Method for embedded synchronous measurement of the normal and tangential stresses of the wall of a silo

Abstract

This invention discloses an embedded method for synchronously measuring the normal and tangential stresses of silo walls. It employs a hardware combination device integrating dual-resistance strain sensors, achieving synchronous monitoring of wall stress through embedded installation. The method first independently calibrates the sensors and then combines them through structural design. Next, adaptable holes are created in the silo wall to embed the measuring device, ensuring direct contact with the material being measured. Finally, the normal and tangential stresses on the wall are calculated by combining the calibration data with the acquisition system. Compared to conventional silo wall stress measurement methods, this method offers advantages such as simple structure, high measurement accuracy, good stability, and immunity to interference from the dynamic process of silo unloading. The application of this method will provide direct data support for preventing silo rupture, material blockage, and other accidents, contributing to improved silo structural design, operational safety, and service life.

Description

Technical Field

[0001] This invention relates to methods for particle mechanics testing and silo safety monitoring, and particularly to an embedded method for synchronously measuring the normal and tangential stresses of the silo wall. Background Technology

[0002] As a core facility for storing bulk materials, the accurate monitoring of stress distribution on the silo wall is crucial for structural safety and operational efficiency. Unlike fluids, bulk materials generate both normal stress perpendicular to the wall and tangential stress along the wall direction during static stacking and dynamic unloading, and these two stresses often exhibit a complex nonlinear coupling relationship. Since the lateral pressure coefficient and wall friction coefficient change in real time with the flow pattern under actual operating conditions, measuring only one dimension of stress cannot accurately reflect the mechanical state of the wall. Therefore, achieving simultaneous measurement of normal and tangential stress is a key prerequisite for accurately analyzing the friction mechanism between particles and the wall, precisely verifying silo design theory, and effectively predicting catastrophic accidents such as silo rupture and material arching.

[0003] Existing silo wall stress measurement technologies are mainly divided into indirect and direct measurement methods. Indirect methods typically place sensors on the outside of the silo wall, avoiding wear, but they cannot capture the actual changes in wall friction. Direct methods place sensors inside the silo; however, surface-mounted sensors, due to their thickness, can cause protrusions that interfere with the particle flow field, leading to data distortion. While conventional drill-embedded measurement methods ensure wall flatness, the lack of gaps between the contact block and the borehole makes them highly susceptible to overall silo vibration during unloading, resulting in significant data fluctuations. A more significant limitation is that most existing sensors employ a single sensing structure, responding only to normal pressure perpendicular to the wall and lacking an effective response mechanism for tangential shear forces. Since the lateral pressure coefficient and friction coefficient of bulk materials are dynamically coupled during flow, simply measuring normal pressure cannot resolve this complex mechanical behavior. Existing composite measurement devices often lack effective decoupling mechanisms, making it difficult to avoid crosstalk between normal and tangential forces, thus preventing high-precision simultaneous measurement of both stress components at the same measuring point. Summary of the Invention

[0004] Purpose of the Invention: To overcome the shortcomings of existing technologies, the purpose of this invention is to provide an embedded method for synchronously measuring the normal and tangential stresses of silo walls. This method, through an embedded structure integrating dual strain sensors, can eliminate the interference of sensor thickness on particle flow, overcome the vibration effects during unloading, and achieve synchronous and accurate measurement of normal pressure and tangential friction.

[0005] Therefore, this method proposes a hardware-based dual-resistance strain measurement scheme. By embedding a hardware combination device integrating dual-resistance strain sensors through a hole of appropriate size drilled in the wall, the sensor can directly contact the material being measured, thereby achieving high-precision synchronous measurement of normal and tangential stresses while ensuring the flatness of the wall surface.

[0006] Technical solution: A method for embedded synchronous measurement of normal and tangential stresses on silo walls is provided, including the following steps: S1. Calibrate a single sensor and obtain the relationship coefficient between its output signal and input signal; S2. Calculate the stress based on the calibration results; S3. Construct a dual strain sensor device, including: a contact block, sensor 1, sensor 2, a conversion element, and a fixing element; S4. Make an adaptation hole on the silo wall, embed the contact block into the hole, and install the dual strain sensor device on the wall by fixing elements; S5. Load bulk materials and collect stress data in real time to obtain the normal and tangential stresses on the silo wall.

[0007] Furthermore, in step S1, the output voltage U under different weights m of the weights is obtained through the acquisition card, and the slope k can be obtained by fitting. ; Further, the stress calculation method in step S2 is as follows: S2-1, the force borne per unit area is the stress at each point on the surface of the material bearing area, and the stress calculation formula is... ; In the formula, g is the acceleration due to gravity, taken as 9.8 N / kg, and S is the bearing area of ​​the material. Therefore, the stress at each point on this bearing area when a weight of 1g is applied is... ; S2-2, the normal stress corresponding to the output voltage can be obtained as follows: ; In the formula, S and k are known quantities, thus the relationship between the output voltage of the data acquisition card and the stress can be obtained.

[0008] Further, step S3: The sensor 1 is used for measuring tangential stress, with one end fixed to the contact block and the other end fixed to the conversion element; The sensor 2 is used to measure normal stress. One end is fixed to the conversion element, and the other end is connected to the fixing element, which is used to fix the entire dual strain sensor device to the silo wall with screws.

[0009] Furthermore, the hole size in step S4 is 10.2 mm × 10.2 mm.

[0010] Furthermore, the contact block in step S4 is set to 10 mm × 10 mm.

[0011] Furthermore, the relationship coefficient in step S1 is =18.6.

[0012] Furthermore, the measurement method with a correlation coefficient of 18.6 involves successively adding weights to 10g, 20g, 40g, 50g and 100g, then successively reducing the weights to 0, measuring the voltage corresponding to each mass, and repeating the above steps 3 times.

[0013] Compared with the prior art, the present invention has the following advantages: An embedded mounting structure is used to ensure the flatness of the bin wall and avoid interference from sensor protrusions on particle flow; a hardware combination of dual-resistance strain sensors is used to achieve simultaneous measurement of normal stress and tangential friction; and a direct contact measurement method is used to replace indirect inversion of the outer wall, significantly improving the authenticity and accuracy of the measurement. Attached Figure Description

[0014] Figure 1 Here are schematic diagrams and physical images of the dual strain sensor hardware assembly according to the present invention; Figure 2 The silo experimental apparatus according to the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Figure 1 Here are schematic diagrams and physical images of the dual strain sensor hardware assembly according to the present invention; The method for simultaneously measuring the normal and tangential stresses of the silo wall in this embodiment includes the following steps: S1. Single Sensor Calibration: First, measure the output under no-load conditions to eliminate baseline errors. Add weights sequentially to 10g, 20g, 40g, 50g, and 100g, then gradually reduce the weights to 0, measuring the voltage corresponding to each mass. Repeat this process three times to obtain the relationship coefficient between the sensor's output and input signals. =18.6, repeat the calibration process for the remaining sensors; S2. Calculate the stress based on the calibration results: S2-1. The force per unit area is the stress at each point on the surface of the material's bearing area. The formula for calculating the stress is: ;

[0017] In the formula, It is the acceleration due to gravity. The strength is taken as 9.8 N / kg, and A is the bearing area of ​​the material. In the experiment, the bearing area of ​​the sensor is 100 mm². 2 Then, the stress at each point on the bearing area caused by a weight of 1g is... ; S2-2, The normal stress corresponding to the output voltage can be calculated as follows: ; Thus, the relationship between the output voltage of the data acquisition card and the stress can be obtained; S3. Construct a dual strain sensor device: S3-1. Calculate the curvature of the contact block based on the silo radius to ensure that the contact block and the silo wall are on the same plane; S3-2, Sensor 1 is used for measuring tangential stress. One end is fixed to the contact block, which is set to 10 mm × 10 mm, and the other end is fixed to the conversion element. S3-3, Sensor 2 is used for measuring normal stress. One end is fixed to the conversion element, and the other end is connected to the fixing element. It is used to fix the entire dual strain sensor device to the silo wall with screws. S4. Make a 10.2 mm × 10.2 mm adapter hole on the silo wall and embed the contact block into it, thus ensuring that there is a certain gap around it. At the same time, fix the dual strain sensor device to the silo wall with screws. S5. Loading bulk materials allows for real-time acquisition of stress data, yielding the normal and tangential stresses on the silo wall.

[0018] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for embedded synchronous measurement of normal and tangential stresses on a silo wall, characterized in that, Includes the following steps: S1. Calibrate a single sensor and obtain the relationship coefficient between its output signal and input signal; S2. Calculate the stress based on the calibration results; S3. Construct a dual strain sensor device, including: a contact block, sensor 1, sensor 2, a conversion element, and a fixing element; S4. Make an adaptation hole on the silo wall, embed the contact block into the hole, and install the dual strain sensor device on the wall by fixing elements; S5. Load bulk materials and collect stress data in real time to obtain the normal and tangential stresses on the silo wall.

2. The method according to claim 1, characterized in that, In step S1, the weights of different weights are obtained through a data acquisition card. Output voltage under The slope can be obtained by fitting. ; 。 3. The method according to claim 1, characterized in that, The stress calculation method in step S2 is as follows: S2-1, the force borne per unit area is the stress at each point on the surface of the material bearing area, and the stress calculation formula is: ； In the formula, It is the acceleration due to gravity. Taking 9.8 N / kg as the load-bearing area, the stress at each point on this load-bearing area when 1g of weight is applied is: ； S2-2, the normal stress corresponding to the output voltage can be obtained as follows: ； In the formula, S and Given the known quantities, the relationship between the output voltage of the data acquisition card and the stress can be obtained.

4. The method according to claim 1, characterized in that, Step S3: The sensor 1 is used for measuring tangential stress, with one end fixed to the contact block and the other end fixed to the conversion element; The sensor 2 is used to measure normal stress. One end is fixed to the conversion element, and the other end is connected to the fixing element, which is used to fix the entire dual strain sensor device to the silo wall with screws.

5. The method according to claim 1, characterized in that, The hole size in step S4 is 10.2 mm × 10.2 mm.

6. The method according to claim 1, characterized in that, The contact block in step S4 is set to 10 mm × 10 mm.

7. The method according to claim 1, characterized in that, The relationship coefficient in step S1 is: =18.

6.

8. The method according to claim 7, characterized in that, The measurement method with a correlation coefficient of 18.6 is as follows: the weights are added sequentially to 10g, 20g, 40g, 50g and 100g, and then the weights are reduced sequentially to 0. The voltage corresponding to each mass is measured, and the above steps are repeated 3 times.

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