A positive and negative air pressure static loading device

Abstract

This invention provides a positive and negative pneumatic static loading device, including a clamp frame for fixing a test specimen. The clamp frame includes a base plate, a cover plate, and a cap. A baffle is provided on the base plate. After the cover plate is fixedly connected to the base plate, the baffle is flush with the cover plate and is used to fix the test specimen on the base plate. The cap is sealed to the cover plate. An annular glue injection groove is provided at the interface between the cover plate and the test specimen. A distributed microchannel network is provided in the annular glue injection groove. After glue is injected into the annular glue injection groove, a glue injection layer is formed. A flexible sealing interface with a continuous transition is formed between the cover plate and the test specimen at the connection. An air filling and defilling port is provided on the cap. The glue injection layer of this invention absorbs local stress concentration through the large deformation elastomer characteristics. Under positive pressure loading, it transmits uniform surface load through volume compression. Under negative pressure suction, it inhibits the propagation of microcracks at the edge of the test specimen through viscoelastic restoring force.

Description

Technical Field

[0001] This utility model relates to the technical field of testing equipment, specifically to a positive and negative air pressure static loading device. Background Technology

[0002] In recent years, my country's aerospace industry has experienced leapfrog development. With the successful commercial operation of the C919 large passenger aircraft, the deployment of the new generation of stealth fighters, and breakthroughs in hypersonic vehicle technology, aircraft design innovation has entered a period of rapid development. In aircraft aerodynamic layout and structural design, the lip structure, as a key component of the air intake system and the transition area between sections, plays a crucial role in optimizing airflow distribution and withstanding complex aerodynamic loads. Its structural performance directly affects the aircraft's aerodynamic efficiency, stealth characteristics, and operational safety; therefore, accurate testing of its strength characteristics has become a core aspect of aircraft research and development.

[0003] Currently, strength testing of air intake lip structures faces two major technical challenges: First, in real flight conditions, the air intake structure must withstand dynamic pressure fluctuations caused by high-speed airflow and maneuvering loads, and its alternating positive and negative pressure effects are difficult to simulate using traditional static loading methods. Existing testing equipment mostly uses step-by-step unidirectional static pressure loading, which cannot reproduce the transient switching characteristics of the pressure field during flight. In recent years, my country's aerospace industry has shown a leapfrog development trend. With the successful commercial operation of the C919 large passenger aircraft, the deployment of the new generation of stealth fighters, and breakthroughs in hypersonic vehicle technology, aircraft design innovation has entered a period of rapid development. In aircraft aerodynamic layout and structural design, the air intake structure, as a key component of the air intake system and the transition area of ​​the compartment, undertakes the important functions of optimizing airflow distribution and withstanding complex aerodynamic loads. Its structural performance is directly related to the aerodynamic efficiency, stealth characteristics, and operational safety of the aircraft. Therefore, accurate testing of its strength characteristics has become a core aspect of aircraft research and development.

[0004] Currently, strength testing of lip structures faces several technical challenges. One major challenge is that, under real flight conditions, the lip structure must withstand dynamic pressure fluctuations caused by high-speed airflow and maneuvering loads. The alternating positive and negative pressure effects are difficult to simulate using traditional static loading methods. Existing testing equipment often employs step-by-step unidirectional static pressure loading, which cannot reproduce the transient switching characteristics of the pressure field during flight, leading to inaccuracies in structural fatigue life prediction. Utility Model Content

[0005] The purpose of this invention is to provide a positive and negative air pressure static loading device, which can effectively solve the technical problem that existing test equipment mostly adopts step-by-step unidirectional static pressure loading, which cannot reproduce the transient switching characteristics of the pressure field during flight, resulting in deviations in the prediction of structural fatigue life.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0007] A positive and negative air pressure static loading device includes a clamp frame for fixing the test piece.

[0008] The fixture frame includes a base plate, a cover plate, and a cover; a baffle is provided on the base plate; after the cover plate is fixedly connected to the base plate, the baffle is flush with the cover plate and is used to fix the test piece on the base plate; the cover is sealed to the cover plate.

[0009] The cover plate and the test piece have an annular glue injection groove at the contact interface. The annular glue injection groove has a distributed microchannel network. After glue is injected into the annular glue injection groove, a glue injection layer is formed. The cover plate and the test piece form a flexible sealing interface with a continuous transition at the connection. The cap is provided with an inflation / deflation port.

[0010] Furthermore, the injection layer is a cured silicone rubber-polyurethane composite injection layer filled in an annular injection groove.

[0011] Furthermore, a distributed microchannel network is provided inside the annular injection groove.

[0012] Furthermore, the elastic modulus of the injection layer is 0.5-5 MPa, and the Poisson's ratio is 0.45-0.49.

[0013] Furthermore, the top of the baffle and cover plate are provided with interconnected mounting grooves, and an elastic sealing ring is provided in the mounting groove.

[0014] Furthermore, the base plate is made of an aluminum alloy frame.

[0015] Furthermore, the width of the annular injection groove is 2-5mm, and the groove depth varies along the curvature gradient of the test piece edge.

[0016] Furthermore, the cover and the lid are connected by screws, and the lid and the base plate are connected by bolts.

[0017] Furthermore, the pressure plate is also equipped with strain gauge outlets.

[0018] Furthermore, positive pressure loading utilizes existing air compressors, in conjunction with the designed SMC IRV series pressure regulating valves, to achieve precise positive pressure control with a control accuracy of ±0.5%.

[0019] Furthermore, negative pressure loading utilizes existing air compressors and leverages the Venturi effect to achieve precise negative pressure control with a control accuracy of ±0.5%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] In practical applications, this invention uses a cover plate to fix the test specimen to a base plate. Simultaneously, an annular injection groove is set at the interface between the cover plate and the test specimen. After injection, an injection layer is formed in the annular injection groove. A continuous, flexible sealing interface is formed between the cover plate and the test specimen at the connection point. The sealant has been optimized through multiple comparative tests, improving its continuity and density, and enhancing its resistance to compressive creep. The injection layer of this invention absorbs local stress concentration through its large deformation elastomer characteristics. Under positive pressure loading, it transmits uniform surface load through volume compression; under negative pressure suction, it inhibits the propagation of microcracks at the edges of the test specimen through viscoelastic restoring force. This effectively solves the technical problem that existing testing equipment often uses step-by-step unidirectional static pressure loading, which cannot reproduce the transient switching characteristics of the pressure field during flight, leading to deviations in structural fatigue life prediction. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0024] Figure 2 This is a schematic diagram of the overall structure of this utility model after the cap has been removed.

[0025] Figure 3 This is an exploded view of the overall structure of this utility model.

[0026] Figure label:

[0027] 101 Test piece, 102 Fixture frame, 103 Base plate, 104 Cover plate, 105 Opening cover, 106 Baffle, 107 Inflation / discharge port, 108 Mounting groove, 109 Screw, 110 Bolt, 111 Strain gauge outlet. Detailed Implementation

[0028] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0029] In the description of the embodiments of this utility model, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.

[0032] In this embodiment of the invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The following disclosure provides many different implementations or examples for different structures of the embodiments of the present invention. To simplify the disclosure of the embodiments of the present invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. Furthermore, reference numerals and / or reference letters may be repeated in different examples of the embodiments of the present invention; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0034] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0035] See Figures 1-3 This embodiment discloses a positive and negative air pressure static loading device, including a clamp frame 102 for fixing the test piece 101.

[0036] The fixture frame 102 includes a base plate 103, a cover plate 104, and a cover 105. A baffle 106 is provided on the base plate 103. After the cover plate 104 is fixedly connected to the base plate 103, the baffle 106 is flush with the cover plate 104. The cover plate 104 is used to fix the test piece 101 on the base plate 103. The cover 105 is sealed to the cover plate 104.

[0037] Among them, the interface between the cover plate 104 and the test piece 101 is provided with an annular glue injection groove, and a distributed microchannel network is provided in the annular glue injection groove. After glue is injected into the annular glue injection groove, a glue injection layer is formed. The cover plate 104 and the test piece 101 form a flexible sealing interface with continuous transition at the connection. The cap 105 is provided with an inflation / deflation port 107.

[0038] In practical applications, this invention uses a cover plate 104 to fix the test piece 101 onto the base plate 103. Simultaneously, an annular injection groove is provided at the interface between the cover plate 104 and the test piece 101. After injection, an injection layer is formed within the groove, creating a continuous, flexible, sealed interface between the cover plate 104 and the test piece 101. The invention absorbs localized stress concentration through the properties of a large-deformation elastomer. Under positive pressure loading, it transmits uniform surface load through volume compression, and under negative pressure suction, it suppresses the propagation of microcracks at the edges of the test piece 101 through viscoelastic restoring force. This effectively solves the technical problem that existing testing equipment often uses step-by-step unidirectional static pressure loading, which cannot reproduce the transient switching characteristics of the pressure field during flight, leading to deviations in structural fatigue life prediction.

[0039] The adhesive layer is a cured silicone rubber-polyurethane composite adhesive layer filled in an annular adhesive groove.

[0040] Furthermore, a distributed microchannel network is provided within the annular injection groove. This distributed microchannel network is arranged radially and symmetrically, connecting all circumferential areas of the annular injection groove, thereby improving the stability of the formed flexible sealing interface.

[0041] The width of the annular injection groove is 2-5 mm, and the groove depth varies with the curvature gradient along the edge of the test piece 101. In this embodiment, the width of the annular injection groove is 3.5 mm.

[0042] In this embodiment, a 2-5mm annular injection groove is reserved at the interface between the cover plate 104 and the test piece 101. A distributed microchannel network is set in the groove to ensure that the injection material penetrates and fills the gap evenly along the circumference.

[0043] Furthermore, the base plate 103 is made of an aluminum alloy frame, which is a high-strength aluminum alloy frame structure that supports bidirectional (positive / negative) pressure loading mode and has a maximum pressure range of ±150kPa.

[0044] Furthermore, in some preferred embodiments, the elastic modulus of the injection layer is 0.5-5 MPa, and the Poisson's ratio is 0.45-0.49. A silicone rubber-polyurethane composite injection material is used, and the elastic modulus (0.5-5 MPa) is gradient-adjustable by adjusting the curing agent ratio to match the edge stiffness variation of test specimen 101.

[0045] In this embodiment, the ratio of silicone rubber to polyurethane composite injection material is 1:1.5.

[0046] In practical applications, this invention utilizes vacuum-assisted injection technology (VARI) to achieve bubble-free gap filling, forming a flexible sealing layer with a continuous transition after curing. Its Poisson's ratio (0.45-0.49) forms a mechanically compatible interface with the metal / composite material test piece 101.

[0047] The adhesive layer absorbs local stress concentration through its large deformation elastomer properties. Under positive pressure loading, it transfers uniform surface load through volume compression. Under negative pressure suction, it inhibits the propagation of microcracks at the edge of test piece 101 through viscoelastic restoring force.

[0048] The baffle 106 and the cover plate 104 are provided with interconnected mounting grooves 108, and an elastic sealing ring is provided in the mounting groove 108.

[0049] Furthermore, the cover 105 is connected to the cover plate 104 by screws 109, and the cover plate 104 is connected to the base plate 103 by bolts 110.

[0050] Furthermore, the pressure plate is also equipped with a strain gauge outlet 111.

[0051] In this invention, the adhesive layer acts as a mechanical impedance matching device, eliminating the boundary effect caused by traditional rigid clamps. This increases the correlation coefficient between the equivalent pressure gradient distribution and the actual aerodynamic load on the test piece 101 to over 0.92, compared to ≤0.75 in the traditional method.

[0052] Meanwhile, it supports alternating positive and negative pressure loading from 0.1Hz to 5Hz, with a pressure switching response time of <50ms, meeting the requirements for dynamic decompression simulation under transonic conditions.

[0053] Furthermore, in practical applications, the silicone rubber-polyurethane composite injection layer has a temperature resistance range of -70℃ to 200℃, covering extreme working conditions such as freezing and pneumatic heating. The resulting flexible sealing interface allows the test piece 101 to deform freely under thermal expansion / contraction, avoiding the introduction of undesigned loads caused by additional constraints.

[0054] This invention addresses the challenge of simulating dynamic pressure loading and boundary conditions in aircraft lip structure strength testing. It proposes a high-precision aerodynamic load transfer method based on a flexible sealing interface. The core innovation lies in the synergistic effect of a composite sealing fixture system and a deformable adhesive layer, achieving flexible transfer of dynamic loads and stress homogenization between the test piece 101 and the fixture. Simultaneously, the simulation is simpler, and the testing accuracy is higher for small-area specimens, more closely resembling actual operating conditions.

[0055] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0056] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. It should be noted that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A positive and negative pneumatic static loading device, comprising a clamp frame for fixing the test piece, characterized in that: The fixture frame includes a base plate, a cover plate, and a cover; a baffle is provided on the base plate; after the cover plate is fixedly connected to the base plate, the baffle is flush with the cover plate and is used to fix the test piece on the base plate; the cover is sealed to the cover plate. The cover plate and the test piece have an annular glue injection groove at the contact interface. The annular glue injection groove has a distributed microchannel network. After glue is injected into the annular glue injection groove, a glue injection layer is formed. The cover plate and the test piece form a flexible sealing interface with a continuous transition at the connection. The cap is provided with an inflation / deflation port.

2. The positive and negative air pressure static loading device according to claim 1, wherein: The adhesive layer is a cured silicone rubber-polyurethane composite adhesive layer filled in an annular adhesive groove.

3. The positive and negative air pressure static loading device of claim 1, wherein: The annular injection tank is equipped with a distributed microchannel network.

4. The positive and negative air pressure static loading device of claim 1, wherein: The elastic modulus of the adhesive layer is 0.5-5 MPa, and the Poisson's ratio is 0.45-0.

49.

5. The positive and negative air pressure static loading device of claim 1, wherein: The top of the baffle and cover plate is provided with interconnected mounting grooves, and an elastic sealing ring is installed in the mounting groove.

6. The positive and negative air pressure static loading device according to claim 1, characterized in that: The base plate is made of an aluminum alloy frame.

7. The positive and negative air pressure static loading device of claim 1, wherein: The width of the annular injection groove is 2-5mm, and the groove depth varies along the curvature gradient of the test piece edge.

8. The positive and negative air pressure static loading device of claim 1, wherein: The lid and the cover plate are connected by screws, and the cover plate and the base plate are connected by bolts.

9. The positive and negative pneumatic static loading device according to claim 1, characterized in that: The pressure plate is also equipped with strain gauge outlets.

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