A device and method for testing the ultimate strength of a ship box beam model

Abstract

The invention relates to a device and method for testing the ultimate strength of a ship box beam model. The device comprises a large door frame, two small door frames, a loading device, a measuring device and two supporting section box beams; the two small door frames are symmetrically arranged with the large door frame as the center, the loading device is fixed on the first cross beam of the large door frame, the loading device comprises a fatigue testing machine and a pressure head, the measuring device comprises a strain gauge and a dial indicator, an experimental section box beam is arranged between the two supporting section box beams, and box beam structure tests of different specifications can be carried out by replacing the experimental section box beam, thereby achieving test repeatability.

Description

Technical Field

[0001] The invention relates to the technical field of ship engineering experiments, and in particular to a ship cabin box beam model strength test device and method. Background Art

[0002] The hull structure is subjected to cyclic wave loads in severe sea conditions, which manifests as alternating sagging and arching bending deformations on the hull beam. Analysis of catastrophic accidents in which ships collapsed and sunk due to insufficient ultimate bearing capacity shows that hull beams rarely break under a one-time extremely large wave load, but generally collapse under repeated extreme loads. The box beam is a commonly used simplified structure of the parallel mid-body compartment in the middle of a ship. The collapse process of the hull structure under repeated extreme loads can be simulated by the box beam cyclic bending ultimate strength test. Therefore, it is of great significance to carry out ultimate strength tests of box beam structures under extreme cyclic loads.

[0003] The existing ultimate strength test of box beam structures has the following problems: during the test, the box beam model is an integrated structure. After the middle structure collapses, the entire model must be replaced and cannot be reused, resulting in low test repeatability and high test cost. During the test loading process, the box beam structure cannot completely eliminate the shear interference of the actuator in the loading system, and cannot well simulate the bending characteristics of the middle section of the ship along the length of the ship. When considering applying a reverse bending load, the test needs to be interrupted and the entire model needs to be flipped, which is cumbersome. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention proposes a device and method for testing the ultimate strength of a ship box girder model. By designing a device for testing the ultimate strength of a ship box girder model, the ultimate strength test of the box girder can be carried out under the application of cyclic tension and compression loads. At the same time, the test section structure is subjected to pure bending moment to eliminate the interference of shear force, and box girder structures of different specifications can be tested without changing the size and structure of the supporting section.

[0005] To achieve the above-mentioned purpose, the present invention is a device for testing the ultimate strength of a ship box beam model, which includes a large door frame, two small door frames, a loading device, a measuring device and two supporting section box beams; the large door frame includes two first columns and a first beam, and the first beam is connected between the two first columns; the small door frame includes two second columns and a second beam, and the second beam is connected between the two second columns; the two small door frames are symmetrically arranged relative to the large door frame, the two supporting section box beams are arranged in the horizontal direction and are perpendicular to the first beam, and one end of the two supporting section box beams is respectively placed under the second beams of the two large door frames, A test section box beam is sandwiched between the other ends of the two support section box beams, and the first cross beam is connected to the two support section box beams through the loading device; the top end surface of the support section box beam extends outward, and through holes are evenly provided on the extension surface, through the through holes, bolts are inserted and connected and fixed with the extension surface of the end of the test section box beam to transfer bending moment, and box beam structures of different specifications can also be replaced for experiments, thereby achieving experimental repeatability; when replacing the sample, only the test section box beam sample needs to be replaced, which saves the test cost and site occupation, and at the same time facilitates the disassembly and assembly of the experiment, reduces the workload caused by replacing the entire test model, and reduces the burden on the test personnel;

[0006] A cylindrical structure is installed on the lower end surface of the supporting section box beam away from the experimental section box beam, a base is provided under the cylindrical structure, the cylindrical structure is hinged to the base, and a semi-cylindrical structure is placed on the upper end surface away from the experimental section box beam, the arc surface of the semi-cylindrical structure is in contact with the lower end surface of the second beam; by arranging the cylindrical structure and the semi-cylindrical structure, the simulation of the free and unconstrained state of the ship in the water is realized, which can provide a more accurate basis for the evaluation of the cyclic tension and compression bending ultimate strength of the box beam.

[0007] Optionally, the loading device includes a fatigue testing machine and a pressure head, the tail end of the fatigue testing machine is fixed to the lower end surface of the first beam by bolts, and the pressure head is installed on the top of the fatigue testing machine; one end that can be connected to the pressure head is the top of the fatigue testing machine, and the other end is the tail.

[0008] Optionally, the ultimate strength test device for a ship box beam model also includes a loading ring, and the loading ring is mounted on the two supporting section box beams. The pressure head is a long cube structure, and the two ends of the pressure head are respectively fixedly connected to the two loading rings. By setting the loading ring, force transmission can be achieved without destroying the supporting section box beam structure, and the cyclic tensile and compressive loads generated by the loading device can be transferred to the box beam.

[0009] Optionally, a plurality of test section box body reinforcement ribs are provided inside the test section box beam. By arranging a plurality of reinforcement ribs, the collapse mode of the test section box beam can be evaluated more accurately.

[0010] Optionally, the measuring device includes strain gauges and dial indicators. The strain gauges are mainly arranged on the middle top plate, side plate, bottom plate and the reinforcing ribs of the box beam of the test section; the dial indicator is arranged on the side of the box beam of the test section facing away from the loading device; the purposes are as follows: the strain gauges are arranged on the upper surface of the middle top plate of the test section to verify the uniformity and effectiveness of the load transferred by the loading device; the strain gauges at the side plate are used to measure the stress applied by the side plate loading device as the external load changes, so as to determine the change in the position of the neutral axis of the cross section; the strain gauges are arranged at the bottom plate to measure the change data of the stress as the applied bending moment gradually increases; the strain gauges are arranged at the reinforcing rib surface to accurately evaluate the collapse mode of the reinforced box beam. The dial indicator is arranged at the bottom of the box beam of the test section, and is used to measure the vertical displacement of each measuring point at the bottom of the test section in real time. After conversion, the curvature data of the box beam model can be obtained.

[0011] Optionally, the end faces of both ends of the test section box beam are respectively bolted to the other ends of the two supporting section box beams. The separate structure of the supporting section and the test section can effectively ensure that the test loading device applies pure bending moments in both positive and negative directions of the middle arch and middle vertical in the middle test section, eliminating shear interference.

[0012] The present invention also provides a ship box girder model ultimate strength test method, the method is implemented based on the above-mentioned ship box girder model ultimate strength test device, and comprises the following steps:

[0013] Step 1), fixing the first crossbeam between two first uprights by fixing bolts to form a large door frame, and fixing the loading device directly below the first crossbeam;

[0014] Step 2), connecting the outer extension surface of the test section box beam and the outer extension surface of the support section box beam by bolts, connecting the loading device to the support section box beam, the test section box beam is located directly below the geometric center of the loading device, and the cylindrical structures are symmetrically arranged on both sides with the gate frame as the center, the tail ends of the two support section box beams are respectively placed on the symmetrically arranged cylindrical structures, and a semi-cylindrical structure is placed on the top of the tail end of the support section box beam;

[0015] Step 3), fixing the second cross beam between the two second columns by fixing bolts to form a small door frame, so that the second cross beam presses the semi-cylindrical structure tightly;

[0016] Step 4), apply pressure load to the test section box beam through the loading device and the supporting section box beam, and check through the measuring device: the uniformity of model loading and the effective transfer of load; the change of stress with external load, so as to determine the change of the neutral axis position of the cross section; evaluate the collapse mode of the test section box beam; measure the vertical displacement of each measuring point at the bottom of the test section in real time, and obtain the curvature data of the box beam model after conversion.

[0017] Step 5), remove the experimental section box beam from the two supporting section box beams, connect the experimental section box beam of different models between the two supporting section box beams, and repeat steps 1) to 4).

[0018] The beneficial effects of the present invention are:

[0019] The present invention can carry out box beam structure tests of different specifications by replacing the test section box beam, thereby achieving test repeatability; when replacing the sample, only the test section box beam sample needs to be replaced, saving test cost and site occupation, while facilitating experimental disassembly and assembly, and reducing the workload caused by replacing the entire test model.

[0020] The present invention is connected with the loading device through a loading ring, and can realize the mid-sag mid-arch cyclic bending load loading without flipping the test device while not destroying the box beam structure.

[0021] The separate structure of the supporting section box girder and the test section box girder in this launch can effectively ensure that the test loading device applies pure bending moment in both positive and negative directions of the middle arch and middle vertical to the box girder of the middle test section, eliminating shear interference; through the setting of cylindrical structure and semi-cylindrical structure, the simulation of the free and unconstrained state of the ship in the water can be realized, which can provide a more accurate basis for the cyclic tension and compression bending ultimate strength evaluation of the box girder of the test section. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the three-dimensional structure of an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the connection structure between the supporting section box beam and the test section box beam according to an embodiment of the present invention;

[0024] Figure 3 is a schematic diagram of a support section box beam structure provided by an embodiment of the present invention;

[0025] Figure 4 It is a schematic diagram of the box beam structure of the test section provided by an embodiment of the present invention;

[0026] Figure 5 is a schematic diagram of the pressure head structure provided by an embodiment of the present invention;

[0027] Figure 6 is a schematic diagram of the loading ring structure provided by an embodiment of the present invention;

[0028] Figure 7 It is a flow chart of a molding method provided by an embodiment of the present invention.

[0029] Reference numerals: 1 large H structure, 101 first crossbeam, 102 first column,

[0030] 2 small H structure, 201 second beam, 202 second column,

[0031] 3 loading device, 301 fatigue testing machine, 302 pressure head,

[0032] 4 semi-cylindrical structure, 5 supporting section box beam, 6 cylindrical structure, 7 loading ring, 8 test section box beam, (including: 801 top plate, 802 side plate, 803 bottom plate, 804 stiffener)

[0033] 9 base. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0035] like Figures 1 to 6 As shown, a ship box beam model ultimate strength test device provided by the present invention comprises a large door frame 1, two small door frames 2, a loading device 3, a measuring device and two supporting section box beams 5; the large door frame comprises two first columns 102 and a first cross beam 101, and the first cross beam 101 is connected between the two first columns 102; the small door frame 2 comprises two second columns 202 and a second cross beam 201, and the second cross beam 201 is connected between the two second columns 202; the two small door frames 2 are symmetrically arranged relative to the large door frame 1, and the two supporting section box beams 5 are arranged in the horizontal direction and perpendicular to the first cross beam 101, and one end of the two supporting section box beams 5 is respectively placed on the second cross beams 201 of the two large door frames 2. 01, a test section box beam 8 is sandwiched between the other ends of the two supporting section box beams 5, and the first crossbeam 101 is connected to the two supporting section box beams 5 through the loading device 3. The top end surface of the supporting section box beam 5 extends outward, and through holes are evenly provided on the extension surface. Through the through holes, bolts are inserted and connected and fixed to the extension surface of the end of the test section box beam 8 to transfer the bending moment. The test section box beam 8 structures of different specifications can also be replaced for experiments, thereby achieving the repeatability of the experiment. When replacing the specimen, only the test section box beam 8 specimen needs to be replaced, which saves the test cost and site occupation, and at the same time facilitates the disassembly and assembly of the experiment, reduces the workload caused by replacing the entire test model, and reduces the burden on the test personnel.

[0036] The lower end face of the supporting section box beam 5 away from the experimental section box beam 8 is equipped with a cylindrical structure 6, a base 9 is provided below the cylindrical structure 6, and the cylindrical structure 6 is hinged to the base 9. A semi-cylindrical structure 4 is placed on the upper end face away from the experimental section box beam 8, and the arc surface of the semi-cylindrical structure 4 is in contact with the lower end face of the second cross beam 201. By setting the cylindrical structure 6 and the semi-cylindrical structure 4, the supporting section box beam 5 and the experimental section box beam 8 are not subject to lateral constraints in the horizontal direction, and the simulation of the free and unconstrained state of the ship in the water is realized. By rotating the cylindrical structure 6, the supporting section box beam 5 can be subjected to horizontal stress. The cylindrical structures 6 at both ends rotate inward at the same time, so that the test section box beam 8 is subjected to the lateral extrusion force of the supporting section box beams 5 on both sides, which can provide a more accurate basis for the evaluation of the cyclic tension and compression bending ultimate strength of the test section box beam 8.

[0037] Preferably, the loading device 3 includes a fatigue testing machine 301 and a pressure head 302. The tail end of the fatigue testing machine 301 is fixed to the lower end surface of the first crossbeam 101 by bolts. The end of the pressure head 302 with a threaded hole is aligned with the threaded hole on the top of the fatigue testing machine 301, and the pressure head 302 is installed on the top of the fatigue testing machine 301 by bolts. During the test loading, a vertical cyclic tensile and compressive load is applied by the fatigue testing machine 301. When applying a compressive load, the pressure head presses the loading ring 7 downward; when applying a tensile load, the pressure head 302 pulls up the loading ring 7 by bolts, and the loading ring 7 transmits the tensile and compressive load to the test section box beam 8 through the supporting section box beam 5, and so on. The total number of cycles is determined according to the curvature curve of the cyclic bending moment in the actual test process. Its ultimate bending moment needs to be significantly attenuated before the plastic collapse. The last step of loading to the ultimate bending moment of the box beam is reduced by no more than 5% compared with the previous step, which is regarded as reaching the post-limit stability state.

[0038] Preferably, a ship box beam model ultimate strength test device further includes a loading ring 7, and the two supporting section box beams 5 are both equipped with a loading ring 7, and the pressure head 302 is a long cube structure, and the two ends of the pressure head 302 are respectively fixedly connected to the two loading rings 7. By setting the loading ring 7 and making the loading ring 7 and the pressure head 302 fixedly connected, the force transmission can be achieved without destroying the structure of the supporting section box beam 5, and the cyclic tension and compression load generated by the loading device 3 is transmitted to the test section box beam 8.

[0039] Preferably, a plurality of test section box body stiffeners 804 are provided inside the test section box beam 8; by arranging a plurality of stiffeners 804 and installing strain gauges on each stiffener 804, the collapse mode of the test section box beam can be evaluated more accurately.

[0040] Preferably, the measuring device includes strain gauges and dial indicators, and the strain gauges are mainly arranged on the middle top plate 801, the side plate 802, the bottom plate 803 and the stiffener 804 of the test section box beam 8; the dial indicator is arranged on the side of the test section box beam 8 facing away from the loading device 3; the dial indicator is arranged on the side of the test section box beam 8 facing away from the loading device; their purposes are respectively: strain gauges are arranged on the upper surface of the middle top plate 801 of the test section to verify the uniformity and effectiveness of the load transferred by the loading device 3; the strain gauges at the side plate 802 are used to measure the changes in the stress applied by the side plate loading device 3 with the external load, so as to determine the changes in the position of the neutral axis of the cross section; strain gauges are arranged at the bottom plate 803 to measure the change data of the stress with the gradual increase of the applied bending moment; strain gauges are arranged on the surface of the stiffener 804 to accurately evaluate the collapse mode of the reinforced box beam. The dial indicator is arranged at the bottom of the test section box beam 8 and is used to measure the vertical displacement of each measuring point at the bottom of the test section in real time. After conversion, the curvature data of the test section box beam 8 model can be obtained.

[0041] Preferably, the end faces of both ends of the test section box beam 8 are respectively bolted to the other ends of the two supporting section box beams 5; the separate structure of the supporting section box beam 5 and the test section box beam 8 can effectively ensure that the test loading device 3 applies pure bending moments in both positive and negative directions of the middle arch and middle vertical in the middle test section, eliminating shear interference.

[0042] Figure 7 1 is a flow chart of a molding method provided by an embodiment of the present invention. Figure 7 As shown, the embodiment of the present invention also provides a molding method for molding and manufacturing such as Figures 1 to 6 A ship box beam model ultimate strength test device is shown, and the forming method includes:

[0043] S1. Fix the first crossbeam 101 between the two first upright posts 102 by means of fixing bolts to form a large door frame 1, and fix the loading device 3 directly below the first crossbeam 101.

[0044] S2. Connect the outer extension surface of the test section box beam 8 and the outer extension surface of the support section box beam 5 by bolts, connect the loading device 3 with the support section box beam 5, the test section box beam 8 is located directly below the geometric center of the loading device 3, and the two cylindrical structures 6 are symmetrically arranged on both sides with the gate frame 1 as the center. The tail ends of the two support section box beams 5 are respectively placed on the symmetrically arranged cylindrical structures 6, and a semi-cylindrical structure 4 is placed on the top of the tail end of the support section box beam 5.

[0045] S3. Fix the second cross beam 201 between the two second upright posts 202 by means of fixing bolts to form a small door frame 2, so that the second cross beam 201 is pressed tightly against the semi-cylindrical structure 4.

[0046] S4. Apply pressure load to the test section box beam 8 through the loading device 3 and the supporting section box beam 5, and check the deformation data of the test section box beam 8 through the measuring device.

[0047] Specifically, in this step, strain gauges are arranged on the middle top plate, side plate, bottom plate and test section box-type stiffener 9 of the test section box beam 8, the purposes of which are as follows: strain gauges are arranged on the upper surface of the middle top plate of the test section to verify the uniformity of model loading and the effective transfer of loads; strain gauges at the side plates are used to measure the change of the side plate stress with the external load, so as to determine the change of the position of the neutral axis of the cross section; strain gauges are arranged at the bottom plate to measure the change data of the stress with the gradual increase of the applied bending moment; strain gauges are arranged at the stiffener 9 to accurately evaluate the collapse mode of the reinforced box beam; a dial indicator is arranged at the bottom of the test section box beam 8 to measure the vertical displacement of each measuring point at the bottom of the test section in real time, and the curvature data of the box beam model can be obtained after conversion;

[0048] Turn on the fatigue testing machine 301 and apply cyclic tensile and compressive loads in the vertical direction through the hydraulic actuator of the fatigue testing machine 301; when applying the compressive load, the pressure head 302 moves up and down to drive the loading ring 7; when applying the tensile load, the pressure head 302 pulls up the loading ring 7 through the bolts; further, the load is transmitted to the supporting section box beam 5 through the loading ring 7, and the supporting section box beam 5 transmits the bending moment to the test section box beam 8 through the bolts on the outer extension surface, thereby realizing pure bending moment loading on the test section box beam 8, simulating the longitudinal mid-arch and mid-sag bending.

[0049] S5, remove the experimental section box beam 8 from the two supporting section box beams 5, connect the experimental section box beam 8 of a different model between the two supporting section box beams 5, and repeat steps 1) to 4).

[0050] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] The above descriptions are merely optional embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A ship box girder model ultimate strength test device, the device comprising a large door frame (1), two small door frames (2), a loading device (3), a measuring device and two supporting section box beams (5); the large door frame (1) comprises two first columns (102) and a first cross beam (101), the first cross beam (101) being connected between the two first columns (102); the small door frame (2) comprises two second columns (202) and a second cross beam (201), the second cross beam (201) being connected between the two second columns (202); the two small door frames (2) are symmetrically arranged relative to the large door frame (1), and the two supporting section box beams (5) are arranged in a horizontal direction and vertically relative to the first cross beam (101). The two support section box beams (5) are arranged on a straight line, one end of each of the two support section box beams (5) is placed below the second cross beams (201) of the two small door frames (2), a test section box beam (8) is sandwiched between the other ends of the two support section box beams (5), the first cross beam (101) is connected to the two support section box beams (5) through the loading device (3), a cylindrical structure (6) is installed on the lower end surface of the support section box beam (5) away from the test section box beam (8), a base (9) is provided below the cylindrical structure (6), the cylindrical structure (6) is hinged to the base (9), a semi-cylindrical structure (4) is placed on the upper end surface away from the test section box beam (8), and the arc surface of the semi-cylindrical structure (4) is in contact with the lower end surface of the second cross beam (201).

2. The ultimate strength test device for a ship box beam model according to claim 1, characterized in that: The loading device (3) comprises a fatigue testing machine (301) and a pressing head (302); the rear end of the fatigue testing machine (301) is fixed to the lower end surface of the first crossbeam (101) by means of bolts, and the pressing head (302) is mounted on the top of the fatigue testing machine (301).

3. The ultimate strength test device for a ship box beam model according to claim 2, characterized in that: The ship box girder model ultimate strength test device further comprises a loading ring (7), the two supporting section box girders (5) are both provided with the loading ring (7), the pressure head (302) is a long cube structure, and the two ends of the pressure head (302) are respectively fixedly connected to the two loading rings (7).

4. The ultimate strength test device for a ship box beam model according to claim 1, characterized in that: A plurality of test section box body reinforcing ribs (9) are arranged inside the test section box beam (8).

5. The ultimate strength test device for a ship box beam model according to claim 4, characterized in that: The measuring device includes a strain gauge and a dial indicator. The strain gauge is mainly arranged on the middle top plate (801), the side plate (802), the bottom plate (803) and the reinforcing rib (804) of the test section box beam (8); the dial indicator is arranged on the side of the test section box beam (8) facing away from the loading device (3).

6. The ultimate strength test device for a ship box beam model according to claim 1, characterized in that: The end surfaces of both ends of the test section box beam (8) are respectively connected with the other ends of the two support section box beams (5) by bolts.

7. A ship box girder model ultimate strength test method, the test method is implemented based on a ship box girder model ultimate strength test device according to any one of claims 1 to 6, characterized in that: The test method comprises the following steps: Step 1), fixing the first crossbeam (101) between two first upright posts (102) by means of fixing bolts to form a gate frame (1), and fixing the loading device (3) directly below the first crossbeam (101); Step 2), connecting the outer extension surface of the test section box beam (8) and the outer extension surface of the support section box beam (5) by bolts, connecting the loading device (3) to the support section box beam (5), the test section box beam (8) is located directly below the geometric center of the loading device (3), the two cylindrical structures (6) are symmetrically arranged on both sides with the gate frame (1) as the center, the tail ends of the two support section box beams (5) are respectively placed on the symmetrically arranged cylindrical structures (6), and a semi-cylindrical structure (4) is placed on the top of the tail end of the support section box beam (5); Step 3), fixing the second cross beam (201) between the two second uprights (202) by means of fixing bolts to form a small door frame (2), so that the second cross beam (201) is pressed tightly against the semi-cylindrical structure (4); Step 4), applying a pressure load to the test section box beam (8) through the loading device (3) and the supporting section box beam (5), and checking the deformation data of the test section box beam (8) through the measuring device; Step 5), remove the test section box beam (8) from the two support section box beams (5), connect the test section box beam (8) of different models between the two support section box beams (5), and repeat steps 1) to 4).

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