Fatigue Damage Mechanism Of Metal Structure Of Bridge Crane Under Impact Effect

Bridge crane is an important mechanical product for material handling in industrial production plants,the huge use of the base and the safety requirements of special equipment to make the crane safe service is of great significance.Bridge cranes for a long time in a complex environment for high frequency lifting work,and the structure is a key component of the crane load.Frequent in-service lifting will cause irreversible degradation of the fatigue load capacity of the structure.It is important to study the fatigue characteristics of crane structures for service life and to accurately quantify the fatigue life of structures.Crane is a complex mechanical system coupled by structure and mechanism,the continuous service movement of the mechanism will trigger continuous changes in structural stress characteristics and make the structure fatigue.As the transient load shock caused by the motion of the components during the lifting process of the institution in service is always unavoidable,which resulted that the structural vibration response when subjected to shock load becomes the key to evaluate the fatigue life of the structure.Therefore,it is necessary to focus on the in-depth integration of crane design and service process research.Modeling the kinematic-dynamic mechanism of mechanism-structure coupling.Exploring the fatigue load capacity degradation mechanism under structural vibration response based on the transient motion characteristics of the mechanism.1)To address the contradiction between the accuracy of crane load spectrum prediction and sample complexity under service condition,machine learning algorithm is used to construct a load spectrum prediction model with high accuracy features.The fusion optimization technique based on intelligent optimization algorithm and machine learning theory is proposed,and the above method can provide theoretical support for crane service load spectrum prediction.2)For the load transient impact caused by the lifting process,the crane lifting process dynamics model based on structural vibration theory is established by fully considering the rigid-flexible coupling characteristics of the crane components.The change law of wire rope traction force when the crane is lifted off the ground was obtained to provide data support for the study of the stress-time history required for structural fatigue damage.3)For the crane sudden unloading and large car operation through the track defects caused by the structural impact effect,the crane structure dynamics model under the corresponding operating conditions was established.The vibration response variation law of the crane load under each working condition is obtained,which provides a theoretical basis for analyzing the impact effect on the fatigue damage of the structure.4)In order to ensure the absolute service safety of the crane structure,the changes of stress indicators of the crane structure under load impact are analyzed.Explore the guidelines for calculating the fatigue life of structures under the coupling effect of complex service conditions.Based on the fracture mechanics theory and dynamics model to explore the fatigue damage influence law of the structure under the complex service condition coupling,it can provide a specific research program for the accurate fatigue life prediction of the crane structure.This paper establishes a structural dynamics model to achieve the accurate acquisition of structural stress index change law under transient load impact.And the research content will achieve the impact effect of the crane metal structure damage mechanism of in-depth investigation.The method will provide a scientific basis for the accurate prediction of fatigue life of cranes,with important theoretical significance and engineering value.