| All terrain crane, the cross-country ability is strong, wheel-pressure is homogeneous, tyre wear is small , it move rapidly like truck crane, cross-country and move with load like wheeled crane. The main characteristic to be loved by many consumers. The All terrain crane will be a main develop direction in our country in the future.With the expands of market, user's requirement became higher than before for capability of crane .great lengths of crane has a good perspective ,but traditional jib calculation methods can't satisfied the people's requirements. This paper provided much theoretical direction for this problem.The most frequent malfunction that happen to crane are overturn and breaking , breaking of arm was caused by overweight and not enough intensity ,many people would died when accidents happen ,at the same time, economical lost are following, so it is important to study the arm of crane.This paper derives from cooperative item of Jilin University and Xu Zhou heavy machinery Co., Ltd. all work was divided into five steps:First step: established finite element model of jib. We established finite element model After talking with designer of Xu Zhou heavy machinery Co., Ltd and further know the drawing .we are all agree with each other at some of parts and connected section, we are succeed after many times modify,at last we check their data of situation ,dimension, material, section characteristic, weight and so on ,and carry out calculation.Second step: carrying out linear static finite element analysis to jib with ALGOR software .After come back form jilin university, according to situation table to load force and imposing constrains, analyzing and calculating the outcome from six kinds of dangerous situations and record the reports which included the situation of variational stress, section of exceeding applicable stress and section of the worst stress .we need to bring advices and modify to jib.Third step: carrying out non-linear buckling analysis to jib by mechanical movement emulation analysis method of non-linear material. times step:100 ;from 0 to 90,loading that is linear was gradually imposed ;from 90 to 100, loading is no vary ,we can educed curve of the buckling analysis of end accord to time variation, contrast the outcome of static analysis and buckling analysis stress ,summarize data table of end section and buckling analysis, then bring advices of structure modify to jib .Fourth step: stress test to jib. Second to Xu Zhou heavy machinery Co., Ltd we handed in our report and communicate with them ,we have a test for crane's jib of QAY240 .adopting static strain gauge ,taking measured point .selecting 12 points on the second jib ,32 points on the primarily jib, connected-brace, rotating-brace. Total 168 points at six situation, measuring them one by one and record the stress value, everyone should be tested three times and calculate the average value.Fifth step: write out analysis and test report and compared with the result of finite element analysis, calculating the relative error and absolute error. Form the table and finding out the reasons of error ,giving some advices of modify for designers .After finished the five steps works, we draw out three section analysis conclusions and advices to jib during the process.One: linear static analysis conclusion and advice: buckling analysis data of end section exceeded primarily the applicable flection; connected-brace, rotating-brace primarily jib and stress of axis data under the applicable stress, adjusting the those data in order to improve the entire coefficient of integer; stress of draw-board is lower than the applicable stress; shearing strength of pin is lower than the applicable stress.Two: non-linear buckling analysis conclusion and advice: at the first situation ,structure stiffness occur the apparent variety when loading was enforced equably ,we can see the relative displacement become the more bigger than before from the buckling analysis curve chart at X and Y direction ,i.e. tangent stiffness happen the variety in both direction .advice to adjust the hoist angle and stiffness of stress section in order to keep the stability ; at the sixth situation ,although nothing change flection on the structure in the curve chart, the end section of Z direction change biggish displacement ,advice to adjust the stiffness of high stress section in order to keep the stability; others are all not occurred the flection ,we can see the high stress section to occur on the primarily jib and connected-brace ,advice to improve both of the integer stability ; because buckling analysis was loaded step by step ,so all changes of the worst stress position has changed in analytic result ,non-linear analysis is closer to practical thing and have a meaningful .Three: test conclusion and advice: through the test, we found that when the elevation of jib is big, it is inevitable for the side-load to increase the discrete degree of test data in the test, thereby we are not easily to catch the valid point. For this conclusion, stress test can be used to solve the strength problems, because test points are not enough to make sure the point which we choose is max point of stress, in addition, place of test is finite for the test situation. But it is meaningful for stress testwhich can ensure the reliability of model, analysis of dynamic loading and the extremum. At the same time, for the result which was calculated by finite element method provided widely for gist and requirement for design, then we can validate the test to get the cognition of structure.We finished the issue in a year, this paper mainly provided an analytic method for jib of the QAY240 all terrain crane and buckling analysis of others parts .which also afforded the theoretic gist for the optimized design and improved the capability of the crane. |
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