The Spectrum Of Grab Unloader Key Parts And Life-span Evaluation

Grab unloader is important equipment for unloading in port, play an important role in the shipping of the world. Grab unloader will be used more and more continually for the number of the ports will be larger and larger. It is more important for grab unloader to maintain, so to prevent big accidents which will affect the normal production. Many grab unloaders are designed based on the traditional strength design, but grab unloader endures fluctuant loading for a long time, it is very easy to be wrecked for fatigue, it makes important sense of how to forecast the life-span of the grab unloader for the maintenance and the design of the grab unloader, just a few people did some work in the evaluation of the life-span of the grab unloader domestic, but it not enough, so this paper could be used for reference in some scale. The main content of the paper is as follows:In chapter 1,discussed the sense of the paper,the present use condition of the grab unloader and the research line of the paper;In chapter 2,at first, discussed the basic concept of the fatigue,the fatigue broken types of the grab unloader and the fatigue design methods of the grab unloader, then describe some curve related with the material character, include the p—S—N, fatigue limited curve and circular stress—shift curve, and finally, describe the stress-circle counting method and life-span evaluating method;In chapter 3, at first, analyzed the grab unloader working procedure, and then described how to do data collection of the elevating steel rope and the opening switching rope, at last, plot the diagram of the loading data;In chapter 4, deal with the loading data elementarily, after that, generated loading spectrum including loading scope,medial loading and frequency with the program made from the MATLAB, then transfer the three-dimensional loading spectrum into two-dimensional spectrum with Goodman fatigue experience formula, and then calculate the loading data of the output shaft,gear and bearing, after get of loading data, it can generate the all the loading spectrums from the data, finally, we calculate the whole year's spectrum of the grab unloader;In chapter 5, according all the parameters of the shaft, get the p—S—N curve from the material's p—S—N curve, then evaluate the life-span of the shaft's bend fatigue in the way of Miner theorem. Then get the material's p—S—N curve from the mechanical performance, and evaluates the contact fatigue life-span and bends fatigue life-span of gear on the base of loading spectrum.In chapter 6, the conclusions and contributions of this thesis are summarized and highlighted. Moreover, some problems for further study are suggested as well.