Device and method for testing ultimate strength of large-scale cabin structural model under complex load

Abstract

The invention discloses a large-scale cabin section structure model ultimate strength test device and test method under a complex load, and relates to the technical field of ship structure test, and the device comprises a large-scale structure test platform, a large-scale cabin section structure model, a boundary constraint device, a support constraint device and a complex load loading device. The bottom of the model is positioned and supported through four sets of supporting constraint devices, one end simulates end boundary conditions through two sets of boundary constraint devices, and the other end applies a composite load of bending moment, torque and surface pressure through a complex load loading device. According to the method, the multi-load coupling effect borne by a ship under the real sea condition can be accurately simulated, the problems that an existing test load working condition is single, boundary constraint is inaccurate and the like are solved, accurate evaluation of the ultimate strength and the failure mechanism of a large-scale cabin section structure model under the multi-load combined effect is achieved, and the test efficiency is improved. And the spanning of a ship structure strength test technology from single-load evaluation to multi-load coupling accurate evaluation is promoted.

Description

Technical Field

[0001] This invention relates to the field of ship structure testing technology, and in particular to a test apparatus and method for ultimate strength testing of a large-scale compartment structure model under complex loads. Background Technology

[0002] Large surface vessels (such as tankers, container ships, and bulk carriers) have hulls that are typically thin-walled and complex structures with large main dimensions and intricate internal longitudinal and transverse components. In the harsh conditions of the open ocean, the hull is subjected to a complex coupling of various loads, including bending moment, torque, and surface hydrodynamic pressure, significantly increasing the risk of structural failure. Therefore, accurately assessing the ultimate structural strength is crucial for ensuring ship safety. Currently, obtaining the ultimate structural strength mainly relies on numerical simulation and physical model testing. However, numerical simulation is limited by factors such as material nonlinearity, residual welding stress, and initial defects, making it difficult to achieve complete accuracy. Therefore, physical model testing has become the most direct and reliable method for studying the ultimate structural strength.

[0003] In model testing, small- to medium-scale scaled models have long been widely used both domestically and internationally. To reduce costs and manufacturing complexity, these models typically reduce the structural form and number of hull components, leading to a significant "longitudinal fracture reduction" effect. This results in non-negligible deviations between the model and the actual ship in terms of cross-sectional moments of inertia, stiffness, and load distribution, severely impacting similarity. Furthermore, the inherent scale effect of small- to medium-scale models, along with differences in material properties and construction processes, prevents many key mechanical properties and failure mechanisms of actual ships from being accurately reflected in the model, limiting the reliability of test results and the confidence level of similarity conversion. To overcome these shortcomings and improve test fidelity, the use of large-scale models has become an international trend. Large-scale models can significantly reduce the impact of scale effects, more realistically reflecting the overall buckling modes, failure paths, and construction process details of the actual ship structure. Their ultimate strength can more accurately represent the ultimate strength of the actual ship structure, thus providing a more quantitative and reliable safety boundary for structural design. Therefore, conducting ultimate strength tests on large-scale compartment structural models is a crucial prerequisite for high-precision ship structural performance evaluation.

[0004] Furthermore, current ultimate strength tests on compartment models generally employ single-load loading devices (such as applying pure bending moment or pure torque through reaction frames and actuators). These methods have significant limitations: firstly, the load conditions are overly idealized and cannot replicate the complex stress state of multiple load components such as bending moment, torque, and surface pressure during actual navigation; secondly, the evaluation conclusions may be distorted. The failure path and ultimate strength of a structure under multi-directional combined loads have a non-linear coupling relationship with the results of each load acting individually, rather than a simple superposition. Single-load tests cannot reveal this coupling effect, potentially leading to misjudgments of the structure's true safety margin or overlooking potential weaknesses. As ship mission requirements expand to more complex sea states, developing a large-scale compartment structural model ultimate strength testing device and method capable of simulating the coordinated loading of multiple loads such as bending moment, torque, and surface pressure has become an urgent need to accurately assess the true performance boundaries of ship structures under complex extreme loads and overcome current technological bottlenecks. Summary of the Invention

[0005] To address the shortcomings of existing production technologies, this applicant provides a testing device and method for ultimate strength testing of large-scale structural module models under complex loads. This solves the problems of current model tests, such as the simplification of load conditions, the inability to realistically simulate the combined effects of bending moment, torque, and surface pressure, and the inability to accurately reveal the coupled failure mechanisms and ultimate bearing capacity of structures under extremely complex stress states. This device and method can achieve ultimate strength testing and accurate evaluation of large-scale ship module models under coupled multi-load conditions, promoting the development of ship structural ultimate strength testing technology from traditional single-load evaluation to precise evaluation of multi-load synergistic loading and coupled failure.

[0006] The technical solution adopted in this invention is as follows: A large-scale module structure model ultimate strength test device under complex loads includes a large-scale structural test platform, which supports the entire test device. The large-scale module structure model is mounted on the upper surface of the large-scale structural test platform through multiple support and constraint devices. Boundary constraint devices are arranged on the large-scale structural test platform located on one side of the large-scale module structure model to simulate the boundary conditions at the end of the model. A complex load loading device is arranged in the middle of the large-scale module structure model and on the large-scale structural test platform. The complex load loading device is connected to the large-scale module structure model and is used to apply one or more composite loads of bending moment, torque and surface pressure to the model.

[0007] Its further technical solution lies in: The structure of the large-scale module structure model includes an effective test section, a transition section, and a loading section, and each section is designed and constructed in a continuous and integrated manner.

[0008] The effective test section, as the core area of ​​the model, is located in the middle of the model. The two ends of the effective test section are rigidly connected to the transition section by welding. The transition section adopts a gradient cross section design and achieves a smooth transition from the effective test section to the loading section through precisely controlled gradient stiffness changes. The loading section is located at both ends and is connected to the transition section by a reinforced structure.

[0009] The boundary constraint device comprises a reaction frame, a fixed crossbeam, a supporting concave spherical hinge, a supporting convex spherical hinge, a connecting plate, and high-strength bolts. Two reaction frames are fixedly installed on a large-scale structural test platform using high-strength anchor bolts. The fixed crossbeam is installed on the panels of the two reaction frames. The supporting concave spherical hinge is fixedly installed on the fixed crossbeam. The connecting plate is welded to a large-scale cabin structural model. The supporting convex spherical hinge has a slotted groove, through which multiple high-strength bolts pass and connect to threaded holes on the connecting plate. The slotted groove allows relative displacement between the supporting convex spherical hinge and the connecting plate along the lateral direction of the model. The supporting concave spherical hinge and the supporting convex spherical hinge are connected by mutually mating spherical features.

[0010] The boundary constraint device releases the rotational degrees of freedom around the ox and oy axes at the model boundary constraint points through ball joint connections, and releases the lateral displacement degrees of freedom along the ox axis through the cooperation of the waist groove and high-strength bolts; all kinematic pairs are coated with grease to minimize the influence of friction on the boundary conditions, thereby accurately simulating the constraint state required for the large-scale compartment structure model.

[0011] The structure of the support and constraint device includes a support base, a rolling wheel assembly, a concave support device, and a convex support device. The support base is fixed to a large structural test platform by anchor bolts. A linear guide groove is formed on the top of the support base along its longitudinal direction. The rolling wheel assembly is fitted into the guide groove through wheel housings and rolls freely in the oz direction. The bottom of the concave support device has an installation interface corresponding to the rolling wheel assembly, and the two are fixedly connected by fasteners. The top of the concave support device is machined with a concave spherical surface. The convex support device is welded and fixed to the bottom of the large-scale cabin section structural model. The bottom of the convex support device is machined with a convex spherical surface that matches the concave spherical surface of the concave support device. The two form a rotating pair through spherical mating.

[0012] The complex load loading device consists of three independent reaction frames, five sets of servo loading actuator units, corresponding load sensors, connecting components, and a surface pressure simulation device.

[0013] The reaction frame of the complex load loading device is located in the center and is fixed to the large structural test platform by a group of high-strength anchor bolts. The No. 5 loading actuator is installed on the panel. The No. 5 load sensor and the surface pressure simulation device are connected in series at the front end of the actuator. The front end of the surface pressure simulation device is formed with a curved surface that matches the curvature of the outer plate of the model compartment. It is used to precisely fit with the surface of the model during the test, so as to apply and accurately control the distributed surface pressure P.

[0014] The reaction frames on the left and right sides of the complex load loading device are also fixed to the large structural test platform by high-strength anchor bolts. Two actuator units are installed on the left reaction frame: the middle unit includes a first-stage loading actuator connecting plate, a first-stage loading actuator, a first-stage load sensor, and a first-stage actuator ball head connected in sequence; the upper unit includes a third-stage loading actuator, a third-stage load sensor, and a third-stage actuator ball head fixed by a third-stage loading actuator connecting plate. Correspondingly, the left loading section of the model... In terms of structural reinforcement, a concave ball head of actuator No. 1 is welded in the middle, forming a spherical pair with the convex ball head of actuator No. 1; a concave ball head of actuator No. 3 is welded in the upper part, forming a spherical pair with the convex ball head of actuator No. 3; the arrangement of the reaction frame on the right side is symmetrical to that on the left side but the position is mirrored, with the middle unit corresponding to actuator No. 2 and the lower unit corresponding to actuator No. 4, and they are connected by a ball joint pair through the convex ball head of actuator No. 2 and the convex ball head of actuator No. 4, and the concave ball head of actuator No. 2 and the concave ball head of actuator No. 4 welded on the right side of the model.

[0015] A test method for an ultimate strength test apparatus for a large-scale module structural model under complex loads includes the following operational steps: S1. Experimental preparation and initial state establishment: A large-scale module structure model is installed on a large-scale structural test platform. The bottom of the model is positioned and supported by a support and constraint device, and a set boundary condition is applied to one end of the model by a boundary constraint device. A complex load loading device is connected, and strain and displacement measurement sensors are installed on the model surface and key locations. The system is preloaded, and after confirming that all devices and measurement systems are working properly, the external load is removed, and the complex load loading device is switched to load control mode, and the model is restored to its initial state without external load. S2. Methods for applying and controlling combined loads: Based on the experimental objectives, a combined load of bending moment, torque, and surface pressure is applied using a complex load loading device, employing one of the following two control methods: First, the bending-to-torsion ratio is fixed: the surface pressure simulation device is controlled to apply and maintain a constant surface pressure P as the initial stress state of the model; under this state, the third and fourth loading actuators are controlled to work together to apply an equal concentrated force load F2, while the first and second loading actuators remain unloaded; under this condition, the bending moment M and torque T borne by the effective test section of the model are determined by the load F2 and the stress arms l1 and r1, and the ratio α of bending moment to torque is a fixed value, i.e., α = M / T = l1 / r1; Second, the bending-to-torsion ratio is adjustable: the surface pressure simulation device applies and maintains a constant surface pressure P; the first and second loading actuators are coordinated to apply a concentrated force load F1, and the third and fourth loading actuators are coordinated to apply a concentrated force load F2; by adjusting the load ratio of F1 and F2, the ratio α of bending moment and torque borne by the effective test section of the model is continuously changed; combined with the structural design of lever arms l1 and r1, the joint loading of any target bending-to-torsion ratio can be achieved. S3, Elasticity Test: Before the formal ultimate strength test, an elastic test is performed: under load control mode, the load is applied from the initial state to the maximum predetermined load according to a predetermined load spectrum. This load value does not exceed 50% of the model's predicted ultimate load, and it is ensured that the model does not produce plastic strain. After stabilization, the load is completely unloaded to verify the accuracy of the measurement system and confirm that the structure is in the linear elastic response stage. S4. Ultimate Strength Test: After completing the elasticity test, conduct the ultimate strength test, selecting one of the following loading schemes: First, load-displacement control switching loading: S4.1 Load Control Loading: Loading is performed gradually in load control mode, so that the model is subjected to force within the linear elastic range until the preset load is reached. This load is generally 90% of the predicted ultimate load. The loading process is divided into multiple load steps, and the load is stabilized for at least 30 seconds after each step is completed. S4.2 Control Mode Switching: After reaching the preset load, the loading system sets displacement protection and switches to displacement control mode; under the combined bending moment-torque loading condition, the loading control system coordinates the movement of each actuator to maintain the set load ratio and avoid motion interference. S4.3 Displacement-controlled loading: Continue loading in displacement-controlled mode until the model reaches its ultimate strength and enters the post-buckling stage. The loading process can be divided into multiple displacement steps and implemented step by step. Second, full-process displacement control loading: From the initial state, the loading system runs directly in displacement control mode, and coordinates and controls each actuator to load through the loading control system until the model reaches the ultimate strength and enters the post-buckling stage. S5. Trial Termination, Unloading, and Data Acquisition: Once the model enters the post-buckling stage and loses its main load-bearing capacity, the loading system performs unloading operations in displacement control mode until the loads of each actuator are restored to or close to their initial values. All load, displacement, and strain data during the loading, failure, and unloading processes are collected and recorded. Based on this, the ultimate strength, failure mechanism, and complete load-displacement response curves of the large-scale segment structure model under specific combined loads are analyzed and obtained.

[0016] The beneficial effects of this invention are as follows: This invention enables the simulation of complex loads that closely approximate real sea conditions: By integrating bending moment, torque and surface pressure loading functions into a complex load loading device, it is possible to accurately simulate the multi-load coupling effect of large surface ships in harsh environments at sea. This overcomes the limitation of traditional test devices that can only apply a single load, making the stress state of the ultimate strength test closer to engineering reality. It provides a key technical means for accurately evaluating the true load-bearing capacity of ship structures under complex and extreme sea conditions.

[0017] This invention significantly improves the authenticity and extrapolation confidence of experimental results: By employing a large-scale segment structure model, the "longitudinal fracture reduction" effect and scale effect, which are unavoidable in traditional scaled-down models, are effectively reduced. This allows the model's stiffness distribution, buckling modes, failure paths, and construction details to represent the actual ship structure with higher fidelity. This innovative design enables the ultimate strength data obtained from experiments to be extrapolated to the actual ship more accurately, providing a more quantitative and reliable safety boundary for ship structural design.

[0018] This invention provides a highly flexible capability for controlling composite loads: By coordinating the control of multiple servo-loaded actuators and adjusting the actuation load and lever arm, precise control of the bending moment to torque ratio (bending-torsion ratio) is achieved, moving from a fixed value to continuous adjustment. This design allows for structural performance testing under various design conditions and extreme sea states with a single model installation, eliminating the need for repeated model disassembly and assembly, thus greatly improving testing efficiency and economic benefits.

[0019] This invention ensures the accuracy of boundaries and constraints during the experiment: By employing boundary constraint devices capable of releasing multiple degrees of freedom and low-friction support constraint devices, the end constraints and bottom support conditions of the compartment model were accurately simulated. The combination of ball joint connections and rolling wheel sets, along with the application of lubricating grease, minimized the interference of the test device itself on the free deformation of the model, ensuring that the failure mechanism and ultimate strength measured in the test truly reflect the performance of the structure itself.

[0020] This invention establishes a complete, reliable, and repeatable testing method: A standardized test procedure was established, which includes elasticity test verification, two combined load control methods (fixed bending-to-torsion ratio and adjustable bending-to-torsion ratio), and two ultimate loading schemes (load-displacement control switching loading and full-range displacement control loading). The loading control system can coordinate and ensure the collaborative work of multiple actuators under complex combined loading conditions, making the entire ultimate strength test process scientific and controllable, and providing a standardized test standard for the performance evaluation of ship structures.

[0021] This invention has driven a leapfrog development in ship structural strength testing technology: It breaks through the technical bottleneck of traditional single load assessment and realizes the technical leap from single load assessment to accurate assessment of multi-load coupling. It provides a pioneering technical solution for revealing the nonlinear coupling failure mechanism of ship structures under multi-directional combined loads, discovering potential weak links, and accurately assessing the true safety margin of the structure.

[0022] This invention relates to an experimental apparatus and method for conducting ultimate strength tests on large-scale structural models of surface ships under the combined effects of bending moment, torque, and surface pressure. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a schematic diagram of the large-scale compartment structure model of the present invention.

[0025] Figure 3 This is a schematic diagram of the boundary constraint device of the present invention.

[0026] Figure 4 for Figure 3 A magnified view of part A in the middle.

[0027] Figure 5 This is a schematic diagram of the structure of the support and constraint device of the present invention.

[0028] Figure 6 This is an exploded view of the support and constraint device of the present invention.

[0029] Figure 7 This is a schematic diagram of the installation of the complex load loading device of the present invention.

[0030] Figure 8 This is a schematic diagram of the lever arm and load of the large-scale compartment structure model of the present invention.

[0031] in: 100. Large-scale structural testing platform; 200. Large-scale module structural model; 300. Boundary constraint device; 400. Support constraint device; 500. Complex load loading device; 201. Effective test section; 202. Transition section; 203. Loading section; 301. Reaction frame; 302. Fixed crossbeam; 303. Supporting concave ball joint; 304. Supporting convex ball joint; 305. Connecting plate; 306. High-strength bolt; 401. Support base; 402. Roller assembly; 403. Concave support device; 404. Convex support device; 501. Loading Actuator No. 1; 502. Loading Actuator No. 2; 503. Loading Actuator No. 3; 504. Loading Actuator No. 4; 505. Loading Actuator No. 5; 506. Load Sensor No. 1; 507. Load Sensor No. 2; 508. Load Sensor No. 3; 509. Load Sensor No. 4; 510. Load Sensor No. 5; 511. Loading Actuator No. 1 Connecting Plate; 512. Loading Actuator No. 2 Connecting Plate; 513. Load Sensor No. 3 Loading actuator connecting plate; 514, No. 4 loading actuator connecting plate; 515, No. 5 loading actuator connecting plate; 516, No. 1 actuator convex ball head; 517, No. 2 actuator convex ball head; 518, No. 3 actuator convex ball head; 519, No. 4 actuator convex ball head; 520, No. 1 actuator concave ball head; 521, No. 2 actuator concave ball head; 522, No. 3 actuator concave ball head; 523, No. 4 actuator concave ball head; 524, surface pressure simulation device. Detailed Implementation

[0032] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0033] like Figures 1-8 As shown in the figure, the specific structure and function of the ultimate strength test device for a segment structure model under complex loads in this embodiment are as follows: It mainly includes: a large-scale structural test platform 100, a large-scale module structural model 200, a boundary constraint device 300, a support constraint device 400, and a complex load loading device 500.

[0034] The large-scale structural test platform 100 is used to support the entire test device; the large-scale module structural model 200 is arranged on the platform, and its bottom is positioned and supported by four sets of support and constraint devices 400; on one side of the model, two sets of boundary constraint devices 300 are installed on the platform to simulate the boundary conditions at the end of the model; on the other side of the model, a complex load loading device 500 is installed on the platform to apply one or more composite loads of bending moment, torque and surface pressure to the model.

[0035] The large-scale module structure model 200 comprises three parts: the effective test section 201, the transition section 202, and the loading section 203. These sections are designed and constructed using a continuous, integrated approach. The effective test section 201, as the core area of ​​the model, is located in the middle of the model, and its two ends are rigidly connected to the transition section 202 by welding. The transition section 202 adopts a gradually changing cross-section design, achieving a smooth transition from the effective test section 201 to the loading section 203 through precisely controlled gradient stiffness changes. The loading section 203 is located at both ends of the model and is connected to the transition section 202 through a reinforced structural design. Its ends are designed with specialized reinforced structures for reliable connection with the boundary constraint device 300 and the complex load loading device 500. Under the combined action of bending moment, torque, and surface pressure, the large-scale module structure model 200 will exhibit a complex coupled deformation morphology, as shown in the coordinate system in the attached figure. o-xyz During the process, the model mainly undergoes the following deformations: the central axis of the model will change from a straight line to a spatial deflection curve, accompanied by lateral shrinkage deformation; each section of the model will experience circumferential deformation. ox The shaft undergoes torsional rotation, accompanied by a circumferential rotation. oy The bending and rotation of the shaft, under the dominant torque, will cause relative torsion between the cross sections of the model, resulting in torsional deformation distributed along the axis. This integrated construction method ensures the effective transfer of load from the loading end to the test section, avoids stress concentration caused by discontinuous connections, and provides a structural basis for accurately simulating the real stress state of a ship's compartment.

[0036] The boundary constraint device 300 includes reaction frames 301, a fixed crossbeam 302, a supporting concave spherical hinge 303, a supporting convex spherical hinge 304, a connecting plate 305, and high-strength bolts 306. The two reaction frames 301 are fixedly mounted on the large structural test platform 100 using high-strength anchor bolts. The fixed crossbeam 302 is mounted on the panels of the two reaction frames 301. The supporting concave spherical hinge 303 is fixedly mounted on the fixed crossbeam 302. The connecting plate 305 is welded to the end of the loading section 203 of the large-scale cabin structural model 200 and has four threaded holes. The supporting convex spherical hinge 304 has a slotted groove, through which the four high-strength bolts 306 connect to the threaded holes on the connecting plate 305. This slotted groove allows relative displacement between the supporting convex spherical hinge 304 and the connecting plate 305 along the lateral direction of the model. The supporting concave spherical hinge 303 and the supporting convex spherical hinge 304 are connected by their mating spherical features. The device releases the rotational degrees of freedom around the ox and oy axes at the model boundary constraint points through ball joint connection, and releases the lateral displacement degrees of freedom along the ox axis through the fit between the waist groove and the high-strength bolt 306; each kinematic pair surface is coated with grease to minimize the influence of friction on the boundary conditions, thereby accurately simulating the constraint state required by the large-scale compartment structure model 200.

[0037] Four sets of support and restraint devices 400 are arranged between the loading section 203 reinforcement structure of the large-scale module structural model 200 and the large-scale structural test platform 100. They provide vertical support while releasing other degrees of freedom required by the model during the test. Each set of support and restraint devices 400 includes a support base 401, a rolling wheel assembly 402, a concave support device 403, and a convex support device 404. The support base 401 is fixed to the large-scale structural test platform 100 by anchor bolts, and a linear guide rail groove is formed on its top along the longitudinal direction of the support base 401. The rolling wheel assembly 402 is fitted into the guide rail groove through wheel housings and can move along... oz The model can roll freely in any direction. The concave support device 403 has a mounting interface at its bottom corresponding to the rolling wheel assembly 402, and the two are fixedly connected by fasteners. Its top is machined with a concave spherical surface. The convex support device 404 is welded and fixed to the bottom of the reinforcing structure of the loading section 203 of the large-scale cabin section structural model 200. Its bottom is machined with a convex spherical surface that matches the concave spherical surface of the concave support device 403. The two form a rotating pair through spherical mating. This device, through a ball joint connection between the convex support device 404 and the concave support device 403, releases the model's free rotation... ox shaft and oy The rotational degree of freedom of the axis; the longitudinal rolling of the rolling wheel set 402 within the guide groove releases the model's rotational freedom. oz The axis has translational degrees of freedom, and the friction in this direction is rolling friction. The rolling wheel assembly 402 integrates bearings, and all moving contact surfaces are coated with grease, thereby minimizing the influence of support constraints on the model's free deformation and ensuring that the model's structural response under complex loads is closer to the actual stress state.

[0038] A complex load application device 500 is installed on a large structural test platform 100 to collaboratively apply bending moment, torque, and surface hydrodynamic pressure to a large-scale compartment structural model 200. The device consists of three independent reaction frames, five sets of servo loading actuator units, corresponding load sensors, connecting components, and a surface pressure simulation device.

[0039] The reaction frame 301, located in the center, is fixed to the platform 100 by a set of high-strength anchor bolts. A No. 5 loading actuator 505 is mounted on its panel. A No. 5 load sensor 510 and a surface pressure simulation device 524 are connected in series at the front end of the actuator. The front end of the surface pressure simulation device 524 is shaped with a curved surface consistent with the curvature of the outer plate of the model section, used to precisely fit against the model surface during the test, thereby applying and accurately controlling the distributed surface pressure. P .

[0040] The reaction frames 301 located on the left and right sides are also fixed to the platform 100 by high-strength anchor bolts. Two actuator units are installed on the left reaction frame 301: the middle unit includes a first loading actuator connecting plate 511, a first loading actuator 501, a first load sensor 506, and a first actuator convex ball head 516 connected in sequence; the upper unit includes a third loading actuator 503, a third load sensor 508, and a third actuator convex ball head 518 fixed by a third loading actuator connecting plate 513. Correspondingly, on the reinforcing structure of the left loading section 203 of the model, a first actuator concave ball head 520 is welded in the middle, forming a spherical pair with the first actuator convex ball head 516; a third actuator concave ball head 522 is welded in the upper part, forming a spherical pair with the third actuator convex ball head 518. The arrangement of the right reaction frame is symmetrical to that of the left side but mirrored in position. The middle unit corresponds to actuator A2 502, and the lower unit corresponds to the fourth loading actuator 504. They are connected by a ball joint through the convex ball head 517 of the second actuator and the convex ball head 519 of the fourth actuator, and the concave ball head 521 of the second actuator and the concave ball head 523 of the fourth actuator welded to the right side of the model.

[0041] In this device, actuator 501 and actuator 502 work together to generate load F1, jointly providing the main bending moment M1; actuator 503 and actuator 504 work together to generate load F2, jointly providing torque T and additional bending moment M2. By independently controlling loads F1 and F2 and design lever arms l1 and r1, composite loading with any ratio (α = M / T) between the combined bending moment M (M = M1 + M2) and torque T can be achieved. All actuator units are connected to the model via ball joints, ensuring that the device can adapt to the bending and torsional deformations generated by the model during the application of combined loads, thereby avoiding the introduction of unintended additional constraints. A test method for an ultimate strength test apparatus for a large-scale segment structure model under complex loads, characterized by comprising the following steps: S1. Experimental Preparation and Initial State Establishment A large-scale module structure model 200 is installed on a large-scale structural test platform 100. The bottom of the model is positioned and supported by a support constraint device 400, and a set boundary condition is applied to one end of the model by a boundary constraint device 300. A complex load loading device 500 is connected, and strain and displacement measurement sensors are installed on the model surface and at key locations. The system is preloaded, and after confirming that all devices and measurement systems are working properly, the external load is removed, and the complex load loading device 500 is switched to load control mode, restoring the model to its initial state without external load.

[0042] S2. Methods for applying and controlling combined loads According to the test objectives, a combined load of bending moment, torque, and surface pressure is applied through a complex load loading device 500, using one of the following two control methods: Method 1 (Fixed Bending-Twist Ratio): The surface pressure simulation device 524 applies and maintains a constant surface pressure. P This serves as the initial stress state of the model. Under this state, the third loading actuator 503 and B2504 are controlled to work together to apply an equal concentrated force load F2. At this time, the first loading actuator 501 and A2502 remain unloaded. Under this condition, the bending moment M and torque T borne by the effective test section 201 of the model are determined by the load F2 and the stress arms l1 and r1. The ratio α of the bending moment to the torque is a fixed value, i.e., α = M / T = l1 / r1. Method 2 (Adjustable bending-to-torsion ratio): The surface pressure simulation device 524 is controlled to apply and maintain a constant surface pressure. P The first loading actuator 501 and A2502 are coordinated to apply a concentrated force load F1, and the third loading actuator 503 and B2504 are coordinated to apply a concentrated force load F2. By adjusting the load ratio of F1 and F2, the ratio α of bending moment to torque borne by the effective test section 201 of the model is continuously changed. Combined with the structural design of lever arm l1 and r1, the joint loading of arbitrary target bending-torsion ratio is realized.

[0043] S3. Elasticity Test Before the formal ultimate strength test, an elastic test is performed: under load control mode, the load is applied from the initial state to the maximum predetermined load according to a predetermined load spectrum. This load value does not exceed 50% of the model's predicted ultimate load, and it is ensured that the model does not generate plastic strain. After stabilization, the load is completely unloaded to verify the accuracy of the measurement system and confirm that the structure is in the linear elastic response stage.

[0044] S4. Ultimate Strength Test After completing the elasticity test, conduct the ultimate strength test, selecting one of the following loading schemes: Option 1 (Load-Displacement Control Switching Loading): (1) Load control loading: Gradually load the load in load control mode so that the model is subjected to force within the linear elastic range until the preset load is reached. This load is generally 90% of the predicted limit load. The loading process is divided into multiple load steps, and the load is kept stable for at least 30 seconds after each step is completed. (2) Control mode switching: After the preset load is reached, the loading system sets displacement protection and switches to displacement control mode; under the combined bending moment-torque loading condition, the loading control system coordinates the movement of each actuator to maintain the set load ratio and avoid motion interference; (3) Displacement-controlled loading: Continue loading in displacement-controlled mode until the model reaches its ultimate strength and enters the post-buckling stage. The loading process can be divided into multiple displacement steps and implemented step by step. Option 2 (Full Displacement Control Loading): From the initial state, the loading system operates directly in displacement control mode. The loading control system coordinates and controls each actuator to perform loading until the model reaches its ultimate strength and enters the post-buckling stage.

[0045] S5. Trial Termination, Unloading, and Data Acquisition Once the model enters the post-buckling stage and loses its main load-bearing capacity, the loading system performs unloading operations in displacement control mode until the loads of each actuator recover to or are close to their initial values. All load, displacement, and strain data during the loading, failure, and unloading processes are collected and recorded. Based on this, the ultimate strength, failure mechanism, and complete load-displacement response curves of the large-scale compartment structure model 200 under specific combined loads (bending moment M, torque T, and surface pressure P) are analyzed and obtained.

[0046] This embodiment achieves a simulation of complex loads that closely approximates real sea conditions: By integrating bending moment, torque and surface pressure loading functions into a complex load loading device, it is possible to accurately simulate the multi-load coupling effect of large surface ships in harsh environments at sea, overcoming the limitation of traditional test devices that can only apply a single load, and making the stress state of the ultimate strength test closer to engineering reality.

[0047] This embodiment significantly improves the authenticity and extrapolation confidence of the experimental results: By adopting a large-scale segment model, the "longitudinal fracture reduction" effect and scale effect are effectively reduced, enabling the model's stiffness distribution, buckling modes, and failure mechanisms to represent the actual ship structure with higher fidelity, providing a reliable basis for accurately extrapolating the ultimate bearing capacity of the actual ship from the test results.

[0048] This embodiment provides a highly flexible capability for adjusting composite loads: By coordinating the control of multiple servo actuators and adjusting the actuation load and lever arm, precise control of the bending moment to torque ratio (bending-torsion ratio) is achieved from a fixed value to continuous adjustment. This allows for structural performance testing under various design conditions and extreme sea states in a single model installation, greatly improving testing efficiency and economic benefits. This embodiment ensures the accuracy of boundaries and constraints during the experiment: By using boundary constraint devices that release multiple degrees of freedom and low-friction support constraint devices, the end constraints and bottom support conditions of the compartment model were accurately simulated, and the interference of the test device itself on the free deformation of the model was minimized, ensuring that the failure mechanism and ultimate strength measured in the test truly reflect the performance of the structure itself.

[0049] This embodiment establishes a complete, reliable, and repeatable testing method: The standardized test procedure, which includes elasticity testing, two combined loading control methods, and two ultimate loading schemes, was clarified. The loading control system coordinates and ensures the synergy of multiple actuators during the displacement control phase, making the entire ultimate strength test process scientific and controllable, and providing a standardized test standard for the evaluation of ship structural performance.

[0050] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A test apparatus for the ultimate strength of a large-scale module structure model under complex loads, characterized in that: The system includes a large-scale structural test platform (100), which is used to support the entire test device. A large-scale module structure model (200) is installed on the upper surface of the large-scale structural test platform (100) through multiple support and constraint devices (400). A boundary constraint device (300) is arranged on the large-scale structural test platform (100) located on one side of the large-scale module structure model (200) to simulate the boundary conditions at the end of the model. A complex load loading device (500) is arranged in the middle of the large-scale module structure model (200) and on the large-scale structural test platform (100). The complex load loading device (500) is connected to the large-scale module structure model (200) and is used to apply one or more composite loads of bending moment, torque and surface pressure to the model.

2. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 1, characterized in that: The structure of the large-scale module structure model (200) includes an effective test section (201), a transition section (202) and a loading section (203), and each section is designed and constructed in a continuous and integrated manner.

3. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 2, characterized in that: The effective test section (201) is the core area of ​​the model and is located in the middle of the model. The two ends of the effective test section (201) are rigidly connected to the transition section (202) by welding. The transition section (202) adopts a gradient cross section design and achieves a smooth transition from the effective test section (201) to the loading section (203) through precise control of gradient stiffness changes. The loading section (203) is located at both ends and is connected to the transition section (202) through a reinforced structure.

4. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 1, characterized in that: The boundary constraint device (300) comprises a reaction frame (301), a fixed crossbeam (302), a supporting concave ball joint (303), a supporting convex ball joint (304), a connecting plate (305), and high-strength bolts (306). The two reaction frames (301) are fixedly installed on the large structural test platform (100) by a set of high-strength anchor bolts. The fixed crossbeam (302) is installed on the panel of the two reaction frames (301), and the supporting concave ball joint (303) is fixedly installed on the fixed crossbeam (304). On the crossbeam (302), the connecting plate (305) is welded to the large-scale compartment structure model (200); the supporting convex ball hinge (304) is machined with a waist-shaped groove, and multiple high-strength bolts (306) pass through the waist-shaped groove and connect to the threaded holes on the connecting plate (305). The waist-shaped groove allows relative displacement between the supporting convex ball hinge (304) and the connecting plate (305) along the transverse direction of the model; the supporting concave ball hinge (303) and the supporting convex ball hinge (304) form a ball hinge connection through mutually matching spherical features.

5. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 4, characterized in that: The boundary constraint device (300) releases the rotational degrees of freedom around the ox and oy axes at the model boundary constraint points through ball joint connection, and releases the lateral displacement degrees of freedom along the ox axis through the cooperation of the waist groove and the high-strength bolt (306); each kinematic pair surface is coated with grease to minimize the influence of friction on the boundary conditions, thereby accurately simulating the constraint state required by the large-scale compartment structure model (200).

6. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 1, characterized in that: The structure of the support and constraint device (400) is as follows: it includes a support base (401), a rolling wheel assembly (402), a concave support device (403), and a convex support device (404). The support base (401) is fixed to the large structural test platform (100) by anchor bolts. A linear guide rail groove is opened on the top of the support base (401) along the longitudinal direction of the support base (401). The rolling wheel assembly (402) is embedded in the guide rail groove through wheel shells and rolls freely in the oz direction. The bottom of the concave support device (403) is provided with an installation interface corresponding to the rolling wheel assembly (402). The two are fixedly connected by fasteners. The top of the concave support device (403) is machined with a concave spherical surface. The convex support device (404) is welded and fixed to the bottom of the large-scale cabin section structural model (200). The bottom of the convex support device (404) is machined with a convex spherical surface that matches the concave spherical surface of the concave support device (403). The two form a rotating pair through spherical mating.

7. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 1, characterized in that: The complex load loading device (500) consists of three independent reaction frames (301), five servo loading actuator units, corresponding load sensors, connecting components and a surface pressure simulation device (524).

8. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 1, characterized in that: The reaction frame (301) of the complex load loading device (500) is fixed to the large structural test platform (100) by a group of high-strength anchor bolts. The panel is equipped with a No. 5 loading actuator (505). The front end of the actuator is connected in series with the No. 5 load sensor (510) and the surface pressure simulation device (524). The front end of the surface pressure simulation device (524) is formed with a curved surface that matches the curvature of the outer plate of the model compartment, which is used to precisely fit with the surface of the model during the test, thereby applying and precisely controlling the distributed surface pressure P.

9. The ultimate strength test device for a large-scale module structure model under complex loads as described in claim 4, characterized in that: The reaction frames (301) on the left and right sides of the complex load loading device (500) are also fixed to the large structural test platform (100) by high-strength anchor bolts. Two sets of actuator units are installed on the left reaction frame (301): the middle unit includes a first loading actuator connecting plate (511), a first loading actuator (501), a first load sensor (506), and a first actuator ball head (516) connected in sequence; the upper unit includes a third loading actuator (503), a third load sensor (508), and a third actuator ball head (518) fixed by a third loading actuator connecting plate (513). Correspondingly, the loading section on the left side of the model ( On the reinforced structure of 203), a concave ball head (520) of actuator No. 1 is welded in the middle, forming a spherical pair with the convex ball head (516) of actuator No. 1; a concave ball head (522) of actuator No. 3 is welded in the upper part, forming a spherical pair with the convex ball head (518) of actuator No. 3; the arrangement of the reaction frame (301) on the right side is symmetrical to that on the left side but the position is mirrored. The middle unit corresponds to the loading actuator No. 2 (502), and the lower unit corresponds to the loading actuator No. 4 (504). They are connected to the convex ball head (517) of actuator No. 2 and the convex ball head (519) of actuator No. 4 with the concave ball head (521) of actuator No. 2 and the concave ball head (523) of actuator No. 4 welded on the right side of the model to form a ball joint pair.

10. A test method for the ultimate strength test apparatus of a large-scale segment structure model under complex loads as described in any one of claims 1-9, characterized in that: The following steps are included: S1. Experimental preparation and initial state establishment: The large-scale module structure model (200) is installed on the large-scale structural test platform (100). The bottom of the model is positioned and supported by the support constraint device (400), and the boundary conditions are applied to one end of the model by the boundary constraint device (300). The complex load loading device (500) is connected, and strain and displacement measurement sensors are installed on the surface of the model and at key locations. After performing system preloading and confirming that all devices and measurement systems are working properly, the external load is removed, and the complex load loading device (500) is switched to load control mode, and the model is restored to the initial state without external load. S2. Methods for applying and controlling combined loads: According to the test objectives, a combined load of bending moment, torque, and surface pressure is applied through a complex load loading device (500), using one of the following two control methods: First, the bending-to-torsion ratio is fixed: the surface pressure simulation device (524) is controlled to apply and maintain a constant surface pressure P as the initial stress state of the model; under this state, the third loading actuator (503) and the fourth loading actuator (504) are controlled to work together to apply equal concentrated force load F2, while the first loading actuator (501) and the second loading actuator (502) remain unloaded; under this condition, the bending moment M and torque T borne by the effective test section (201) of the model are determined by the load F2 and the stress arms l1 and r1, and the ratio α of bending moment to torque is a fixed value, that is, α = M / T = l1 / r1; Second, the bending-to-torsion ratio is adjustable: the surface pressure simulation device (524) is controlled to apply and maintain a constant surface pressure P; the first loading actuator (501) and the second loading actuator (502) are coordinated to apply a concentrated force load F1, and the third loading actuator (503) and the fourth loading actuator (504) are coordinated to apply a concentrated force load F2; by adjusting the load ratio of F1 and F2, the ratio α of the bending moment and torque borne by the effective test section (201) of the model is continuously changed; combined with the structural design of lever arm l1 and r1, the joint loading of any target bending-to-torsion ratio can be realized. S3, Elasticity Test: Before the formal ultimate strength test, an elastic test is performed: under load control mode, the load is applied from the initial state to the maximum predetermined load according to a predetermined load spectrum. This load value does not exceed 50% of the model's predicted ultimate load, and it is ensured that the model does not produce plastic strain. After stabilization, the load is completely unloaded to verify the accuracy of the measurement system and confirm that the structure is in the linear elastic response stage. S4. Ultimate Strength Test: After completing the elasticity test, conduct the ultimate strength test, selecting one of the following loading schemes: First, load-displacement control switching loading: S4.1 Load Control Loading: Loading is performed gradually in load control mode, so that the model is subjected to force within the linear elastic range until the preset load is reached. This load is generally 90% of the predicted ultimate load. The loading process is divided into multiple load steps, and the load is stabilized for at least 30 seconds after each step is completed. S4.2 Control Mode Switching: After reaching the preset load, the loading system sets displacement protection and switches to displacement control mode; under the combined bending moment-torque loading condition, the loading control system coordinates the movement of each actuator to maintain the set load ratio and avoid motion interference. S4.3 Displacement-controlled loading: Continue loading in displacement-controlled mode until the model reaches its ultimate strength and enters the post-buckling stage. The loading process can be divided into multiple displacement steps and implemented step by step. Second, full-process displacement control loading: From the initial state, the loading system runs directly in displacement control mode, and coordinates and controls each actuator to load through the loading control system until the model reaches the ultimate strength and enters the post-buckling stage. S5. Trial Termination, Unloading, and Data Acquisition: When the model enters the post-buckling stage and loses its main load-bearing capacity, the loading system performs unloading operation in displacement control mode until the load of each actuator is restored to or close to the initial value; all load, displacement and strain data during loading, failure and unloading are collected and recorded throughout the process, and based on this, the ultimate strength, failure mechanism and complete load-displacement response curve of the large-scale compartment structure model (200) under specific combined load are analyzed and obtained.

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