Under alternating stress, even if the stress on a mining vibrating screen is below the yield limit, the structure may suddenly fail as the operating time increases. This phenomenon is known as fatigue damage, and therefore, it is essential to perform a strength check using the fatigue limit when evaluating structures subjected to cyclic loading. Large-scale mining vibrating screens are challenging to analyze using traditional elastic continuum methods due to the high computational demand. Instead, by dividing the structure into sub-structures, the state space method can be applied. This approach simplifies the analysis of dynamic relationships and energy transfer between components, making it easier to study vibration energy flow and its impact on structural integrity, which in turn provides a foundation for structural optimization.
Mining vibrating screen boxes are typically composed of side plates, beams, spring supports, and other components, which are connected using common fastening methods such as threaded joints, riveting, or welding. When dividing the system into sub-structures based on these components, the process becomes intuitive and aligns with conventional engineering thinking. Additionally, transient dynamic analysis reveals that the joints between the beam and side plate, as well as between the spring bracket and side plate, experience high stress and are more prone to failure.
Moreover, since the side plates of the mining vibrating screen are large thin plates, insufficient design or actual rigidity can lead to significant deformation during operation, especially during vibration. Therefore, it's crucial to conduct research on this aspect. During sub-structure division, the side plates can be further subdivided depending on their deformation behavior—such as treating areas with minimal deformation as rigid bodies, while simplifying regions with concentrated elastic components or mass into separate sub-structures for deeper investigation.
The introduction of power flow in mining vibrating screens was initially aimed at more effectively describing the vibration isolation performance of the system. By focusing on energy transfer, power flow can also be used to assess the vibration strength of the structure. If a sub-structure receives a higher input power flow, it is more likely to suffer damage. Thus, power flow serves as a comprehensive indicator for evaluating both the strength and transmission characteristics of the vibration.
Power flow is a scalar quantity, and its value can be positive or negative depending on the location on the vibrating screen. A negative power flow indicates that energy is being absorbed rather than transmitted, playing a role in damping and reducing vibrations.
During operation, the spring bracket comes into direct contact with the spring and carries a significant load, including the spring’s support force and the forces and moments from the side plates. According to early-time history analysis, the spring bracket experiences high stress. If it fails due to cracking or breaking, the vibrating screen will not function properly. Therefore, it is a critical component, and its energy distribution and transmission must be thoroughly analyzed. Below is the power flow calculation for the spring bracket.
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