cylinder is established, and the stress of the pipe wall is calculated:
when the thin-wall cylinder is under the action of the axial force T and the internal water pressure p, the main stress of the pipe wall is expressed as follows:
In the above formula, σ θ is the hoop principal stress, σ z is the axial principal stress, τ θz is the shear stress, T is the axial force, R is the average radius of the thin-walled tube, T is the wall thickness of the thin-walled tube, the radial stress σ r =0 has the magnitude of p, for R/T > 1, the radial stress σ r is small compared with σ θ、σz and can be ignored, since the shear stress in different directions is 0, and the stress σ r、σθ、σz is the principal stress;
When the stress state of the pipe wall is Τ θz =0, which is divided into the following cases:
When the composite material test piece is subjected to biaxial pre-tensioning load, sigma θ＞0,σz is more than 0, the formula is as follows:
when the composite material test piece is subjected to biaxial pre-pressing load, sigma θ＜0,σz is less than 0, the formula is as follows:
when the composite material test piece is subjected to biaxial asymmetric pretension or ballast load, sigma θσz is less than 0, the formula is as follows:
or/>
In the above formula, f y is the pre-tensioning load of the composite material test piece in the y-axis direction, N y is the pre-tensioning load of the composite material test piece in the y-axis direction, f x is the pre-tensioning load of the composite material test piece in the x-axis direction, N x is the pre-tensioning load of the composite material test piece in the x-axis direction, and a, b and c are the length, width and height of the composite material test piece respectively;
S2: simulation verification is carried out on the clamping area and the clamping force range of the clamp calculated in the step S1, the specific process is that stress field numerical simulation is carried out on a composite material test piece under different clamping areas and clamping force ranges based on finite element software, and reasonable clamping area and clamping force range are verified according to stress and strain fields of the test piece under the clamping state by setting different clamping forces and clamping area sizes; when the stress field of the test piece is most uniform under the combined action of the clamping area and the clamping force, the test piece is the most reasonable clamping area and clamping force.
According to the uniformity index, calculating the standard deviation or variance of the stress field to evaluate the uniformity, the maximum stress difference and the equivalent stress distribution of the stress distribution as judgment standards;
S3: selecting a proper force sensor according to the main stress range in the step S1, and selecting a clamp with proper size according to the clamping area and the clamping force range calculated in the step S2;
s4: and installing the composite material test piece into the clamp, clamping four sides of the test piece by the clamp plate layer and the bottom plate layer, carrying out backing up by the clamp plate layer in an auxiliary manner, applying corresponding prestress to the test piece clamped by the clamp by the rotating screw according to data monitored by the force sensor, enabling the sliding block to move by the rotating screw, pushing or pulling the test piece by the sliding block, and applying the prestress.
S5: and carrying out subsequent impact experiments on the clamp applied with the prestress load.
In conclusion, the axial force T and the internal water pressure p of the actual use working condition of the composite material hydrogen storage cylinder of the hydrogen energy input automobile can be obtained through the calculation of the stress state model of the composite material hydrogen storage cylinder: the clamping pressure p y、px that the material of bottom plate, slider, backing plate, clamp plate should be born, the clamping force F n(y)、Fn(x) that screw and screw should be exerted, the pretension load of anchor clamps to test piece is F y and F x this moment, and the prestressing force is N x and N y, prestressing force state sigma r、σθ、σz of test piece.
The method has the advantages that accurate and monitorable non-cooperative pulling/pressing load is applied to the composite material, the operation is simple and convenient, the portability is good, the corresponding clamp size, clamping area size and the applied prestress application range size used in an experiment are obtained through a reasonable calculation mode.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that: the technical scheme of the invention can be modified or replaced by the same, and the modified technical scheme cannot deviate from the spirit and scope of the technical scheme of the invention.
Claims (7)
1. A clamp for monitoring multi-working-condition prestress loading in real time is characterized in that: including the cross mount, four terminal surfaces of cross mount all are provided with the baffle, two of opposite direction setting are provided with testing arrangement and stiff end respectively on the baffle, be provided with anchor clamps in the cross mount, two adjacent sides of anchor clamps respectively with two stiff end fixed connection, other two adjacent sides respectively with two testing arrangement fixed connection.
2. The clamp for monitoring multi-condition prestress loading in real time according to claim 1, wherein: the fixture is set to rectangular structure, and the hollow position in the middle sets up to the clamping area, the fixture includes four-layer structure, from down upwards in proper order be the bottom plate layer, slip sheet layer, cushion sheet layer and clamp plate layer, the bottom plate layer the slip sheet layer the cushion sheet layer with all be provided with a plurality of bolt hole on the clamp plate layer, the bolt is fixed four-layer structure.
3. The clamp for monitoring multi-condition prestress loading in real time according to claim 2, wherein: the top surface of slip sheet layer with the top surface setting of bottom plate layer is in same horizontal plane, the slip sheet layer includes first side sliding block and second side sliding block, first side sliding block with the bottom of second side sliding block all is provided with a plurality of slip tongue, the bottom plate layer be in the corresponding position department of slip tongue be provided with the slip recess of slip tongue meshing.
4. A clamp for monitoring multi-condition pre-stressing in real time according to claim 3, characterized in that: the backing plate layer includes first fixed side backing plate, second fixed side backing plate, first slip side backing plate and second slip side backing plate, the clamp plate layer includes first side clamp plate, the second side clamp plate and the L shape clamp plate that the level set up of vertical setting, the backing plate layer with all be provided with the clearance between the part of clamp plate layer.
5. The fixture for monitoring multi-condition pre-stressing in real time according to claim 4, wherein: the backing plate layer and the pressing plate layer are both arranged in rectangular structures, and the size of the backing plate layer is smaller than that of the pressing plate layer.
6. The fixture for monitoring multi-condition pre-stressing in real time according to claim 5, wherein: the testing device comprises a screw rod, the screw rod horizontally penetrates through the baffle, one end of the screw rod is provided with a rotary handle, the other end of the screw rod is connected with a force sensor, and the force sensor is connected with the corresponding side pressing plate through a fixing rod.
7. The clamp using method for monitoring the prestress loading under the multiple working conditions in real time is characterized by comprising the following steps of:
s1: the method comprises the steps of establishing a stress state model of a composite material hydrogen storage cylinder, and calculating main stress, pre-tensioning or pre-pressing load, clamping force range and clamping pressure, wherein the process is as follows:
When the thin-wall cylinder is under the action of the axial force T and the internal water pressure p, the stress state of the pipe wall is expressed as follows:
In the above formula, σ θ is the circumferential main stress, σ z is the axial main stress, τ θz is the shear stress, T is the axial force, R is the average radius of the thin-wall tube, T is the wall thickness of the thin-wall tube, radial stress σ r =0 has the magnitude of p, the shear stresses in different directions are all 0, and stress σ r、σθ、σz is the main stress;
When the stress state of the pipe wall is The following is the case:
when the composite material test piece is subjected to biaxial pre-tensioning load, sigma θ＞0,σz is more than 0, and the load formula is as follows:
When the composite material test piece is subjected to biaxial pre-pressing load, sigma θ＜0,σz is smaller than 0, and the load formula is as follows:
When the composite material test piece is subjected to biaxial asymmetric pretension or ballast load, sigma θσz is less than 0, and the load formula is as follows:
or/>
In the above formula, f y is the pre-tensioning load of the composite material test piece in the y-axis direction, N y is the pre-tensioning load of the composite material test piece in the y-axis direction, f x is the pre-tensioning load of the composite material test piece in the x-axis direction, N x is the pre-tensioning load of the composite material test piece in the x-axis direction, and a, b and c are the length, width and height of the composite material test piece respectively;
When the tensile load state of the test piece is The formula of the clamping force range of the clamp is as follows:
in the above formula, F n(y) is the clamping force of the clamp on the composite material test piece in the y-axis direction, F n(x) is the clamping force of the clamp on the composite material test piece in the x-axis direction, and mu is the friction coefficient of the surface of the composite material test piece;
When the clamping force range of the clamp to the composite material test piece is When the clamping pressure of the clamping force of the clamping part of the base or the sliding block and the pressing plate contacted with the test piece is as follows:
In the above formula, S y is the clamping area of one side of the clamp and the composite material test piece in the y-axis direction, p y is the clamping pressure of the corresponding clamping surface of S y, S x is the clamping area of one side of the clamp and the composite material test piece in the x-axis direction, and p x is the clamping pressure of the corresponding clamping surface of S x;
S2: simulating and calculating the clamping area and the clamping force range of the clamp calculated in the step S1, wherein the specific process is to perform stress field numerical simulation on the composite material test piece under different clamping areas and clamping force ranges based on finite element software, and verifying reasonable clamping area and clamping force range according to stress and strain fields of the test piece under the clamping state by setting different clamping forces and clamping area sizes;
S3: selecting a proper force sensor according to the main stress range in the step S1, and selecting a clamp with proper size according to the clamping area and the clamping force range calculated in the step S2;
S4: installing a composite material test piece into a clamp, and rotating a screw rod to apply a required preload to the test piece clamped by the clamp;
S5: subsequent impact experiments were performed on the clamps to which the preload was applied.
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| CN202410333562.1A CN118168910A (en) | 2024-03-22 | 2024-03-22 | Clamp and method for monitoring prestress loading under multiple working conditions in real time |
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