An ice layer vertical ice breaking test device suitable for field conditions

Abstract

The application discloses an ice layer vertical ice breaking test device suitable for field conditions and belongs to the technical field of sea ice mechanical property testing. During use, an output torque is provided by a motor, the torque is transmitted to a lifting machine through a steering device and a connecting shaft, the lifting machine converts the horizontal torque into a vertical lifting force and drives a I-beam to move in the vertical direction, and vertical loading on the ice layer is realized. The lifting machine and the I-beam are flexibly connected through a flange universal joint. The I-beam moves in the vertical direction and applies a vertical loading force on the ice layer through an eccentricity-preventing pressure head. A generator provides power for the system, and the data of the pressure head and a displacement sensor during the test are recorded through a data acquisition device. The application provides a load which is perpendicular to the ice surface and vertically upward in the form of a reaction force, is not limited by water depth during use, can still provide a vertical stable loading force under the condition that the ice surface is uneven and avoid unintended bending moment on the tool itself, is more suitable for field ice test, and can reduce the requirements for waterproofing and corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of sea ice mechanical property testing technology, and relates to a test device for quasi-static icebreaking resistance, and in particular to a vertical icebreaking loading test device that can provide vertical loading force to the ice layer under the condition of lack of on-site tooling. Background Technology

[0002] The polar regions are rich in mineral, biological, and freshwater resources, making them the last treasure trove of resources on Earth. Whether it's icebreakers navigating during polar scientific expeditions or submarines breaking through ice to surface, a deeper understanding of the ice's carrying capacity is essential.

[0003] The publicly known literature includes:

[0004] The invention, titled "A High-Speed ​​Rotating Underwater Icebreaking System (CN202110459819.4)," primarily utilizes a catapult device to provide loading force for vertical icebreaking. The system described relies mainly on the inertia after catapult launch to drive vertical loading; however, this loading method not only fails to provide a constant loading rate but also makes initial velocity difficult to control. Furthermore, it cannot provide low-speed or quasi-static loading capabilities.

[0005] "An underwater ejection ice-breaking experimental device CN202220727264.7" This invention belongs to the indoor model test system. The loading and ejection devices described in the invention are all provided by a set of tooling in the laboratory. This device is not suitable for on-site ice test conditions.

[0006] The invention, "Method and Apparatus for Testing Ice Load Bearing Capacity" (CN105547839A), provides a vertical loading device for ice layers suitable for field environments. However, the loading force described in this invention is applied along the direction of gravity, i.e., squeezing the ice layer downwards from above, and is not suitable for testing the ice-breaking process as the structure emerges from below the ice layer. Furthermore, the flexible connection using anchor rods in the loading device cannot accurately control the displacement and velocity at the loading head. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a vertical ice-breaking test device suitable for field conditions. This test device is mainly used in field ice environments. Through the design of transmission devices such as turbines and lead screws, the bearing capacity of the ice layer itself is converted into the supporting force required for the loading process, thereby enabling experimental loading in the field environment.

[0008] The main technical problems solved by this invention are: 1) providing a support reaction force opposite to the direction of the loading force for vertical loading of the ice layer in the field environment through the bearing capacity of the ice layer itself; 2) providing a controllable loading speed through the rigid bearing capacity of the ice layer during the loading process; and 3) accurately measuring the loading speed and the deflection of the ice layer during the loading process through the rigid displacement transmission of the loading device.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A vertical ice-breaking test device suitable for field conditions includes a data acquisition device 1, a generator 2, a motor 3, a lifting platform 4, a flange universal joint 5, an anti-eccentric pressure head 6, a displacement sensor 7, an I-beam 8, a connecting rod 9, a steering gear 10, and a load-bearing support 11. During operation, the motor 3 provides output torque, which is transmitted to the lifting platform 4 via the steering gear 10 and the connecting rod 9. The lifting platform 4 converts the horizontal torque into a vertical lifting force, driving the I-beam 8 to move vertically, thereby achieving vertical loading on the ice layer. To prevent directional deviation of the four lifting platforms in the vertical direction from generating torque or bending forces on the I-beam 8, the lifting platform 4 and the I-beam 8 are flexibly connected via the flange universal joint 5. The I-beam 8 moves vertically and applies a vertical loading force to the ice layer through the anti-eccentric pressure head 6. The generator 2 provides power to the motor 3 and the data acquisition device 1, which records data from the spoke-type sensor 6-2 and the displacement sensor 7 during the test. The specific structure is described below:

[0011] The bottom surface of the elevator 4 is arranged on the ice surface via a support bracket 11, and adjacent elevators 4 are connected by a connecting rod 9. The elevator 4 consists of four elevators arranged synchronously in a rectangular array. Using four elevators provides four support points when driving the I-beam 8, thus preventing the entire device from overturning due to tilting of the crossbeam of the I-beam 8 caused by eccentricity or other reasons. Under the action of vertical load, the ice layer will first develop cracks at the point of action. After the cracks expand, they will divide the ice layer into multiple fan-shaped areas. When the fan-shaped areas undergo bending failure, the ice layer reaches its ultimate load-bearing capacity. Therefore, the full expansion of cracks is an important indicator of the validity of the test results. Since the worm gear of the elevator 4 needs to break and penetrate the ice layer, the spacing between the four elevators 4, i.e., the size of the rectangular array, determines the area of ​​ice layer that the device can load, i.e., the sample size. Based on the bending strength and fracture toughness of sea ice, it can be calculated that the crack radius of a square sea ice at the time of failure is approximately 1 / 3 of the ice thickness, and the crack propagation length is approximately 5 times. Therefore, it can be calculated that the length of the rectangular array composed of four elevators 4 needs to be more than 5 times the ice thickness.

[0012] The flange universal joint 5 is located below the ice surface, with one flange universal joint 5 under each elevator 4. The flange universal joint 5 connects the worm gear of the elevator 4 to the I-beam 8. Due to the structural characteristics of the flange universal joint 5, the direction of the connecting rods can be freely adjusted while subjected to a large vertical tensile force. Because naturally formed ice surfaces have low flatness, it is difficult to control the positional accuracy of the elevator 4 during operation. When the positional accuracy is insufficient, the worm gears of the four elevators 4 are not completely parallel. Continued vertical movement of the worm gear in this case will generate a large torque on the I-beam 8. Using the flange universal joint 5 can effectively release the torque generated when the vertical accuracy between the worm gear of the elevator 4 and the I-beam 8 is insufficient, thus making the device suitable for the field environment.

[0013] The anti-eccentricity pressure head 6 is positioned in the middle of the crossbeam of the I-beam 8 to prevent load eccentricity from generating torque on the spoke-type force sensor when the load is at the bottom of the ice surface. The lower surface of naturally formed ice layers typically has low flatness, and in field tests, the ice surface where the supporting bracket 11 is located is also uneven. Therefore, the movement direction of the I-beam 8 cannot be guaranteed to be completely perpendicular to the ice surface. Consequently, it is difficult for the anti-eccentricity pressure head 6 to be completely perpendicular to the ice surface when loading the ice layer, and the angular error between the anti-eccentricity pressure head 6 and the ice surface will cause overall structural eccentricity.

[0014] The displacement sensor 7 is fixed on the elevator 4. It indirectly measures the vertical displacement of the anti-eccentric pressure head 6 by measuring the vertical movement stroke of the worm gear inside the elevator 4. With this design, the displacement sensor 7 does not need to directly measure the displacement of the anti-eccentric pressure head 6, thereby reducing the protection level requirements of the displacement sensor 7.

[0015] The steering gear 10 can synchronously transmit the output torque of the motor 3 to the elevator 4 through the connecting rod 9, thereby ensuring the synchronicity of the vertical displacement of the four elevators 4 and avoiding the instability of the I-beam 8 when loading ice surface in the vertical direction.

[0016] The upper end of the bearing support 11 supports the elevator 4, and the lower end is fixed to the ice surface. The supporting force required by the screw of the elevator 4 during its ascent is transmitted to the ice surface through the bearing support 11, meaning the bearing support 11 provides a reaction force for the loading of the device. Since there is a lack of infinitely rigid tooling for on-site loading tests on the ice surface, the bearing capacity of the ice surface itself provides the reaction force for the loading. The vertically downward load on the bearing support 11 can be evenly distributed onto the ice surface through its bottom support area. During the test, both the I-beam 8 and the anti-eccentric pressure head 6 apply force to the ice surface in the same way. To ensure that the damage to the ice surface is caused by the anti-eccentric pressure head 6 rather than the bearing support 11, the contact area between the bearing support 11 and the ice layer must be more than 20 times larger than the projected area of ​​the anti-eccentric pressure head 6 onto the ice surface.

[0017] Furthermore, the anti-eccentric pressure head 6 includes a detachable pressure head 6-1, a spoke-type force sensor 6-2, a hinge 6-3, and a hinge bracket 6-4. To avoid the torque generated by eccentric loading on the spoke-type force sensor 6-2, the detachable pressure head 6-1 is fixed to one end of the hinge baffle 6-5. The other end of the hinge baffle 6-5 is connected to the hinge bracket 6-4 via the hinge 6-3. The spoke-type force sensor 6-2 is placed above the I-beam 8, and its upper surface contacts the end of the hinge baffle 6-5 where the detachable pressure head 6-1 is mounted. When the detachable pressure head 6-1 compresses the ice layer, the horizontal force generated by the loading direction not being completely perpendicular to the ice surface is transmitted to the hinge bracket 6-4 through the hinge baffle 6-5, thereby preventing bending moment from being generated on the spoke-type force sensor 6-2.

[0018] Furthermore, the detachable pressure head 6-1 is fixed to the folding baffle 6-5 by bolts. During the test, pressure heads of different diameters and shapes can be replaced according to the test requirements without replacing the I-beam 8 or other loading fixtures.

[0019] Furthermore, the 6-2 spoke sensor typically has a smaller dimension (thickness) in the direction of force application, which can effectively reduce the bending moment on the sensor itself even if the direction of force application deviates from the direction perpendicular to the ice surface during the test.

[0020] Furthermore, the selection of the dimensions of the I-beam 8 needs to consider the relationship between the structural bending stiffness and cross-sectional area. Bending stiffness is related to the deformation of the I-beam 8 under stress, while the cross-sectional area is related to the weight of the I-beam 8. If the bending stiffness / cross-sectional area ratio is too small, the structure will either crush the ice surface due to excessive self-weight or deform too much to break through the ice. Given that the bearing capacity of sea ice is generally no higher than 20 kN / cm², the bending stiffness / cross-sectional area ratio when using ordinary Q235 structural steel square tubing should be higher than 0.5 / cm². 2 The maximum length of the crossbeam in the middle of the I-beam 8 should be greater than 2m. The length of the I-beam determines the maximum side length of the ice surface being loaded. If the size of the ice surface is small, the cracks in the ice cannot grow completely during the loading process, thus affecting the accuracy of the mechanical parameter test. An ice sample length of 2m can meet the testing requirements of ice layers with a thickness of less than 50cm.

[0021] Furthermore, the middle part of the connecting rod 9 is connected by a coupling. When conducting experiments on naturally formed ice surfaces, the flatness of the ice surface is low and cannot meet the horizontal position accuracy of the output torque of the elevator 4. At this time, the coupling can reduce the shaft torque and vibration caused by the horizontal position difference of the elevator 4 by its own angular deflection.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) This invention provides a load perpendicular to the ice surface and vertically upward in the form of reaction force, converting the supporting force of the ice layer itself into a loading force, so that the use of the device is not limited by the water depth. The motor 3 converts the horizontal torque into a vertical lifting force through the elevator 4. The bearing bracket 11 transmits the vertical lifting force to the flange universal joint 5 through the vertical supporting force on the ice layer. The flange universal joint 5 transmits the vertical lifting force to the I-beam 8. The I-beam 8 transmits the vertical lifting force to the anti-eccentric pressure head 6, which finally forms a vertically upward compressive force on the ice layer.

[0024] (2) Through multiple lifting, universal joint flange and anti-eccentric pressure head design, the present invention can still provide vertical stable loading force and avoid generating unexpected bending moment on the loading tool itself under the condition of uneven ice surface in the field test, making the device more suitable for ice test.

[0025] (3) By calculating the self-weight of the tooling, the load-bearing capacity of the ice layer and the loading capacity, this invention ensures that the tooling will not crush the ice surface and fall into the water due to excessive self-weight when providing the required loading force, making the device suitable for on-site ice testing.

[0026] (4) The present invention enables the loading of ice layers from underwater by installing transmission devices such as elevators and steering gears above the water surface, thereby reducing the requirements for the waterproof and corrosion-resistant levels of the transmission devices. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall invention.

[0028] Figure 1 The components are: 1. Data acquisition device, 2. Generator, 3. Electric motor, 4. Elevator, 5. Flange universal joint, 6. Anti-eccentric pressure head, 7. Displacement sensor, 8. I-beam, 9. Connecting shaft, 10. Steering gear, 11. Bearing support.

[0029] Figure 2 A side view showing the vertical lifting force of the invention.

[0030] Figure 3 A partial schematic diagram to prevent eccentric pressure heads.

[0031] Figure 3 In the middle: 6-1 Detachable pressure head, 6-2 Spoke-type force sensor, 6-3 Folding, 6-4 Folding bracket, 6-5 Folding baffle. Detailed Implementation

[0032] The structure, operation process, testing process, and implementation examples of the present invention will be further described below with reference to the accompanying drawings.

[0033] Figure 1The diagram shows the overall configuration of the device. Generator 2 supplies power to data acquisition device 1 and motor 3. Motor 3 is fixed to the support bracket 11 by nuts. Motor 3 is connected to four elevators 4 via connecting rod 9. The four elevators 4 are supported on the ice surface by the support bracket 11. The vertical lead screw of elevator 4 is connected to I-beam 8 via flange universal joint 5. Anti-eccentric pressure head 6 is installed above I-beam 8, which applies a vertical loading force to the ice layer.

[0034] Figure 2 The diagram illustrates the force transmission process of the torque from the motor 3 to the anti-eccentric pressure head 6 during vertical movement. The rotational torque of the motor 3 is transmitted to the four lifting platforms 4 via the connecting rod 9. The lifting platforms 4 convert the horizontal torque into a vertical lifting force. The vertical lead screw of the lifting platform 4 is connected to the I-beam 8, causing it to move vertically. The I-beam 8 provides a vertical lifting force to the anti-eccentric pressure head 6 mounted on its upper surface.

[0035] Figure 3 The diagram shows the specific structure of the anti-eccentric pressure head 6. The detachable pressure head 6-1 is fixed on the folding baffle 6-5. The folding baffle 6-5 is connected to the folding bracket 6-4 through the folding 6-3. The lower end of the folding baffle 6-5 presses on the spoke-type force sensor 6-2. Both the spoke-type force sensor 6-2 and the folding bracket 6-4 are mounted on the I-beam 8.

[0036] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A vertical ice-breaking test device suitable for field conditions, characterized in that, The ice layer vertical ice-breaking test device includes a data acquisition device (1), a generator (2), a motor (3), a lift (4), a flange universal joint (5), an anti-eccentric pressure head (6), a displacement sensor (7), an I-beam (8), a connecting rod (9), a steering gear (10), and a load-bearing bracket (11). There are four elevators (4), and their bottom surfaces are arranged on the ice surface through the bearing brackets (11); the flange universal joints (5) and the I-beams (8) are located below the ice surface. Each elevator (4) has a flange universal joint (5) below it. The flange universal joints (5) are used to connect the worm gear of the elevator (4) and the I-beams (8); the anti-eccentric pressure head (6) is installed on the top of the I-beams (8). The four elevators (4) form a rectangular array and operate synchronously. The electric motor (3) provides output torque, which is transmitted to the elevator (4) through the steering gear (10) and the connecting rod (9). The elevator (4) converts the horizontal torque into a vertical lifting force and drives the I-beam (8) to move in the vertical direction, thereby realizing the vertical loading of the ice layer. The elevator (4) and the I-beam (8) are flexibly connected through the flange universal joint (5) to avoid the torque generated on the I-beam (8) by the directional deviation when the four elevators move in the vertical direction. The I-beam (8) moves in the vertical direction and applies a vertical loading force to the ice layer through the anti-eccentric pressure head (6). The generator (2) provides power to the electric motor (3) and the data acquisition device (1). The data acquisition device (1) records the data of the anti-eccentric pressure head (6) and the displacement sensor (7) during the test.

2. The ice-breaking test device for vertical ice breaking under field conditions according to claim 1, characterized in that: Adjacent elevators (4) are connected by a connecting rod (9); four elevators are used to provide four support points when driving the I-beam (8); The anti-eccentric pressure head (6) is arranged in the middle of the crossbeam of the I-beam (8) to prevent the load from being eccentric on the spoke force sensor when the bottom of the ice surface is uneven and to prevent the torque generated by the load on the spoke force sensor. The displacement sensor (7) is fixed on any one of the elevators (4). The displacement of the anti-eccentric pressure head (6) in the vertical direction is indirectly measured by measuring the vertical stroke of the worm gear inside the elevator (4). The steering gear (10) can synchronously transmit the output torque of the motor (3) to the elevator (4) through the connecting rod (9), thereby ensuring the synchronicity of the vertical displacement of the four elevators (4) and improving the stability of the I-beam (8) when loading ice surface in the vertical direction.

3. The ice-breaking test device for vertical ice breaking under field conditions according to claim 2, characterized in that, The distance between the four elevators (4) determines the area of ​​the ice layer that the rectangular array can be loaded, i.e. the sample size. The length of the rectangular array formed by the four elevators (4) needs to be greater than 5 times the ice thickness.

4. The ice-breaking test device for vertical ice breaking under field conditions according to claim 2, characterized in that, The upper end of the bearing support (11) is used to support the elevator (4), and the lower end is fixed on the ice surface. During the test, the I-beam (8) and the anti-eccentric pressure head (6) apply force to the ice surface in the same way. In order to ensure that the damage to the ice surface is caused by the anti-eccentric pressure head (6) rather than the bearing support (11), the area of ​​the bearing support (11) in contact with the ice layer must be greater than 20 times the projected area of ​​the anti-eccentric pressure head. The anti-eccentric pressure head projection refers to the projection of the anti-eccentric pressure head (6) on the ice surface.

5. The ice-breaking test device for vertical ice breaking under field conditions according to claim 2, characterized in that, The anti-eccentric pressure head (6) includes a detachable pressure head (6-1), a spoke-type force sensor (6-2), a hinge (6-3), and a hinge bracket (6-4). To avoid the torque generated by eccentric loading on the spoke-type force sensor (6-2), the detachable pressure head (6-1) is fixed to the top of one end of the hinge baffle (6-5). The other end of the hinge baffle (6-5) is connected to the hinge bracket (6-4) via the hinge (6-3). The hinge bracket (6-4) and... The spoke-type force sensor (6-2) is placed above the I-beam (8). The upper surface of the spoke-type force sensor (6-2) is in contact with one end of the hinge baffle (6-5) where the detachable pressure head (6-1) is installed. When the detachable pressure head (6-1) squeezes the ice layer, the horizontal force generated by the loading direction not being completely perpendicular to the ice surface is transmitted to the hinge bracket (6-4) through the hinge baffle (6-5), thus avoiding torque on the spoke-type force sensor (6-2).

6. The ice-breaking test device for vertical ice breaking under field conditions according to claim 5, characterized in that, During the test, the anti-eccentric pressure head (6) of different diameters and / or shapes can be replaced according to the test requirements without replacing the I-beam (8) or other loading fixtures.

7. The vertical ice-breaking test device for ice layers suitable for field conditions according to claim 2, characterized in that, The maximum length of the crossbeam in the middle of the I-beam (8) should be greater than 2m, and the length of the I-beam determines the maximum side length of the ice surface being loaded.

8. The vertical ice-breaking test device for ice layers suitable for field conditions according to claim 2, characterized in that, The middle part of the connecting rod (9) is connected by a coupling.

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