CN112199780B - Design method of equal-thickness shrinkage ratio strength and fatigue combined test model of transition forging ring - Google Patents

Design method of equal-thickness shrinkage ratio strength and fatigue combined test model of transition forging ring Download PDF

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CN112199780B
CN112199780B CN202011173114.8A CN202011173114A CN112199780B CN 112199780 B CN112199780 B CN 112199780B CN 202011173114 A CN202011173114 A CN 202011173114A CN 112199780 B CN112199780 B CN 112199780B
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党之凡
耿黎明
雷加静
张伯奇
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China Ship Development and Design Centre
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Abstract

The invention relates to a design method of a transition forging ring equal-thickness shrinkage ratio strength and fatigue combined test model, which comprises the following steps: step 1, determining a fatigue test node and the size of a real ship; step 2, calculating a scaling ratio: according to the maximum diameter 2R of a transition forging ring node2SAnd the maximum load dimension D determines the model radial scaling ratio 1: a,
Figure DDA0002747916550000011
step 3, calculating the size of the model: keeping the integral axial length, the rib distance C and the first half cone angle alpha of the model1And a second half-cone angle alpha2Consistent with a real ship; radial dimension R of model circular truncated cone1MAnd R2MAnd the axial dimension is reduced according to the reduction scale ratio of 1: a; radial dimension R of model transition cylinder2MReduced according to a reduced scale ratio of 1: a and axially extended by LM(ii) a And 4, selecting the thickness of the shell plate of each part of the model according to the real shell plate thickness, and adopting the welding seam form and the forming size which are the same as those of the pressure-resistant structure in the node welding process. The test model designed by the method can reflect the composite stress state of the maximum stress position of the actual structure node relatively truly and embody the fatigue failure mechanism of the test model.

Description

Design method of equal-thickness shrinkage ratio strength and fatigue combined test model of transition forging ring
Technical Field
The invention belongs to the field of design of a combined test model for engineering strength and fatigue of a pressure-resistant structure of marine equipment, and particularly relates to a design method of a combined test model for equal-thickness shrinkage ratio strength and fatigue of a transition forged ring.
Background
The connection structure of the conical shell and the cylindrical shell is often used in the pressure-resistant structural engineering of marine equipment. Due to the imbalance of radial film stress at the joint of the conical columns, the conical column combination part generates large local stress, and the transition forged ring is a reinforcing measure which is applied more generally. The strength of the transition forging ring is closely related to the manufacturing process, and with the application of high-strength materials in pressure-resistant structure engineering becoming more and more extensive, the influence of the high-stress state on the strength and fatigue of the transition forging ring structure cannot be ignored.
The fatigue problem is the result of the comprehensive effect of metallurgical factors and mechanical factors on the structure, and is mainly reflected in two aspects of welding and stress in structural engineering. From the welding point of view, the size of the initial defect of the weld, the metallographic structure of the welded joint and the dimensional extent of the weld heat affected zone all have an effect on the fatigue properties of the structural joint, and the factors that determine the above are the shell thickness, the form and size of the weld, and the welding method. From the stress perspective, the local composite high stress state at the maximum stress point of the structural node is a control factor of the fatigue performance of the structural node.
At present, a test method is mainly adopted for the fatigue life research of the structural node, and the test model is divided into a real-scale model and a scaling model. The real-scale model has the advantages of truly reflecting the mechanical property of the structure and the like, but the defects of high manufacturing cost, long construction period, limitation of space and size by a loading device and the like are not ignored. Therefore, the scaling model adopting the theorem of similar structure is widely applied.
The most key factors of the design of the combined test model of the strength and the fatigue of the transition forging ring are as follows: the connection between the structural strength of the transition forging ring and the manufacturing process is reflected truly, the fatigue nature and the internal mechanism of the conical column combined node are reflected, and accurate simulation of welding and stress factors is realized. Because the actual shell plate thickness of the transition forging ring, the welding influence and the composite stress state at the maximum stress point of the node must be reflected, if the strength and the fatigue influence of the transition forging ring structure are researched by adopting a scale model test of a structural plate thickness scale, the connection between the structural strength of the transition forging ring and the manufacturing process cannot be really reflected, the fatigue essence and the internal mechanism of the conical column combined node are reflected, and the accurate simulation of the welding and stress factors is realized. The full geometric scaling model will no longer be applicable.
Disclosure of Invention
The invention aims to solve the technical problem that the existing complete geometric scaling model for scaling the plate thickness cannot truly reflect the strength and fatigue characteristics in the test process, and provides a design method of a combined test model for the equal-thickness scaling strength and fatigue of a transition forging ring.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a design method of a transition forging ring equal-thickness shrinkage ratio strength and fatigue combined test model is used for designing an equal-thickness shrinkage ratio aiming at a transition forging ring of a pressure-resistant structure cone-column combining part, wherein the transition forging ring comprises a transition cylinder and a circular table which are coaxially connected, the front end of the circular table is connected with a pressure-resistant structure cone, and the rear end of the transition cylinder is connected with a pressure-resistant structure main body cylinder; the design method comprises the following steps:
step 1, determining a fatigue test node and a real ship size:
selecting a highest stress node of the cone column combined transition forging ring as a fatigue test node according to a finite element analysis result;
the real ship size includes: first half cone angle alpha of the cone1Bottom radius R1S(ii) a A first radius R of the circular truncated cone1SSecond radius R2SSecond half cone angle alpha2(ii) a Radius R of the main body cylinder2SRib pitch C, plate thickness T;
step 2, calculating a scaling ratio:
according to the selected maximum diameter 2R of the transition forging ring node2SAnd the maximum loading size D of the loading device, and determining the radial scale ratio of the model according to the following formula:
Figure BDA0002747916530000021
namely the radial scale ratio of the model is 1: a, wherein D is the maximum loading diameter of the loading device,
Figure BDA0002747916530000022
represents rounding up;
step 3, calculating the size of the model:
keeping the integral axial length, the rib distance C and the first half cone angle alpha of the model1And a second half-cone angle alpha2Consistent with a real ship;
radial dimension R of model circular truncated cone1MAnd R2MAnd the axial dimension is reduced according to a reduction scale ratio of 1: a, wherein R1MIs the first radius, R, of the model circular truncated cone2MThe second radius of the model circular truncated cone is also the radius of the model transition cylinder;
radial dimension R of model transition cylinder2MReduced according to a reduced scale ratio of 1: a and axially extended by LMWherein, in the step (A),
Figure BDA0002747916530000031
and 4, selecting the thickness of the shell plate of each part of the model according to the real thickness of the shell plate of the pressure-resistant structure to obtain T, wherein the welding process of the node adopts the welding seam form and the forming size which are the same as those of the pressure-resistant structure.
In the above method, the radial dimension R of the model cone1MAnd the axial dimension are reduced according to the reduction scale ratio of 1: a.
In the above method, the radial dimension R of the model main body cylinder2MThe reduction is carried out according to the reduction scale ratio of 1: a, and the axial size is consistent with that of a real ship.
The invention has the beneficial effects that:
the invention provides a design method of a transition forging ring equal-thickness shrinkage ratio strength and fatigue combined test model, which keeps the thickness of shell plates of all parts of the model the same as the thickness of a real shell plate of a pressure-resistant structure, ensures that the welding process of a node is the same as the welding seam form and the forming size of the real structure, can reflect the compound stress state of the maximum stress position of the node of the actual structure relatively truly, and can embody the fatigue failure mechanism.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic structural diagram of a node of an actual pressure-resistant equipment in the embodiment of the present invention;
fig. 2 is a model node structure diagram in the embodiment of the present invention.
In the figure: 1. transition forging ring; 11. a transition cylinder; 12. a circular truncated cone; 13. a cone; 14. a main body cylinder;
21. a model transition cylinder; 22. a model circular table; 23. a model cone; 24. and (4) a model main body cylinder.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
The invention provides a design method of a combined test model of equal-thickness shrinkage ratio strength and fatigue of a transition forged ring, which is mainly applied to the design of a combined test model of engineering strength and fatigue of a pressure-resistant structure of marine equipment and aims at designing the equal-thickness shrinkage ratio of a transition forged ring 1 of a conical column combination part of the pressure-resistant structure. As shown in fig. 1, the transition forged ring 1 comprises a transition cylinder 11 and a circular truncated cone 12 which are coaxially connected, the front end of the circular truncated cone 12 is connected with a pressure-resistant structure cone 13, and the rear end of the transition cylinder 11 is connected with a pressure-resistant structure main body cylinder 14. The design method comprises the following steps:
step 1, determining a fatigue test node and a real ship size:
and carrying out finite element modeling calculation on the pressure-resistant structure of the marine equipment, and selecting a highest stress node of the conical column combined transition forging ring as a fatigue test node according to a finite element analysis result. The real ship sizes to be determined are: the first half-cone angle of cone 13 is alpha1Bottom radius of R1S(ii) a The first radius of the circular truncated cone 12 is R1SThe second radius is R2SSecond half cone angle of alpha2(ii) a The main cylinder 14 has a radius R2SThe rib pitch is C and the plate thickness is T.
Step 2, calculating a scaling ratio:
according to the selected maximum diameter 2R of the transition forging ring node2SAnd the maximum loading size D of the loading device, and determining the radial scale ratio of the model according to the following formula:
Figure BDA0002747916530000041
namely the radial scale ratio of the model is 1: a, wherein D is the maximum loading diameter of the loading device,
Figure BDA0002747916530000042
indicating rounding up.
Step 3, calculating the size of the model:
keeping the integral axial length, the rib distance C and the first half cone angle alpha of the model1And a second half-cone angle alpha2In line with a real ship.
Radial dimension R of model circular truncated cone 221MAnd R2MAnd the axial dimension is reduced according to a reduction scale ratio of 1: a, wherein R1MIs a first radius, R, of the dummy round table 222MThe second radius of the model circular truncated cone 22 is also the radius of the model transition cylinder 21.
Radial dimension R of model transition cylinder 212MReduced according to a reduced scale ratio of 1: a and axially extended by LM. The reason why the model transition cylinder 21 needs to be extended in the axial direction is: when the model is designed, the first half cone angle alpha of the model is1And a second half-cone angle alpha2Since the axial length of the model cone 23 and the model circular truncated cone 22 is shortened and the length of the model main body cylinder 24 is kept constant when the model cone and the model circular truncated cone 22 are reduced, it is necessary to satisfy the requirement that the axial length of the entire model is kept consistent with that of a real ship by extending the model transition cylinder 21. Axial extension L of the model transition cylinder 21MCalculating the model taper shortening plus the model circular truncated cone shortening as follows:
(1) length of cone L of real shipSZ＝R1S/tanα1Length L of round platform of real shipST＝(R2S-R1S)/tanα2；
(2) Length L of model coneMZ＝R1S/atanα1Length L of model circular truncated coneMT＝(R2S-R1S)/atanα2；
(3) Axial extension L of model transition cylinderM，
Figure BDA0002747916530000051
And 4, selecting the thickness of the shell plate of each part of the model according to the real thickness of the shell plate of the pressure-resistant structure of the marine equipment, namely T, wherein the welding process of the node adopts the welding seam form and the forming size which are the same as those of the pressure-resistant structure of the marine equipment.
The design method of the invention is described in detail below by taking the example of combining a pressure-resistant structure cone column with a transition forged ring of marine equipment.
As shown in FIG. 1, the first half-cone angle of the solid boat cone 13 is α1At 45 °, the second half-cone angle is α2Radius R10 °1SThe first radius of the solid boat round platform 12 is R which is 1000mm1S1000mm, second radius R2S1250 mm; the radius of the transition cylinder 11 of the real ship is R2S1250 mm. The maximum loading cross-sectional dimension D of the loading device is 1500 mm.
The model radial scaling ratio is then selected as:
Figure BDA0002747916530000052
so the scale ratio is chosen to be 1:2, then, as shown in FIG. 2, the radius of the model cone 23 is R1M1000/2-500 mm; the first radius of the model circular truncated cone 22 is R1M1000/2 mm, and a second radius R2M1250/2 mm 625 mm; the radius of the model transition cylinder 21 is R2M1250/2 mm, axial extension L of the model transition cylinder 21MIn order to realize the purpose,
Figure BDA0002747916530000053
the invention provides a design method of a combined test model of equal-thickness shrinkage ratio strength and fatigue of a transition forging ring, which reflects the actual shell plate thickness of the transition forging ring, welding influence and the composite stress state at the maximum stress point of a node when a fatigue life test research is carried out on the structural node.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (3)

1. A design method of a transition forging ring equal-thickness shrinkage ratio strength and fatigue combined test model is used for designing an equal-thickness shrinkage ratio aiming at a transition forging ring of a pressure-resistant structure cone-column combining part, wherein the transition forging ring comprises a transition cylinder and a circular table which are coaxially connected, the front end of the circular table is connected with a pressure-resistant structure cone, and the rear end of the transition cylinder is connected with a pressure-resistant structure main body cylinder; the design method is characterized by comprising the following steps:
step 1, determining a fatigue test node and a real ship size:
selecting a highest stress node of the cone column combined transition forging ring as a fatigue test node according to a finite element analysis result;
the real ship size includes: first half cone angle alpha of the cone1Bottom radius R1S(ii) a A first radius R of the circular truncated cone1SSecond radius R2SSecond half cone angle alpha2(ii) a Radius R of the main body cylinder2SRib pitch C, plate thickness T;
step 2, calculating a scaling ratio:
according to the selected maximum diameter 2R of the transition forging ring node2SAnd the maximum loading size D of the loading device, and determining the radial scale ratio of the model according to the following formula:
Figure FDA0002747916520000011
namely the radial scale ratio of the model is 1: a, wherein D is the maximum loading diameter of the loading device,
Figure FDA0002747916520000012
represents rounding up;
step 3, calculating the size of the model:
keeping the integral axial length, the rib distance C and the first half cone angle alpha of the model1And a second half-cone angle alpha2Consistent with a real ship;
radial dimension R of model circular truncated cone1MAnd R2MAnd the axial dimension is reduced according to a reduction scale ratio of 1: a, wherein R1MIs the first radius, R, of the model circular truncated cone2MThe second radius of the model circular truncated cone is also the radius of the model transition cylinder;
radial dimension R of model transition cylinder2MReduced according to a reduced scale ratio of 1: a and axially extended by LMWherein, in the step (A),
Figure FDA0002747916520000013
and 4, selecting the thickness of the shell plate of each part of the model according to the real thickness of the shell plate of the pressure-resistant structure to obtain T, wherein the welding process of the node adopts the welding seam form and the forming size which are the same as those of the pressure-resistant structure.
2. The method for designing a combined test model of equal thickness reduction ratio strength and fatigue of a transition forging ring according to claim 1, wherein the radial dimension R of the model cone1MAnd the axial dimension are reduced according to the reduction scale ratio of 1: a.
3. The method for designing a combined test model of equal thickness reduction ratio strength and fatigue of a transition forging ring according to claim 1, wherein the radial dimension R of the model main body cylinder2MThe reduction is carried out according to the reduction scale ratio of 1: a, and the axial size is consistent with that of a real ship.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011108032A (en) * 2009-11-18 2011-06-02 Ihi Corp Device and method for evaluating fatigue strength of polycrystalline metallic material
CN110979591A (en) * 2019-12-09 2020-04-10 华南理工大学 Simplified structure model for ship water elasticity test and design method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011108032A (en) * 2009-11-18 2011-06-02 Ihi Corp Device and method for evaluating fatigue strength of polycrystalline metallic material
CN110979591A (en) * 2019-12-09 2020-04-10 华南理工大学 Simplified structure model for ship water elasticity test and design method thereof

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
厚钢板疲劳裂纹扩展前缘应力状态试验与数值仿真;党之凡等;《中国舰船研究》;20160430(第02期);全文 *
基于DEFORM-3D的300M超高强度钢切削性能的比较;任家隆等;《组合机床与自动化加工技术》;20141231(第12期);全文 *
船用柴油机连杆结构有限元分析;胡安元等;《计算机辅助工程》;20131015;全文 *

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