Asymmetric double-beam truss portal beam lifting device and stress monitoring system

Abstract

The application relates to the field of door type beam lifting machine monitoring, and particularly discloses an asymmetric double-beam truss door type beam lifting device and a stress monitoring system, which comprises a first beam lifting mechanism, a second beam lifting mechanism, a main beam and a monitoring mechanism. The two ends of the main beam are rotationally connected with the first beam lifting mechanism and the second beam lifting mechanism through first rotation connecting parts and second rotation connecting parts. The second beam lifting mechanism can be telescopically extended upwards and downwards. The monitoring mechanism comprises a sensor group, a data processor and a warning unit. The application aims to solve the technical problem of how to monitor the stress of the beam lifting device.

Description

Technical Field

[0001] This invention relates to the field of gantry crane monitoring, and specifically discloses an asymmetric double-beam truss gantry crane device and stress monitoring system. Background Technology

[0002] Gantry cranes are large, critical pieces of equipment used in bridge prefabrication yards, ports, and other locations to lift large concrete beams or heavy structural components. The safety and reliability of their structure directly affect the safety, efficiency, and cost of engineering construction.

[0003] Traditional portal frame lifting devices mostly adopt symmetrical double-beam truss structures, with identical main beams and relatively balanced stress, and their design and safety assessment methods are relatively mature. However, under specific site layouts and process requirements (for example, the lifting machine needs to pick up beams from the beam-making platform and then rotate or move them laterally to the beam transport vehicle; or the site is inclined or has stepped strata), an asymmetrical double-beam truss portal frame lifting device has emerged. One type of device typically has one main beam designed with an outstretched cantilever to facilitate flexible beam picking in limited space, while the other main beam has a conventional structure; another type of device has asymmetrical legs on both sides, with one side's legs being retractable. Although this asymmetrical design has significant advantages in terms of functionality and spatial adaptability, it also brings unprecedented complex mechanical problems: uneven stiffness and mass distribution on both sides of the structure lead to severe eccentric loading under lifting, traveling, and especially loaded rotation conditions, and the stress distribution is fundamentally different from that of a symmetrical structure. The stress states at the root of the cantilever side main beam, the mid-span of the non-cantilever side main beam, and the four legs (especially the two side legs) are quite different, and traditional mechanical analysis and safety assessment methods based on the symmetry assumption are no longer applicable.

[0004] In existing technologies, there have been some research and applications of stress monitoring for lifting machinery, but these mainly focus on general-purpose, symmetrical structures. Common monitoring methods include: 1. Periodic testing or short-term testing based on resistance strain gauges: This method is mostly manual single-point measurement, which cannot achieve long-term, continuous, and automated monitoring. The data is isolated and has poor timeliness, making it difficult to capture the true stress peak under dynamic and unsteady conditions. 2. Simple online monitoring systems: Some systems install a small number of sensors on key sections, but the arrangement of measuring points is often based on experience with symmetrical structures, failing to specifically target the stress concentration areas and deformation-sensitive areas unique to asymmetrical structures. The monitoring network has blind spots and cannot fully reflect the true load spectrum of the structure. 3. Shallow data utilization: Most existing systems only realize data display, recording, and over-limit alarms, lacking in-depth fusion analysis of multi-source heterogeneous data (such as strain, temperature, tilt angle, load, and location), and cannot intelligently correlate real-time stress state with precise working conditions (what weight, where). More importantly, it is impossible to conduct evolutionary trend analysis and predictive assessment of the structure's "health status" based on long-term monitoring data, and operation and maintenance decisions remain in a passive mode of "post-event maintenance" or "regular overhaul".

[0005] Due to the aforementioned technical limitations, there is currently a lack of effective, comprehensive, and intelligent means to perceive and assess the stress state of asymmetric double-beam truss portal frame lifting devices. Operators struggle to grasp the true safety margin under asymmetric eccentric loading in real time, and managers are unable to scientifically formulate maintenance plans. This leads to two potential risks: first, excessive conservatism reduces equipment efficiency; second, under extreme or long-term alternating loads, the accumulation of localized fatigue damage may trigger unknown structural safety hazards.

[0006] Therefore, there is an urgent need to develop a dedicated stress monitoring system that is deeply coupled with the structural characteristics of the asymmetric double-beam truss portal lifting device. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide an asymmetric double-beam truss portal lifting device and a stress monitoring system to solve the technical problem of how to monitor the stress of the lifting device.

[0008] To achieve the above objectives, the present invention provides the following technical solution: An asymmetric double-beam truss portal lifting device and stress monitoring system includes a first lifting mechanism, a second lifting mechanism, a main beam, and a monitoring mechanism. The two ends of the main beam are rotatably connected to the first lifting mechanism and the second lifting mechanism through a first rotating connection and a second rotating connection, respectively. The second lifting mechanism is capable of vertical extension and retraction. The monitoring mechanism includes a sensor group, a data processor, and an early warning unit. The sensor group includes at least: The first stress sensor, which includes a resistance strain gauge, is attached to the pin, ear plate, or adjacent main beam web / flange plate of the first rotating connection part, and is used to monitor the local alternating stress caused by the extension and rotation of the second lifting beam mechanism. The second stress sensor, which includes a vibrating wire strain sensor or a resistance strain gauge, is installed at the junction of the telescopic movable section and the fixed section of the second lifting beam mechanism to monitor the tensile and compressive stresses of the telescopic structure. An attitude sensor, including a tilt sensor or a linear displacement sensor, is mounted on the second lifting beam mechanism to monitor its tilt angle or telescopic displacement. The data processor is configured to: receive real-time data from the sensor group; calculate the stress change characteristic value of the first stress sensor under the extension and loading conditions of the second lifting beam mechanism based on the monitoring data of the first stress sensor; and compare and analyze the stress change characteristic value with a preset safety threshold. The early warning unit is configured to issue an early warning signal when the comparative analysis result is abnormal.

[0009] Optionally, the sensor group further includes a third stress sensor, which is a resistance strain gauge and is attached to the main beam structure in the connection area between the first lifting beam mechanism and the main beam. The data processor is configured to: synchronously acquire monitoring data from the first stress sensor and the third stress sensor; The stress asymmetry coefficient K in the connection area of ​​the two lifting beam mechanisms is calculated using the following formula: or In the formula, σ A σ is the real-time stress value of the first stress sensor. B This represents the real-time stress value from the third stress sensor. When the stress asymmetry coefficient K exceeds the preset asymmetry threshold K th If the load imbalance or structural abnormality warning continues for more than a preset time, the warning unit will issue a warning.

[0010] Optionally, the data processor is further configured to perform fatigue cumulative damage assessment, specifically including: Based on the dynamic stress amplitude Δσ monitored by the first stress sensor and the corresponding number of cycles n i The cumulative damage degree D is calculated using Miner's linear cumulative damage rule; The formula for calculating the dynamic stress amplitude Δσ is: , Where σ max and σ min The peak and trough values ​​of stress within a complete working cycle; The formula for calculating the cumulative damage (D) is as follows: In the formula, N i For stress amplitude Δσ i Below, the number of cycles until failure is determined based on the material's SN curve; Δσ i For the i-th stress amplitude level, N i Fatigue life at this amplitude When the cumulative damage D reaches the preset damage threshold D th At that time, the early warning unit issues a maintenance warning.

[0011] Optionally, the sensor group further includes a fourth stress sensor, which includes a fiber optic strain sensor arranged along the lower flange or main chord of the main beam at mid-span, for monitoring the overall bending stress of the main beam; the data processor is configured to: Establish a real-time estimation model for the mid-span bending moment M of the main beam: In the formula, σ S4 , where is the average or characteristic stress value monitored by the fourth stress sensor, k is the correction coefficient, and W is the flexural modulus of the main beam section. The estimated bending moment M1 is compared with the theoretical allowable bending moment M2 based on the current lifting weight to achieve a redundant safety determination of the load-bearing capacity.

[0012] Optionally, the early warning unit implements multi-level early warning, including: Level 1 Warning (Alert): When the dynamic stress amplitude Δσ of the first stress sensor exceeds 80% of the allowable stress amplitude [Δσ] for the first time, or when the stress asymmetry coefficient K exceeds K for the first time. th Triggered when 80%; Level 2 Warning: When Δσ continuously exceeds 80% of [Δσ] for a set duration, or exceeds 95% of [Δσ] in a single instance, or K continuously exceeds K th Triggered when the set duration is reached; Level 3 Warning (Emergency): When Δσ exceeds [Δσ], or the cumulative damage D reaches D th It can be triggered when the estimated bending moment M1 exceeds M2, and an automatic safety interlock will be executed.

[0013] Optionally, the sensor group further includes a temperature sensor for temperature compensation, which is attached near the resistance strain gauge or the fiber Bragg grating strain sensor; the data processor is configured to use the data from the temperature sensor to correct the temperature drift of the monitoring value of the corresponding stress sensor; the data acquisition and transmission module includes an industrial wireless transmission node and / or a wired Ethernet interface, the resistance strain gauge and the vibrating wire sensor are connected to the transmission node via signal lines, and the fiber Bragg grating strain sensor is connected to the demodulator and then to the data processor via an optical cable.

[0014] Optionally, the stress monitoring and health assessment method includes the following steps: S1: The sensor group is used to collect stress, attitude and displacement data of the second lifting beam mechanism under telescopic and load conditions in real time; S2: The data processor performs temperature compensation and filtering on the monitoring values ​​of the first stress sensor, the third stress sensor and the fourth stress sensor; S3: Calculate the dynamic stress amplitude Δσ, stress asymmetry coefficient K, cumulative damage degree D, and estimate the bending moment M1; S4: Compare the calculation results of step S3 with their respective multi-level early warning thresholds in real time; S5: Based on the comparison results, trigger the corresponding level of warning, and automatically restrict the movement of the telescopic drive component (31) or stop the lifting operation when a level 3 warning is triggered.

[0015] The working principle and beneficial effects of this solution are as follows: 1. This solution addresses the monitoring problem of movable structures in asymmetric lifting beam devices. Specifically, it defines a stress asymmetry coefficient K as a core evaluation index for the retractable second lifting beam mechanism and its first rotating connection. This directly addresses the main issue of uneven stress distribution affecting structural safety under asymmetric and dynamic load conditions. In the dynamic stress concentration areas of the first rotating connection and the telescopic mechanism itself, high-response resistance strain gauges and vibrating wire sensors are used to achieve millisecond-level stress capture. A fiber optic grating sensor array is used at the mid-span of the main beam to monitor the overall bending deformation of the structure. Multiple data points are cross-checked, and through multi-source information such as lifting weight, position, and tilt angle, each stress data point is precisely linked to specific working conditions (lifting weight, extension length, and tilt angle), giving the data clear physical meaning.

[0016] 2. This plan uses the formula A quantified, dimensionless asymmetry coefficient K is calculated. Operators and managers can then visually see, like looking at a dashboard, whether the "asymmetry" is 35% or 45%.

[0017] 3. In this scheme, the dynamic stress amplitude Δσ is calculated, and the cumulative damage degree D is calculated in real time based on the Miner criterion and the material SN curve.

[0018] 4. Upgraded Early Warning Mode: From single-point over-limit alarms to multi-source fusion intelligent diagnosis, this solution implements multi-level early warning based on cause analysis. Level 1 (Alert): K value or Δσ approaches the threshold, reminding you to pay attention; Level 2 (Warning): K value continuously exceeds the limit or Δσ single peak value is too high, combined with the working condition judgment, it is judged as an abnormal operation or load; Level 3 (Emergency / Interlock): As shown in the test example, when the system comprehensively judges "abnormal stress change (K↑) + abnormal displacement change (sliding) + no operation command", it can diagnose the specific fault of hydraulic outrigger instability and trigger the highest level alarm and automatic safety interlock (stop action). Attached Figure Description

[0019] Figure 1 This is the main view of the embodiment; Figure 2 This is the left view of an embodiment; Figure 3 This is a schematic diagram of the structure of the hydraulic cylinder and the second rotating connection.

[0020] The following are the markings in the attached diagram: 1. First lifting beam mechanism; 2. Second lifting beam mechanism; 3. Main beam; 4. First rotating connection part; 5. Second rotating connection part; 6. Hydraulic cylinder; 7. Outer rod part; 8. Inner rod part; 9. Annular gasket; 10. Upper spring; 11. Lower spring. Detailed Implementation

[0021] The following detailed description illustrates the specific implementation method: Example An asymmetric double-beam truss portal frame lifting device and stress monitoring system, such as Figure 1-3 As shown, the device includes a first lifting beam mechanism 1, a second lifting beam mechanism 2, a main beam 3, and a monitoring mechanism. The two ends of the main beam 3 are rotatably connected to the first lifting beam mechanism 1 and the second lifting beam mechanism 2 through a first rotating connection part 4 and a second rotating connection part 5, respectively. The second lifting beam mechanism 2 can extend and retract vertically. The monitoring mechanism includes a sensor group, a data processor, and an early warning unit. The first rotating connection part 4 and the second rotating connection part 5 are both rotatably connected by a pin. The second lifting beam mechanism 2 is equipped with a hydraulic cylinder 6, the upper end of which is connected to the second rotating connection part 5 to realize the extension and retraction function. Both the first rotating connecting part 4 and the second rotating connecting part 4 are provided with a buffer connecting rod. The buffer connecting rod includes an outer rod part 7, an inner rod part 8, an upper spring 10, a lower spring 11 and an annular washer 9. The inner rod part 8 is inserted into the outer rod part 7. The annular washer 9 is fixedly installed on the inner rod part 8 and is slidably connected to the outer rod part 7. The upper spring 10 and the lower spring 11 are both installed in the outer rod part 7, with the upper spring 10 located at the upper end of the annular washer 9 and the lower spring 11 located at the lower end of the annular washer 9.

[0022] The sensor group includes at least: 1. A first stress sensor, comprising a resistance strain gauge, is attached to the pin, lug plate, or adjacent main beam web / flange plate of the first rotating connection, for monitoring local alternating stress generated by the extension and rotation of the second lifting beam mechanism; a data processor is configured to: receive real-time data from the sensor group; calculate the stress change characteristic value of the first stress sensor under the extension and rotation and load conditions of the second lifting beam mechanism based on the monitoring data; compare the stress change characteristic value with a preset safety threshold; an early warning unit is configured to issue an early warning signal when the comparison analysis result is abnormal; the data processor is also configured to perform fatigue cumulative damage assessment, specifically including: based on the dynamic stress amplitude Δσ monitored by the first stress sensor and the corresponding number of cycles n i The cumulative damage degree D is calculated using Miner's linear cumulative damage rule; The formula for calculating the dynamic stress amplitude Δσ is: , Where σ max and σ min The peak and trough values ​​of stress within a complete working cycle; The formula for calculating cumulative damage (D) is: In the formula, N i For stress amplitude Δσ i The number of cycles until failure is determined based on the material's SN curve. When the cumulative damage D reaches the preset damage threshold D th At that time, the early warning unit issues a maintenance warning.

[0023] 2. The second stress sensor, including a vibrating wire strain sensor or a resistance strain gauge, is installed at the junction of the telescopic movable section and the fixed section of the second lifting beam mechanism to monitor the tensile and compressive stresses of the telescopic structure. 3. Attitude sensor, including tilt sensor or linear displacement sensor, is installed on the second lifting beam mechanism to monitor its tilt angle or telescopic displacement. 4. The sensor group also includes a third stress sensor, which is a resistance strain gauge and is attached to the main beam structure in the connection area between the first lifting beam mechanism and the main beam; the data processor is configured to simultaneously acquire the monitoring data of the first stress sensor and the third stress sensor. The stress asymmetry coefficient K in the connection area of ​​the two lifting beam mechanisms is calculated using the following formula: In the formula, σA σ is the real-time stress value of the first stress sensor. B This represents the real-time stress value from the third stress sensor. When the stress asymmetry coefficient K exceeds the preset asymmetry threshold K th If the load imbalance or structural abnormality warning is issued by the early warning unit after the preset time has been exceeded; 5. The sensor group also includes a fourth stress sensor, which comprises a fiber optic strain gauge sensor arranged along the lower flange or main chord of the main beam at mid-span, for monitoring the overall bending stress of the main beam; the data processor is configured as follows: Establish a real-time estimation model for the mid-span bending moment M of the main beam: In the formula, σ S4 , where is the average or characteristic stress value monitored by the fourth stress sensor, k is the correction coefficient, and W is the flexural modulus of the main beam section. The estimated bending moment M1 is compared with the theoretical allowable bending moment M2 based on the current lifting weight to achieve a redundant safety determination of the load-bearing capacity; 6. The sensor group also includes a temperature sensor for temperature compensation, which is mounted near the resistance strain gauge or fiber optic strain sensor; the data processor is configured to use the data from the temperature sensor to correct the temperature drift of the corresponding stress sensor's monitoring value; the data acquisition and transmission module includes an industrial wireless transmission node and / or a wired Ethernet interface, the resistance strain gauge and vibrating wire sensor are connected to the transmission node via signal lines, and the fiber optic strain sensor is connected to the demodulator and then to the data processor via an optical cable.

[0024] The early warning unit implements multi-level early warning, including: Level 1 Warning (Alert): When the dynamic stress amplitude Δσ of the first stress sensor exceeds 80% of the allowable stress amplitude [Δσ] for the first time, or when the stress asymmetry coefficient K exceeds K for the first time. th Triggered when 80%; Level 2 Warning: When Δσ continuously exceeds 80% of [Δσ] for a set duration, or exceeds 95% of [Δσ] in a single instance, or K continuously exceeds K th Triggered when the set duration is reached; Level 3 Warning (Emergency): When Δσ exceeds [Δσ], or the cumulative damage D reaches D th It can be triggered when the estimated bending moment M1 exceeds M2, and an automatic safety interlock will be executed.

[0025] In practice: Stress monitoring and health assessment methods include the following steps: S1: Real-time acquisition of stress, attitude and displacement data of the second lifting beam mechanism under telescopic and load conditions through sensor group; S2: The data processor performs temperature compensation and filtering on the monitoring values ​​of the first stress sensor, the third stress sensor and the fourth stress sensor; S3: Calculate the dynamic stress amplitude Δσ, stress asymmetry coefficient K, cumulative damage degree D, and estimate the bending moment M1; S4: Compare the calculation results of step S3 with their respective multi-level early warning thresholds in real time; S5: Based on the comparison results, trigger the corresponding level of warning, and automatically restrict the movement of the telescopic drive component (31) or stop the lifting operation when the warning level is three.

[0026] Experimental example: 1. Prototype 1.1 Parameters of the test prototype 1.1.1 Rated lifting capacity: 450 tons.

[0027] 1.1.2 Main beam span: 42 meters.

[0028] 1.1.3 Asymmetric design: The first main beam has an 8.5-meter fixed cantilever (used for beam removal area), and the second main beam is a conventional structure.

[0029] 1.1.3.1 Second lifting beam mechanism: Equipped with a hydraulic synchronous telescopic system, with a maximum telescopic stroke of ±1.5 meters (relative to the calibration zero point), and an adjustable telescopic speed of 0-1.0 meters / minute. The top end is hinged to the main beam via a 42CrMo alloy steel pin with a diameter of 120mm.

[0030] 1.1.4 Vehicle weight: approximately 680 tons.

[0031] 1.2 Detailed Installation Plan for Stress Monitoring System First stress sensor: BE120-3AA type foil resistance strain gauge, resistance 120.0±0.1Ω, sensitivity coefficient 2.08±1%. It is mounted on the lower surface of the lower chord of the main beam (stress concentration point) directly above the first rotating connection pin, using a full-bridge (bending bridge) connection to eliminate the influence of axial force. The surface is polished, cleaned, and coated with an epoxy resin protective layer. Sampling frequency: 100 Hz. Function: To monitor alternating bending stress at the cantilever side hinge point.

[0032] Second stress sensor: VWS-10F vibrating wire strain gauge, measuring range ±1500µε, resolution 0.1µε. It is mounted on the root flange of the piston rod of the telescopic cylinder of the second lifting mechanism using a special fixture, parallel to the piston rod axis. Sampling frequency 10 Hz. Function: To monitor the tensile and compressive stresses within the telescopic actuator.

[0033] The third stress sensor is a BE120-3AA type foil resistance strain gauge. It is mounted on the lower surface of the lower chord of the main beam at a symmetrical position at the connection between the first lifting beam mechanism and the main beam. Its connection method and sampling frequency are the same as the first stress sensor. Its function is to obtain the reference stress for comparison, used to calculate the asymmetry coefficient.

[0034] The fourth stress sensor is an OS1100 fiber optic strain sensor with a wavelength range of 1510-1590nm, consisting of six measuring points connected in series. The sensor series is fixed to the surface of the lower chord of the main beam (non-cantilever side) at mid-span using high-strength adhesive, with measuring points spaced 0.5 meters apart, covering an area of ​​3 meters. The fiber optic cable is run through a conduit to the junction box at the end of the main beam. The sampling frequency is 50 Hz. Its function is to monitor the overall bending stress distribution of the main beam.

[0035] Attitude sensor: CX-3T dual-axis tilt sensor, measuring range ±30°, accuracy ±0.05°. Rigidly mounted on the side of the fixed section at the top of the second lifting beam mechanism, it measures its tilt angle (θ) relative to the vertical. Sampling frequency: 50 Hz. Function: To monitor the attitude of the lifting beam mechanism.

[0036] Displacement sensor: MTS magnetostrictive displacement sensor, measuring range 0-2m, accuracy ±0.5mm. The sensor body is fixed to the fixed section of the second lifting beam mechanism, and the magnetic ring is fixed to the movable section. Sampling frequency: 50 Hz, used for precise measurement of telescopic displacement L.

[0037] Temperature sensor: PT100 platinum resistance temperature sensor, accuracy ±0.5℃. One is mounted close to strain gauge S1; the other is mounted close to strain gauge S4. Sampling frequency 10 Hz, function: to perform temperature compensation on the strain gauge measurements.

[0038] Load sensor: HBM C6 high-precision pressure sensor, integrated into the hoisting hydraulic system. Installed in the main hoisting oil circuit. Sampling frequency 50 Hz, used for real-time monitoring of the hoisted weight W.

[0039] Data acquisition and transmission: An Ethernet chassis is used, equipped with corresponding analog input, digital input, and bridge conditioning modules. All sensor signals are connected to this chassis and transmitted to the data processing server located in the control room via an industrial-grade gigabit Ethernet switch.

[0040] Data processing and analysis platform: Enables real-time data display, recording, analysis, and early warning.

[0041] 2. Detailed test procedures and processes 2.1 Preliminary Tests: System Calibration and Zero-Point Calibration ① Start the monitoring system when the prototype is completely unloaded and stationary on a level and solid ground.

[0042] ② Record the output data of all sensors for 10 minutes and take the average value as the system zero point.

[0043] ③ Conduct calibration test: Use standard weights (total weight 50 tons) to suspend below the lifting point of the second lifting beam mechanism, measure and record the stress response of S1, S4 and S5, compare with the theoretical calculation value, calibrate the system gain, and ensure that the measurement accuracy error is <±5%.

[0044] 2.2 Formal Test Conditions Condition A: Cyclic fatigue stress test during telescopic movement Objective: To verify the system's ability to capture dynamic stress amplitude Δσ and its function in calculating cumulative fatigue damage.

[0045] step: ①The hoisting mechanism is unloaded.

[0046] ② Control the second lifting beam mechanism to continuously extend and retract in a cycle at a speed of 0.6 m / min within the stroke range (-1.0 m to +0.5 m).

[0047] ③ Repeat the cycle 50 times.

[0048] ④ The data processor calculates Δσ for each cycle S1 in real time.

[0049] Typical data record: 25th cycle: σ was measured. max =+31.2 MPa, σ min =-18.7 MPa.

[0050] Calculate: Δσ 25 =|31.2-(-18.7)|=49.9 MPa.

[0051] The preset allowable stress amplitude [Δσ] is 75 MPa (based on the material fatigue limit). The system determines Δσ. 25 <[Δσ], no warning.

[0052] The platform automatically records this cycle and, based on the SN curve (material constants m=3.5, C=2.1×10),... 12 Calculate the fatigue life N under this Δσ. 25 ≈ 8.2×10 5 Times, single injury d 25 = 1 / N 25 ≈1.22×10 -6 .

[0053] After 50 cycles, the system displays the cumulative damage level D. A =Σd i ≈6.1×10 -5It is far below the preset damage threshold D. th =0.2. The interface indicates to maintenance personnel that the current operating mode has minimal impact on the fatigue of the hinge point.

[0054] Operating Condition B: Verification of Asymmetric Monitoring and Early Warning under Rated Off-center Load Objective: To verify the calculation, display, and multi-level early warning functions of the stress asymmetry coefficient K.

[0055] step: 1. Move the lifting equipment to the outermost end of the cantilever side to pick up the beam.

[0056] 2. Lift a 410-ton test counterweight (91% of rated load).

[0057] 3. After stabilization, instruct the second lifting beam mechanism to extend and retract in stages, stopping at three positions: L = -0.8m, 0m, and +0.7m, respectively, and holding the load at each position for 5 minutes.

[0058] Experimental data and system response (taking L=0m position as an example): After the load stabilized, the stress σ of S1 was measured. A =+138.6 MPa; S4 stress σ B = +85.3MPa.

[0059] The system calculates in real time: K=|138.6-85.3| / max(138.6,85.3)=53.3 / 138.6≈0.385.

[0060] Preset asymmetric threshold K th =0.40.

[0061] Since the value of K (0.385) is close to but does not exceed K th The system displays the cantilever side connection of the main beam model in yellow on the visualization interface (note the status), and displays the force asymmetry in the status bar: 38.5%.

[0062] When the instruction is scaled up to L = +0.7m (further increasing the asymmetry), the K value rises to 0.42, exceeding K0. th The system immediately triggered a level-two warning: the warning lights in the control room flashed, a warning window popped up on the screen, and the event was logged.

[0063] Operating Condition C: Safety Diagnosis and Interlocking Test for Simulated Hydraulic System Faults Objective: To verify the system's diagnostic capabilities and safety interlocking mechanisms under component failure conditions.

[0064] step: 1. Lift a 300-ton load and stabilize it at a certain height.

[0065] 2. In the control circuit of the hydraulic locking valve of the second lifting beam mechanism, a small electrical signal leakage (not a real physical leakage to avoid danger) is simulated, which causes the locking valve to experience pressure instability of about 2 Bar under load.

[0066] 3. Observe and monitor the system response.

[0067] System response process (timeline): t=0s: Fault injection.

[0068] t+15s: Displacement sensor L s A slow, continuous descent of approximately 8 mm was detected in the second lifting beam mechanism (exceeding the normal fluctuation range).

[0069] t+22s: The stress data for S1 and S4 begin to show a clear inverse trend (σ A σ continues to increase B (Continued to decrease).

[0070] t+30s: The K value, calculated based on real-time data, continuously rises from 0.35 to 0.45, and exceeds K for 5 consecutive seconds. th (0.40).

[0071] t+35s: The data processing platform makes a comprehensive judgment (rules: abnormal displacement growth + K value continuously exceeding the limit + no operation instructions), and determines that "the support system may fail".

[0072] t+36s: The system triggers a Level 3 warning (emergency): a continuous buzzer alarm is sounded, and the control screen displays a message indicating abnormal subsidence of the second outrigger. Simultaneously, a hard-wired safety interlock signal is automatically sent to the vehicle's PLC control system.

[0073] t+37s: The PLC receives the interlock signal and immediately executes: ① Stop all lifting and traveling actions; ② Put the second lifting beam mechanism's telescopic hydraulic system into a pressure-holding lock state.

[0074] The experiment successfully verified the complete closed loop from anomaly detection to intelligent diagnosis and then to automatic safety intervention.

[0075] 3. Overall Experimental Results and Conclusions The above detailed and representative experiments have fully verified the effectiveness and superiority of the technical solution of the present invention: 1. Accuracy and comprehensiveness of monitoring: Through optimized multi-type sensor fusion arrangement, the system realizes multi-scale stress perception from local hinge points, comparison benchmark points, the actuator itself to the overall main beam. The data corroborate each other, making it comprehensive and reliable.

[0076] 2. Intelligent and forward-looking assessment: The system not only displays raw stress data, but also calculates the K value of quantitative asymmetry and Δσ reflecting dynamic load strength in real time through embedded special algorithms. Based on the industry-recognized Miner criterion, it predicts fatigue life (D value), elevating monitoring to the level of health assessment.

[0077] 3. Proactive and Closed-Loop Safety: The system establishes a clear multi-level early warning (attention, warning, emergency) and response mechanism (prompt, alarm, interlock). Especially in operating condition C, it successfully demonstrated how to diagnose potential faults in their early stages and take automatic protection measures through multi-parameter fusion analysis, achieving a leap from passive alarm to proactive protection.

[0078] 4. System's engineering applicability: The sensors and data acquisition equipment used in the experiment were all industrial-grade products, with standardized installation methods, clear algorithm logic, and stable system operation, fully demonstrating that the solution can be directly applied to actual engineering projects and meets the reliability requirements of complex industrial environments.

[0079] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics in the solutions is not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or its practicality.

Claims

1. An asymmetric double-beam truss portal frame lifting device and stress monitoring system, characterized in that: It includes a first lifting beam mechanism, a second lifting beam mechanism, a main beam, and a monitoring mechanism. The two ends of the main beam are rotatably connected to the first lifting beam mechanism and the second lifting beam mechanism through a first rotating connection part and a second rotating connection part, respectively. The second lifting beam mechanism can extend and retract vertically. The monitoring mechanism includes a sensor group, a data processor, and an early warning unit. The sensor group includes at least: The first stress sensor, which includes a resistance strain gauge, is attached to the pin, ear plate, or adjacent main beam web / flange plate of the first rotating connection part, and is used to monitor the local alternating stress caused by the extension and rotation of the second lifting beam mechanism. The second stress sensor, which includes a vibrating wire strain sensor or a resistance strain gauge, is installed at the junction of the telescopic movable section and the fixed section of the second lifting beam mechanism to monitor the tensile and compressive stresses of the telescopic structure. An attitude sensor, including a tilt sensor or a linear displacement sensor, is mounted on the second lifting beam mechanism to monitor its tilt angle or telescopic displacement. The data processor is configured to: receive real-time data from the sensor group; calculate the stress change characteristic value of the first stress sensor under the extension and loading conditions of the second lifting beam mechanism based on the monitoring data of the first stress sensor; and compare and analyze the stress change characteristic value with a preset safety threshold. The early warning unit is configured to issue an early warning signal when the comparative analysis result is abnormal.

2. The asymmetric double-beam truss portal frame lifting device and stress monitoring system according to claim 1, characterized in that: The sensor group also includes a third stress sensor, which is a resistance strain gauge and is attached to the main beam structure in the connection area between the first lifting beam mechanism and the main beam. The data processor is configured to: synchronously acquire monitoring data from the first stress sensor and the third stress sensor; The stress asymmetry coefficient K in the connection area of ​​the two lifting beam mechanisms is calculated using the following formula: In the formula, σ A σ is the real-time stress value of the first stress sensor. B This represents the real-time stress value from the third stress sensor. When the stress asymmetry coefficient K exceeds the preset asymmetry threshold K th If the load imbalance or structural abnormality warning continues for more than a preset time, the warning unit will issue a warning.

3. The asymmetric double-beam truss portal frame lifting device and stress monitoring system according to claim 2, characterized in that: The data processor is also configured to perform fatigue cumulative damage assessment, specifically including: Based on the dynamic stress amplitude Δσ monitored by the first stress sensor and the corresponding number of cycles n i The cumulative damage degree D is calculated using Miner's linear cumulative damage rule; The formula for calculating the dynamic stress amplitude Δσ is: ， Where σ max and σ min The peak and trough values ​​of stress within a complete working cycle; The formula for calculating the cumulative damage (D) is as follows: In the formula, N i For stress amplitude Δσ i The number of cycles until failure is determined based on the material's SN curve. When the cumulative damage D reaches the preset damage threshold D th At that time, the early warning unit issues a maintenance warning.

4. The asymmetric double-beam truss portal frame lifting device and stress monitoring system according to claim 3, characterized in that: The sensor group further includes a fourth stress sensor, which comprises a fiber optic strain sensor arranged along the lower flange or main chord of the main beam at mid-span, for monitoring the overall bending stress of the main beam; the data processor is configured to: Establish a real-time estimation model for the mid-span bending moment M of the main beam: In the formula, σ S4 , where is the average or characteristic stress value monitored by the fourth stress sensor, k is the correction coefficient, and W is the flexural modulus of the main beam section. The estimated bending moment M1 is compared with the theoretical allowable bending moment M2 based on the current lifting weight to achieve a redundant safety determination of the load-bearing capacity.

5. The asymmetric double-beam truss portal frame lifting device and stress monitoring system according to claim 4, characterized in that: The early warning unit implements multi-level early warning, including: Level 1 Warning (Alert): When the dynamic stress amplitude Δσ of the first stress sensor exceeds 80% of the allowable stress amplitude [Δσ] for the first time, or when the stress asymmetry coefficient K exceeds K for the first time. th Triggered when 80%; Level 2 Warning: When Δσ continuously exceeds 80% of [Δσ] for a set duration, or exceeds 95% of [Δσ] in a single instance, or K continuously exceeds K th Triggered when the set duration is reached; Level 3 Warning (Emergency): When Δσ exceeds [Δσ], or the cumulative damage D reaches D th It can be triggered when the estimated bending moment M1 exceeds M2, and an automatic safety interlock will be executed.

6. The asymmetric double-beam truss portal frame lifting device and stress monitoring system according to claim 5, characterized in that: The sensor group also includes a temperature sensor for temperature compensation, which is attached near the resistance strain gauge or the fiber optic strain sensor. The data processor is configured to use the data from the temperature sensor to correct the temperature drift of the monitoring value of the corresponding stress sensor. The data acquisition and transmission module includes an industrial wireless transmission node and / or a wired Ethernet interface. The resistance strain gauge and the vibrating wire sensor are connected to the transmission node via signal lines, and the fiber optic strain sensor is connected to the demodulator and then to the data processor via an optical cable.

7. The asymmetric double-beam truss portal frame lifting device and stress monitoring system according to claim 6, characterized in that: The stress monitoring and health assessment method includes the following steps: S1: The sensor group is used to collect stress, attitude and displacement data of the second lifting beam mechanism under telescopic and load conditions in real time; S2: The data processor performs temperature compensation and filtering on the monitoring values ​​of the first stress sensor, the third stress sensor and the fourth stress sensor; S3: Calculate the dynamic stress amplitude Δσ, stress asymmetry coefficient K, cumulative damage degree D, and estimate the bending moment M1; S4: Compare the calculation results of step S3 with their respective multi-level early warning thresholds in real time; S5: Based on the comparison results, trigger the corresponding level of warning, and automatically restrict the movement of the telescopic drive component (31) or stop the lifting operation when a level 3 warning is triggered.

Images