CN-120951851-B - Method for designing strength of deep-sea light annular rib cylindrical shell

Abstract

The invention provides a deep sea light annular rib cylindrical shell strength design method which specifically comprises the following steps of (1) establishing a geometric model of an annular rib cylindrical shell when the annular rib cylindrical shell bears hydrostatic pressure outside, (2) carrying out stress analysis on the geometric model to obtain a cylindrical shell deflection line expression containing unknown parameters, (3) confirming boundary conditions of the geometric model and solving the unknown parameters in the flexible cylindrical shell deflection line expression according to the boundary conditions, substituting the unknown parameters into the cylindrical shell deflection line expression to obtain a complete flexible line analysis expression, calculating stress values of different positions of the shell based on the flexible line analysis expression, and carrying out structural strength design according to the geometric parameters of the annular rib cylindrical shell structure. The invention has reasonable conception, and the elastic boundary condition is changed at the rib, so that the new boundary condition can better describe the constraint condition of the reinforced cylindrical shell at the joint of the rib and the shell according to the material characteristics, can be used for annular rib cylindrical shell structures of different materials, and is more universal and accurate.

Inventors

• TANG MIN
• ZHU SHIYANG
• Chen cen
• ZHANG JUNFENG
• WU XIAOLEI
• WANG WENQUN
• XIONG JINGYI

Assignees

• 中国船舶集团有限公司第七一九研究所

Dates

Publication Date

20260508

Application Date

20250724

Claims (2)

1. 1. The method for designing the strength of the deep-sea light annular rib cylindrical shell is characterized by comprising the following steps of: (1) Establishing a geometric model of the annular rib cylindrical shell when the outside bears hydrostatic pressure; (2) Carrying out stress analysis on the geometric model to obtain a cylindrical shell deflection line expression containing unknown parameters, wherein the specific process is as follows: The geometric model is subjected to stress analysis, a closed thin-wall cylindrical shell subjected to hydrostatic pressure is considered, and under the combined action of the hydrostatic pressure and the longitudinal pressure, the differential equation of the closed thin-wall cylindrical shell is as follows: ; In the above formula (1), w is the deflection of the cylindrical shell, p is the hydrostatic pressure born by the outer part of the cylindrical shell, E is Young's modulus, μPoisson's ratio, t is the thickness of the shell, R is the radius of the cylindrical shell, and the flexural rigidity of the cylindrical shell ; Solving the differential equation, and taking symmetry of the structure into consideration to obtain a cylindrical shell flexible line expression as follows: (2); In the above formula (2), w is the deflection of the cylindrical shell, p is the hydrostatic pressure born by the outer part of the cylindrical shell, E is Young's modulus, mu is Poisson's ratio, t is the thickness of the shell, R is the radius of the cylindrical shell, C 1 、C 4 is an unknown parameter, and the unknown parameter is obtained by solving the boundary condition; ; ; ; (3) Confirming the boundary condition of a geometric model, solving the unknown parameters in the flexible line expression of the flexible cylindrical shell according to the boundary condition, substituting the unknown parameters into the flexible line expression of the cylindrical shell, thus obtaining a complete flexible line analysis expression, calculating stress values of different positions of the shell based on the flexible line analysis expression, and carrying out structural strength design according to the geometric parameters of the annular rib cylindrical shell structure, wherein the specific process is as follows: Considering that the rigidity of the ribs is the same, the rib spacing is the same, a section of cylindrical shell between any two adjacent ribs is taken as a study object, the distance between two adjacent circumferential ribs is l, the rigid clamped boundary in the traditional theory is changed into the elastic boundary of a torsion spring type at the two ribs, the middle of the two ribs is taken as the origin of coordinates, and the boundary condition of a flexible line equation (2) at the two ribs is as follows: (6); in the above formula (6), w is the deflection of the cylindrical shell, p is the hydrostatic pressure borne by the outer part of the cylindrical shell, E is Young's modulus, μPoisson's ratio, t is the thickness of the shell, R is the radius of the cylindrical shell, Is torsional rigidity at the elastic boundary, and solving coefficients C 1 and C 4 in the flexible line expression (3) in conjunction with the boundary condition in expression (6) is: (7); in the above-mentioned (7), The expression of (2) is: (8); (9); (10); The calculation formula of the longitudinal stress of the cylindrical shell is as follows: (11); The calculation formula of the lateral stress of the cylindrical shell is as follows: (12); rib stress was calculated as: (13); substituting the formulas (2) and (7) - (10) into the formulas (11) - (13) to obtain the stress value of any position on the cylindrical shell.
2. 2. The method for designing the strength of a cylindrical shell of a deep sea light annular rib according to claim 1, wherein the geometric model in the step (1) comprises a cylindrical shell and annular ribs arranged on the cylindrical shell, and the annular ribs are assumed to have the same rigidity and are arranged at equal intervals.

Description

Method for designing strength of deep-sea light annular rib cylindrical shell Technical Field The invention relates to the technical field of deep sea equipment manufacturing, in particular to a method for designing the strength of a deep sea light annular rib cylindrical shell. Background The annular rib cylindrical shell structure is widely used for deep sea large-scale equipment, the main body material of the traditional annular rib cylindrical shell is high-strength steel generally, but along with the development of deep sea engineering, higher requirements are put forward on the submergence depth of the deep sea pressure-resistant structure, the high-strength steel can not meet the engineering requirements at the present stage, and other light materials such as titanium alloy with higher specific strength are needed. Compared with the traditional high-strength steel, the light materials such as titanium alloy and the like have the advantages of more excellent comprehensive properties, such as high specific strength, strong corrosion resistance, impact resistance, good formability, low magnetism, high sound transmittance and the like, and can better meet the requirements of safety and reliability of the pressure-resistant structure in service in deep sea. The strength design method of the traditional annular rib cylindrical shell is based on the material characteristics of high-strength steel, and in the calculation process, some simplification methods and assumptions are provided, and the material properties of other metal materials and the high-strength steel have large differences, so that the design method of the traditional theory is not applicable any more. Disclosure of Invention Aiming at the technical problems in the background technology, the invention provides a deep sea light annular rib cylindrical shell strength design method which is reasonable in conception, an elastic boundary condition is changed at a rib, the new boundary condition can better describe the constraint condition of the reinforced cylindrical shell at the joint of the rib and the shell according to the material characteristics, and the method can be used for annular rib cylindrical shell structures of different materials, and is more universal and accurate. In order to solve the technical problems, the invention provides a method for designing the strength of a deep-sea light annular rib cylindrical shell, which specifically comprises the following steps: (1) Establishing a geometric model of the annular rib cylindrical shell when the outside bears hydrostatic pressure; (2) Carrying out stress analysis on the geometric model to obtain a cylindrical shell deflection line expression containing unknown parameters; (3) And confirming the boundary condition of the geometric model, solving the unknown parameters in the flexible line expression of the flexible cylindrical shell according to the boundary condition, substituting the unknown parameters into the flexible line expression of the cylindrical shell, thus obtaining a complete flexible line analysis expression, calculating stress values at different positions of the shell based on the flexible line analysis expression, and carrying out structural strength design according to the geometric parameters of the annular rib cylindrical shell structure. The geometric model in the step (1) comprises a cylindrical shell and circumferential ribs arranged on the cylindrical shell, and the circumferential ribs are assumed to have the same rigidity and are arranged at equal intervals. The method for designing the strength of the deep-sea light annular rib cylindrical shell comprises the following specific processes of: The geometric model is subjected to stress analysis, a closed thin-wall cylindrical shell subjected to hydrostatic pressure is considered, and under the combined action of the hydrostatic pressure and the longitudinal pressure, the differential equation of the closed thin-wall cylindrical shell is as follows: In the above formula (1), w is the deflection of the cylindrical shell, p is the hydrostatic pressure born by the outer part of the cylindrical shell, E is Young's modulus, μPoisson's ratio, t is the thickness of the shell, R is the radius of the cylindrical shell, and the flexural rigidity of the cylindrical shell Solving the differential equation, and taking symmetry of the structure into consideration to obtain a cylindrical shell flexible line expression as follows: In the above formula (2), w is the deflection of the cylindrical shell, p is the hydrostatic pressure born by the outer part of the cylindrical shell, E is Young's modulus, mu is Poisson's ratio, t is the thickness of the shell, R is the radius of the cylindrical shell, C 1、C4 is an unknown parameter, and the unknown parameter is obtained by solving the boundary condition; the method for designing the strength of the deep-sea light annular rib cylindrical shell comprises the following specific proce