Broadband-domain balance

Abstract

The invention discloses a wide-frequency-domain balance, and relates to the technical field of aerodynamic wind tunnel tests. The balance comprises an elastic body, a metal resistance strain gauge unit, a silicon-based semiconductor strain gauge unit, a double-track power supply module and a data acquisition circuit board. The metal resistance strain gauge unit and the silicon-based semiconductor strain gauge unit are respectively arranged in a high-strain area and a low-strain area of the elastomer, the metal resistance strain gauge unit is composed of vertical and horizontal double-loop grids, the silicon-based semiconductor strain gauge unit is composed of an N-type semiconductor and a P-type semiconductor, and the metal resistance strain gauge unit and the silicon-based semiconductor strain gauge unit form a Wheatstone bridge and are connected with the data acquisition circuit board. And double-track power supply modules are respectively used for supplying power, so that wide-frequency-domain combined measurement of static and dynamic aerodynamic loads is realized. The structure has high-precision static measurement and high-sensitivity dynamic response, the measurement precision is improved, the effective frequency domain is expanded, the temperature effect is effectively inhibited, and the structure is suitable for a wide-frequency-domain force measurement scene in a hypersonic wind tunnel test.

Description

Technical Field

[0001] The present invention relates to a broadband balance, belonging to the technical field of aerodynamic wind tunnel tests. Background Art

[0002] For the wind tunnel force measurement test of high-speed aircraft, the strain balance is required to have both good static characteristics and dynamic performance, with high measurement accuracy and short response time, so as to be able to quickly and accurately measure the dynamic change process of aerodynamic loads and achieve high-precision and broadband continuous measurement of aerodynamic loads in wind tunnel tests. At present, although the commonly used metal foil strain gauges for strain balances can be miniaturized, their strain sensitivity coefficient is low (generally 2-3), and it is difficult to measure small deformations. At the same time, their effective frequency response mainly falls within 1 kHz, and the frequency domain range is insufficient to respond to the high-frequency pulsating aerodynamic loads in hypersonic wind tunnel tests. Bulk semiconductor strain gauges have a high sensitivity coefficient (1-2 orders of magnitude higher than metal foil strain gauges) and broadband response characteristics from steady state to ultra-dynamic (MHz level), but they have a large volume, which is not conducive to the miniaturization of strain balances. Especially, their high temperature sensitivity severely restricts their application in variable temperature environments. At present, in domestic hypersonic wind tunnel experiments, in order to make full use of the high sensitivity of bulk semiconductor strain gauges, devices such as heat insulation or cooling are used to suppress temperature drift; however, this method is complex, not conducive to the miniaturization of the balance, and the compensation effect is limited. Piezoelectric sensors can be used for the measurement of high-frequency aerodynamic loads (the highest frequency response can reach GHz), but their force measurement accuracy and stability are poor in the mid-low frequency band, which limits the measurement accuracy and applicable frequency domain of piezoelectric balances for mid-low frequency aerodynamic loads.

[0003] Combined with the research and analysis of the dynamic / static characteristics of wind tunnel balances at home and abroad, there are still some difficulties in the broadband, high-sensitivity and dynamic measurement of new aircraft: (1) Piezoelectric balances have a large stiffness and a wide frequency response, but their low-frequency characteristics are poor, and their static characteristics and temperature characteristics are poor, making it difficult to be extended to conventional force measurement tests and dynamic tests; (2) The existing resistance strain balances have a narrow frequency domain range, and it is difficult to meet the test requirements for measurement accuracy at high frequencies; (3) The current contradictions between static use and dynamic use and between dynamic use and static use of force sensors under high-low frequency mixed measurement cannot be solved, and there is insufficient research on mixed measurement considering both dynamic and static broadband domains; (4) High-sensitivity wind tunnel balances represented by semiconductor strain gauges have not been applied in engineering, and problems such as temperature effects, unstable sensitivity, and poor linearity under large strains of wind tunnel balances based on this principle have not been solved.

[0004] Therefore, it is urgent to propose a broadband balance to solve the above technical problems. Summary of the Invention

[0005] The present invention aims to solve the problem of wide - frequency - domain measurement of mixed static and dynamic aerodynamic loads in wind tunnel tests, expand the effective working frequency domain of wind tunnel balances, and improve measurement accuracy, and thus provides a wide - frequency - domain balance.

[0006] The technical solution of the present invention: A wide - frequency - domain balance includes an elastomer, a metallic resistive strain gauge unit, a silicon - based semiconductor strain gauge unit, a dual - rail power supply module, and a data acquisition circuit board.

[0007] The metallic resistive strain gauge unit and the silicon - based semiconductor strain gauge unit are respectively pasted on four surfaces of a rectangular beam of the elastomer. A conical inner hole is opened in the middle of the rectangular beam where the silicon - based semiconductor strain gauge unit is installed. The dual - rail power supply module and the data acquisition circuit board are mechanically connected to the elastomer. The output end of the dual - rail power supply module is connected to the terminals of the metallic resistive strain gauge unit and the silicon - based semiconductor strain gauge unit, and the signal lines of the metallic resistive strain gauge unit and the silicon - based semiconductor strain gauge unit are connected to the data acquisition circuit board.

[0008] Particularly, the elastomer is made of an isoeastic alloy material.

[0009] The area where the metallic resistive strain gauge unit is installed is a high - strain area, and the designed strain range is 150 - 500 με. The area where the silicon - based semiconductor strain gauge unit is installed is a low - strain area, and the designed strain range is 50 - 100 με.

[0010] The metallic resistive strain gauge unit includes a longitudinal double - loop grid and a transverse double - loop grid. The longitudinal double - loop grid and the transverse double - loop grid are connected into a Wheatstone bridge through copper pads. Two groups of longitudinal resistance wires of the longitudinal double - loop grid and two groups of resistance wires of the transverse double - loop grid are respectively grouped into a bridge in opposite arms and are manufactured with high density in a flexible substrate micro - domain.

[0011] The silicon - based semiconductor strain gauge unit includes two N - type semiconductors and two P - type semiconductors, which are connected into a Wheatstone bridge through gold pads. The two N - type semiconductors and the two P - type semiconductors are respectively grouped into a bridge in opposite arms and are manufactured with high density in a flexible substrate micro - domain.

[0012] The beneficial effects of the present invention: (1) By jointly using a silicon - based semiconductor strain gauge and a metallic resistive strain gauge for hybrid measurement on the same balance, the high - sensitivity characteristic of the silicon - based semiconductor strain gauge and the high - precision static measurement characteristic of the metallic resistive strain gauge are effectively utilized. The two measurement methods compensate each other, realizing wide - frequency - domain static and dynamic load measurement of aerodynamic forces in wind tunnel tests.

[0013] (2) Microdomain strain measurement is achieved through the combined layout of the vertical double-loop grid and the horizontal double-loop grid metal strain gauge's vertical and horizontal structures, the combined layout of P / N semiconductor strain gauges with different polarities, and the high-density manufacturing process, while effectively reducing the temperature effect.

[0014] (3) The discrete power supply to the metal resistance strain gauge unit and the silicon-based semiconductor strain gauge unit is achieved through the dual-rail power supply module, and the in-situ signal measurement is realized through the integration of the data acquisition circuit board on the elastomer, improving the measurement accuracy.

[0015] (4) The new measurement idea of the silicon-based semiconductor strain gauge and the metal resistance strain gauge proposed by the present invention plays an important supporting role in solving problems such as the temperature effect, unstable sensitivity, and poor linearity under large strain of the semiconductor balance, and is of great significance for expanding the effective working frequency domain of the wind tunnel balance and improving the measurement accuracy. Description of the Drawings

[0016] Figure 1 is a schematic diagram of a broadband balance structure; Figure 2 is a schematic diagram of the longitudinal section of the conical inner hole; Figure 3 is a schematic diagram of the metal resistance strain gauge unit; Figure 4 is a schematic diagram of the silicon-based semiconductor strain gauge unit; In the figure, 1 - elastomer, 2 - metal resistance strain gauge unit, 2.1 - vertical double-loop grid, 2.2 - copper pad, 2.3 - horizontal double-loop grid, 2.4 - first flexible substrate, 3 - silicon-based semiconductor strain gauge unit, 3.1 - gold pad, 3.2 - N-type semiconductor, 3.3 - P-type semiconductor, 3.4 - second flexible substrate, 4 - dual-rail power supply module, 5 - data acquisition circuit board, 6 - conical inner hole. Detailed Embodiments

[0017] To make the purpose, technical solutions, and advantages of the present invention clearer, the present invention will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are exemplary and not intended to limit the scope of the present invention.

[0018] A broadband balance mentioned in the present invention, as Figure 1 shown, includes an elastomer 1, a metal resistance strain gauge unit 2, a silicon-based semiconductor strain gauge unit 3, a dual-rail power supply module 4, and a data acquisition circuit board 5.

[0019] The metal resistance strain gauge unit 2 and the silicon-based semiconductor strain gauge unit 3 are respectively pasted on four surfaces of the rectangular beam of the elastic body 1. The area where the metal resistance strain gauge unit 2 is installed is the high-strain area, with a designed strain range of 150 - 500 με, and the area where the silicon-based semiconductor strain gauge unit 3 is installed is the low-strain area, with a designed strain range of 50 - 100 με.

[0020] Specifically, as Figure 2 shown, a tapered inner hole 6 is opened in the middle of the rectangular beam where the silicon-based semiconductor strain gauge unit 3 is installed, and the strain gradient inside the outer surface of this rectangular beam is close to zero to prevent the brittle fracture of the silicon-based semiconductor strain gauge unit 3.

[0021] Specifically, the elastic body 1 is made of an isoeastic alloy material to ensure the constancy of the balance sensitivity at different temperatures.

[0022] As Figure 3 shown, the metal resistance strain gauge unit 2 includes a longitudinal double-loop grid 2.1 and a transverse double-loop grid 2.3. The longitudinal double-loop grid 2.1 and the transverse double-loop grid 2.3 are connected into a Wheatstone bridge through a copper pad 2.2. The two groups of longitudinal resistance wires of the longitudinal double-loop grid 2.1 and the two groups of resistance wires of the transverse double-loop grid 2.3 are grouped into a bridge according to opposite arms and are manufactured with high density in the microdomain of the first flexible substrate 2.4.

[0023] As Figure 4 shown, the silicon-based semiconductor strain gauge unit 3 includes two N-type semiconductors 3.2 and two P-type semiconductors 3.3, which are connected into a Wheatstone bridge through a gold pad 3.1. The two N-type semiconductors 3.2 and the two P-type semiconductors 3.3 are grouped into a bridge according to opposite arms and are manufactured with high density in the microdomain of the second flexible substrate 3.4.

[0024] The dual-rail power supply module 4 and the data acquisition circuit board 5 are mechanically connected to the elastic body 1. The dual-rail power supply module 4 is connected to the terminals of the metal resistance strain gauge unit 2 and the silicon-based semiconductor strain gauge unit 3. The signal wires of the metal resistance strain gauge unit 2 and the silicon-based semiconductor strain gauge unit 3 are connected to the data acquisition circuit board 5. The dual-rail power supply module 4 supplies power to the data acquisition circuit board 5, the metal resistance strain gauge unit 2, and the silicon-based semiconductor strain gauge unit 3 on the elastic body 1.

[0025] The dual-rail power supply module 4 can provide constant-current excitation (i+, i-) and constant-voltage excitation (U+, U-). The constant-current excitation is used to supply power to the silicon-based semiconductor strain gauge unit 3, and the constant-voltage excitation is used to supply power to the metal resistance strain gauge unit 2.

[0026] The data acquisition circuit board 5 is used to collect the output signals (S+, S-) of the metal resistance strain gauge unit 2 and the silicon-based semiconductor strain gauge unit 3, and perform in-situ amplification, filtering, and A / D conversion on the analog signals.

[0027] In the present invention, a metal resistance strain gauge unit and a silicon-based semiconductor strain gauge unit are combined and arranged on an elastomer. The low-frequency steady-state large load is measured by the metal resistance strain gauge unit, and the high-frequency dynamic small load is measured by the silicon-based semiconductor strain gauge unit, thereby realizing wide-frequency high-precision measurement of aerodynamic forces in a wind tunnel test.

[0028] The present invention makes full use of the static high-precision performance of the resistance strain gauge and the high-sensitivity characteristics of the semiconductor strain gauge. Through the combined layout of the longitudinal double-loop grid and the transverse double-loop grid metal strain gauge vertical and horizontal structures and the P / N semiconductor strain gauge different-polarity combined layout, a Wheatstone full bridge is formed. Micro-domain strain measurement is realized through a high-density manufacturing process. At the same time, on the basis of the micro-domain temperature field balance of the full bridge, the use of an isoeastic alloy and an equal-strength beam design effectively reduces the temperature effect. The discrete power supply for the metal resistance strain gauge unit and the silicon-based semiconductor strain gauge unit is realized through a dual-rail power supply module. The integrated data acquisition circuit board directly collects the bridge signals of the metal resistance strain gauge unit and the silicon-based semiconductor strain gauge unit, and finally realizes wide-frequency high-precision measurement of aerodynamic forces in a wind tunnel test.

[0029] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A broadband balance, characterized in that, Including: An elastomer (1), a metallic resistive strain gauge unit (2), a silicon-based semiconductor strain gauge unit (3), a dual-rail power supply module (4), and a data acquisition circuit board (5). The metallic resistive strain gauge unit (2) and the silicon-based semiconductor strain gauge unit (3) are respectively pasted on four surfaces of a rectangular beam of the elastomer (1). A tapered inner hole (6) is formed in the middle of the rectangular beam where the silicon-based semiconductor strain gauge unit (3) is installed. The dual-rail power supply module (4) and the data acquisition circuit board (5) are mechanically connected to the elastomer (1). The output end of the dual-rail power supply module (4) is connected to the terminals of the metallic resistive strain gauge unit (2) and the silicon-based semiconductor strain gauge unit (3). The signal lines of the metallic resistive strain gauge unit (2) and the silicon-based semiconductor strain gauge unit (3) are connected to the data acquisition circuit board (5).

2. The broadband domain balance according to claim 1, wherein The elastomer (1) is made of an isoeastic alloy material.

3. The broadband domain balance according to claim 1 or 2, characterized in that, The metallic resistive strain gauge unit (2) is pasted in the high-strain area of the rectangular beam of the elastomer (1), and the designed strain range is 150 - 500 με. The silicon-based semiconductor strain gauge unit (3) is pasted in the low-strain area of the rectangular beam of the elastomer (1), and the designed strain range is 50 - 100 με.

4. The broadband domain balance according to claim 3, wherein, The metallic resistive strain gauge unit (2) includes: a longitudinal double-loop grid (2.1) and a transverse double-loop grid (2.3). The longitudinal double-loop grid (2.1) and the transverse double-loop grid (2.3) are connected into a Wheatstone bridge through a copper pad (2.2). Two groups of longitudinal resistance wires of the longitudinal double-loop grid (2.1) and two groups of resistance wires of the transverse double-loop grid (2.3) are respectively grouped into a bridge in opposite arms and are manufactured with high density in the microdomain of the first flexible substrate (2.4).

5. The broadband domain balance according to claim 4, characterized in that The silicon-based semiconductor strain gauge unit (3) includes: two N-type semiconductors (3.2) and two P-type semiconductors (3.3), which are connected into a Wheatstone bridge through a gold pad (3.1). The two N-type semiconductors (3.2) and the two P-type semiconductors (3.3) are respectively grouped into a bridge in opposite arms and are manufactured with high density in the microdomain of the second flexible substrate (3.4).

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