| Screening and crushing workshop is an important type of building in the industrial production system,which is widely used in coal,metallurgy and other industries.In order to meet the production requirements,screening and crushing workshops have continuously introduced large-scale foreign power equipment with the development of China’s coal washing industry.As a result,the structural vibration caused by increased equipment disturbances has become increasingly prominent.Abnormal vibrations not only endanger the safety of structures and affect industrial production,but also harm the physical and mental health of workers.The vibration problem of screening and crushing workshops has become an urgent issue which need to be studied and discussed.Based on the power flow theory,data of the dynamic test and finite element analysis of the specific project,the cause of the structural vibration is found and the vibration control scheme is proposed.The main work and the results obtained from the researches of this article are summarized as follows:(1)Based on power flow theory,vector visualization of structural intensity about the beam and plate are realized by using MATLAB programming;the calculation formula of the excitation force of the screening machine and the crusher is deduced,and the vibration transmission of the main vibration source layer is acquired.The following conlusions is obtained by the analysis of the vibration transmission: the vibration is mainly transmitted through the vicinity of the vibration source and its surrounding area on the same layer;moreover vibration transmits up and down through the structural columns.(2)According to the vibration transmission,actual situation in the field,a dynamic test scheme for screening and crushing workshop was developed;the spectrum of the test data was analyzed to obtain the dynamic characteristics of the structure,and it was was found that the forced frequency of the structure was relatively closed with the operating frequency of the screening machine and the crusher.it is clear that the screening machine and the crusher are the main vibration sources that cause structural abnormal vibration.(3)According to the domestic and international standards about structural vibration limition,impact of vibration on structure,human body,and equipment was evaluated respectively.Through the field test data processing and analysis,it is clear that structural vibration in horizontal and vertical direction is stronger.(4)The solid element model and the beam-shell element model of the screening and crushing workshop were respectively built using ANSYS,and the modal analysis was performed.The obtained modal parameters were compared with the actual field measurement results,and the rationality of the finite element model was verified;Dynamic time history analysis was performed with he beam-shell element model,and numerical analysis results are basically consistent with the field measurement data,as well as structural vibration characteristics are more consistent;With further study,it is found that the lack of stiffness is the main reason for excessive vibration.(5)In order to reduce the structural vibration,three vibration control schemes were proposed,which are increasing structural rigidity,adopting secondary vibration isolation,adding two-way MTMD damping systems.Through comprehensive comparison of each scheme,the results show that the adoption of secondary vibration isolation and MTMD damping system can greatly reduce the dynamic response parameters of the structure,and the secondary vibration isolation program has better results;compared to improving the structural rigidity,the method of the secondary vibration isolation and TMD vibration control has a short construction period and has little impact on normal production.It can provide some references for solving the vibration program of new structures,as well as vibration control of existing buildings. |
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