A method, device, equipment and medium for selecting a shafting empty diameter ratio of a ship

Abstract

The present application relates to a kind of ship shafting empty diameter ratio selection method, device, equipment and medium, belong to ship technology field, wherein, ship shafting empty diameter ratio selection method includes obtaining the multiple ship shafting models considering the relationship between shafting weight reduction quality and empty diameter ratio based on hollow design construction, the strength performance of ship shafting model is checked, the strength stress of ship shafting is obtained, and intensity performance parameter is determined;Dynamic characteristics checking is carried out to ship shafting model based on the strength stress of ship shafting, and vibration performance parameter and impact resistance performance parameter are determined;Based on intensity performance parameter, vibration performance parameter and impact resistance performance parameter, the optimal empty diameter ratio is determined using multi-objective optimization method, the lightweight degree of shafting is maximized, and the performance is optimal.

Description

Technical Field

[0001] The present invention relates to the field of ship technology, and in particular to a method, device, equipment and medium for selecting the space-to-diameter ratio of a ship shaft system. Background Art

[0002] The ship's propulsion shaft system is the connecting structure between the main engine and the propeller. The power generated from the main engine is transmitted to the propeller end through the shaft system. The rotation of the propeller generates a reaction force on the hull, pushing the ship forward.

[0003] For the lightweight design of ship shafting, on the one hand, advanced composite materials can be used, and on the other hand, the structure of the shafting can be hollowed out. With the development of larger ships, most ships currently use solid shafts. Hollowing out the shafting can effectively achieve lightweighting of the shaft. In the design of hollow shafts of ships and the selection of the hollow-to-diameter ratio, the hollow-to-diameter ratio is mainly selected based on the strength characteristics of the shafting.

[0004] However, the shafting ratio is selected based on the strength characteristics of the shafting. Although the selected shafting ratio has higher safety in terms of strength, it does not take into account the vibration characteristics and impact resistance requirements of the shafting, and cannot achieve the goal of maximum shafting lightweight and optimal performance. Summary of the Invention

[0005] In view of this, it is necessary to provide a method, device, equipment and medium for selecting the air-to-diameter ratio of a ship shaft system, so as to solve the technical problem that when designing the lightweight design of a ship shaft system, only the strength characteristics are considered but the vibration characteristics and impact resistance requirements of the shaft system are not considered, and the maximum lightweight degree and optimal performance of the shaft system cannot be achieved.

[0006] In order to solve the above problems, the present invention provides a method for selecting the space-to-diameter ratio of a ship shaft system, comprising:

[0007] Acquire multiple ship shafting models based on hollow design that consider the relationship between shafting weight reduction and hollow-to-diameter ratio, perform strength performance verification on the ship shafting models, obtain strength stress of the ship shafting, and determine strength performance parameters;

[0008] Performing a dynamic characteristic check on the ship shafting model based on the strength stress of the ship shafting to determine vibration performance parameters and shock resistance performance parameters;

[0009] Based on the strength performance parameters, vibration performance parameters and impact resistance performance parameters, a multi-objective optimization method is used to determine the optimal air-to-diameter ratio.

[0010] In a possible implementation, the obtaining of multiple ship shafting models based on hollow design and considering the relationship between shafting weight reduction and hollow-to-diameter ratio includes:

[0011] Determine the range of air-to-diameter ratio;

[0012] Based on the range of the void-to-diameter ratio, multiple ship shafting models are constructed that consider the relationship between the shafting weight reduction mass and the void-to-diameter ratio.

[0013] In a possible implementation, the relationship between the shaft system weight reduction mass and the air-to-diameter ratio is calculated as follows:

[0014] ,

[0015] in, The weight reduction of the ship's shafting system, is the shaft material density, is the air-to-diameter ratio, is the shaft diameter, is the shaft diameter, is the axis length.

[0016] In a possible implementation, performing strength performance verification on the ship shafting model to obtain the strength stress of the ship shafting includes:

[0017] Presetting a space-to-diameter ratio threshold to determine the space-to-diameter ratio of the ship shafting model;

[0018] When the space-to-diameter ratio is greater than the space-to-diameter ratio threshold, adjusting the outer diameter of the ship shafting to obtain a corrected outer diameter of the ship shafting;

[0019] Performing strength performance verification on the ship shafting model based on the corrected outer diameter of the ship shafting to obtain strength stress of the ship shafting;

[0020] When the space-to-diameter ratio is less than or equal to the space-to-diameter ratio threshold, performing a strength performance check on the ship shafting model to obtain strength stress of the ship shafting, wherein the strength stress of the ship shafting includes axial stress of the shafting, shear stress of the shafting, bending stress of the shafting, and equivalent stress of the shafting;

[0021] The allowable stress of the shafting material is determined. When the strength stress of the ship shafting is greater than the allowable stress of the shafting material, the space-to-diameter ratio is adjusted within the space-to-diameter ratio range so that the strength stress of the ship shafting is less than or equal to the allowable stress of the shafting material.

[0022] In a possible implementation, the calculation formula for the corrected outer diameter of the ship shafting is:

[0023] ,

[0024] ,

[0025] in, is the corrected outer diameter of the ship shafting, is the shaft diameter, is the shaft diameter;

[0026] The calculation formula of the axial stress of the shaft system is:

[0027] ,

[0028] in, is the axial stress of the shaft system, is the propeller thrust, is the cross-sectional area;

[0029] The calculation formula of the shear stress of the shaft system is:

[0030] ,

[0031] in, is the bending stress of the shaft system, is the rotational moment on the shaft section, is the torsional section modulus;

[0032] The calculation formula of the bending stress of the shaft system is:

[0033] ,

[0034] in, is the bending stress of the shaft system, is the bending moment on the axial section, is the bending section modulus;

[0035] The calculation formula for the equivalent stress of the shaft system is:

[0036] ,

[0037] in, is the equivalent stress of the shaft system.

[0038] In a possible implementation, the performing dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting to obtain vibration performance parameters and shock resistance performance parameters includes:

[0039] When the strength stress of the ship shafting is less than or equal to the allowable stress of the shafting material, a dynamic characteristic check is performed on the ship shafting model to determine vibration performance parameters and shock resistance performance parameters, wherein the dynamic characteristics include vibration characteristics and shock resistance characteristics of the shafting, the vibration performance parameters include torsional vibration parameters, whirling vibration parameters, and longitudinal vibration performance parameters, and the shock resistance performance parameters include shock resistance stress parameters;

[0040] The allowable stress of the ship shafting and the maximum impact stress of the ship shafting are determined. When the maximum impact stress is greater than the allowable stress, the space-to-diameter ratio is adjusted within the space-to-diameter ratio range so that the maximum impact stress of the ship shafting is less than or equal to the allowable stress of the ship shafting.

[0041] In a possible implementation, determining the optimal air-to-diameter ratio using a multi-objective optimization method based on the strength performance parameter, the vibration performance parameter, and the impact resistance performance parameter includes:

[0042] Determining the weight reduction of the shaft system based on the strength performance parameter and the air-to-diameter ratio;

[0043] determining a torsion angle of the shaft system based on the vibration performance parameter and the air-to-diameter ratio;

[0044] determining the impact stress of the shafting based on the impact resistance parameter and the air-to-diameter ratio;

[0045] The optimization objectives are to maximize the weight reduction mass, minimize the impact stress, and minimize the torsion angle, the shaft system's air-to-diameter ratio is used as the independent variable, and the torsion angle and impact stress are used as dependent variables. A multi-objective optimization method is used to determine the optimal air-to-diameter ratio.

[0046] On the other hand, the present invention also provides a device for selecting the space-to-diameter ratio of a ship shaft system, comprising:

[0047] A strength performance verification module is used to obtain multiple ship shafting models based on hollow design that take into account the relationship between shafting weight reduction and hollow-to-diameter ratio, perform strength performance verification on the ship shafting models, obtain the strength stress of the ship shafting, and determine the strength performance parameters;

[0048] A dynamic characteristic verification module is used to perform dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting to determine vibration performance parameters and shock resistance performance parameters;

[0049] The optimal air-to-diameter ratio determination module is used to determine the optimal air-to-diameter ratio using a multi-objective optimization method based on the strength performance parameters, vibration performance parameters and impact resistance performance parameters.

[0050] On the other hand, the present invention also provides an electronic device, comprising: a processor and a memory;

[0051] The memory stores a computer-readable program executable by the processor;

[0052] When the processor executes the computer-readable program, the steps in the method for selecting the space-to-diameter ratio of a ship shafting as described above are implemented.

[0053] On the other hand, the present invention also provides a computer-readable storage medium, which stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the ship shafting air-to-diameter ratio selection method as described above.

[0054] The beneficial effects of the present invention are: constructing multiple ship shafting models to provide a basis for strength performance verification and dynamic characteristic verification, performing strength performance verification on the ship shafting model so that the selected air-to-diameter ratio can meet the strength performance of the shafting, performing dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting, after the shafting meets the strength performance requirements, performing dynamic characteristic verification on the ship shafting model so that the selected air-to-diameter ratio can meet the dynamic characteristic requirements of the shafting, effectively improving the impact resistance of the shafting, using a multi-objective optimization method to determine the optimal air-to-diameter ratio, taking strength performance parameters, vibration performance parameters and impact resistance performance parameters as optimization targets, and using a multi-objective optimization algorithm to further select the optimal air-to-diameter ratio, thereby achieving the maximum lightweight degree and optimal performance of the shafting. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A flow chart of an embodiment of a method for selecting a ship shafting pitch-to-diameter ratio provided by the present invention;

[0056] Figure 2 A schematic diagram of a hollow shaft for selecting the hollow-to-diameter ratio of a ship shafting system provided by the present invention;

[0057] Figure 3 A schematic structural diagram of an embodiment of a device for selecting the space-to-diameter ratio of a ship shafting provided by the present invention;

[0058] Figure 4 This is a schematic structural diagram of an embodiment of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0059] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0060] The present invention discloses a method, device, equipment, and medium for selecting the pitch-to-diameter ratio of a ship shaft system, which can be used in a computer. The method, equipment, or computer-readable storage medium involved in the present invention can be integrated with the above-mentioned equipment or can be relatively independent.

[0061] A specific embodiment of the present invention discloses a method for selecting the space-to-diameter ratio of a ship shafting, which can be executed by a computer, specifically by one or more processors of the computer. Figure 1 This is a flow chart of the method for selecting the shafting ratio of a ship provided by an embodiment of the present invention. Figure 1 , the methods for selecting the ship shafting void diameter ratio include:

[0062] S101. Acquire multiple ship shafting models based on hollow design that consider the relationship between shafting weight reduction and hollow-to-diameter ratio, perform strength performance verification on the ship shafting models, obtain strength stress of the ship shafting, and determine strength performance parameters;

[0063] S102. Performing a dynamic characteristic check on the ship shafting model based on the strength stress of the ship shafting to determine vibration performance parameters and shock resistance performance parameters;

[0064] S103. Based on the strength performance parameters, vibration performance parameters, and impact resistance performance parameters, a multi-objective optimization method is used to determine the optimal air-to-diameter ratio.

[0065] Among them, multiple ship shafting models considering the relationship between the shafting weight reduction and the air-to-diameter ratio are constructed, that is, ship shafting models with different air-to-diameter ratios are constructed, and the strength performance of the ship shafting models is checked. By adjusting the air-to-diameter ratio, the strength performance of the ship shafting does not exceed the maximum allowable stress and meets the strength performance requirements. The multi-objective optimization method is used to determine the optimal air-to-diameter ratio, and the NSGA-Ⅱ multi-objective optimization algorithm is used to further select the optimal air-to-diameter ratio.

[0066] Compared with the prior art, the method for selecting the void-to-diameter ratio of a ship shafting system provided in this embodiment obtains multiple ship shafting system models based on hollow design that consider the relationship between the shafting system weight reduction mass and the void-to-diameter ratio, providing a basis for strength performance verification and dynamic characteristic verification. The strength performance verification of the ship shafting system model is performed to obtain the strength stress of the ship shafting system, and the strength performance parameters are determined so that the selected void-to-diameter ratio can meet the strength performance of the shafting system. The dynamic characteristics verification of the ship shafting system model is performed based on the strength stress of the ship shafting system to determine the vibration performance parameters and the impact resistance performance parameters. After the strength stress of the shafting system meets the strength performance requirements, the dynamic characteristics verification of the ship shafting system model is performed so that the selected void-to-diameter ratio can meet the dynamic characteristics requirements of the shafting system, effectively improving the impact resistance of the shafting system. The optimal void-to-diameter ratio is determined based on the strength performance parameters, vibration performance parameters, and impact resistance performance parameters using a multi-objective optimization method. The void-to-diameter ratio is used as the independent variable, and the strength performance parameters, vibration performance parameters, and impact resistance performance parameters are used as optimization targets. The multi-objective optimization algorithm is used to further select the optimal void-to-diameter ratio to achieve maximum lightweighting and optimal performance of the shafting system.

[0067] In some embodiments, in step S101, in order to meet the lightweight requirements of the ship shaft system and reduce the weight of the shaft system to improve the propulsion performance of the ship shaft system, the ship shaft system is hollow designed. The schematic diagram of the hollow shaft is shown in FIG. Figure 2 ,like Figure 2 As shown, is the shaft diameter, is the shaft diameter, is the outer diameter of the shaft after expansion, is the shaft length; determine the range of the air-to-diameter ratio, which is Based on the range of the void-diameter ratio, multiple ship shafting models considering the relationship between the shafting weight reduction mass and the void-diameter ratio are constructed. That is, within the range of the void-diameter ratio, multiple void-diameter ratios are selected according to the void-diameter ratio value density. That is, with the void-diameter ratio of 0.1 as an increment, multiple void-diameter ratios are selected within the range of the void-diameter ratio to construct 3D models of ship shafting with different void-diameter ratios. The 3D models of ship shafting with different void-diameter ratios are multiple ship shafting models considering the relationship between the shafting weight reduction mass and the void-diameter ratio. The larger the void-diameter ratio value density, the better. At this time, the amount of calculation is large, but there are more results, which is conducive to solving the optimal void-diameter ratio. The calculation formula for the relationship between the shafting weight reduction mass and the void-diameter ratio is:

[0068] ,

[0069] in, The weight reduction of the ship's shafting system, is the shaft material density, is the air-to-diameter ratio, is the shaft diameter, is the shaft diameter, is the shaft length, and the weight reduction of the shaft system is in a quadratic function relationship with the air-to-diameter ratio;

[0070] When the ship shaft system is hollow, the hollow structure will affect the strength of the shaft system. When the strength is affected too much, the outer diameter of the shaft needs to be revised. According to the requirements, when the hollow diameter ratio of the shaft system is When it is greater than 0.4, the shaft outer diameter is recalculated and corrected to ensure that the ship shafting has sufficient strength; the ship shafting model is strength checked to obtain the strength stress of the ship shafting, and the strength performance parameters are determined, wherein the strength stress of the ship shafting includes the axial stress of the shafting, the shear stress of the shafting, the bending stress of the shafting and the equivalent stress of the shafting, and the strength performance parameters include the axial stress parameter, the shear stress parameter, the bending stress parameter and the equivalent stress parameter; first, the air-diameter ratio threshold is preset, and the air-diameter ratio threshold is 0.4 to determine the air-diameter ratio of the ship shafting model. When the air-diameter ratio of the ship shafting model is greater than the air-diameter ratio threshold of 0.4, the outer diameter of the ship shafting is adjusted to obtain the corrected outer diameter of the ship shafting. , the corrected calculation formula for the outer diameter of the ship shafting is:

[0071] ,

[0072] ,

[0073] in, is the corrected outer diameter of the ship shafting, is the shaft diameter, The diameter of the shaft hole is changed by changing the outer diameter of the ship shaft system, and the size of the hole-to-diameter ratio is also changed;

[0074] Secondly, when the void-diameter ratio is greater than the void-diameter ratio threshold, the strength performance of the ship shafting model is checked based on the corrected outer diameter of the ship shafting to obtain the strength stress of the ship shafting. When the void-diameter ratio is less than or equal to the void-diameter ratio threshold, the strength performance of the ship shafting model is checked to obtain the strength stress of the ship shafting. Finally, the allowable stress of the shafting material is determined. The allowable stress is obtained by the yield limit of the shafting material and the safety factor of the shafting material. When the strength stress of the ship shafting is greater than the allowable stress of the shafting material, the void-diameter ratio is adjusted within the range of the void-diameter ratio, that is, the outer diameter of the ship shafting is corrected and checked. By expanding the outer diameter of the ship shafting, the strength stress of the ship shafting is made less than or equal to the allowable stress of the shafting material, ensuring that the strength stress of the ship shafting does not exceed the allowable stress range of the shafting material, thereby weakening the influence of the void-diameter ratio on the shafting strength until the strength performance requirements of the shafting are met. The calculation formula of the axial stress of the shafting is:

[0075] ,

[0076] ,

[0077] in, is the axial stress of the shaft system, is the propeller thrust, is the cross-sectional area;

[0078] The calculation formula of the shear stress of the shaft system is:

[0079] ,

[0080] in, is the bending stress of the shaft system, is the rotational moment on the shaft section, is the torsional section modulus;

[0081] The calculation formula of the bending stress of the shaft system is:

[0082] ,

[0083] in, is the bending stress of the shaft system, is the bending moment on the axial section, is the bending section modulus;

[0084] The calculation formula of the equivalent stress of the shaft system under multiple loads is:

[0085] ,

[0086] in, is the equivalent stress of the shafting. If the load remains unchanged, the larger the void-to-diameter ratio, the greater the axial stress, shear stress, bending stress and equivalent stress on the hollow shaft. That is, the stress of the solid shaft is less than that of the hollow shaft, resulting in the weakening of the hollow shaft strength due to the void-to-diameter ratio. The strength performance of ship shafting models with different void-to-diameter ratios is checked. The strength performance is a limiting condition for the reasonable application of ship shafting. The strength performance of the shafting is measured based on the equivalent stress. The larger the void-to-diameter ratio, the greater the strength stress on the shafting and the greater the weight reduction of the shafting.

[0087] In some embodiments, in step S102, the hollow design will also affect the dynamic characteristics of the shafting, and the dynamic characteristics include the vibration characteristics and impact resistance characteristics of the shafting. Therefore, it is necessary to check the vibration performance and impact resistance characteristics of the shafting, and perform dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting to determine the vibration performance parameters and impact resistance performance parameters. The vibration performance parameters include torsional vibration parameters, cyclotron vibration parameters and longitudinal vibration performance parameters, and the impact resistance performance parameters include impact resistance stress parameters. When the strength stress of the shafting meets the strength performance requirements, that is, the strength stress of the ship shafting is less than or equal to the allowable stress of the shafting material, the dynamic characteristics of the ship shafting model are verified. If the vibration and impact resistance performance of the shafting cannot meet the requirements of the specification, the outer diameter is corrected, that is, the hollow-diameter ratio is adjusted until the dynamic characteristic requirements of the specification are met.

[0088] The Von-Mises failure theory is used to evaluate the impact resistance of the shafting system. The effective stress of each mode and the modal stress synthesized by the modal synthesis method should be less than the allowable stress. The effective stress of each mode is obtained using the NRL (United States Naval Research Laboratory) method, and the calculation formula is:

[0089] ,

[0090] in, is the Von-Mises dynamic stress at node mode a, is the maximum value of Von-Mises dynamic stress of all modes of the node, is the effective dynamic stress of the node, the total stress is the sum of the absolute values ​​of the working stress and the effective impact dynamic stress, and the total stress corresponds to the maximum impact stress of the ship shafting. The calculation formula is:

[0091] ,

[0092] in, is the Von-Mises working stress of node mode a;

[0093] Determine the allowable stress of the ship shafting. When the maximum impact stress is greater than the allowable stress, adjust the outer diameter of the ship shafting and the void-to-diameter ratio within the void-to-diameter ratio range so that the maximum impact stress of the ship shafting is less than or equal to the allowable stress of the ship shafting. The smaller the maximum impact stress, the better the performance of the shafting.

[0094] The free torsional vibration of shafting models with different pitch-to-diameter ratios is calculated. By calculating the torsional vibration stress and the torsional angle, it is judged whether the allowable stress exceeds the safety range. First, the ROTX degree of freedom of the bearing is set to an unconstrained condition, and the other degrees of freedom of the bearing are set to displacement constraints. A uniformly distributed gravity load is applied to the shaft segment to obtain the first-order natural frequency of the shafting corresponding to each pitch-to-diameter ratio. Based on the solved first-order natural frequency, the corresponding load is applied to solve the torsional vibration stress of the stern shaft and propeller with different pitch-to-diameter ratios at the first-order natural frequency to obtain the maximum torsional vibration stress, which is less than the allowable torsional vibration stress; the torsional angle of each key part of the model with different pitch-to-diameter ratio is calculated, without considering the reverse torsional angle, and only the absolute value is taken. As the pitch-to-diameter ratio increases, the maximum torsional angle of the shafting first gradually decreases and then gradually increases. The outer diameter of the shafting before and after correction and the maximum torsional angle of the shafting remain unchanged, that is, the outer diameter correction has no effect on the torsional angle.

[0095] In some embodiments, in step S103, based on the strength performance parameters, vibration performance parameters and impact resistance performance parameters, a multi-objective optimization method is used to determine the optimal air-to-diameter ratio. By performing a strength performance check on the ship shafting model, it can be seen that the larger the air-to-diameter ratio, the smaller the shafting mass, but the greater the strength stress it is subjected to. By performing a dynamic characteristic check on the ship shafting model, it can be seen that the smaller the maximum torsion angle and the maximum impact stress, the better the performance of the shafting. The weight reduction mass of the ship shafting is determined by the strength performance parameters and the air-to-diameter ratio, and the weight reduction mass of the ship shafting is determined by the vibration performance parameters and the air-to-diameter ratio. The torsion angle of the ship's shafting is determined, and the impact stress of the shafting is determined by the impact resistance parameters and the air-to-diameter ratio. Considering the lightweight degree and optimal performance of the shafting, the optimization goals are to maximize weight reduction, minimize impact stress, and minimize torsion angle. The air-to-diameter ratio of the shafting is used as the independent variable, and the torsion angle and impact stress are used as dependent variables. A multi-objective optimization method is used to determine the optimal air-to-diameter ratio. First, a polynomial function is constructed based on the torsion angle and impact stress. There is no obvious difference in the torsion angle before and after the shafting correction, so only a torsion angle polynomial function needs to be fitted. The calculation formula of the polynomial function is:

[0096] ,

[0097] in, is the torsion angle polynomial fitting function, To correct the impact stress polynomial fitting function before the outer diameter, is the polynomial fitting function of impact stress after correcting the outer diameter, is the decision variable, i.e., the air-to-diameter ratio;

[0098] Based on the polynomial function, the NSGA-Ⅱ multi-objective genetic algorithm is used to obtain the Pareto optimal solution of the air-to-diameter ratio. The calculation formula is:

[0099] ,

[0100] in, is the target variable, the target space is Y, the decision space is X, the decision space X is the range of the air-to-air ratio 0.0-0.8, the set of all Pareto optimal solutions is the Pareto solution set, and the projection of all Pareto solution sets in the target space is the Pareto frontier, which is calculated as follows:

[0101] ,

[0102] in, is the Pareto frontier, is the Pareto solution set, with the air-to-diameter ratio as the decision variable , decision space is 0.0-0.8, torsion angle and impact stress are target vectors , the minimum to maximum value of the two is the target space , the boundary condition is that the impact stress does not exceed the allowable stress, and the optimal air-to-diameter ratio is determined by extracting the optimal decision variables from the Pareto front.

[0103] In some embodiments, the finite element analysis method is used to analyze the strength performance, vibration performance and impact resistance of the shaft system. The shaft system of a ship is used as the object. The material of the shaft system is 45 steel with a density of 7850 kg / m3 and a Young's modulus of Pa, Poisson's ratio is 0.31, yield strength is 355MPa, the shafting is designed to be hollow, and the hollow-diameter ratio is selected within the hollow-diameter ratio range. When the hollow-diameter ratio is 0.5-0.8, according to the specification requirements, the outer diameter of the shafting needs to be corrected to design 13 ship shafting models, calculate the inner diameter, outer diameter and mass of the shafting. The calculation results are shown in Table 1.

[0104] Table 1

[0105]

[0106] As shown in Table 1, the hollow shafting design can reduce the mass of the shafting. However, according to the strength requirements in the specification, its strength will be affected. Taking the shafting with a hollow-to-diameter ratio of 0.8 as an example, the strength calculation is performed using the finite element method. The friction coefficient at the connection between the thrust bearing and the intermediate bearing and the shafting is set to 0.02. The front and rear suspension stern bearings use compression-only support. The load borne by the shafting includes thrust and torque. The thrust increases from 500kN to 750kN at a constant speed and the torque increases from 500N to 1000kN in 10s. m increases at a constant speed to 750N m, the maximum equivalent stress on the shaft at the connection between the stern shaft and the intermediate shaft is 237.24 MPa, and the corresponding minimum safety factor is 1.50, which does not exceed the material yield limit of 355 MPa. When the air-to-diameter ratio is 0.8, the shaft load cross-sectional area is the smallest, the equivalent stress of the model is the largest, and the safety factor is the smallest, but it does not exceed the material limit and meets the strength requirements. That is, when the air-to-diameter ratio is 0.8, the shafting strength is safe.

[0107] An analysis of vibration performance shows that when the air-to-diameter ratio is 0.1, the natural frequency is the largest, at 9.886 Hz. Between air-to-diameter ratios of 0.5 and 0.7, the natural frequency of the shafting changes little before and after the outer diameter correction. When the air-to-diameter ratio is 0.8, the first-order natural frequency of the shafting increases. Based on the solved first-order natural frequency, 20 nodes within its 1 / 6 frequency band are selected and the corresponding load is applied. The torsional vibration stress of the stern shaft and propeller at the first-order natural frequency of different air-to-diameter ratios is calculated. The maximum torsional vibration stress of the models with different air-to-diameter ratios varies. The size of the air-to-diameter ratio affects the vibration response and stress distribution of the shafting.

[0108] The maximum torsional vibration stresses in the stern shaft and propeller parts both appear at the first-order natural frequency and are concentrated near the front and rear stern bearings. Among all the air-to-diameter ratios, when the air-to-diameter ratio is 0.6, the maximum torsional vibration stress in the propeller part of the shaft system is 1.38 MPa, which is less than the allowable torsional vibration stress. Compared with before the correction, the torsional vibration stress of the shaft system after the correction is smaller. With the increase of the air-to-diameter ratio, the maximum torsional angle of the shaft system first gradually decreases, reaching the minimum at the air-to-diameter ratio of 0.6, with a torsional angle of 1.002×10-2°, and then gradually increases. Between the air-to-diameter ratio of 0.0-0.4, the maximum torsional angle occurs in the intermediate shaft, and when the air-to-diameter ratio is greater than 0.4, it occurs in the stern shaft. The maximum torsional angle of the shaft system remains unchanged before and after the correction, that is, whether the outer diameter is corrected or not has no effect on the torsional angle.

[0109] The dynamic design analysis method is used to analyze the impact resistance of the shafting system. The result is obtained by superimposing the response peaks generated by each mode, which is larger than the actual situation. The impact load on the shafting system is expressed in the form of an impact spectrum. To ensure the accuracy of the results and the integrity of the modal information, sufficient vibration modes must be analyzed to ensure that the total modal mass is not less than 80% of the total mass of the system. The acceleration of the shafting shock spectrum is obtained by the effective modal mass obtained by modal analysis. The calculation formula is:

[0110] ,

[0111] ,

[0112] in, is the acceleration, is the acceleration, For the effective modal mass, after determining the impact coefficients in the vertical, horizontal, and longitudinal directions, substitute the effective modal mass greater than 1% in the first 100 modes into the above formula to calculate the standard acceleration and table acceleration , using impact acceleration as input condition, the equivalent stress is obtained. The maximum equivalent stress of the solid shaft is located in the propeller, with a stress of 339.04Mpa, which does not exceed the yield strength of the material, proving that the shaft has good impact resistance. Under the same impact conditions, the maximum impact stress of the shaft system is concentrated in the intermediate shaft and propeller, and the maximum impact stress of the stern shaft and thrust shaft is relatively small. When the air-to-diameter ratio is 0.7, the maximum impact stress of the shaft system occurs in the intermediate shaft, with a stress value of 376.78Mpa, which is 40.36Mpa different from the impact stress of the shaft system with a corrected air-to-diameter ratio of 0.7, and exceeds the yield limit of the shaft system; when the air-to-diameter ratio is 0.5, the maximum impact stress of the shaft system is the smallest, with a stress of 317.53Mpa, which does not exceed the yield limit of the shaft system.

[0113] Compared with the impact stress of the solid shaft, the maximum impact stress of the hollow shaft with a void-to-diameter ratio of 0.4-0.6 is smaller than the corresponding stress of the solid shaft. The stress of the corrected shaft system is smaller than the corresponding stress of the solid shaft within some void-to-diameter ratio range, indicating that the impact resistance of the hollow shaft is better than that of the solid shaft within a specific range.

[0114] The Pareto optimal solution of the air-to-diameter ratio is determined by the NSGA-Ⅱ multi-objective genetic algorithm. The optimal decision variables extracted by the Pareto frontier determine the optimal air-to-diameter ratio to be 0.649 and 0.788, corresponding to the objective function value. That is, the torsion angles are ° and °, corrected front impact stress 343.96Mpa, corrected impact stress It is 322.58Mpa. Compared with the solid shaft, the hollow shaft corresponding to the optimal air-to-diameter ratio before and after correction is reduced by about 28t and 40t respectively.

[0115] In order to better implement the method for selecting the ship shafting space-diameter ratio in the embodiment of the present invention, based on the method for selecting the ship shafting space-diameter ratio, correspondingly, Figure 3 As shown, an embodiment of the present invention further provides a device for selecting a ship shafting space-to-diameter ratio. The device 300 for selecting a ship shafting space-to-diameter ratio includes:

[0116] Strength performance verification module 301 is used to obtain multiple ship shafting models based on hollow design that consider the relationship between shafting weight reduction and hollow-to-diameter ratio, perform strength performance verification on the ship shafting models, obtain strength stress of the ship shafting, and determine strength performance parameters;

[0117] A dynamic characteristic verification module 302 is used to perform dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting to determine vibration performance parameters and shock resistance performance parameters;

[0118] The optimal air-to-diameter ratio determination module 303 is used to determine the optimal air-to-diameter ratio using a multi-objective optimization method based on strength performance parameters, vibration performance parameters, and impact resistance performance parameters.

[0119] like Figure 4 As shown, based on the method for selecting the space-to-diameter ratio of a ship shaft system, the present invention also provides an electronic device 400. The electronic device 400 can be a computing device such as a mobile terminal, a desktop computer, a notebook, a PDA, or a server. The electronic device 400 includes a processor 401, a memory 402, and a display 403. Figure 4 Only some of the components of the electronic device 400 are shown, but it should be understood that implementation of all of the shown components is not required, and more or fewer components may be implemented instead.

[0120] In some embodiments, memory 402 may be an internal storage unit of electronic device 400, such as a hard drive or memory of electronic device 400. In other embodiments, memory 402 may also be an external storage device of electronic device 400, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card, etc. Furthermore, memory 402 may include both an internal storage unit of electronic device 400 and an external storage device. Memory 402 is used to store application software installed on electronic device 400 and various data, such as program code installed on electronic device 400. Memory 402 may also be used to temporarily store data that has been output or is about to be output. In one embodiment, memory 402 stores a program for selecting a ship shafting pitch-to-diameter ratio. This program can be executed by processor 401 to implement the ship shafting pitch-to-diameter ratio selection method according to various embodiments of the present invention.

[0121] In some embodiments, the processor 401 may be a central processing unit (CPU), a microprocessor, or other data processing chip, configured to execute program codes or process data stored in the memory 402, such as a method for selecting a ship shafting pitch-to-diameter ratio.

[0122] In some embodiments, display 403 can be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. Display 403 is used to display identification information for the ship shafting pitch-to-diameter ratio selection program and to display a visual user interface. Components 401-403 of electronic device 400 communicate with each other via a system bus.

[0123] In some embodiments, when the processor 401 executes the ship shafting pitch-to-diameter ratio selection program in the memory 402, the various steps in the ship shafting pitch-to-diameter ratio selection method described in the above embodiments are implemented. Since the ship shafting pitch-to-diameter ratio selection method has been described in detail above, it will not be repeated here.

[0124] Accordingly, an embodiment of the present application also provides a computer-readable storage medium, which is used to store computer-readable programs or instructions. When the program or instructions are executed by a processor, it can implement the steps or functions of the ship shafting air-to-diameter ratio selection method provided in the above-mentioned method embodiments.

[0125] In summary, the method, device, equipment and medium for selecting the void-to-diameter ratio of a ship shafting system provided by the present invention obtain multiple ship shafting models based on hollow design that consider the relationship between the shafting weight reduction mass and the void-to-diameter ratio, perform strength performance verification on the ship shafting model, obtain the strength stress of the ship shafting system, and determine the strength performance parameters; perform dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting system, and determine the vibration performance parameters and impact resistance performance parameters; based on the strength performance parameters, vibration performance parameters and impact resistance performance parameters, a multi-objective optimization method is used to determine the optimal void-to-diameter ratio, thereby achieving the maximum lightweight degree and optimal performance of the shafting system.

[0126] Those skilled in the art will appreciate that all or part of the process steps of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0127] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for selecting the space-to-diameter ratio of a ship shaft system, characterized in that: include: Acquire multiple ship shafting models based on hollow design that consider the relationship between shafting weight reduction and hollow-diameter ratio, perform strength performance verification on the ship shafting models, obtain strength stress of the ship shafting, and determine strength performance parameters, wherein the strength performance verification on the ship shafting models to obtain strength stress of the ship shafting includes: Presetting a space-to-diameter ratio threshold to determine the space-to-diameter ratio of the ship shafting model; When the space-to-diameter ratio is greater than the space-to-diameter ratio threshold, the outer diameter of the ship shafting is adjusted to obtain a corrected outer diameter of the ship shafting. The calculation formula for the corrected outer diameter of the ship shafting is: ， ， in, is the corrected outer diameter of the ship shafting, is the shaft diameter, is the shaft diameter, is the space-to-diameter ratio; Performing strength performance verification on the ship shafting model based on the corrected outer diameter of the ship shafting to obtain strength stress of the ship shafting; When the space-to-diameter ratio is less than or equal to the space-to-diameter ratio threshold, the ship shafting model is strength checked to obtain the strength stress of the ship shafting, wherein the strength stress of the ship shafting includes the axial stress of the shafting, the shear stress of the shafting, the bending stress of the shafting, and the equivalent stress of the shafting. The calculation formula of the axial stress of the shafting is: ， in, is the axial stress of the shaft system, is the propeller thrust, is the cross-sectional area; The calculation formula of the shear stress of the shaft system is: ， in, is the shear stress of the shaft system, is the rotational moment on the shaft section, is the torsional section modulus; The calculation formula of the bending stress of the shaft system is: ， in, is the bending stress of the shaft system, is the bending moment on the axial section, is the bending section modulus; The calculation formula for the equivalent stress of the shaft system is: ， in, is the equivalent stress of the shaft system; determining an allowable stress of a shafting material, and when the strength stress of the ship shafting is greater than the allowable stress of the shafting material, adjusting the space-to-diameter ratio within the space-to-diameter ratio range so that the strength stress of the ship shafting is less than or equal to the allowable stress of the shafting material; Performing a dynamic characteristic check on the ship shafting model based on the strength stress of the ship shafting to determine vibration performance parameters and shock resistance performance parameters; Based on the strength performance parameters, vibration performance parameters and impact resistance performance parameters, a multi-objective optimization method is used to determine the optimal air-to-diameter ratio.

2. The method for selecting the space-to-diameter ratio of a ship shaft system according to claim 1, characterized in that: The method of obtaining multiple ship shafting models based on hollow design and taking into account the relationship between shafting weight reduction and hollow-to-diameter ratio includes: Determine the range of air-to-diameter ratio; Based on the range of the void-to-diameter ratio, multiple ship shafting models are constructed that consider the relationship between the shafting weight reduction mass and the void-to-diameter ratio.

3. The method for selecting the space-to-diameter ratio of a ship shaft system according to claim 2, characterized in that: The calculation formula for the relationship between the shaft system weight reduction mass and the air-to-diameter ratio is: ， in, The weight reduction of the ship's shafting system, is the shaft material density, is the air-to-diameter ratio, is the shaft diameter, is the axis length.

4. The method for selecting the space-to-diameter ratio of a ship shaft system according to claim 2, characterized in that: The dynamic characteristic verification of the ship shafting model based on the strength stress of the ship shafting to obtain vibration performance parameters and shock resistance performance parameters includes: When the strength stress of the ship shafting is less than or equal to the allowable stress of the shafting material, a dynamic characteristic check is performed on the ship shafting model to determine vibration performance parameters and shock resistance performance parameters, wherein the dynamic characteristics include vibration characteristics and shock resistance characteristics of the shafting, the vibration performance parameters include torsional vibration parameters, whirling vibration parameters, and longitudinal vibration performance parameters, and the shock resistance performance parameters include shock resistance stress parameters; The allowable stress of the ship shafting and the maximum impact stress of the ship shafting are determined. When the maximum impact stress is greater than the allowable stress, the space-to-diameter ratio is adjusted within the space-to-diameter ratio range so that the maximum impact stress of the ship shafting is less than or equal to the allowable stress of the ship shafting.

5. A device for selecting the space-to-diameter ratio of a ship shaft system, characterized in that: include: The strength performance verification module is used to obtain multiple ship shafting models based on hollow design that consider the relationship between shafting weight reduction and hollow-diameter ratio, perform strength performance verification on the ship shafting models, obtain the strength stress of the ship shafting, and determine the strength performance parameters. The strength performance verification of the ship shafting models to obtain the strength stress of the ship shafting includes: Presetting a space-to-diameter ratio threshold to determine the space-to-diameter ratio of the ship shafting model; When the space-to-diameter ratio is greater than the space-to-diameter ratio threshold, the outer diameter of the ship shafting is adjusted to obtain a corrected outer diameter of the ship shafting. The calculation formula for the corrected outer diameter of the ship shafting is: ， ， in, is the corrected outer diameter of the ship shafting, is the shaft diameter, is the shaft diameter, is the space-to-diameter ratio; Performing strength performance verification on the ship shafting model based on the corrected outer diameter of the ship shafting to obtain strength stress of the ship shafting; When the space-to-diameter ratio is less than or equal to the space-to-diameter ratio threshold, the ship shafting model is strength checked to obtain the strength stress of the ship shafting, wherein the strength stress of the ship shafting includes the axial stress of the shafting, the shear stress of the shafting, the bending stress of the shafting, and the equivalent stress of the shafting. The calculation formula of the axial stress of the shafting is: ， in, is the axial stress of the shaft system, is the propeller thrust, is the cross-sectional area; The calculation formula of the shear stress of the shaft system is: ， in, is the shear stress of the shaft system, is the rotational moment on the shaft section, is the torsional section modulus; The calculation formula of the bending stress of the shaft system is: ， in, is the bending stress of the shaft system, is the bending moment on the axial section, is the bending section modulus; The calculation formula for the equivalent stress of the shaft system is: ， in, is the equivalent stress of the shaft system; determining an allowable stress of a shafting material, and when the strength stress of the ship shafting is greater than the allowable stress of the shafting material, adjusting the space-to-diameter ratio within the space-to-diameter ratio range so that the strength stress of the ship shafting is less than or equal to the allowable stress of the shafting material; A dynamic characteristic verification module is used to perform dynamic characteristic verification on the ship shafting model based on the strength stress of the ship shafting to determine vibration performance parameters and shock resistance performance parameters; The optimal air-to-diameter ratio determination module is used to determine the optimal air-to-diameter ratio using a multi-objective optimization method based on the strength performance parameters, vibration performance parameters and impact resistance performance parameters.

6. An electronic device, characterized in that: including memory and processor; The memory stores a computer-readable program executable by the processor; When the processor executes the computer-readable program, the steps of the method for selecting the space-to-diameter ratio of a ship shafting system as described in any one of claims 1 to 4 are implemented.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the method for selecting the space-to-diameter ratio of a ship shafting as described in any one of claims 1 to 4.

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