Research On Fatigue Life Characteristic Curve Of Bridge Crane And The Sensitivity Analysis

As a leading force in the national economy, the rapid development of industry is driving the rapid growth of various other industries. The vigorous development of modern manufacturing makes various of mechanical equipment become more and more large-scale, high-end, intelligent, so more and more is also high to the requirement of large transport tools. As the most common handling tool, crane can effectively save manpower, improve production efficiency, promote the industrial production processes to achieve mechanization and automation, and play an important role in ports, hydropower,nuclear power, aerospace and other fields.Due to the long-term effects of high frequency, alternating and dynamic load, coupled with a harsh work environment, crane sometimes occurs safety accidents in the process of using. And the crane structural fatigue damage is the major cause of accidents, so it has great significance to take an in-depth study of the crane fatigue failure.According to the structure form, operating conditions and load characteristics of the bridge crane, this paper has carried the depth and comprehensive discussion and analysis on metal structure fatigue failure. Then this paper proposes the fatigue life prediction for different structural models and develops a full command stream using ANSYS finite element software on bridge crane in random conditions to obtain the stress-time history, which can quickly obtain crane random stress spectrum combined with rain-flow counting program.Most studies only conduct the fatigue life prediction of dangerous point on the dangerous sections of the bridge crane girder structure, which can not determine the fatigue failure of the main girder from the trend, and can not study the fatigue failure regularity in azimuth. In order to solve this limitation, this paper divides the main girder into sections by a limited number of representativecross-section point of fatigue life calculation, and makes the curve of bridge crane metal structure which can reflect the fatigue life distribution(referred to as the fatigue life characteristics curve). This curve can reflect the whole fatigue damage law of the main beam visually and clearly, and can be used as the basis to predict fatigue damage path of the metal structure. It also can provide data for engineering design reference in the design phase, and it is convenient for repair and maintenance personnel to pay attention to the fatigue damage dangerous parts in the cycle of the detection, for regular reinforcement of prophylactic treatment.In addition,taking the optimization analysis of the key size on the main beam sections can gain the optimal size result when the main beam reaches the lightest weight, under the requirements of strength and stiffness. Then through the local sensitivity analysis, this paper takes a further analysis of the impact of the changes of cross-sectional key dimensions to structural fatigue life to make the influence diagrams of different variables on fatigue life.