Device and method for testing ultimate strength of marine stiffened plate under action of multi-axial load

Abstract

The invention discloses a marine stiffened plate ultimate strength test device and method under the action of multi-axial load.The test device comprises a test frame, a transverse loading device, a longitudinal loading device and a stiffened plate clamp, the transverse loading device, the longitudinal loading device and the stiffened plate clamp are installed in the test frame, the test frame is in a right-angle quadrangle shape, and the stiffened plate clamp is used for clamping a to-be-tested stiffened plate; the two perpendicular side edges of the stiffened plate clamp are connected with the transverse loading device and the longitudinal loading device respectively, and the transverse loading device and the longitudinal loading device are used for applying transverse loads and longitudinal loads to a stiffened plate to be tested respectively. When the test is carried out, the plate surface of the stiffened plate to be tested is perpendicular to the ground. A vertical structure is adopted, the influence of the gravity of the stiffened plate on the test is avoided, the real working state of the stiffened plate is simulated, and more accurate test data are obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of ship engineering structural strength, and particularly to a test device and method for the ultimate strength of a ship stiffened panel under multi-axial loads. Background Art

[0002] The ship stiffened panel is an important part of the ship structure, mainly used in parts such as the ship's deck, side, and bottom. Through the arrangement of stiffeners, the stiffened panel can effectively improve the stiffness and strength of the ship's structure, thereby enhancing the overall load-bearing capacity and anti-deformation ability of the ship. During the ship design and construction process, the ultimate strength of the stiffened panel is one of the key indicators for evaluating the safety and reliability of the ship's structure.

[0003] Currently, the testing of the ultimate strength of the stiffened panel mainly relies on traditional horizontal test devices. Such devices usually place the stiffened panel horizontally and apply loads to simulate the complex stress states such as bending, shear, and compression that the hull experiences during actual navigation. However, the horizontal test device has some limitations: Firstly, since the stiffened panel is placed horizontally, its own weight will have a certain impact on the test results, especially when testing large-sized stiffened panels, this impact is more significant; Secondly, there is a certain deviation when the horizontal test device simulates the vertical stress state of the hull, and it is difficult to fully restore the stress situation of the ship during actual navigation. Summary of the Invention

[0004] Objective of the Invention: Aiming at the above disadvantages, the present invention provides a test device and method for the ultimate strength of a ship stiffened panel under multi-axial loads.

[0005] Technical Solution: To solve the above problems, the present invention adopts a test device for the ultimate strength of a ship stiffened panel under multi-axial loads, which includes a test frame and a transverse loading device, a longitudinal loading device, and a stiffened panel clamp installed in the test frame. The test frame is in the shape of a right-angled quadrilateral. The stiffened panel clamp is used to hold the stiffened panel to be tested. The two mutually perpendicular sides of the stiffened panel clamp are respectively connected to the transverse loading device and the longitudinal loading device. The transverse loading device and the longitudinal loading device are respectively used to apply transverse and longitudinal loads to the stiffened panel to be tested. When conducting the test, the plate surface of the stiffened panel to be tested is perpendicular to the ground.

[0006] Furthermore, the test frame includes a support platform, a first column, a second column, and a cross beam. The first column and the second column are installed on the upper end surface of the support platform, and the cross beam is installed on the tops of the first column and the second column. The transverse loading device is installed on the first column, and the longitudinal loading device is installed on the cross beam.

[0007] Further, the stiffened plate fixture includes an upper fixture, a lower fixture, a left fixture, and a right fixture. Each fixture is respectively used to clamp one side of the test loading plate to be measured. The upper fixture is connected to the longitudinal loading device, the lower fixture is installed on the upper end surface of the support platform, the left fixture is connected to the transverse loading device, and the right fixture is installed on the second column.

[0008] Further, grooves for placing the stiffened plate to be measured are provided in the middle of the upper fixture, the lower fixture, the left fixture, and the right fixture. The bottom of the groove is straight or arc-shaped.

[0009] Further, a longitudinal loading box is provided between the upper fixture and the longitudinal loading device; the side of the longitudinal loading box away from the upper fixture is connected to the longitudinal loading device; a transverse loading box is provided between the left fixture and the transverse loading device, and the side of the transverse loading box away from the left fixture is connected to the transverse loading device.

[0010] Further, a slide rail is provided on the upper end surface of the support platform, and a slider is provided at the bottom of the transverse loading box. The slider is installed on the slide rail.

[0011] Further, a pressure sensor is provided on the side of the transverse loading device connected to the transverse loading box, and a pressure sensor is also provided on the side of the longitudinal loading device connected to the longitudinal loading box.

[0012] Further, a controller is further included. The controller is used to control the transverse loading device and the longitudinal loading device to apply loads and receive data from the pressure sensors.

[0013] Further, both the transverse loading device and the longitudinal loading device adopt hydraulic cylinders.

[0014] The present invention also provides a test method for the above-mentioned vertical test device for the strength of marine stiffened plates, including the following steps:

[0015] Step 1: Use the loading plate fixture to fix the stiffened plate to be measured within the test frame;

[0016] Step 2: Apply loads to the stiffened plate to be measured transversely and longitudinally through the transverse loading device and the longitudinal loading device, and record the force and deformation conditions of the stiffened plate to be measured.

[0017] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are as follows: (1) By adopting a vertical structure, the influence of the gravity of the stiffening plate on the test is avoided, the real working state of the stiffening plate is simulated, and more accurate test data can be obtained; (2) By setting a transverse loading box and a longitudinal loading box, the load applied by the loading device is evenly transmitted to the loading plate to be tested, avoiding direct connection of the loading device, where the load is concentrated at the connection point, resulting in inaccurate test results; (3) Sliders are provided at the bottom of the transverse loading box, enabling it to move flexibly to adapt to stiffening plates to be tested with different widths, expanding the scope of use of the test device; (4) The control algorithm of the loading device is optimized to make the loading device operate more stably. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the overall structure of the vertical test device of the present invention;

[0019] Figure 2 It is a schematic diagram of the first groove shape of the stiffening plate fixture of the present invention;

[0020] Figure 3 It is a schematic diagram of the second groove shape of the stiffening plate fixture of the present invention;

[0021] Figure 4 It is a schematic diagram of the connection structure between the loading device and the loading box of the present invention;

[0022] Figure 5 It is a schematic diagram of the slide rail structure of the present invention;

[0023] Figure 6 It is a schematic diagram of the principle of improving the algorithm of the hydraulic cylinder of the present invention. Detailed Embodiments

[0024] As Figure 1 shown, a multi-axis load acting on a marine stiffening plate ultimate strength test device in this embodiment includes a test frame and a transverse loading device, a longitudinal loading device, a stiffening plate fixture, and a controller installed in the test frame. The test frame is in the shape of a right-angled quadrilateral, including a support platform 11, a first column 2, a second column 3, and a cross beam 1. The first column 2 and the second column 3 are installed on the upper end surface of the support platform 11, and the cross beam 1 is installed on the tops of the first column 2 and the second column 3. The transverse loading device is installed on the first column 2, and the other side is connected to a side edge of the loading plate fixture to apply a transverse load to the stiffening plate to be tested. The longitudinal loading device is installed on the cross beam 1, and the other side is also connected to a side edge of the loading plate fixture to apply a longitudinal load to the stiffening plate to be tested.

[0025] The stiffening plate fixture includes an upper fixture 6, a lower fixture 7, a left fixture 8, and a right fixture 9. Each fixture is used to clamp a side edge of the loading plate to be tested, and a groove for placing the stiffening plate to be tested is provided in the middle of each fixture. The bottom of the groove is straight or arc-shaped, as Figure 2and Figure 3 As shown, the groove with a straight bottom is used to simulate the fixed boundary condition, and the groove with an arc bottom is used to simulate the hinged boundary condition. Fixtures with different-shaped grooves can be selected according to different test requirements.

[0026] As Figure 4 shown, a longitudinal loading box 5 is provided at the top of the upper fixture 6, and the other side of the longitudinal loading box 5 is connected to the longitudinal loading device. The lower fixture 7 is installed on the upper end face of the support platform 11. A transverse loading box 4 is provided on the left side of the left fixture 8, and the other side of the transverse loading box 4 is connected to the transverse loading device. The right fixture 9 is installed on the second column 3. The settings of the transverse loading box 4 and the longitudinal loading box 5 can evenly conduct the load applied by the loading device to the test loading plate to be measured, avoiding direct connection of the loading device and concentration of the load at the connection point, resulting in inaccurate test results.

[0027] As Figure 5 shown, a slide rail 10 is provided on the upper end face of the support platform 11, and a slider is provided at the bottom of the transverse loading box 4. The slider is installed on the slide rail 10, enabling the transverse loading box 4 to slide left and right on the support platform 11 to adapt to the test stiffened plates of different widths and expand the application range of the test device.

[0028] To monitor the magnitude of the load applied by the loading device in real time, a high-precision pressure sensor 12 is provided on one side of the transverse loading device connected to the transverse loading box 4, and a high-precision pressure sensor 12 is also provided on one side of the longitudinal loading device connected to the longitudinal loading box 5. The controller receives the data from the pressure sensors and flexibly adjusts the magnitude of the load applied by the loading device.

[0029] In this embodiment, both the transverse loading device and the longitudinal loading device adopt hydraulic cylinders 13. As Figure 6 shown, for the control of the hydraulic cylinders, this embodiment adopts an improved particle swarm optimization (IPSO) algorithm combined with the FPID control algorithm. Specifically, on the basis of FPID, in order to avoid the limitations caused by the given quantization and scale factors, the present invention combines the improved particle swarm optimization (IPSO) algorithm to optimize the quantization and scale factors. According to IPSO, the formulas for updating the particle velocity and position are as follows:

[0030]

[0031] where c1 and c2 are learning factors, r1 and r2 are random numbers in [0, 1], represents the current best position, represents the global best position, and w is the inertia weight. A linearly decreasing weight is used in the IPSO algorithm:

[0032]

[0033] In the formula, t is the iteration count, tmax is the maximum count of iteration, w max and w min represent the maximum value and the minimum value of w respectively.

[0034] In parameter tuning, integral time and absolute error (ITAE) are used as indicators, and its formula is written as

[0035] J ITAE = ∫0 ∞ T|e|dT

[0036] The optimization of FPID parameters is achieved through the IPSO algorithm, and the adjustment amount of PID parameters is obtained through a fuzzy controller, thereby completing the adjustment of PID parameters. Then, by implementing a PID controller, stable control of the hydraulic cylinder is achieved.

[0037] This embodiment also provides a test method for the above-mentioned vertical test device for the strength of marine stiffened plates, including the following steps:

[0038] Step 1: Fix the stiffened plate to be tested in the test frame using a loading plate fixture. Place the stiffened plate to be tested in the grooves of each fixture, so that the longitudinal loading box 5 abuts against the upper fixture 6; and adjust the position of the transverse loading box 4 according to the width of the loading plate to be tested, so that the transverse loading box 4 abuts against the left fixture 8. The plane where the quadrilateral of the test frame is located is perpendicular to the ground, and the plate surface of the stiffened plate to be tested is perpendicular to the ground, so as to perform a vertical test on the stiffened plate, avoid the influence of the gravity of the stiffened plate on the test, simulate the real working state of the stiffened plate, and obtain more accurate test data.

[0039] Step 2: The controller controls the transverse loading device and the longitudinal loading device to apply loads to the stiffened plate to be tested transversely and longitudinally, and records the force and deformation conditions of the stiffened plate to be tested.

[0040] In summary, the test device of the present invention adopts a vertical structure, avoids the influence of the gravity of the stiffened plate on the test, simulates the real working state of the stiffened plate, and obtains more accurate test data. By setting a transverse loading box and a longitudinal loading box, the load applied by the loading device is evenly transmitted to the loading plate to be tested, avoiding direct connection of the loading device and concentrating the load at the connection point, resulting in inaccurate test results. A slider is set at the bottom of the transverse loading box, so that it can move flexibly to adapt to stiffened plates to be tested with different widths, expanding the use range of the test device. At the same time, the control algorithm of the loading device is optimized to make the loading device operate more stably.

Claims

1. A marine stiffened plate ultimate strength test device under multi-axial load, characterized in that It includes a test frame, a lateral loading device, a longitudinal loading device, and a stiffened plate fixture installed within the test frame. The test frame is in the shape of a right-angled quadrilateral. The stiffened plate fixture is used to clamp the stiffened plate to be tested. Two mutually perpendicular sides of the stiffened plate fixture are respectively connected to the lateral loading device and the longitudinal loading device. The lateral loading device and the longitudinal loading device are respectively used to apply lateral and longitudinal loads to the stiffened plate to be tested. During the test, the plate surface of the stiffened plate to be tested is perpendicular to the ground.

2. The ultimate strength test device for marine stiffened plates under multi-axis loads according to claim 1, characterized in that, The test frame includes a support platform (11), a first upright column (2), a second upright column (3), and a cross beam (1). The first upright column (2) and the second upright column (3) are installed on the upper end surface of the support platform (11). The cross beam (1) is installed on the tops of the first upright column (2) and the second upright column (3). The lateral loading device is installed on the first upright column (2), and the longitudinal loading device is installed on the cross beam (1).

3. The ultimate strength test device for marine stiffened plates under multi-axial loads according to claim 2, wherein The stiffened plate fixture includes an upper fixture (6), a lower fixture (7), a left fixture (8), and a right fixture (9). Each fixture is respectively used to clamp a side edge of the stiffened plate to be loaded. The upper fixture (6) is connected to the longitudinal loading device. The lower fixture (7) is installed on the upper end surface of the support platform (11). The left fixture (8) is connected to the lateral loading device. The right fixture (9) is installed on the second upright column (3).

4. The ultimate strength test device for marine stiffened plates under multi-axial load as claimed in claim 3, wherein, Grooves for placing the stiffened plate to be tested are provided in the middle of the upper fixture (6), the lower fixture (7), the left fixture (8), and the right fixture (9). The bottom of the groove is a straight line or an arc.

5. The ultimate strength test device for marine stiffened plates under multi-axis load as described in claim 3, characterized in that, A longitudinal loading box (5) is provided between the upper fixture (6) and the longitudinal loading device. The side of the longitudinal loading box (5) away from the upper fixture (6) is connected to the longitudinal loading device. A lateral loading box (4) is provided between the left fixture (8) and the lateral loading device. The side of the lateral loading box (4) away from the left fixture (8) is connected to the lateral loading device.

6. The ultimate strength test device for a marine stiffened plate under multi-axial loading according to claim 5, wherein A slide rail (10) is provided on the upper end surface of the support platform (11). A slider is provided at the bottom of the lateral loading box (4), and the slider is installed on the slide rail (10).

7. The ultimate strength test device for marine stiffened plates under multi-axial load as claimed in claim 5, wherein, A pressure sensor is provided on the side of the lateral loading device connected to the lateral loading box (4), and a pressure sensor is also provided on the side of the longitudinal loading device connected to the longitudinal loading box (5).

8. The ultimate strength test device for marine stiffened plates under multi-axis loadings according to claim 7, characterized in that It further includes a controller, which is used to control the lateral loading device and the longitudinal loading device to apply loads and receive the data from the pressure sensors.

9. The ultimate strength test device for marine stiffened plates under multi-axial loads according to claim 1, characterized in that, Both the lateral loading device and the longitudinal loading device adopt hydraulic cylinders.

10. A test method for the test device of the ultimate strength of a marine stiffened plate under multi-axial load according to any one of claims 1-9, characterized in that, It includes the following steps: Step 1: Use the loading plate fixture to fix the stiffened plate to be tested within the test frame. Step 2: Apply lateral and longitudinal loads to the stiffened plate to be tested through the lateral loading device and the longitudinal loading device, and record the force and deformation conditions of the stiffened plate to be tested.

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