Testing device and method for measuring rigidity of composite propeller of real ship

Abstract

The invention belongs to the technical field of ship propellers, and provides a test device and a test method for measuring the rigidity of a composite material propeller of a real ship aiming at the problem that the rigidity of a conventional metal propeller is not measured and the rigidity of the composite material propeller needs to be measured due to large elastic deformation. The test device comprises a reaction frame and a blade root fixing base, the blade root fixing base is arranged on the front side face of the reaction frame, a paddle is arranged on the front side face of the blade root fixing base, a loading fixing platform is arranged below the paddle, and a plurality of loading mechanisms are arranged at the top of the loading fixing platform. The top of each loading mechanism is in contact with the lower surface of the blade, the displacement meter fixing support is arranged at the top of the blade root fixing base, the displacement meter is arranged at the bottom of the displacement meter fixing support, and the displacement meter is in contact with the upper surface of the blade. According to the method, the rigidity components of the composite propeller of the real ship in the bending and torsion directions can be accurately reflected, so that the deformation of profile parameters such as trim and pitch can be analyzed.

Description

Technical Field

[0001] The invention belongs to the technical field of ship propellers, and in particular relates to a test device and method for measuring the stiffness of a composite material propeller of an actual ship. Background Art

[0002] Conventional ship propellers are generally made of nickel-aluminum bronze, which has a large stiffness and its deformation is generally negligible. However, for large side-skew propellers and composite propellers, their deformation cannot be ignored. Composite propellers generally use fiber-reinforced resin matrix, such as glass fiber and carbon fiber composite propellers, which are widely used internationally. Although the stiffness in the fiber direction is comparable to or even higher than that of metal materials, the stiffness of the resin matrix is ​​low, resulting in a low stiffness in the direction perpendicular to the fiber of the composite propeller, which results in anisotropic stiffness characteristics, and its overall stiffness is much lower than that of metal propellers. The diameter of a real ship propeller is generally more than 2 meters. Under the condition of hydrodynamic load, a single composite blade can produce a deformation of several millimeters or even tens of millimeters under the action of several tons of thrust, which has a great impact on the prediction of hydrodynamic force and speed. Therefore, the stiffness measurement of real ship composite propellers is very important.

[0003] The propeller has a complex geometry, with characteristics such as gradual thickness change, sharp outer edge, and distorted shape. It is difficult to accurately predict the structural characteristics such as stiffness and frequency of metal propellers, and it is even more difficult for composite propellers because their structural modeling involves the laying of composite materials (generally each layer is about 0.2mm thick), the determination of anisotropic material parameters (including 9 engineering constants such as elastic modulus, shear modulus and Poisson's ratio in 3 directions), etc., which makes the stiffness prediction model of composite propellers extremely complex. Therefore, experimental verification is required to determine the design scheme. At the same time, for composite propellers with large deformation, pre-deformation design is also required, that is, the deformation is preset in the opposite direction of the deformation to compensate for the hydrodynamic loss caused by fluid-solid coupling deformation. Then the stiffness test also provides important input for pre-deformation design.

[0004] The geometric shape of the propeller is generally expressed by the radial and chordal parameters, which will determine the hydrodynamic performance of the propeller. Therefore, the measurement of stiffness should also accurately reflect the stiffness components in the bending and torsion directions, so as to analyze the deformation of the parameters such as trim and pitch, and then analyze the correlation with the change of hydrodynamic performance. The stiffness measurement of the real ship composite propeller should not only capture the characteristic points reflecting the bending and torsion stiffness, but also have a certain degree of accuracy. Therefore, it is necessary to use a combination of simulation and experiment to more clearly grasp the maximum deformation of the blade and the local deformation at the characteristic points. At present, due to the large stiffness of conventional metal propellers, certain strength specifications are met during design. Under the design consideration of more than 8 times the strength safety margin, the deformation of the metal propeller is within 0.5mm, so there is no stiffness measurement method for conventional metal propellers. However, the real ship composite propeller needs to measure stiffness due to its large elastic deformation. Therefore, the design of the test device and the precise measurement method proposed in this patent are the key to the stiffness test method of the real ship composite propeller, which is of great significance for evaluating the fluid-solid coupling effect and propeller-shaft coupling vibration characteristics of the composite propeller. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a test device and method for measuring the stiffness of a composite propeller of a real ship.

[0006] The present invention converts the pressure field load into a multi-point concentrated force normal load, uses multiple jacks to apply concentrated force in stages, and transmits it to the pressure surface of the blade through a conformal pad to deform the blade. A probe displacement meter is used to measure the normal displacement of a specific measuring point in real time. The maximum deformation, 80% maximum deformation contour lines, and normal deformation values ​​of points on 0.9 and 0.7 radius lines comprehensively reflect the bending and torsional stiffness characteristics of the composite material blade.

[0007] The first object of the present invention is to provide a test device for measuring the stiffness of a real ship composite propeller, comprising a reaction frame and a blade root fixing base, the blade root fixing base is arranged on the front side of the reaction frame, the blade is arranged on the front side of the blade root fixing base, the loading fixing platform is arranged below the blade, a plurality of loading mechanisms are arranged on the top of the loading fixing platform, and the top of each loading mechanism is in contact with the lower surface of the blade, the displacement meter fixing bracket is arranged on the top of the blade root fixing base, the displacement meter is arranged at the bottom of the displacement meter fixing bracket, and the displacement meter is in contact with the upper surface of the blade.

[0008] Preferably, each loading mechanism comprises a jack fixed bottom block, a jack and a jack loading head, the jack fixed bottom block is slidably arranged on the top of the loading fixed platform, the jack is arranged on the top of the jack fixed bottom block, and the jack loading head is arranged on the top of the jack.

[0009] Preferably, a first cylindrical groove is formed on the top of the jack fixing bottom block, and the bottom of the jack is plugged into the first cylindrical groove of the jack fixing bottom block;

[0010] A second cylindrical groove is provided at the bottom of the jack loading head, and the top of the jack is plugged into the second cylindrical groove of the jack loading head.

[0011] Preferably, the loading mechanism also includes a conformable loading pad and a rubber sheet. A third cylindrical groove is provided at the bottom of the conformable loading pad. The conformable loading pad is plugged into the jack loading head through the third cylindrical groove. The rubber sheet is arranged on the top of the conformable loading pad, and the rubber sheet is in contact with the lower surface of the blade.

[0012] Preferably, the diameter of the conformable loading pad is 200-300 mm, the depth of the third cylindrical groove is 40-70 mm, the top outer edge of the conformable loading pad is set as a rounded corner, and a strip groove is opened at the bottom of the conformable loading pad.

[0013] Preferably, the jack is also connected to a hydraulic mechanism and a force sensor, and the force sensor is connected to a display.

[0014] The second object of the present invention is to provide a test method for measuring the stiffness of a composite propeller of a real ship, which is implemented by using the above-mentioned test device for measuring the stiffness of a composite propeller of a real ship, and includes the following steps:

[0015] S1. Calculate the equivalent concentrated normal loading point and load value as well as the displacement measurement point information and normal deformation value;

[0016] S2, based on step S1, using the test device to perform step-by-step loading and testing to obtain loading data;

[0017] S3, obtaining the normal deformation value of each displacement measuring point according to the loading data obtained in step S2, and averaging the normal deformation values ​​to obtain an average value;

[0018] S4. Compare and analyze the average value obtained in step S3 with the normal deformation value obtained in step S1 to obtain an error value, correct the composite material modeling parameters in finite element modeling according to the error value, obtain the bending and torsional stiffness characteristics of the composite material blade according to the normal deformation value of the displacement measuring point, and then determine the stiffness characteristics of the composite material propeller of the actual ship.

[0019] Preferably, step S1 comprises the following steps:

[0020] S11, obtain pressure field load based on CFD fluid calculation;

[0021] S12, establishing a single blade composite material layup and structural model in a structural finite element software, applying the pressure field load obtained in step S11 to the composite material blade to obtain a blade deformation field;

[0022] S13, calculating the force and moment of the pressure field load in the three directions of the blade deformation field, establishing multivariate equations of the force and moment of the multi-point concentrated normal load in the three directions, taking the force and moment deviation of the two loads of 20% as a constraint condition, and calculating the multi-point concentrated normal load;

[0023] S14, setting a concentrated force loading mode in the finite element software, and calculating the blade deformation under the multi-point concentrated normal load obtained in step S13;

[0024] S15, fine-tuning the position of the loading point so that the blade deformation obtained in step S14 is equal to the blade deformation field obtained in step S12, determining the equivalent concentrated normal loading point and load value, and determining the displacement measuring point information and the normal deformation value of the displacement measuring point.

[0025] Preferably, in step S15, the displacement measurement point information includes the number and positions of the displacement measurement points, and the positions of the displacement measurement points are at the maximum deformation point of the blade tip, at 0.9 and 0.7 radii, and at 80% maximum deformation contour lines.

[0026] Preferably, step S2 comprises the following steps:

[0027] S21, calibrate the force sensor and the displacement meter, and make the pointer of the displacement meter point normally to the mark of each displacement measuring point, and adjust the positions of multiple jacks on the loading fixed platform so that the conformal loading pads are respectively located at the corresponding equivalent concentrated normal loading points;

[0028] S22, lifting and lowering the jack by the hydraulic mechanism to preload, loading the load from zero in two stages to 0.5 times the design load and then unloading;

[0029] S23. Based on the equivalent concentrated normal load value, load is applied in 2 to 3 stages. During the loading process, the loads of multiple jacks increase or decrease in proportion. The loads of each loading point in each stage are recorded by a force sensor, and the normal displacement of each displacement measuring point is recorded by a displacement meter to obtain loading data.

[0030] Preferably, in step S23, the loading method at each stage of load loading is:

[0031] The first stage is to load to 50% of the total load of the design condition. This stage is divided into five levels of loading: 10%, 20%, 30%, 40%, and 50%;

[0032] The second stage is to load to 100% of the total load of the design condition. This stage is divided into five levels of loading: 50%, 60%, 70%, 80%, and 100%;

[0033] The third stage is loaded to 200% of the total load of the design condition. This stage is divided into 5 loading levels: 100%, 120%, 150%, 180%, and 200%.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention can measure the maximum deformation and normal deformation value at the characteristic point of the real ship composite propeller under the action of multi-point concentrated loads equivalent to the pressure field load, which makes up for the shortcomings of the existing propeller stiffness detection means and can also reflect the linear elastic relationship between the deformation and the loading process, and is used to evaluate the stiffness level of the real ship composite propeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the structure of a test device for measuring the stiffness of a composite propeller of a real ship provided in Example 1 of the present invention;

[0037] Figure 2 This is a left side view of a test device for measuring stiffness of a composite propeller of a real ship provided in Example 1 of the present invention;

[0038] Figure 3 is a cross-sectional view of the loading mechanism in Embodiment 1 of the present invention;

[0039] Figure 4 is a cross-sectional view of the loading and fixing platform in Example 1 of the present invention;

[0040] Figure 5 It is a schematic diagram of the simulation of the deformation field under the action of concentrated force;

[0041] Figure 6 It is a simulation diagram of equivalent concentrated normal loading point;

[0042] Figure 7 It is a simulation schematic diagram of displacement measurement points;

[0043] In the figure: 1. reaction frame; 2. blade root fixing base; 3. blade; 4. loading fixing platform; 401. transverse steel beam; 402. longitudinal steel beam; 403. vertical steel beam; 404. groove; 405. column; 406. support beam; 407. sliding groove; 5. loading mechanism; 501. jack fixing bottom block; 502. jack; 503. jack loading head; 504. conformal loading pad; 505. rubber sheet; 506. third cylindrical groove; 507. bottom block; 508. first cylindrical groove; 509. second cylindrical groove; 6. displacement meter fixing bracket; 7. displacement meter. DETAILED DESCRIPTION

[0044] The following is a description of the embodiments of the present invention. Figures 1 to 7 , the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] like Figures 1 to 4 As shown, an embodiment of the present invention provides a test device for measuring the stiffness of a real ship composite propeller, comprising a reaction frame 1 and a blade root fixing base 2, wherein the blade root fixing base 2 is arranged on the front side of the reaction frame 1, the blade 3 is arranged on the front side of the blade root fixing base 2, the loading fixing platform 4 is arranged below the blade 3, a plurality of loading mechanisms 5 are arranged on the top of the loading fixing platform 4, and the top of each loading mechanism 5 is in contact with the lower surface of the blade 3, the displacement meter fixing bracket 6 is arranged on the top of the blade root fixing base 2, and the displacement meter 7 is arranged on the bottom of the displacement meter fixing bracket 6, and the displacement meter 7 is in contact with the upper surface of the blade 3. The embodiment of the present invention can ensure that the root of the blade 3 is completely fixed by designing the reaction frame 1 and the blade root fixing base 2, and can control the horizontal placement of the propeller surface to ensure that the jack 502 does not slip when loading, and the design of the loading fixing platform 4 can ensure that the jack 502 is loaded stably, and the design of the displacement meter fixing bracket 6 can ensure that the probe type displacement meter 7 is fixed and the measurement is stable. The displacement meter 7 in this embodiment is a magnetic suction probe displacement meter.

[0047] In the embodiment of the present invention, the main board of the reaction frame 1 is trapezoidal, and reinforcement plates are welded on the sides and the bottom. The material is stainless steel or cast iron with a thickness of 15-25 mm. A lifting hole is reserved at the center of mass of the main board, and holes are drilled in the bottom plate for bolting to the ground. Double rows of through holes are reserved in the side plates for bolting the blade root fixing base 2. There are about 20 double rows of through holes from bottom to top, which is convenient for adjusting the height of the blade 3.

[0048] In the embodiment of the present invention, the blade root fixing base 2 is a part of the hub. The blade surface is roughly in a horizontal state by rotating the blade 3, so as to determine the vertical section of the hub. The end face of the base is a steel plate with a thickness of 20-30mm. The reserved threaded holes match the double-row through holes of the reaction frame, and the M30 bolts are screwed in to play a fixing and supporting role.

[0049] In the embodiment of the present invention, the loading and fixing platform 4 is located below the blade 3 and is in a frame structure. The loading and fixing platform 4 includes an upper frame and a lower frame arranged in parallel with each other. The upper frame is located above the lower frame, and the upper frame and the lower frame are connected and fixed by a column 405. The upper frame and the lower frame have the same structure and are both obtained by connecting two mutually parallel transverse steel beams 401 and two mutually parallel longitudinal steel beams 402 in sequence end to end. The inner sides of the two transverse steel beams 401 of the upper frame and the lower frame are respectively provided with grooves 404. A plurality of support beams 406 are arranged in parallel between the two transverse steel beams 401 of the frame, and both ends of each support beam 406 are slidably connected to the corresponding groove 404, and a vertical steel beam 403 is arranged between the two support beams 406 corresponding to the upper frame and the lower frame, and both ends of the vertical steel beam 403 are respectively connected to the bottom of the corresponding support beam 406 above and the top of the corresponding support beam 406 below, and a sliding groove 407 is opened at the top of the support beam 406 arranged on the upper frame, and the loading mechanism 5 is arranged on the sliding groove 407.

[0050] By moving the support beam 406 left and right along the groove 404, the lateral position of the support beam 406 can be easily adjusted, and then the position of the loading mechanism 5 set on the support beam 406 can be adjusted. After the position of the support beam 406 is adjusted, the support beam 406 and the transverse steel beam 401 are locked by the angle code to avoid the position of the support beam 406 changing during the test, which affects the test effect and improves the stability of the test.

[0051] In the embodiment of the present invention, the displacement meter fixing bracket 6 is located above the blade 3 and has a frame structure. The frame can be a curved surface to facilitate the adsorption of the magnetic probe displacement meter 7 and enable the displacement meter 7 to touch the upper surface of the blade 3. The displacement meter fixing bracket 6 should have sufficient rigidity to ensure that the displacement meter 7 does not shake.

[0052] In the embodiment of the present invention, each loading mechanism 5 comprises a jack fixed bottom block 501, a jack 502 and a jack loading head 503. The jack fixed bottom block 501 is slidably arranged on the top of the loading fixed platform 4, the jack 502 is arranged on the top of the jack fixed bottom block 501, and the jack loading head 503 is arranged on the top of the jack 502. In the embodiment of the present invention, a first cylindrical groove 508 is provided on the top of the jack fixed bottom block 501, and the bottom of the jack 502 is plugged into the first cylindrical groove 508 of the jack fixed bottom block 501; through the joint design of the jack fixed bottom block 501, the jack loading head 503, the conformable loading pad 504 and the rubber sheet 505 in the embodiment of the present invention, it can be ensured that the loading direction of the jack 502 is along the local normal direction of the loading point, and at the same time, it can avoid the problem of slippage and local stress concentration during loading that causes the top collapse of the blade 3 skin.

[0053] The design of the first cylindrical groove 508 facilitates the insertion of the cylindrical bottom of the jack 502 therein for fixing. A bottom block 507 is arranged below the jack fixing bottom block 501 so as to slide horizontally in the sliding groove 407. After the position is adjusted, the bottom block 507 is fixed to the loading fixing platform 4 by bolts to prevent the bottom block 507 from moving randomly in the sliding groove 407. The number of the jack fixing bottom blocks 501 is the same as that of the jack 502, and the bottom of the first cylindrical groove 508 is arranged to be inclined at a specific angle, which is accurately modeled by virtual simulation so that the jack 502 is locally perpendicular to the loading point.

[0054] In the embodiment of the present invention, a second cylindrical groove 509 is provided at the bottom of the jack loading head 503, and the top of the jack 502 is plugged into the second cylindrical groove 509 of the jack loading head 503. A thread is provided on the inner wall of the second cylindrical groove 509 in the embodiment of the present invention, and the second cylindrical groove 509 and the thread design can facilitate plugging with the cylindrical head of the fixed jack 502, and the jack loading head 503 can be easily fixed to the jack 502 by screwing; the jack loading head 503 specifically includes a conversion head and a sensor, the sensor is provided on the conversion head, and the second cylindrical groove 509 is provided on the conversion head.

[0055] In the embodiment of the present invention, the loading mechanism 5 further comprises a conformable loading pad 504 and a rubber sheet 505. A third cylindrical groove 506 is provided at the bottom of the conformable loading pad 504. The conformable loading pad 504 is plugged with the jack loading head 503 through the third cylindrical groove 506. The rubber sheet 505 is arranged on the top of the conformable loading pad 504. The rubber sheet 505 is in contact with the lower surface of the blade 3. The rubber sheet 505 is 3-8 mm thick and its area should be larger than the upper surface of the conformable loading pad 504, so as to play a role in loading buffer and protect the lower surface of the blade 3.

[0056] In the embodiment of the present invention, the diameter of the conformable loading pad 504 is 200-300mm, the depth of the third cylindrical groove 506 is 40-70mm, the top outer edge of the conformable loading pad 504 is set to a rounded corner to avoid the situation where stress concentration tops the skin of the blade 3, and the upper surface of the conformable loading pad 504 is a curved surface, which is taken from the curved surface of the blade 3 at the loading point to ensure that it conforms to the lower surface of the blade 3 to avoid the problem of stress concentration tops the skin of the blade 3. Considering that the top surface of the conformable loading pad 504 is circular and the installation direction cannot be identified, a cross-shaped structure mark needs to be processed on its top in advance so that the placement angles in the two horizontal directions can be identified during installation, so as to better fit the lower surface of the blade 3.

[0057] In the embodiment of the present invention, the jack 502 is also connected to a hydraulic mechanism and a force sensor, and the force sensor is connected to a display.

[0058] The test device for measuring the stiffness of a composite propeller of a real ship provided in an embodiment of the present invention is installed by the following method:

[0059] First, fix the reaction frame 1 to the ground with M30 bolts, install the blade 3 on the blade root fixing base 2, and then fix the blade root fixing base 2 to the reaction frame 1 with M30 bolts, and check the horizontal state and tightening state of the blade 3.

[0060] Secondly, draw a line on the ground below the blade 3 to determine the placement of the loading and fixing platform 4, and accurately measure its distance from the reaction frame 1 and the specific reference point of the blade 3 to ensure that it corresponds to the simulation modeling. Assemble the loading and fixing platform 4 and fix it to the ground, adjust its horizontality and adjust the position of the support beam 406 along the groove 404, then adjust the position of the bottom block 507 and the jack fixing bottom block 501 along the sliding groove 407 so that the jack 502 can be in the corresponding position, and then place the jack 502, the jack loading head 503, the conformable loading pad 504, and the rubber sheet 505 in sequence, connect the jack 502, the hydraulic mechanism, the force sensor and the display to form a set of load control system, and lift the jack 502 through the hydraulic mechanism to make it at a suitable height for later loading.

[0061] Finally, install the displacement meter fixing bracket 6 on the blade root fixing base 2, adjust its position, place multiple displacement meters 7 on the horizontal and vertical beams of the displacement meter fixing bracket, adjust the primary and secondary folding arms of the displacement meter 7, ensure that the displacement meter 7 probe is in a compressed state, point the normal direction of the displacement meter 7 pointer to the mark of each displacement measurement point according to the on-site space, tighten the magnetic base, and make the displacement meter 7 uniformly magnetically attracted to the displacement meter fixing bracket 6, ensure that the displacement meter 7 is slightly deformed with the whole device, and eliminate the error caused by the displacement of the device. Connect the displacement meter 7, data acquisition line and test computer to form a deformation measurement system to realize real-time measurement and data acquisition of deformation.

[0062] Example 2

[0063] The embodiment of the present invention provides a test method for measuring the stiffness of a composite propeller of a real ship, which is implemented using the test device for measuring the stiffness of a composite propeller of a real ship in Example 1, and includes the following steps:

[0064] S1. Calculate the equivalent concentrated normal loading point and load value as well as the displacement measurement point information and normal deformation value, including the following steps:

[0065] S11, obtain pressure field load based on CFD fluid calculation;

[0066] The propeller rotates in the flow field, and the force it is subjected to is the hydrodynamic pressure field load at a certain speed and rotation speed. In order to carry out stiffness tests, it needs to be equivalent to multi-point concentrated loads. In order to ensure that the loading process is smooth and does not slip, the concentrated load should be a local normal load. The pressure field load is obtained based on CFD fluid calculation.

[0067] S12, establishing a single blade composite material layup and structural model in the structural finite element software, applying the pressure field load obtained in step S11 to the composite material blade, and obtaining the blade deformation field, such as Figure 5 As shown;

[0068] S13. Calculate the force and moment of the pressure field load in the three directions of the blade coordinate system, establish the multivariate equations of force and moment of the multi-point concentrated normal load (4 points are the best) in the three directions, and use the 20% deviation of the force and moment of the two loads as the constraint condition to calculate the multi-point concentrated normal load. The design of the equivalent concentrated normal loading point is as follows: Figure 6 As shown;

[0069] S14, setting a concentrated force loading mode in the finite element software, and calculating the blade deformation under the multi-point concentrated normal load obtained in step S13;

[0070] S15. By fine-tuning the position of the loading point, the blade deformation obtained in step S14 is made equal to the blade deformation field obtained in step S12, and the equivalent concentrated normal loading point and load value are determined, and the bending and torsion characteristics of the deformation cloud map are comprehensively analyzed to determine the information of the displacement measuring point and the normal deformation value of the displacement measuring point. The displacement measuring point information includes the number and position of the displacement measuring point, and the position of the displacement measuring point is at the maximum deformation point of the blade tip, at the 0.9 and 0.7 radii, and at the 80% maximum deformation contour line.

[0071] The displacement measurement points are determined through simulation analysis. There must be the maximum deformation point of the blade tip, points on the 0.9 and 0.7 radii, which reflect the radial bending stiffness of the blade, and points on the leading edge, the midpoint of the chord length, and the trailing edge on a certain radius, which reflect the chord-wise torsional stiffness of the blade. In actual operation, the number of measurement points can be determined based on the space of the test device and the operating space of the probe displacement meter. The more measurement points there are, the more they can reflect the changing laws of bending and torsional stiffness, but the maximum deformation point P should be selected first. max , points P1 to P5 on the 80% maximum deformation contour, points D1 to D5 on the 0.9 and 0.7 radii 10 ,like Figure 7 As shown in the figure, P1~P5 are five points formed by dividing the 80% maximum deformation contour line into four equal parts, D1~D5 are five points formed by dividing the chord length arc line at the radius of 0.9 into four equal parts, and D6~D7 are five points formed by dividing the chord length arc line at the radius of 0.9 into four equal parts. 10 The five points are formed by dividing the chord length arc at the radius of 0.7 into four equal parts. If the operating space is limited, the above-mentioned equal-division points can also be divided into two equal parts, that is, only three points are taken on the chord length arc at the 80% maximum deformation contour line, 0.9 and 0.7 radii. If the displacement data acquisition lines or channels are limited, measurements can also be taken alternately in batches.

[0072] S2, based on step S1, using the test device to perform step-by-step loading and testing to obtain loading data, specifically comprising the following steps:

[0073] S21, calibrate the force sensor and displacement meter 7 to ensure the accuracy of loading and displacement measurement, and make the pointer of the displacement meter 7 point normally to the mark of each displacement measurement point, adjust the positions of the multiple jacks 502 on the loading fixed platform, and make the conformable loading pads 504 respectively located at the corresponding equivalent concentrated normal loading points;

[0074] S22. The jack 502 is slightly raised and lowered by the hydraulic mechanism for preloading. The load is loaded in two stages from zero to 0.5 times the design load and then unloaded. The entire test system is debugged so that the loading process can proceed slowly and smoothly to release possible errors such as residual stress and tooling porosity.

[0075] S23. Based on the equivalent concentrated normal load value, load loading is performed in a step-by-step manner in 2 to 3 stages. During the loading process, the loads of multiple jacks 502 increase or decrease in the same proportion. The loading rate and synergy of multi-point loading are ensured during the loading process, thereby ensuring that the test process is stable and reliable. The load of each loading point in each stage is recorded by a force sensor, and the normal displacement of each displacement measuring point is recorded by a displacement meter 7 to obtain loading data. The loading process of the three stages should be measured by incremental and decremental regression, and repeated more than 3 times.

[0076] In step S23, the loading method of each stage of load loading is:

[0077] The first stage is to load to 50% of the total load of the design condition. This stage is divided into five levels of loading: 10%, 20%, 30%, 40%, and 50%;

[0078] The second stage is to load to 100% of the total load of the design condition. This stage is divided into five levels of loading: 50%, 60%, 70%, 80%, and 100%;

[0079] Depending on the design safety margin of the composite propeller and the range of the test equipment, the third stage can be added. The third stage is loaded to 200% of the total load of the design operating condition. This stage is divided into 5 loading levels, namely: 100%, 120%, 150%, 180%, and 200%.

[0080] S3, exporting and post-processing the loading data obtained in step S2, obtaining the normal deformation value of each displacement measuring point according to the sensitivity during calibration, and converting it to 100% load to form a statistical table as shown in Table 1 below, and averaging the normal deformation values ​​to obtain an average value;

[0081] S4. Compare and analyze the average value obtained in step S3 with the normal deformation value obtained in step S1 to obtain an error value, correct the composite material modeling parameters in finite element modeling according to the error value, and obtain the bending and torsional stiffness characteristics of the composite material blade according to the maximum deformation, 80% maximum deformation contour line, and the normal deformation values ​​of points on the 0.9 and 0.7 radius lines, and then determine the stiffness characteristics of the actual ship composite material propeller.

[0082] Table 1 Stage 1: First load (similar to Stages 2 and 3)

[0083]

[0084] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A test device for measuring the stiffness of a composite propeller of a real ship, characterized in that: It comprises a reaction frame (1) and a blade root fixing base (2), wherein the blade root fixing base (2) is arranged on the front side of the reaction frame (1), the blade (3) is arranged on the front side of the blade root fixing base (2), and the loading fixing platform (4) is arranged below the blade (3); A plurality of loading mechanisms (5) are arranged on the top of the loading fixing platform (4), and the top of each loading mechanism (5) is in contact with the lower surface of the blade (3); a displacement meter fixing bracket (6) is arranged on the top of the blade root fixing base (2); a displacement meter (7) is arranged on the bottom of the displacement meter fixing bracket (6), and the displacement meter (7) is in contact with the upper surface of the blade (3).

2. The test device for measuring the stiffness of a composite propeller of a real ship according to claim 1, characterized in that: Each loading mechanism (5) comprises a jack fixed bottom block (501), a jack (502) and a jack loading head (503), wherein the jack fixed bottom block (501) is slidably arranged on the top of the loading fixed platform (4), the jack (502) is arranged on the top of the jack fixed bottom block (501), and the jack loading head (503) is arranged on the top of the jack (502); The jack (502) is connected with a hydraulic mechanism and a force sensor, and the force sensor is connected with a display.

3. The test device for measuring the stiffness of a composite propeller of a real ship according to claim 2, characterized in that: A first cylindrical groove (508) is provided on the top of the jack fixing bottom block (501), and the bottom of the jack (502) is plugged into the first cylindrical groove (508) of the jack fixing bottom block (501); A second cylindrical groove (509) is provided at the bottom of the jack loading head (503), and the top of the jack (502) is plugged into the second cylindrical groove (509) of the jack loading head (503).

4. The test device for measuring the stiffness of a composite propeller of a real ship according to claim 3, characterized in that: The loading mechanism (5) further comprises a conformable loading pad (504) and a rubber sheet (505); a third cylindrical groove (506) is provided at the bottom of the conformable loading pad (504); the conformable loading pad (504) is plugged into the jack loading head (503) via the third cylindrical groove (506); the rubber sheet (505) is arranged on the top of the conformable loading pad (504); and the rubber sheet (505) is in contact with the lower surface of the blade (3).

5. The test device for measuring the stiffness of a composite propeller of a real ship according to claim 3, characterized in that: The diameter of the conformable loading pad (504) is 200-300 mm, the depth of the third cylindrical groove (506) is 40-70 mm, the top outer edge of the conformable loading pad (504) is set as a rounded corner, and a cross-shaped structure mark is opened on the top of the conformable loading pad (504).

6. A test method for measuring the stiffness of a composite propeller of a real ship, characterized in that: The method is implemented by using the test device for measuring the stiffness of a composite propeller of a real ship as described in any one of claims 1 to 5, comprising the following steps: S1. Calculate the equivalent concentrated normal loading point and load value as well as the displacement measurement point information and normal deformation value; S2, based on step S1, using the test device to perform step-by-step loading and testing to obtain loading data; S3, obtaining the normal deformation value of each displacement measuring point according to the loading data obtained in step S2, and averaging the normal deformation values ​​to obtain an average value; S4. Compare and analyze the average value obtained in step S3 with the normal deformation value obtained in step S1 to obtain an error value, correct the composite material modeling parameters in finite element modeling according to the error value, obtain the bending and torsional stiffness characteristics of the composite material blade according to the normal deformation value of the displacement measuring point, and then determine the stiffness characteristics of the composite material propeller of the actual ship.

7. The test method for measuring the stiffness of a composite propeller of a real ship according to claim 6, characterized in that: Step S1 comprises the following steps: S11, obtain pressure field load based on CFD fluid calculation; S12, establishing a single blade composite material layup and structural model in a structural finite element software, applying the pressure field load obtained in step S11 to the composite material blade to obtain a blade deformation field; S13, calculating the force and moment of the pressure field load in the three directions of the blade deformation field, establishing multivariate equations of the force and moment of the multi-point concentrated normal load in the three directions, taking the force and moment deviation of the two loads of 20% as a constraint condition, and calculating the multi-point concentrated normal load; S14, setting a concentrated force loading mode in the finite element software, and calculating the blade deformation under the multi-point concentrated normal load obtained in step S13; S15, fine-tuning the position of the loading point so that the blade deformation obtained in step S14 is equal to the blade deformation field obtained in step S12, determining the equivalent concentrated normal loading point and load value, and determining the displacement measuring point information and the normal deformation value of the displacement measuring point.

8. The test method for measuring the stiffness of a composite propeller of a real ship according to claim 7, characterized in that: In step S15, the displacement measurement point information includes the number and positions of the displacement measurement points, and the positions of the displacement measurement points are the maximum deformation point of the blade tip, the 0.9 and 0.7 radii, and the 80% maximum deformation contour line.

9. The test method for measuring the stiffness of a composite propeller of a real ship according to claim 6, characterized in that: Step S2 comprises the following steps: S21, calibrating the force sensor and the displacement meter (7), and making the pointer of the displacement meter (7) point normally to each displacement measurement point mark, adjusting the positions of the plurality of jacks (502) on the loading fixed platform (4), so that the conformable loading pads (504) are respectively located at the corresponding equivalent concentrated normal loading points; S22, lifting the jack (502) by means of a hydraulic mechanism to perform preloading, wherein the load is loaded in two stages from zero to 0.5 times the design load and then unloaded; S23. Based on the equivalent concentrated normal load value, load loading is performed in a step-by-step manner of 2 to 3 stages. During the loading process, the loads of the multiple jacks (502) increase or decrease in the same proportion. The loads of each loading point in each stage are recorded by a force sensor, and the normal displacement of each displacement measuring point is recorded by a displacement meter (7) to obtain loading data.

10. The test method for measuring the stiffness of a composite propeller of a real ship according to claim 6, characterized in that: In step S23, the loading method of each stage of load loading is: The first stage is to load to 50% of the total load of the design condition. This stage is divided into five levels of loading: 10%, 20%, 30%, 40%, and 50%; The second stage is to load to 100% of the total load of the design condition. This stage is divided into five levels of loading: 50%, 60%, 70%, 80%, and 100%; The third stage is loaded to 200% of the total load of the design condition. This stage is divided into 5 loading levels: 100%, 120%, 150%, 180%, and 200%.

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