Decoupling patch method for shimmy load test of helicopter main blade airfoil section

Abstract

The invention provides a decoupling patch method for shimmy load test of a helicopter main blade airfoil section. The method comprises the following steps: firstly, acquiring a section position of shimmy load measurement; a strain gauge is pasted on the upper surface of the main blade away from the edge of the main blade front edge coated iron; a strain gauge is pasted on the lower surface of the main blade away from the edge of the main blade front edge coated iron; a strain gauge is adhered to the lower surface of the main blade and the rear edge of the blade; measuring the vertical distance from the strain gauge to the chord line of the helicopter main blade; a proper position is selected on the upper surface of the rear edge of the helicopter main blade, the distance between the point and the chord line is adjusted, and a strain gauge is pasted with the position as the center; two strain gauges are respectively adhered to the left side and the right side of the strain gauge; measuring the flapping response output of the strain gauges; and then whether decoupling succeeds or not is judged. The invention provides a helicopter main blade airfoil section shimmy load measurement decoupling patch method, which is used for helicopter main blade airfoil section shimmy load measurement decoupling patch, provides patch guidance for helicopter main blade airfoil section shimmy load measurement test modification, and improves the comprehensive efficiency of helicopter main blade load test patch modification.

Description

Technical Field

[0001] The invention belongs to the technical field of helicopter flight test load test patch modification, and in particular relates to a decoupling patch method for helicopter main blade airfoil section shimmy load test. Background Art

[0002] Helicopters have the characteristics of vertical take-off and landing and strong maneuverability, and are extremely suitable for low-altitude, low-speed, fixed-point operations and other flight conditions. At present, helicopters have been widely used in ground reconnaissance / attack, surprise landing, weapon delivery, logistics support and short-distance transportation, medical rescue, disaster relief, geological exploration, equipment lifting, forest protection and fire fighting and other fields. The main rotor system is the only source of lift for the helicopter and is one of the most important system components of the helicopter. In flight, the flapping motion, shimmying motion, and torsional motion of the main rotor blades are important representations of the motion characteristics of the main rotor system. Therefore, in the process of helicopter development, it is necessary to obtain the main rotor blade flapping, shimmying, and torsional loads under various real working conditions through flight tests for dynamic analysis, strength design, and life assessment of the helicopter rotor system.

[0003] Helicopter main blade load measurement is a key test technology for helicopter load test flight. How to quickly complete the patching, decoupling, and calibration of the main blade test piece is particularly important for the flight load test of the helicopter main rotor system. At present, the decoupling work of the helicopter main blade airfoil section swing measurement is mainly to paste strain gauges evenly distributed on the main blade, and determine the appropriate strain gauge pasting position through decoupling measurement selection to complete the decoupling patch. However, this method requires pasting a large number of strain gauges, which occupies human resources and has low overall efficiency. Summary of the invention

[0004] In order to solve the problem that a large number of strain gauges need to be pasted when performing decoupling patches in the related technology, which occupies human resources and has low comprehensive efficiency, the present invention provides a method for decoupling patches for measuring the swing load of helicopter main rotor blade airfoil segments, which is used for decoupling patches for measuring the swing load of helicopter main rotor blade airfoil segments, provides patch guidance for the modification of the swing load measurement test of helicopter main rotor blade airfoil segments, and improves the comprehensive efficiency of the modification of helicopter main rotor blade load test patches. The technical solution is as follows:

[0005] In a first aspect, a decoupling patch method for a helicopter main rotor blade airfoil section shimmy load test is provided, the method comprising:

[0006] Step 1: According to the requirements for the vibration measurement of the helicopter main rotor blade airfoil section, obtain the cross-sectional position for vibration load measurement;

[0007] Step 2: Paste a strain gauge R1 on the upper surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade;

[0008] Step 3: Paste a strain gauge R2 on the lower surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade;

[0009] Step 4: Paste a strain gauge R3 on the lower surface of the main blade at a certain distance from the rear edge of the blade;

[0010] Step 5: Take a cross-sectional view of the helicopter main rotor blade swing measurement surface from the digital model, and measure the vertical distances L1, L2, and L3 from the strain gauges R1, R2, and R3 to the helicopter main rotor blade chord line, which is the line connecting the front end of the leading edge and the rear end of the trailing edge of the helicopter main rotor blade;

[0011] Step 6: Select a suitable position on the upper surface of the trailing edge of the helicopter main rotor blade so that the distance from this point to the chord line is L4 = L1 + L3 - L2, and paste a strain gauge R5 with this position as the center;

[0012] Step 7: Paste a strain gauge R4 and R6 at a certain distance to the left and right of the strain gauge R5;

[0013] Step 8: Install the helicopter main rotor blade on the calibration platform, and perform flapping loading on the section to measure the flapping response outputs ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 of strain gauges R1, R2, R3, R4, R5, and R6;

[0014] Step 9: Under the same swinging loading condition, calculate the strain relationship of ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, and ΔR6, so that ΔR=ΔR1+ΔR3-ΔR2-ΔRC,

[0015] Wherein, ΔRC is ΔR4, ΔR5, ΔR6, and the step nine obtains three ΔRs;

[0016] Step 10: When there is a ΔR less than ±100 microstrains, it can be determined that the decoupling is successful.

[0017] Furthermore, the method further comprises:

[0018] Step 11: When the three ΔRs are not less than ±100 microstrains, according to the true value of each ΔR, paste a strain gauge RX for supplementary decoupling; repeat steps 8, 9, and 10. If the ΔR corresponding to the strain gauge RX is less than ±100 microstrains, the decoupling is successful.

[0019] Furthermore, the method further comprises:

[0020] Step 12: If the added RX still cannot make the corresponding ΔR less than ±100 microstrains, continue to paste the strain gauges according to the rules of step 11, and continue to paste the strain gauges until the decoupling is successful.

[0021] The present invention graphically processes the cross section of the helicopter main blade airfoil, approximates the line connecting the leading edge and trailing edge of the blade as the blade stiffness center plane, and the strain response of different patch positions on the blade surface is approximately proportional to the distance from its stiffness center plane. Through this method, a theoretical decoupling patch position can be provided for the blade swing measurement patch. Compared with the traditional method, the number of strain gauges pasted can be greatly reduced, the cost of strain gauge consumables can be reduced, human resources can be saved, and the work efficiency of helicopter main blade load patch test modification can be effectively improved.

[0022] Among them, the rule for supplementary pasting of strain gauges in step eleven is: when ΔR is greater than 100 microstrain, RX is pasted on strain gauge R6 at a certain distance from the trailing edge of the main blade; when ΔR is less than -100 microstrain, RX is pasted on strain gauge R4 at a certain distance from the leading edge of the main blade.

[0023] Wherein, in the step 2, the distance between the strain gauge pasting position and the edge of the iron clad is 20 to 40 mm.

[0024] Among them, in the step three, the distance between the strain gauge pasting position and the edge of the iron clad is 20 to 40 mm.

[0025] Wherein, in the step 4, the distance between the strain gauge pasting position and the trailing edge of the main blade is 40 to 60 mm.

[0026] Wherein, in the step seven, a strain gauge R4 is pasted at 20 to 30 mm to the left of the strain gauge R5; and a strain gauge R6 is pasted at 20 to 30 mm to the right of the strain gauge R5.

[0027] Among them, in the step eleven, when selecting the pasting position of the strain gauge RX, the flapping loading response R4, R5, R6 of the strain gauges R4, R5, R6 and the distance L from the strain gauges R4, R5, R6 to the rear edge of the main blade are fitted with a second-order polynomial as the theoretical value of the flapping response of the supplementary pasted strain gauge to determine the pasting position of the compensation strain gauge

[0028] The beneficial effects of the present invention are at least:

[0029] The present invention can be used as a guide for the decoupling patch work of the main blade vibration measurement of helicopter flight tests. Compared with the traditional method, it can greatly reduce the number of strain gauges pasted, reduce the cost of strain gauge consumables, save human resources, and effectively improve the work efficiency of helicopter main blade load patch test modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the blade airfoil section section and patch position of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through specific implementation modes and drawings.

[0032] The present invention is further described in detail below through specific implementation modes and drawings.

[0033] The present invention can provide a theoretically supported main blade airfoil section swing load measurement decoupling patch position as a reference, reduce the number of strain gauges pasted, save manpower and material costs, and greatly improve the work efficiency of the helicopter main blade airfoil section load test modification patch.

[0034] See also Figure 1 The present invention provides a decoupling patch method for testing the shimmy load of a helicopter main rotor blade airfoil section, comprising the following steps:

[0035] Step 1: According to the requirements for the vibration measurement of the helicopter main rotor blade airfoil section, obtain the cross-sectional position for vibration load measurement;

[0036] Step 2: Paste a strain gauge R1 on the upper surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade; the distance between the strain gauge pasting position and the iron edge is 20 to 40 mm.

[0037] Step 3: Paste a strain gauge R2 on the lower surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade; the distance between the strain gauge pasting position and the iron edge is 20 to 40 mm.

[0038] Step 4: Paste a strain gauge R3 on the lower surface of the main blade at a certain distance from the rear edge of the blade; the distance between the strain gauge pasting position and the rear edge of the main blade is 40 to 60 mm.

[0039] Step 5: Take a cross-sectional view of the helicopter main rotor blade vibration measurement surface from the digital model, and measure the vertical distances L1, L2, and L3 from the strain gauges R1, R2, and R3 to the helicopter main rotor blade chord (usually the line connecting the front end of the leading edge and the rear end of the trailing edge of the helicopter main rotor blade). The specific measurement positions are as follows: Figure 1 shown.

[0040] Step 6: Select a suitable position on the upper surface of the trailing edge of the helicopter main rotor blade so that the distance from this point to the chord line is L4 = L1 + L3 - L2 (Formula 1), and paste a strain gauge R5 with this position as the center.

[0041] Step 7: Paste a strain gauge R4 and R6 at a certain distance to the left and right of the strain gauge R5; the distance between the center positions of the strain gauges R4, R6 and R5 is 20 to 30 mm.

[0042] Step 8: Install the helicopter main rotor blade on the calibration platform, and perform flapping loading on the section to measure the flapping response outputs ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 of strain gauges R1, R2, R3, R4, R5, and R6;

[0043] Step nine: Under the same swinging loading condition, calculate the strain relationship of ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, and ΔR6, so that ΔR=ΔR1+ΔR3-ΔR2-ΔRC (Formula 2), where ΔRC is ΔR4, ΔR5, and ΔR6.

[0044] Step 10: When ΔR is less than ±100 microstrains, it can be determined that the decoupling is successful.

[0045] In another embodiment, the method of the present invention may further include, in addition to the above steps 1 to 10:

[0046] Step 11: Substituting ΔR4, ΔR5, and ΔR6 into Formula 2, if ΔR cannot be less than ±100 microstrains, according to the true value of ΔR, paste a strain gauge RX for supplementary decoupling (supplementary strain gauge paste rule: when ΔR is greater than 100 microstrains, RX can be pasted on strain gauge R6 at a certain distance from the trailing edge of the main blade. When ΔR is less than -100 microstrains, RX can be pasted on strain gauge R4 at a certain distance from the leading edge of the main blade). Repeat steps 8, 9, and 10. If ΔR is less than ±100 microstrains, the decoupling is successful.

[0047] In step 11, when selecting the pasting position of the strain gauge RX, the flapping load responses ΔR4, ΔR5, ΔR6 of the strain gauges R4, R5, R6 and the distance L from each strain gauge (R4, R5, R6) to the rear edge of the main blade (defined as Figure 1 Substitute ΔR(L) = aL 2 +bL+c, a, b, c are obtained by calculation, and the L value corresponding to ΔR(L)=0 is calculated as the pasting position of the supplementary strain gauge RX.

[0048] Step 12: If the added RX still cannot make ΔR less than ±100 microstrains, continue to paste the strain gauges according to the rules for additionally pasting strain gauges described in step 11 until the decoupling is successful.

[0049] For example, the present invention provides a decoupling patch method for testing the shimmy load of a helicopter main rotor blade airfoil section, comprising the following steps:

[0050] Step 1: According to the requirements for the vibration measurement of the helicopter main rotor blade airfoil section, obtain the cross-sectional position for vibration load measurement;

[0051] Step 2: If Figure 1As shown, a strain gauge R1 is pasted on the upper surface of the main blade at a certain distance from the iron-clad edge of the leading edge of the main blade; the distance between the strain gauge pasting position and the iron-clad edge is 20 mm.

[0052] Step 3: If Figure 1 As shown, a strain gauge R2 is pasted on the lower surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade; the distance between the strain gauge pasting position and the iron edge is 20 mm.

[0053] Step 4: If Figure 1 As shown, a strain gauge R3 is pasted on the lower surface of the main blade at a certain distance from the rear edge of the blade; the distance between the strain gauge pasting position and the rear edge of the main blade is 40 mm.

[0054] Step 5: Take a cross-sectional view of the helicopter main rotor blade vibration measurement surface from the digital model, and measure the vertical distances L1, L2, and L3 from the strain gauges R1, R2, and R3 to the helicopter main rotor blade chord (usually the line connecting the front end of the leading edge and the rear end of the trailing edge of the helicopter main rotor blade). The specific measurement positions are shown in the attached figure. Figure 1 As shown;

[0055] Step 6: Select a suitable position on the upper surface of the trailing edge of the helicopter main rotor blade so that the distance from this point to the chord line is L4 = L1 + L3 - L2 (Formula 1), and paste a strain gauge R5 with this position as the center;

[0056] Step 7: Paste a strain gauge R4 and a strain gauge R6 at a certain distance to the left and right of the strain gauge R5; in step 7, the distance between the center positions of the strain gauges R4, R6 and R5 is 20 mm.

[0057] Step 8: Install the helicopter main rotor blade on the calibration platform, and perform flapping loading on the section to measure the flapping response outputs ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 of strain gauges R1, R2, R3, R4, R5, and R6;

[0058] Step 9: Under the same swinging loading condition, calculate the strain relationship of ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, and ΔR6, so that ΔR = ΔR1 + ΔR3 - ΔR2 - ΔRC (Formula 2), where ΔRC is the substitution of ΔR4, ΔR5, and ΔR6;

[0059] Step 10: Substitute ΔR4, ΔR5, and ΔR6 into Formula 2. The result is that the ΔR corresponding to ΔR4 is less than ±100 microstrains, and the decoupling is determined to be successful.

[0060] For another example, the present invention provides a decoupling patch method for testing the shimmy load of a helicopter main blade airfoil section, comprising the following steps:

[0061] Step 1: According to the requirements for the vibration measurement of the helicopter main rotor blade airfoil section, obtain the cross-sectional position for vibration load measurement;

[0062] Step 2: If Figure 1 As shown, a strain gauge R1 is pasted on the upper surface of the main blade at a certain distance from the iron-clad edge of the leading edge of the main blade; the distance between the strain gauge pasting position and the iron-clad edge is 40 mm.

[0063] Step 3: If Figure 1 As shown, a strain gauge R2 is pasted on the lower surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade; the distance between the strain gauge pasting position and the iron edge is 40 mm.

[0064] Step 4: If Figure 1 As shown, a strain gauge R3 is pasted on the lower surface of the main blade at a certain distance from the rear edge of the blade; the distance between the strain gauge pasting position and the rear edge of the main blade is 60 mm.

[0065] Step 5: Take a cross-sectional view of the helicopter main rotor blade vibration measurement surface from the digital model, and measure the vertical distances L1, L2, and L3 from the strain gauges R1, R2, and R3 to the helicopter main rotor blade chord (usually the line connecting the front end of the leading edge and the rear end of the trailing edge of the helicopter main rotor blade). The specific measurement positions are shown in the attached figure. Figure 1 As shown;

[0066] Step 6: Select a suitable position on the upper surface of the trailing edge of the helicopter main rotor blade so that the distance from this point to the chord line is L4 = L1 + L3 - L2 (Formula 1), and paste a strain gauge R5 with this position as the center;

[0067] Step 7: Paste a strain gauge R4 and R6 at a certain distance to the left and right of the strain gauge R5; the distance between the center positions of the strain gauges R4, R6 and R5 is 30mm.

[0068] Step 8: Install the helicopter main rotor blade on the calibration platform, and perform flapping loading on the section, and measure the flapping response output ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 of the strain gauges R1, R2, R3, R4, R5, and R6.

[0069] Step nine: Under the same swinging loading condition, calculate the strain relationship of ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, and ΔR6, so that ΔR=ΔR1+ΔR3-ΔR2-ΔRC (Formula 2), where ΔRC is ΔR4, ΔR5, and ΔR6.

[0070] Step 10: Substituting ΔR4, ΔR5, and ΔR6 into formula 2, none of them can make ΔR less than ±100 microstrains. According to the true value of ΔR, paste a strain gauge RX for additional decoupling. Repeat steps 8, 9, and 10. If ΔR is less than ±100 microstrains, the decoupling is successful.

[0071] The above only expresses the implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. In addition, the parts not detailed in the present invention are all conventional technologies.

Claims

1. A decoupling patch method for the vibration load test of the helicopter main rotor blade airfoil section, characterized in that: The method comprises: Step 1: According to the requirements for the vibration measurement of the helicopter main rotor blade airfoil section, obtain the cross-sectional position for vibration load measurement; Step 2: Paste a strain gauge R1 on the upper surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade; Step 3: Paste a strain gauge R2 on the lower surface of the main blade at a certain distance from the iron edge of the leading edge of the main blade; Step 4: Paste a strain gauge R3 on the lower surface of the main blade at a certain distance from the rear edge of the blade; Step 5: Take a cross-sectional view of the helicopter main rotor blade swing measurement surface from the digital model, and measure the vertical distances L1, L2, and L3 from the strain gauges R1, R2, and R3 to the helicopter main rotor blade chord line, which is the line connecting the front end of the leading edge and the rear end of the trailing edge of the helicopter main rotor blade; Step 6: Select a suitable position on the upper surface of the trailing edge of the helicopter main rotor blade so that the distance from this point to the chord line is L4 = L1 + L3 - L2, and paste a strain gauge R5 with this position as the center; Step 7: Paste a strain gauge R4 and R6 at a certain distance to the left and right of the strain gauge R5; Step 8: Install the helicopter main rotor blade on the calibration platform, and perform flapping loading on the section to measure the flapping response outputs ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, ΔR6 of strain gauges R1, R2, R3, R4, R5, and R6; Step 9: Under the same swinging loading condition, calculate the strain relationship of ΔR1, ΔR2, ΔR3, ΔR4, ΔR5, and ΔR6, so that ΔR=ΔR1+ΔR3-ΔR2-ΔRC, Wherein, ΔRC is ΔR4, ΔR5, ΔR6, and the step nine obtains three ΔRs; Step 10: When there is a ΔR less than ±100 microstrains, it can be determined that the decoupling is successful.

2. The method according to claim 1, characterized in that The method further comprises: Step 11: When the three ΔRs are not less than ±100 microstrains, according to the true value of each ΔR, paste a strain gauge RX for supplementary decoupling; repeat steps 8, 9, and 10. If the ΔR corresponding to the strain gauge RX is less than ±100 microstrains, the decoupling is successful.

3. The method according to claim 2, characterized in that The method further comprises: Step 12: If the added RX still cannot make the corresponding ΔR less than ±100 microstrains, continue to paste the strain gauges according to the rules of step 11, and continue to paste the strain gauges until the decoupling is successful.

4. The method according to claim 2, characterized in that: The rule for supplementary pasting of strain gauges in step 11 is: when ΔR is greater than 100 microstrain, paste RX on strain gauge R6 at a certain distance from the trailing edge of the main blade; when ΔR is less than -100 microstrain, paste RX on strain gauge R4 at a certain distance from the leading edge of the main blade.

5. The main blade airfoil section shimmy load test decoupling patch method according to claim 1, characterized in that: In the step 2, the distance between the strain gauge pasting position and the edge of the iron clad is 20 to 40 mm.

6. The main blade airfoil section shimmy load test decoupling patch method according to claim 1, characterized in that: In the step three, the distance between the strain gauge pasting position and the edge of the iron clad is 20 to 40 mm.

7. The main blade airfoil section shimmy load test decoupling patch method according to claim 1, characterized in that: In the step 4, the distance between the strain gauge pasting position and the trailing edge of the main blade is 40 to 60 mm.

8. The main blade airfoil section shimmy load test decoupling patch method according to claim 1, characterized in that: In the step 7, a strain gauge R4 is pasted at 20 to 30 mm to the left of the strain gauge R5; and a strain gauge R6 is pasted at 20 to 30 mm to the right of the strain gauge R5.

9. The main blade airfoil section shimmy load test decoupling patch method according to claim 2, characterized in that: In the step eleven, when selecting the pasting position of the strain gauge RX, the flapping loading responses R4, R5, R6 of the strain gauges R4, R5, R6 and the distance L from the strain gauges R4, R5, R6 to the rear edge of the main blade are fitted with a second-order polynomial as the theoretical value of the flapping response of the supplementary pasted strain gauge to determine the pasting position of the compensation strain gauge.

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