Impact Characteristics Analysis And Safety Evaluation Of Main Hinge Structure Of Bridge Crane

Due to characteristics of separate structures,the pitching main hinge structure of quay crane has structure impact at the beginning of the service.Without intervention,pathological problem may occur,such as: wear of the pads,looseness of fastening system and the height difference of the sea and land side structure.The pathological problem will further aggravate the impact of the main hinge structure,and even cause parts failure,affecting the normal operation and transportation safety of the crane.The ’Transport Safety Emergency Standard System(2022)’issued by the Ministry of Transport emphasizes the importance of establishing a transport safety system,which includes the safety of cargo transport,improving the essential safety level of transport facilities and equipment,and enhancing safety emergency rescue and support capabilities.As a port logistics equipment,quay crane is also one of the objects for the system establishment.At present,the research on the safety of the main hinge structure is very scarce.Therefore,the research on the impact mechanism of the pathological problems affecting the safety performance of the main hinge structure,the vibration feature extraction method and the safety assessment method of the pitching main hinge structure based on the vibration characteristics are the main research contents of this paper,and also the urgent problems to be solved in engineering applications.In this paper,the pathological impact and safety assessment methods of the main hinge structure of the quay crane are studied.The main contents and results are summarized as follows:(1)In view of the problem that the mechanism of pathological impact on the main hinge structure of the bridge crane is still unclear in the current research field,and there is a lack of practical and reliable pathological impact data set,based on the bridge crane test platform,the impact experiment is designed,the data set of pathological joint looseness in the laboratory environment is established,and the power spectrum is used to analyze the change law of vibration and shock with the change of pathological degree.The numerical model of the test bench is established,and the accuracy of the model is verified by the experimental results.The vibration characteristics of the improved joint are analyzed by establishing the model of the improved joint.The experimental and theoretical vibration characteristics of the test bench are used as the research basis for establishing the numerical model of the main hinge structure of the actual bridge crane.(2)Aiming at the problems of close-set fastening system,complex nonlinear contact relationship between parts and high calculation cost of actual main hinge structure model,’Nonlinear equivalent model of rigid fastening system based on numerical model constitutive relationship’ is proposed to effectively reduce the complexity of modeling,analysis,and calculation cost on the main hinge system.Different from common linear equivalent models,the equivalent model proposed in this paper can simulate the complex nonlinear characteristics between parts better while greatly reducing the calculation time,making it more suitable for the pathological analysis of main hinge structures.At the same time,the equivalent model and fault injection technology were used to establish the numerical model of the pathological problem of the main hinge structure of the quay crane,and the pathological shock vibration data set of the main hinge of the bridge crane was obtained.The accuracy of the above model was verified by comparing with the vibration response of the main hinge structure after measured filtering.The foundation is laid for vibration feature extraction of main hinge structure.(3)In view of the characteristic of the pathological impact signal of the main hinge structure and the poor robustness of the current impact peak value extraction,in accordance with the requirements of national norm on the impact safety of crane structures,in order to effectively extract the acceleration peak value of the main hinge structure,combined with the wavelet packet decomposition(WPD),which has outstanding ability to decompose time domain signals at both high and low frequencies,and the advantages of weighted overlapping average method(pwelch)for frequency extraction of energy signals,’wavelet decomposition and weighted overlapping average with peak-to-peak value extraction method’ was proposed to extract impact features suitable for safety assessment of main hinge structures.The accuracy of the feature extraction method is verified by comparing with the vibration response of the main hinge structure after filtering.Compared with the traditional time-domain characteristic impact value extraction based on peak-to-peak value extraction,the method proposed in this paper can effectively extract impact peak values from the acceleration signal without omission and numerical inaccuracy,so the stability is better.(4)In view of the unclear influence of various pathological problems on the safety of the main hinge structure and the lack of research on the safety assessment methods for the main hinge structure of the bridge crane at home and abroad,’Model-based multi-stage fuzzy safety assessment model for the main hinge structure of the quay crane based on the pathological impact characteristics of the main hinge and fuzzy comprehensive evaluation’ is proposed.It is referred to as’ Multistage fuzzy pathological diagnosis and Safety evaluation model of main hinge structure’(MF-PDSEM).Based on crane dynamic performance specifications and pathological impact characteristics,the diagnostic parameters based on vibration characteristics is established.According to the opinions of crane industry experts and related practitioners,the membership relationship between the vibration characteristics and the pathological problems as well as the pathological problems and the safety of the hinge structure is established.The evaluation elements in the fuzzy comprehensive evaluation system are improved,and the first layer realizes the diagnosis of structural pathological problems,and the second layer realizes the comprehensive safety assessment of the main hinge structure.Through the example verification,the proposed model can effectively diagnose the pathological problems and severity of the actual crane main hinge structure,which is suitable for the safety assessment of the main hinge structure of the bridge crane affected by the pathological problems.At present,there is a lack of complete research for the safety assessment of the main hinge structure of the bridge crane.In this paper,the pathological problems of the main hinge structure are taken as the starting point,and the diagnosis and safety assessment methods based on numerical model are proposed in combination with theory and practice,which lays a certain foundation for the establishment of the safety assessment and decision-making method of the main hinge structure in scientific research.In engineering practice,the safety evaluation model established in this paper can diagnose and evaluate the status and safety of the main hinge structure of the quay crane at any time based on the collected acceleration data,which is an important part of the establishment of the overall structure health monitoring and safety management system of the bridge crane.