A method, device, equipment and storage medium for diagnosing abnormal torsional vibration of a propulsion shafting

Abstract

The application discloses a propeller shaft system abnormal torsional vibration diagnosis method, device, equipment and storage medium, relates to the ship propulsion system technical field, and the method comprises the steps of obtaining the torsional vibration inherent frequency and the torsional vibration mode shape under a plurality of target orders of the propeller shaft system; calculating the modal mass and the modal damping ratio under each target order of the propeller shaft system, and calculating the support reaction force at the rear stern bearing and the front stern bearing; fitting the friction coefficient between the rear stern bearing, the front stern bearing and the propeller shaft system; according to the support reaction force, the friction coefficient and the torsional vibration mode shape under the target order, the friction excitation torque under the corresponding order torsional vibration mode shape is calculated, and the corresponding Taylor expansion coefficient of the friction excitation torque; according to the torsional vibration inherent frequency, the modal mass, the modal damping ratio and the Taylor expansion coefficient under the target order, it is judged whether the torsional vibration mode of the target order of the propeller shaft system is abnormal vibration. According to the shaft system design parameters, whether the friction torsional abnormal vibration will be generated can be predicted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship propulsion systems, in particular to a propulsion shafting abnormal torsional vibration diagnosis method, device, equipment and storage medium. BACKGROUND

[0002] The propulsion shafting of a ship is a mechanical transmission system that connects the ship's power plant and the propeller. Its main function is to transmit the power and torque generated by the engine to the propeller, thereby propelling the ship forward.

[0003] During the operation of the propulsion shafting, the friction excitation generated by the water-lubricated bearing may induce abnormal torsional vibration, which may further cause vibration and noise, adversely affecting the smooth operation of the propulsion shafting.

[0004] However, there is no effective suppression measure for the friction excitation inducing the propulsion shafting to produce abnormal torsional vibration in the prior art. The reason is that the mechanism of its generation is not well understood, and the specific conditions and boundary range of its occurrence are not fully understood. Moreover, the current method requires frequent on-site collection of vibration data, which is relatively cumbersome to operate. SUMMARY

[0005] The present application provides a propulsion shafting abnormal torsional vibration diagnosis method, device, equipment and storage medium, which can effectively reduce the probability of false triggering of forward collision warning caused by visual interference.

[0006] In a first aspect, the present application provides a propulsion shafting abnormal torsional vibration diagnosis method, which comprises:

[0007] Obtaining the torsional vibration natural frequency and the torsional vibration modal shape of the propulsion shafting at a plurality of target orders;

[0008] Calculating the modal mass and modal damping ratio of the propulsion shafting at each target order, and calculating the support reaction force at the aft stern bearing and the forward stern bearing;

[0009] Fitting the friction coefficient between the aft stern bearing, the forward stern bearing and the propulsion shafting;

[0010] According to the support reaction force, the friction coefficient and the torsional vibration modal shape at each target order, the friction excitation torque corresponding to the order torsional vibration modal shape is calculated, as well as the Taylor expansion coefficient corresponding to the friction excitation torque;

[0011] According to the torsional vibration natural frequency, the modal mass, the modal damping ratio and the Taylor expansion coefficient at each target order, it is judged whether the torsional vibration modal of the propulsion shafting at each target order occurs abnormal vibration.

[0012] In combination with the first aspect, in an implementation, the determining whether the torsional vibration mode of the propulsion shaft system at the corresponding order is abnormal vibration is performed according to the torsional vibration natural frequency, the modal mass, the modal damping ratio and the Taylor expansion coefficient of each target order, and includes:

[0013] determining whether the following condition is met at each target order:

[0014] wherein, ξ j is the modal damping ratio of the jth order, γ 1,j is the Taylor expansion coefficient, M j is the modal mass of the jth order, ω j is the torsional vibration natural frequency of the jth order;

[0015] If the condition is met, it is determined that the torsional vibration mode of the propulsion shaft system at the corresponding order is abnormal vibration.

[0016] In combination with the first aspect, in an implementation, the fitting of the friction coefficient between the aft stern bearing, the front stern bearing and the propulsion shaft system includes:

[0017] According to the formula: the friction coefficient between the aft stern bearing and the propulsion shaft system is fitted;

[0018] wherein, μ b is the friction coefficient between the aft stern bearing and the propulsion shaft system, μ b,1 is the dynamic friction coefficient between the aft stern bearing and the propulsion shaft system, μ b,0 is the static friction coefficient between the aft stern bearing and the propulsion shaft system, a b is a constant, R b is the outer radius of the shaft system at the aft stern bearing, and ω is the relative angular velocity between the bearing and the shaft surface, and sign() is a sign function.

[0019] According to the formula: the friction coefficient between the front stern bearing and the propulsion shaft system is fitted;

[0020] wherein, μ f is the friction coefficient between the front stern bearing and the propulsion shaft system, μ f,1 is the dynamic friction coefficient between the front stern bearing and the propulsion shaft system, μ f,0 is the static friction coefficient between the front stern bearing and the propulsion shaft system, a f is a constant, R f is the outer radius of the shaft system at the front stern bearing, and ω is the relative angular velocity between the bearing and the shaft surface, and sign() is a sign function.

[0021] In combination with the first aspect, in an implementation, the calculating the friction excitation torque under the torsional vibration modal shape of the corresponding order and the Taylor expansion coefficients corresponding to the friction excitation torque according to the support reaction force, the friction coefficient and the torsional vibration modal shape under each target order comprises:

[0022] According to the formula:

[0023]

[0024] The friction excitation torque under the torsional vibration modal shape of the corresponding order is calculated.

[0025] In the formula, F j is the friction excitation torque under the torsional vibration modal shape of the corresponding order, and are the modal shape values at the rear stern bearing and the front stern bearing under the torsional vibration modal shape of the corresponding order, N b and N f are the support reaction forces at the rear stern bearing and the front stern bearing, R b and R f are the outer radii at the rear stern bearing and the front stern bearing of the shafting, Ω is the rotation speed of the shafting, q j (t) is the torsional vibration displacement under the torsional vibration modal coordinate of the corresponding order.

[0026] According to the formula: The friction excitation torque is Taylor expanded.

[0027] In the formula, γ 0,j , γ 1,j , γ 2,j , γ 3,j are the coefficients of Taylor expansion.

[0028] In which, γ 1,j is represented as:

[0029]

[0030] In combination with the first aspect, in an implementation, the obtaining the torsional vibration natural frequencies and the torsional vibration modal shapes of the plurality of target orders of the propulsion shafting comprises:

[0031] A torsional vibration analysis model of the propulsion shafting is established, and the torsional vibration natural frequencies and the torsional vibration modal shapes under the first n orders of the torsional vibration analysis model are obtained, wherein n is a natural number greater than or equal to 1.

[0032] In combination with the first aspect, in an implementation, it further comprises:

[0033] The torsional vibration modal shape of each order is normalized according to the maximum absolute value.

[0034] In combination with the first aspect, in an implementation manner,

[0035] According to the formula: Calculate the modal mass under each target order;

[0036] Wherein, is the normalized jth order torsional mode shape, M j is the modal mass of the jth order.

[0037] The second aspect, the application embodiment provides a kind of propulsion shafting abnormal torsional vibration diagnostic device, the propulsion shafting abnormal torsional vibration diagnostic device includes:

[0038] Calculation module, for:

[0039] Obtain the torsional vibration natural frequency and torsional mode shape under a plurality of target orders of propulsion shafting;

[0040] Calculate the modal mass and modal damping ratio under each target order of propulsion shafting, and calculate the support reaction force at the aft stern bearing and the front stern bearing;

[0041] Friction coefficient between aft stern bearing, front stern bearing and propulsion shafting is fitted;

[0042] According to support reaction force, friction coefficient and torsional mode shape under each target order, the friction excitation torque under corresponding order torsional mode shape is calculated, and the Taylor expansion coefficient corresponding to the friction excitation torque;

[0043] Judgment module, for judging according to torsional vibration natural frequency, modal mass, modal damping ratio and Taylor expansion coefficient under each target order, whether the torsional mode of each target order of propulsion shafting occurs abnormal vibration.

[0044] The third aspect, the application embodiment provides a kind of propulsion shafting abnormal torsional vibration diagnostic equipment, the propulsion shafting abnormal torsional vibration diagnostic equipment includes processor, memory and the propulsion shafting abnormal torsional vibration diagnostic program stored on the memory and can be executed by the processor, wherein the propulsion shafting abnormal torsional vibration diagnostic program is executed by the processor, realizes the steps of the propulsion shafting abnormal torsional vibration diagnostic method described above.

[0045] The fourth aspect, a computer readable storage medium, the computer readable storage medium has propulsion shafting abnormal torsional vibration diagnostic program stored on it, wherein the propulsion shafting abnormal torsional vibration diagnostic program is executed by processor, realizes the steps of the propulsion shafting abnormal torsional vibration diagnostic method described above.

[0046] The technical scheme provided by the application embodiment has at least the following beneficial effects:

[0047] The abnormal torsional vibration diagnosis method of the propulsion shafting in the application obtains the torsional vibration natural frequency and the torsional vibration modal shape of the propulsion shafting at multiple target orders; calculates the modal mass and the modal damping ratio of the propulsion shafting at each target order, and calculates the support reaction force at the aft stern bearing and the forward stern bearing; fits the friction coefficient between the aft stern bearing, the forward stern bearing and the propulsion shafting; according to the support reaction force, the friction coefficient and the torsional vibration modal shape at each target order, the friction excitation torque corresponding to the torsional vibration modal shape at each target order is calculated, and the Taylor expansion coefficient corresponding to the friction excitation torque is calculated; according to the torsional vibration natural frequency, the modal mass, the modal damping ratio and the Taylor expansion coefficient at each target order, it is judged whether the torsional vibration modal of the propulsion shafting at each target order is abnormal vibration.

[0048] Therefore, according to the shafting design parameters, without collecting the vibration data on site, the application can accurately predict whether the propulsion shafting will encounter the torsional abnormal vibration problem induced by friction in the service stage, so as to meet the evaluation and prediction needs of the propulsion shafting which is still in the design stage and has not been put into service. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 The flowchart of an embodiment of the abnormal torsional vibration diagnosis method of the propulsion shafting in the application;

[0050] Figure 2 The simplified diagram of the propulsion shafting in the application;

[0051] Figure 3 The torsional vibration response spectrum of the propulsion shafting in Example 1 of the application, Figure 3 (a) is a time domain curve, Figure 3 (b) is a frequency domain curve;

[0052] Figure 4 The torsional vibration response spectrum of the propulsion shafting in Example 2 of the application, Figure 4 (a) is a time domain curve, Figure 4 (b) is a frequency domain curve;

[0053] Figure 5 The torsional vibration response spectrum of the propulsion shafting in Example 3 of the application, Figure 5 (a) is a time domain curve, Figure 5 (b) is a frequency domain curve;

[0054] Figure 6 The structure block diagram of an embodiment of the abnormal torsional vibration suppression device of the propulsion shafting in the application;

[0055] Figure 7 The hardware structure diagram of the abnormal torsional vibration suppression device of the propulsion shafting involved in the embodiment of the application. DETAILED DESCRIPTION

[0056] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0057] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0058] In a first aspect, embodiments of this application provide a method for diagnosing abnormal torsional vibration in a propulsion shaft system.

[0059] In one embodiment, reference is made to Figure 1 , Figure 1 This is a schematic flowchart of an embodiment of the method for diagnosing abnormal torsional vibration in a propulsion shaft system according to this application. Figure 1 As shown, the diagnostic methods for abnormal torsional vibration in propulsion shaft systems include:

[0060] S1. Obtain the torsional vibration natural frequencies and torsional vibration mode shapes of the propulsion shaft system at multiple target orders;

[0061] In practice, a torsional vibration analysis model of the propulsion shaft system can be established using finite element software. Based on the finite element model, the first n torsional vibration natural frequencies and their mode shapes of the propulsion shaft system can be calculated (where n is a natural number greater than or equal to 1, and the selection of n depends on the number of torsional vibration modes of interest). Furthermore, the mode shapes of each order can be normalized by the maximum absolute value.

[0062] S2. Calculate the modal mass and modal damping ratio of the propulsion shaft system at each target order, and calculate the support reaction forces at the stern and fore-stern bearings.

[0063] First, the modal masses of the first n torsional vibration modes of the propulsion shaft system are obtained using normalized mode shapes. Modal masses can be obtained directly in finite element software such as ANSYS, or by using the mass matrix. M and the mode shapes of abnormal vibrations After exporting, calculate using the following formula:

[0064]

[0065] In the formula, This represents the normalized j-th order torsional vibration mode shape. for The transpose of the matrix, M j Let be the modal mass of the j-th order torsional vibration.

[0066] Then, the modal damping ratio of the jth torsional vibration mode of the propulsion shafting is obtained, which can be obtained through modal experiment. If it is difficult to perform modal test on site, the experience value of 0.01-0.1 can be taken.

[0067] Finally, the support reaction forces N b and N f at the aft stern bearing and the front stern bearing are calculated based on the finite element model.

[0068] S3, fitting the friction coefficient between the aft stern bearing, the front stern bearing and the propulsion shafting;

[0069] The friction coefficient μ b between the aft stern bearing bush and the shafting at different rotating speeds is provided by the manufacturer or measured through experiment. b,0 The three coefficients μ b,1 , a b are fitted by using the following exponential function:

[0070]

[0071] In the formula, μ b is the friction coefficient between the aft stern bearing bush and the propulsion shafting, μ b,1 is the dynamic friction coefficient between the aft stern bearing and the propulsion shafting, μ b,0 is the static friction coefficient between the aft stern bearing and the propulsion shafting, a b is a constant, R b is the outer radius of the shafting at the aft stern bearing, ω is the relative angular velocity between the bush and the surface of the propulsion shafting, and sign() is a sign function.

[0072] Similarly, the friction coefficient μ f between the front stern bearing bush and the shafting at different rotating speeds is provided by the manufacturer or measured through experiment. f,0 The three coefficients μ f,1 , a f are fitted by using the following exponential function:

[0073]

[0074] In the formula, μ f is the friction coefficient between the front stern bearing bush and the propulsion shafting, μ f,1 is the dynamic friction coefficient between the front stern bearing and the propulsion shafting, μ f,0 is the static friction coefficient between the front stern bearing and the propulsion shafting, a f is a constant, R f is the outer radius of the shafting at the front stern bearing, ω is the relative angular velocity between the bush and the surface of the propulsion shafting, and sign() is a sign function.

[0075] It is worth mentioning that the embodiment only considers two water-lubricated bearings, and for a propulsion shafting with three or more water-lubricated bearings, the steps S3 can be extended to multiple bearings.

[0076] S4, according to the support reaction force, the friction coefficient, and the torsional vibration modal shape under each target order, the friction excitation torque under the corresponding order torsional vibration modal shape is calculated, and the Taylor expansion coefficient corresponding to the friction excitation torque is calculated;

[0077] Specifically, the friction excitation torque F of the stern bearing and the propulsion shafting under the jth modal shape is calculated by using the support reaction force and the friction coefficient obtained above, combining the normalized jth modal shape obtained. j :

[0078]

[0079] In the formula, F j is the friction excitation torque under the jth modal shape, and are the modal shape values of the jth torsional vibration mode at the rear stern bearing and the front stern bearing, respectively, N b and N f are the support reaction forces at the rear stern bearing and the front stern bearing, respectively, R b and R f are the outer radii of the rear stern bearing and the front stern bearing of the propulsion shafting, respectively, Ω is the rotation speed of the propulsion shafting, and q j (t) is the torsional vibration displacement under the jth torsional vibration modal coordinate system.

[0080] Then, F j is Taylor expanded:

[0081]

[0082] In the formula, γ 0,j , γ 1,j , γ 2,j , γ 3,j are the Taylor expansion coefficients, and γ 1,j can be expressed as:

[0083]

[0084] It is worth mentioning that the Taylor expansion coefficients mainly consider γ 1,j , considering the weight occupied and the association with the parameters involved in the friction excitation torque; since the amplitude of the torsional vibration of the propulsion shafting is very small, most cases in engineering can be concluded to the first formula of formula (6).

[0085] S5, judging according to the torsional vibration natural frequency, modal mass, modal damping ratio and Taylor expansion coefficient under each target order, checking whether the torsional vibration mode of each target order of the propulsion shaft system is abnormal vibration.

[0086] Specifically, the application mainly uses the following formula for judgment:

[0087]

[0088] That is, judging whether each target order satisfies:

[0089] In the formula, ξ j is the modal damping ratio of the jth order, γ 1,j is the Taylor expansion coefficient, M j is the modal mass of the jth order, ω j is the jth order torsional vibration natural frequency.

[0090] If it is satisfied, it is determined that the torsional vibration mode of the corresponding order of the propulsion shaft system is abnormal vibration.

[0091] Wherein, the derivation process of the judgment formula (7) is as follows:

[0092] The jth order torsional mode vibration differential equation is established:

[0093]

[0094] In the formula, M j is the modal mass of the jth order torsional vibration, q j (t) is the torsional displacement under the jth order torsional vibration modal coordinate system, ξ j is the modal damping of the jth order torsional vibration, ω j is the jth order torsional vibration natural frequency, γ 0,j , γ 1,j , γ 2,j , γ 3,j is the Taylor expansion coefficient of the modal excitation torque.

[0095] The dimensionless of formula (8) is introduced as follows:

[0096]

[0097] In the formula, q0 is a constant.

[0098] Bring formula (9) into formula (8) to get:

[0099]

[0100] In the formula, β 0,j , β 1,j , β2,j , β 3,j may be expressed as:

[0101]

[0102] The critical condition of abnormal vibration of the system can be obtained by solving equation (10) using the perturbation method, as shown in equation (7).

[0103] The above steps will be further described in combination with three specific examples as follows:

[0104] Example 1:

[0105] Suppose a ship propeller shaft system can be simplified as the shaft segment model shown in FIG. 1. The detailed geometric dimensions of each shaft segment are shown in Table 1. In the table, L represents the length of the shaft segment, Ro represents the outer radius of the shaft segment, and Ri represents the inner radius thereof. The polar moment of inertia of the propeller is 8000 Kg.m 2 , the polar moment of inertia of the high-elasticity clutch driving end is 7000 Kg.m 2 , and the working rotational speed is 20 rpm. It is checked whether abnormal vibration will occur.

[0106] Table 1: Dimensions of each shaft segment (m)

[0107]

[0108] (1) The friction coefficients provided by the manufacturer are fitted to obtain six coefficients μ b,0 , μ b,1 , a b , μ f,0 , μ f,1 , a f , as shown in Table 2.

[0109] Table 2: Fitted friction coefficient values

[0110] Variable μ b,0 ]]> μ b,1 ]]> a b ]]> μ f,0 ]]> μ f,1 ]]> a f ]]> Fitted value 0.9 0.1 2 0.9 0.1 2

[0111] (2) The steps described above are used to establish a finite element model of the propeller shaft system torsional vibration, to obtain the first n-order torsional vibration natural frequencies and modes (only the first 5-order torsional vibration is concerned in this example, so only the 5th order needs to be calculated), and to normalize the modes to obtain the support reaction forces at the aft and forward stern bearings, the numerical values of which are shown in Table 3.

[0112] Table 3: Torsional vibration natural frequencies and support reaction forces (ω unit: rad / s)

[0113] Variable ​ <![CDATA[ω2]]> <![CDATA[ω3]]> [["ω4"]] [CDATA[ω5]] <![CDATA[N b ]]> [0009CH f ​ Value 63.3 Hz 71.7 Hz 191.1 Hz 205.5 Hz 284.7 Hz 39784N 28110N

[0114] (3) The first n-order torsional vibration modal mass of the propeller shaft system is obtained, as shown in Table 4.

[0115] Table 4: First n-order torsional vibration modal mass

[0115] Table 4 modal quality

[0116] Variable M1 [M2] [M3] M4 [M5] Value 74.9 69.8 36.4 72.5 26.1

[0117] (4) Obtain the damping ratio of the first n order torsional vibration modal of the propulsion shafting, as shown in Table 5.

[0118] Table 5 modal damping ratio

[0119] Variable ​ ​ [CDATA[ξ3]] ​ ​ Value 0.01 0.0095 0.01 0.0104 0.0129

[0120] (5) Using the above steps, the coefficient γ 1,j , as shown in Table 6.

[0121] Table 6 coefficient γ 1,j value

[0122] Variable 1,1 ]]> ​ 1,2 ]]> ​ 1,3 ]]> ​ gamma 1,4 ]] gamma 1,5 ]]> Value 0.7534 1057.3 1.879 964.9 0.0277

[0123] (6) Calculate and compare it with ξ j , if , the order torsional modal will have abnormal vibration phenomenon. The checking results are shown in Table 7.

[0124] Table 7 checking results

[0125]

[0126] From Table 7, it can be seen that the second order modal will have abnormal vibration. In order to verify the correctness of the method proposed in the application, the nonlinear dynamics modeling simulation of the propulsion shafting is carried out, the nonlinear response of the propulsion shafting under friction excitation is studied, and the calculation results are shown in Figure 7 , from which it can be seen that the time domain curve does not decay, so the propulsion shafting has abnormal torsional vibration. Comparing with Table 7, it can be seen that the abnormal torsional vibration frequency component is characterized by the second order torsional natural frequency and its multiple frequency, so the second order torsional modal has abnormal vibration, which is consistent with the checking results of Table 7, proving the effectiveness of the method of the application.

[0127] Example 2:

[0128] Still taking the propulsion shafting shown in Figure 2 as an example, assuming that its working speed is 40 rpm, whether it will have abnormal torsional vibration is checked.

[0129] (1)-(4) are the same as in application example 1.

[0130] (5) Using the above steps, the coefficient γ 1,j , as shown in Table 8.

[0131] Table 8 coefficient γ 1,j value

[0132] Variable 1,1 ]]> ​ 1,2 ]]> ​ 1,3 ]]> ​ 1,4 ]]> ​ gamma 1,5 ]] Value 0.326 457.48 0.813 417.47 0.012

[0133] (6) Calculate and compare with ξ j , if , the torsional mode will produce abnormal vibration phenomenon. The checking results are shown in Table 9.

[0134] Table 9 Checking results

[0135]

[0136] From Table 9, it can be seen that the propulsion shafting will not occur torsional abnormal vibration. In order to verify the correctness of the method proposed in the application, the nonlinear dynamics modeling of the propulsion shafting is carried out, the nonlinear response of the propulsion shafting under friction excitation is studied, and the calculation results are shown in Figure 4 , the time domain curve decays to zero, so the propulsion shafting does not occur abnormal torsional vibration. This is consistent with the checking results of Table 9, which proves the effectiveness of the method proposed in the application.

[0137] Example 3:

[0138] Still taking the propulsion shafting shown in Figure 2 as an example, it is assumed that the working speed of the propulsion shafting is 40 rpm, and whether it will occur abnormal torsional vibration is checked.

[0139] (1)-(3) are the same as application example 1.

[0140] (4) Obtain the first n order torsional vibration modal damping ratio of the propulsion shafting, as shown in Table 10.

[0141] Table 10 Modal damping ratio

[0142] Variable ​ ​ ​ ​ ​ Value 0.0229 0.02 0.0048 0.004 6.3496e-4

[0143] (5) Using the steps described above, the coefficient γ 1,j can be obtained, as shown in Table 11.

[0144] Table 11 Coefficient γ 1,j value

[0145] Variable 1,1 ]]> ​ 1,2 ]]> ​ 1,3 ]]> ​ 1,4 ]]> ​ 1,5 ]]> ​ Value 0.7534 1057.3 1.879 964.9 0.0277

[0146] (6) Calculate and compare with ξ j , if , the torsional mode will produce abnormal vibration phenomenon. The checking results are shown in Table 12.

[0147] Table 12 Checking results

[0148]

[0149] As shown in Table 12, abnormal vibrations will occur in the fourth mode. To verify the correctness of the method proposed in this application, a nonlinear dynamic model of the propulsion shaft system was performed to study its nonlinear response under frictional excitation. The calculation results are as follows: Figure 5 As shown, the time-domain curve shows no decay, indicating abnormal vibration. Comparison with Table 3 reveals that the frequency components of the abnormal torsional vibration are characterized by the fourth-order torsional natural frequency and its harmonics, thus indicating abnormal vibration in the fourth-order torsional mode. This is consistent with the verification results in Table 12, demonstrating the effectiveness of the method presented in this application.

[0150] In summary, the abnormal torsional vibration diagnosis method for propulsion shafting in this application obtains the torsional natural frequencies and torsional mode shapes of the propulsion shafting at multiple target orders; calculates the modal mass and modal damping ratio of the propulsion shafting at each target order, and calculates the support reactions at the aft and stern bearings and the fore and stern bearings; fits the friction coefficients between the aft and stern bearings, the fore and stern bearings and the propulsion shafting; calculates the frictional excitation torque under the corresponding torsional mode shape and the Taylor expansion coefficient of the frictional excitation torque based on the support reactions, friction coefficients and the torsional mode shapes of each target order; and judges whether abnormal vibration occurs in the torsional modes of each target order of the propulsion shafting based on the torsional natural frequencies, modal masses, modal damping ratios and Taylor expansion coefficients of each target order.

[0151] Therefore, this application can accurately predict whether the propulsion shaft will encounter abnormal torsional vibration caused by friction during the service stage based solely on the shaft design parameters, without the need for cumbersome on-site vibration data collection. Thus, it is highly suitable for the assessment and prediction needs of the propulsion shaft when it is still in the design stage and has not yet been put into service.

[0152] Secondly, embodiments of this application also provide a diagnostic device for abnormal torsional vibration of a propulsion shaft system.

[0153] In one embodiment, reference is made to Figure 6 , Figure 6 This is a functional module diagram of an embodiment of the propulsion shaft abnormal torsional vibration diagnostic device of this application. Figure 6 As shown, the abnormal torsional vibration diagnostic device for propulsion shafts includes a calculation module and a judgment module.

[0154] The calculation module is used for:

[0155] Obtain the torsional vibration natural frequencies and torsional vibration mode shapes of the propulsion shaft system at multiple target orders;

[0156] Calculate the modal mass and modal damping ratio of the propulsion shaft system at each target order, and calculate the support reaction forces at the aft and forward stern bearings;

[0157] the friction coefficient between the aft stern bearing, the front stern bearing and the propulsion shafting after fitting;

[0158] According to the support reaction force, the friction coefficient and the torsional vibration modal shape under each target order, the friction excitation torque under the corresponding order torsional vibration modal shape is calculated, and the Taylor expansion coefficient corresponding to the friction excitation torque is calculated.

[0159] The judging module is used for judging whether the torsional vibration modal of each target order of the propulsion shafting is abnormal vibration according to the torsional vibration natural frequency, the modal mass, the modal damping ratio and the Taylor expansion coefficient under each target order.

[0160] Further, in an embodiment, the judging module judges whether the torsional vibration modal of each target order of the propulsion shafting is abnormal vibration according to the torsional vibration natural frequency, the modal mass, the modal damping ratio and the Taylor expansion coefficient under each target order, which comprises:

[0161] It is judged whether the following condition is met under each target order:

[0162] In the formula, ξ j is the modal damping ratio of the jth order, γ 1,j is the Taylor expansion coefficient, M j is the modal mass of the jth order, ω j is the torsional vibration natural frequency of the jth order.

[0163] If the condition is met, it is determined that the torsional vibration modal of the corresponding order of the propulsion shafting is abnormal vibration.

[0164] Further, in an embodiment, the calculating module fits the friction coefficient between the aft stern bearing, the front stern bearing and the propulsion shafting after fitting, which comprises:

[0165] According to the formula: the friction coefficient between the aft stern bearing and the propulsion shafting after fitting is fitted;

[0166] In the formula, μ b is the friction coefficient between the aft stern bearing and the propulsion shafting, μ b,1 is the dynamic friction coefficient between the aft stern bearing and the propulsion shafting, μ b,0 is the static friction coefficient between the aft stern bearing and the propulsion shafting, a b is a constant, R b is the outer radius of the shafting at the aft stern bearing, and ω is the relative angular velocity between the bearing and the shafting surface, and sign() is a sign function.

[0167] According to the formula: the friction coefficient between the front stern bearing and the propulsion shafting is fitted;

[0168] In the formula, μ fμ is the friction coefficient between the front stern bearing and the propulsion shafting f,1 μ is the dynamic friction coefficient between the front stern bearing and the propulsion shafting f,0 μ is the static friction coefficient between the front stern bearing and the propulsion shafting f R is a constant f R is the outer radius of the shafting at the front stern bearing, ω is the relative angular velocity between the bearing and the shafting surface, and sign() is the sign function.

[0169] Further, in an embodiment, the calculating module calculates the friction excitation torque under the torsional vibration modal shape of the corresponding order and the Taylor expansion coefficients corresponding to the friction excitation torque according to the support reaction force, the friction coefficient, and the torsional vibration modal shape under each target order, including:

[0170] According to the formula:

[0171]

[0172] The friction excitation torque under the torsional vibration modal shape of the corresponding order is calculated.

[0173] In the formula, F j is the friction excitation torque under the torsional vibration modal shape of the corresponding order, and are the modal shape values at the rear stern bearing and the front stern bearing under the torsional vibration modal shape of the corresponding order, respectively b and f are the support reaction forces at the rear stern bearing and the front stern bearing, respectively b and f are the outer radii of the shafting at the rear stern bearing and the front stern bearing, respectively, and Ω is the rotation speed of the shafting.

[0174] According to the formula: The friction excitation torque is Taylor expanded.

[0175] In the formula, γ 0,j , γ 1,j , γ 2,j , γ 3,j are the coefficients of the Taylor expansion.

[0176] In the formula, γ 1,j is represented as:

[0177]

[0178] Further, in an embodiment, the calculating module obtains the torsional vibration natural frequencies and the torsional vibration modal shapes of the propulsion shafting under multiple target orders, including:

[0179] A torsional vibration analysis model of the propulsion shafting is established to obtain torsional vibration inherent frequencies and torsional vibration modal shapes under the first n orders of the torsional vibration analysis model, where n is a natural number greater than or equal to 1.

[0180] Further, in an embodiment, the computing module is further configured to:

[0181] The torsional vibration modal shape of each order is normalized according to the maximum absolute value.

[0182] Further, in an embodiment, the computing module is configured to

[0183] According to the formula: The modal mass under each target order is calculated;

[0184] wherein, is the jth order of the normalized torsional vibration modal shape, M j is the modal mass of the jth order.

[0185] The functions of each module in the propulsion shafting abnormal torsional vibration diagnosis apparatus correspond to the steps in the propulsion shafting abnormal torsional vibration diagnosis method, and the functions and implementation processes will not be repeated here.

[0186] In a third aspect, the embodiments of the present application provide a propulsion shafting abnormal torsional vibration diagnosis device. The propulsion shafting abnormal torsional vibration diagnosis device can be a personal computer (PC), a notebook computer, a server, or other devices with data processing functions.

[0187] Referring to Figure 7 , Figure 7 is a hardware structure diagram of the propulsion shafting abnormal torsional vibration diagnosis device involved in the embodiments of the present application. In the embodiments of the present application, the propulsion shafting abnormal torsional vibration diagnosis device can include a processor, a memory, a communication interface, and a communication bus.

[0188] The communication bus can be of any type, used to interconnect the processor, the memory, and the communication interface.

[0189] The communication interface includes an input / output (I / O) interface, a physical interface, and a logical interface, and other interfaces for interconnecting devices inside the propulsion shafting abnormal torsional vibration diagnosis device, and interfaces for interconnecting the propulsion shafting abnormal torsional vibration diagnosis device with other devices (such as other computing devices or user devices). The physical interface can be an Ethernet interface, a fiber interface, an ATM interface, etc.; the user device can be a display (Display), a keyboard (Keyboard), etc.

[0190] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), and the like.

[0191] The processor can be a general-purpose processor, which can invoke the propulsion shaft system abnormal torsional vibration diagnosis program stored in the memory and execute the propulsion shaft system abnormal torsional vibration diagnosis method provided by the embodiments of the present application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the propulsion shaft system abnormal torsional vibration diagnosis program is invoked can refer to various embodiments of the propulsion shaft system abnormal torsional vibration diagnosis method of the present application, which will not be described here.

[0192] Those skilled in the art can understand that the hardware structure shown in the above-mentioned embodiments is not a limitation of the present application, and can include more or less components than the figure, or combine certain components, or different component arrangements. Figure 7

[0193] In a fourth aspect, the embodiments of the present application further provide a readable storage medium.

[0194] The readable storage medium of the present application stores the propulsion shaft system abnormal torsional vibration diagnosis program, wherein when the propulsion shaft system abnormal torsional vibration diagnosis program is executed by the processor, the steps of the propulsion shaft system abnormal torsional vibration diagnosis method as described above are implemented.

[0195] The method implemented when the propulsion shaft system abnormal torsional vibration diagnosis program is executed can refer to various embodiments of the propulsion shaft system abnormal torsional vibration diagnosis method of the present application, which will not be described here.

[0196] It should be noted that the above-mentioned sequence numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0197] ​Those skilled in the art can clearly understand, through the description of the foregoing embodiments, that the foregoing example method can be implemented by means of software and a necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation manner. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as a ROM / RAM, a magnetic disk, or an optical disk) and includes a plurality of instructions for causing a terminal device to execute the methods described in the various embodiments of the present application.

[0198] The terms "comprise", "have" and "include" and any variations thereof in the specification and claims of the present application and the above-described drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product, or device. The terms "first", "second", and "third" and the like descriptions are used to distinguish different objects, and do not represent the order of sequence or limit the "first", "second", and "third" to different types.

[0199] In the description of the embodiments of the present application, "exemplary", "for example", "for instance", or "such as" is used to represent an example, illustration, or description. Any embodiment or design scheme described as "exemplary", "for example", or "for instance" in the embodiments of the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words "exemplary", "for example", or "for instance" are intended to present the relevant concept in a specific manner.

[0200] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in the text only describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0201] In some of the processes described in the embodiments of the present application, a plurality of operations or steps are included in a specific order, but it should be understood that these operations or steps can be executed or performed in parallel or in an order different from that in which they appear in the embodiments of the present application. The serial number of the operation is only used to distinguish different operations, and the serial number itself does not represent any execution order. In addition, these processes can include more or fewer operations, and these operations or steps can be executed in sequence or in parallel, and these operations or steps can be combined.

[0202] The preferred embodiments of the present application have been described above with the specific details of the preferred embodiments to provide complete understanding of the application. However, it will be apparent to persons having ordinary skill in the technology related to the application that various changes in form and details can be made without departing from the spirit and scope of the application. Therefore, the above- described specific details should not limit the scope of the present application, and should be considered as merely exemplary, and the present application is defined by the scope of claims.

[0203] The preferred embodiments of the present application have been described above with the specific details of the preferred embodiments to provide complete understanding of the application. However, it will be apparent to persons having ordinary skill in the technology related to the application that various changes in form and details can be made without departing from the spirit and scope of the application. Therefore, the above- described specific details should not limit the scope of the present application, and should be considered as merely exemplary, and the present application is defined by the scope of claims.

Claims

1. A method of diagnosing abnormal torsional vibration of a propulsion shafting, characterized by, The propulsion shafting abnormal torsional vibration diagnosis method comprises: obtaining torsional vibration natural frequencies and torsional vibration modal shapes of the propulsion shafting at multiple target orders; calculating modal mass and modal damping ratio of the propulsion shafting at each target order, and calculating support reaction forces at the aft stern bearing and the forward stern bearing; fitting friction coefficients between the aft stern bearing, the forward stern bearing and the propulsion shafting; calculating friction excitation torques at the corresponding order torsional vibration modal shape and Taylor expansion coefficients corresponding to the friction excitation torques according to the support reaction forces, the friction coefficients and the torsional vibration modal shape at each target order; discriminating according to the torsional vibration natural frequencies, the modal mass, the modal damping ratio and the Taylor expansion coefficients at each target order, and checking whether the torsional vibration modal shape of the propulsion shafting at each target order is abnormal.

2. The abnormal torsional vibration diagnostic method for a propulsion shafting according to claim 1, characterized by, The discriminating according to the torsional vibration natural frequencies, the modal mass, the modal damping ratio and the Taylor expansion coefficients at each target order, and checking whether the torsional vibration modal shape of the propulsion shafting at each target order is abnormal comprises: determining whether each target order satisfies: wherein ξ j is the modal damping ratio of the jth order, γ 1,j is the Taylor expansion coefficient, M j is the modal mass of the jth order, ω j is the jth order torsional natural frequency; if the condition is met, it is determined that the torsional vibration modal shape of the propulsion shafting at the corresponding order is abnormal.

3. The abnormal torsional vibration diagnostic method for a propulsion shafting according to claim 2, characterized by, The fitting friction coefficients between the aft stern bearing, the forward stern bearing and the propulsion shafting comprises: According to the formula: The friction coefficient between the fitted stern bearing and the propulsion shafting; where μ b is the friction coefficient between the aft stern bearing and the propulsion shafting, μ b,1 is the dynamic friction coefficient between the aft stern bearing and the propulsion shafting, μ b,0 is the static friction coefficient between the aft stern bearing and the propulsion shafting, a b is a constant, R b is the outer radius of the shafting at the aft stern bearing, ω is the relative angular velocity between the bearing shell and the shafting surface, and sign() is the sign function. According to the formula: The friction coefficient between the front bearing and the propulsion shafting before fitting; where μ f is the friction coefficient between the front stern bearing and the propulsion shafting, μ f,1 is the dynamic friction coefficient between the front stern bearing and the propulsion shafting, μ f,0 is the static friction coefficient between the front stern bearing and the propulsion shafting, a f is a constant, R f is the outer radius of the shafting at the front stern bearing, ω is the relative angular velocity between the bearing and the shafting surface, and sign() is the sign function.

4. The abnormal torsional vibration diagnostic method for a propulsion shafting according to claim 3, characterized by, The calculating friction excitation torques at the corresponding order torsional vibration modal shape and Taylor expansion coefficients corresponding to the friction excitation torques according to the support reaction forces, the friction coefficients and the torsional vibration modal shape at each target order comprises: calculating the friction excitation torques at the corresponding order torsional vibration modal shape according to the formula: The obtaining torsional vibration natural frequencies and torsional vibration modal shapes of the propulsion shafting at multiple target orders comprises: where F j is the friction excitation torque corresponding to the torsional vibration mode shape of the i-th order, and are the mode shape values at the aft and fore stern bearings respectively corresponding to the torsional vibration mode shape of the i-th order, N b and N f are the support reaction forces at the aft and fore stern bearings respectively, R b and R f are the outer radii of the shafting at the aft and fore stern bearings respectively, Ω is the rotational speed of the shafting, q j (t) is the torsional vibration displacement in the coordinate system corresponding to the torsional vibration mode shape of the i-th order. According to the formula: The Taylor expansion is performed on the frictional excitation moment; where γ 0,j , γ 1,j , γ 2,j , and γ 3,j are coefficients of the Taylor expansion; wherein γ 1,j is represented by:

5. The abnormal torsional vibration diagnostic method for a propulsion shafting according to claim 1, characterized by, establishing a torsional vibration analysis model of the propulsion shafting, and obtaining torsional vibration natural frequencies and torsional vibration modal shapes at the first n orders of the torsional vibration analysis model, wherein n is a natural number greater than or equal to 1. It also comprises:

6. The abnormal torsional vibration diagnostic method for a propulsion shafting according to claim 5, characterized by normalizing each order of the torsional vibration modal shape according to the maximum absolute value.

7. The propulsion shafting abnormal torsional vibration diagnosis method according to claim 6, wherein: The propulsion shafting abnormal torsional vibration diagnosis device comprises: The modal mass at each target order is calculated according to the formula: M = ω2 / 2πf2 wherein, Mj is the jth mode shape after normalization, j Mj is the jth mode mass.

8. A propeller shaft abnormal torsional vibration diagnosis device characterized by comprising: a calculation module configured to: obtain torsional vibration natural frequencies and torsional vibration modal shapes of the propulsion shafting at multiple target orders; calculate modal mass and modal damping ratio of the propulsion shafting at each target order, and calculate support reaction forces at the aft stern bearing and the forward stern bearing; fit friction coefficients between the aft stern bearing, the forward stern bearing and the propulsion shafting; calculate friction excitation torques at the corresponding order torsional vibration modal shape and Taylor expansion coefficients corresponding to the friction excitation torques according to the support reaction forces, the friction coefficients and the torsional vibration modal shape at each target order; a judgment module configured to discriminate according to the torsional vibration natural frequencies, the modal mass, the modal damping ratio and the Taylor expansion coefficients at each target order, and check whether the torsional vibration modal shape of the propulsion shafting at each target order is abnormal. The propulsion shafting abnormal torsional vibration diagnosis device comprises a processor, a memory and a propulsion shafting abnormal torsional vibration diagnosis program stored in the memory and executable by the processor, wherein when the propulsion shafting abnormal torsional vibration diagnosis program is executed by the processor, the steps of the propulsion shafting abnormal torsional vibration diagnosis method according to any one of claims 1 to 7 are implemented.

9. A propeller shaft abnormal torsional vibration diagnosis device characterized by comprising: ​ 10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a propeller shaft abnormal torsional vibration diagnosis program, and when the propeller shaft abnormal torsional vibration diagnosis program is executed by the processor, the steps of the propeller shaft abnormal torsional vibration diagnosis method according to any one of claims 1 to 7 are implemented.

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