Method for checking connection stability of ship propeller base

Abstract

The invention discloses a ship thruster base connection stability checking method, and relates to the technical field of component connection checking, and the method comprises the steps: calculating the longitudinal thrust caused by the longitudinal impact acceleration according to the longitudinal acceleration and the total weight of a thruster; according to the friction coefficient between the nut and the connecting deck surface, the number of the bolts at the base connecting position and the pre-tightening force of the connecting bolts, the friction force generated by the pre-tightening force is calculated; longitudinal thrust and the friction force are judged, and when the longitudinal thrust is smaller than the friction force, the influence of the longitudinal impact acceleration cannot cause equipment movement; calculating a first shear stress generated by the longitudinal impact acceleration; and judging the first shear stress and the allowable shear stress of the bolt, and if the first shear stress is smaller than the allowable shear stress of the bolt, determining that the bolt meets the longitudinal impact acceleration requirement. The invention provides a base connection checking method which is closer to the operation condition of a real ship, safer and more reliable, and more sufficient in demonstration.

Description

Technical Field

[0001] The invention relates to the technical field of component connection verification, and in particular to a method for verifying the connection stability of a ship propeller base. Background Art

[0002] As human beings continue to explore the ocean, especially the polar research, the requirements for the economy and reliability of thrusters are getting higher and higher. This requires the designers of the supplier to start from the source and consider the design method comprehensively to ensure both economy and reliability.

[0003] Usually, the strength check of the fasteners between the base and the hull takes into account the overturning moment caused by the axial thrust of the propeller and the overturning moment caused by the ice load. After the overturning moment acts, the bolts on one side of the symmetry axis are further tightened, and the axial tension of the bolts is further increased. The bolts on the other side of the symmetry axis are loosened, and the preload of the bolts is also reduced. Since the force on the bolts is proportional to the distance from the symmetry axis, the bolts farthest from the symmetry axis are subjected to the greatest force. The usual verification method is to check that the actual tensile stress of the farthest bolt is less than the allowable tensile stress of the bolt. It is considered that the strength of the fasteners between the base and the hull can withstand the overturning moment caused by the maximum propeller ice load.

[0004] However, this type of verification has limitations. It does not fully consider the actual operating conditions of the ship, does not fully demonstrate the factors that affect reliability, and has the problem of insufficient verification. Summary of the invention

[0005] The present invention provides a method for checking the stability of a ship propeller base connection, which is closer to the actual ship operating conditions, safer and more reliable, and is a more fully demonstrated base connection checking method.

[0006] According to one aspect of the present disclosure, a method for checking the connection stability of a ship thruster base is provided, the method comprising: Calculate the longitudinal thrust caused by the longitudinal impact acceleration based on the longitudinal acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the longitudinal thrust and the friction force. When the longitudinal thrust is smaller than the friction force, the influence of the longitudinal impact acceleration will not cause the device to move. Calculate the first shear stress generated by the longitudinal impact acceleration; Determine the magnitude of the first shear stress and the allowable shear stress of the bolt, if the first shear stress is less than the allowable shear stress of the bolt, then the bolt meets the longitudinal impact acceleration requirement; Among them, the longitudinal acceleration is positive when it points from the stern to the bow.

[0007] In a possible implementation, the method further includes: Calculate the lateral thrust caused by the lateral impact acceleration based on the lateral impact acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the lateral thrust and the friction force. When the lateral thrust is smaller than the friction force, the influence of the lateral impact acceleration will not cause the device to move. Calculate the second shear stress generated by the lateral impact acceleration; The magnitude of the second shear stress and the allowable shear stress of the bolt is determined. If the second shear stress is less than the allowable shear stress of the bolt, the bolt meets the lateral impact acceleration requirement.

[0008] In a possible implementation, the method further includes: The vertical thrust caused by the vertical impact acceleration is calculated based on the vertical impact acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the vertical thrust and the friction force. When the vertical thrust is smaller than the friction force, the vertical impact acceleration will not cause the device to move. Calculate the tensile stress generated by vertical impact acceleration; Determine the magnitude of the tensile stress and the allowable shear stress of the bolt. If the tensile stress is less than the allowable shear stress of the bolt, the bolt meets the vertical impact acceleration requirement. Among them, the vertical acceleration is positive from top to bottom.

[0009] In one possible implementation, if the effects of longitudinal impact acceleration, vertical impact acceleration and lateral acceleration do not cause the equipment to move, and the bolts meet the vertical impact acceleration requirements, meet the lateral impact acceleration requirements and meet the longitudinal acceleration requirements, then the calculation and verification of the base connection fasteners of the thruster pass.

[0010] In a possible implementation, the calculating the longitudinal thrust caused by the longitudinal impact acceleration according to the longitudinal acceleration and the total weight of the thruster includes: The longitudinal thrust is calculated by formula (1): (1) in, is the longitudinal thrust, M is the total weight of the propeller, is the longitudinal impact acceleration.

[0011] In a possible implementation, the friction force generated by the preload force is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection, and the preload force of the connecting bolts, including: The friction force generated by the preload is calculated by formula (2): (2) in, is the friction force, μ is the friction coefficient between the nut and the connecting deck surface, n is the number of bolts at the base connection, Preload the connecting bolts.

[0012] In a possible implementation, calculating the first shear stress generated by the longitudinal impact acceleration includes: The first shear stress is calculated by formula (3): (3) in, is the first shear stress, is the longitudinal thrust, n is the number of bolts at the base connection, and d1 is the root diameter of the bolt thread.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The strength check of the fasteners between the base and the hull in the verification method of the embodiment of the present disclosure takes into account the overturning moment caused by the axial thrust of the propeller and the overturning moment caused by the ice load. The strength check of the fasteners between the base and the hull takes into account the acceleration impact force generated by the propeller's own weight under the acceleration of the ship's fastening load.

[0014] By adding the verification of the ship's fastening load acceleration, the ship's design verification is closer to the actual ship's working conditions, and the verification results are more comprehensive and reliable. By adding the base verification of the fastening load acceleration, the appropriate fastener specifications and quantity are selected under the premise of fully considering the various working conditions faced by the fasteners, which can not only ensure the safety factor after the equipment is put into operation, but also make the initial investment most economical and reasonable, and make the demonstration sufficient and powerful. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flowchart of a method for verifying the connection stability of a ship propeller base according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0016] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0017] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0018] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present disclosure.

[0019] According to one aspect of the present disclosure, a method for checking the connection stability of a ship thruster base is provided, the method comprising: S01, calculate the longitudinal thrust caused by the longitudinal impact acceleration based on the longitudinal acceleration and the total weight of the thruster; S02, calculate the friction force generated by the preload force based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload force of the connecting bolts; S03, determining the magnitude of the longitudinal thrust and the friction force, when the longitudinal thrust is smaller than the friction force, the influence of the longitudinal impact acceleration will not cause the device to move; S04, calculating the first shear stress generated by the longitudinal impact acceleration; S05, determining the magnitude of the first shear stress and the allowable shear stress of the bolt. If the first shear stress is less than the allowable shear stress of the bolt, the bolt meets the longitudinal impact acceleration requirement. Among them, the longitudinal acceleration is positive when it points from the stern to the bow.

[0020] In a possible implementation, the calculating the longitudinal thrust caused by the longitudinal impact acceleration according to the longitudinal acceleration and the total weight of the thruster includes: The longitudinal thrust is calculated by formula (1): (1) in, is the longitudinal thrust, M is the total weight of the propeller, is the longitudinal impact acceleration.

[0021] In a possible implementation, the friction force generated by the preload force is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection, and the preload force of the connecting bolts, including: The friction force generated by the preload is calculated by formula (2): (2) in, is the friction force, μ is the friction coefficient between the nut and the connecting deck surface, n is the number of bolts at the base connection, Preload the connecting bolts.

[0022] In a possible implementation, calculating the first shear stress generated by the longitudinal impact acceleration includes: The first shear stress is calculated by formula (3): (3) in, is the first shear stress, is the longitudinal thrust, n is the number of bolts at the base connection, and d1 is the root diameter of the bolt thread.

[0023] In a possible implementation, the method further includes: Calculate the lateral thrust caused by the lateral impact acceleration based on the lateral impact acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the lateral thrust and the friction force. When the lateral thrust is smaller than the friction force, the influence of the lateral impact acceleration will not cause the device to move. The second shear stress generated by the lateral impact acceleration is calculated by formula (4), including: (4) in, is the second shear stress, is the longitudinal thrust, n is the number of bolts at the base connection, and d1 is the root diameter of the bolt thread; The magnitude of the second shear stress and the allowable shear stress of the bolt is determined. If the second shear stress is less than the allowable shear stress of the bolt, the bolt meets the lateral impact acceleration requirement.

[0024] In a possible implementation, the method further includes: The vertical thrust caused by the vertical impact acceleration is calculated based on the vertical impact acceleration and the total weight of the thruster; Determine the magnitude of the vertical thrust and the preload of the connection bolts. When the vertical thrust is smaller than the preload of the connection bolts, the vertical impact acceleration will not cause the equipment to move. The tensile stress generated by the vertical impact acceleration is calculated by formula (5), including: (5) in, is the tensile stress, is the longitudinal thrust, n is the number of bolts at the base connection, and d1 is the root diameter of the bolt thread; Determine the magnitude of the tensile stress and the allowable shear stress of the bolt. If the tensile stress is less than the allowable tensile stress of the bolt, the bolt meets the vertical impact acceleration requirement. Among them, the vertical acceleration is positive from top to bottom.

[0025] In one possible implementation, if the effects of longitudinal impact acceleration, vertical impact acceleration and lateral acceleration do not cause the equipment to move, and the bolts meet the vertical impact acceleration requirements, meet the lateral impact acceleration requirements and meet the longitudinal acceleration requirements, then the calculation and verification of the base connection fasteners of the thruster pass.

[0026] The propeller generates axial force through the rotation of the propeller at the shaft end. The axial force is transmitted to the hull through the propeller, driving the ship forward. The base of the propeller is connected to the hull, and the middle is connected by fasteners. The reliability of the propeller base and the hull fasteners directly affects the performance of the entire propeller. Once the fasteners fail, the entire propeller will lose its function and the ship will lose power. Therefore, the design verification of the fasteners here becomes particularly important. The bow collision and icebreaking of the ship is one of the design conditions for verifying the overall strength of the ship. During the collision, longitudinal impact acceleration, vertical impact acceleration, and lateral impact acceleration will be generated. Under the above accelerations, the propeller has a large weight, and the acceleration impact force generated on the connecting fasteners is also large, which directly affects the reliability of the fasteners connecting the base of the propeller and the hull.

[0027] The verification of the thruster base and hull fasteners first considers the influence of the torque generated by the thruster thrust at the base on the fasteners under normal operating conditions, and then examines the influence of the overturning torque generated by the maximum ice load at the base on the fasteners. Finally, combined with the actual operating conditions of the ship, the influence of the longitudinal impact acceleration, vertical impact acceleration, and lateral impact acceleration generated by the ship during the collision on the base and ship fasteners is considered.

[0028] The values ​​of longitudinal impact acceleration, vertical impact acceleration, and transverse impact acceleration depend on the ship's overall dimensions and design parameters. The design input of each ship is different, and the resulting fastening load acceleration is also different. By taking into account the fastening load acceleration of the ship, the verification of fasteners is more complete and more in line with the design concept of the actual ship.

[0029] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for checking the connection stability of a ship propeller base, characterized in that: The method comprises: Calculate the longitudinal thrust caused by the longitudinal impact acceleration based on the longitudinal acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the longitudinal thrust and the friction force. When the longitudinal thrust is smaller than the friction force, the influence of the longitudinal impact acceleration will not cause the device to move. Calculate the first shear stress generated by the longitudinal impact acceleration; Determine the magnitude of the first shear stress and the allowable shear stress of the bolt, if the first shear stress is less than the allowable shear stress of the bolt, then the bolt meets the longitudinal impact acceleration requirement; Among them, the longitudinal acceleration is positive when it points from the stern to the bow.

2. A method for checking the connection stability of a ship propeller base according to claim 1, characterized in that: The method further comprises: Calculate the lateral thrust caused by the lateral impact acceleration based on the lateral impact acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the lateral thrust and the friction force. When the lateral thrust is smaller than the friction force, the influence of the lateral impact acceleration will not cause the device to move. Calculate the second shear stress generated by the lateral impact acceleration; The magnitude of the second shear stress and the allowable shear stress of the bolt is determined. If the second shear stress is less than the allowable shear stress of the bolt, the bolt meets the lateral impact acceleration requirement.

3. A method for checking the connection stability of a ship propeller base according to claim 2, characterized in that: The method further comprises: The vertical thrust caused by the vertical impact acceleration is calculated based on the vertical impact acceleration and the total weight of the thruster; The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts; Determine the magnitude of the vertical thrust and the friction force. When the vertical thrust is smaller than the friction force, the vertical impact acceleration will not cause the device to move. Calculate the tensile stress generated by vertical impact acceleration; Determine the magnitude of the tensile stress and the allowable shear stress of the bolt. If the tensile stress is less than the allowable tensile stress of the bolt, the bolt meets the vertical impact acceleration requirement. Among them, the vertical acceleration is positive from top to bottom.

4. A method for checking the connection stability of a ship propeller base according to claim 3, characterized in that: If the effects of longitudinal impact acceleration, vertical impact acceleration and lateral acceleration do not cause the equipment to move, and the bolts meet the vertical impact acceleration requirements, meet the lateral impact acceleration requirements and meet the longitudinal acceleration requirements, then the calculation and verification of the base connection fasteners of the thruster are passed.

5. A method for checking the connection stability of a ship propeller base according to claim 1, characterized in that: The calculating the longitudinal thrust caused by the longitudinal impact acceleration according to the longitudinal acceleration and the total weight of the propeller comprises: The longitudinal thrust is calculated by formula (1): (1) in, is the longitudinal thrust, M is the total weight of the propeller, is the longitudinal impact acceleration.

6. A method for checking the connection stability of a ship propeller base according to claim 1, characterized in that: The friction force generated by the preload is calculated based on the friction coefficient between the nut and the connecting deck surface, the number of bolts at the base connection and the preload of the connecting bolts, including: The friction force generated by the preload is calculated by formula (2): (2) in, is the friction force, μ is the friction coefficient between the nut and the connecting deck surface, n is the number of bolts at the base connection, Preload the connecting bolts.

7. A method for checking the connection stability of a ship propeller base according to claim 1, characterized in that: Calculate the first shear stress generated by the longitudinal impact acceleration, including: The first shear stress is calculated by formula (3): （3） in, is the first shear stress, is the longitudinal thrust, n is the number of bolts at the base connection, and d1 is the root diameter of the bolt thread.

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