Reliability Analysis And Design Method Study On Truck Crane Boom Structure

Truck crane is widely used in engineering construction because of its good mobility and working environment adaptability. The inadequate of manufacturing technology and uncertainty of site construction condition in application may cause many uncertainty factors in load, structure dimension, material property and so on. The calculating working condition according to design specification in current structure design of truck crane can not contain uncertainty factors. That is to say, the structure reliability can not be guaranteed under these uncertainty factors. The hoist boom is the main load bearing component, and its structure failure is the main factor resulting in truck crane accidents and seriously failure loss. The reliability of hoist boom has great influence on the crane performance and hoist boom becomes one of the main design forces. So it is very important to analyze the reliability of hoist boom structure and study the structure design method based on reliability. This study is conducted according to a project from National Science Foundation of China, which is ’Research on Design Method for the Special Equipment Based on Non-probabilistic Risk Assessment Theory’.Probabilistic reliability model applies to random variables with large number of statistic data to know the distribution function, but applying in small sample parameter analysis may cause big error. Non-probabilistic reliability theory needs less original data and the boundary of uncertainty factors without the distribution. The reliability is determined by the comparison between fluctuation range of structure performance and demand range. Non-probabilistic reliability theory is usually used in study of small sample events. The hoist boom structure analysis in this paper considers three uncertainty factors, which are dynamic lifting coefficient, rope swing angle and plate thickness respectively. Plate thickness is random variable conforming to normal distribution, which can be described with probabilistic method. Dynamic lifting coefficient and rope swing angle are interval variables with known boundary, which can be described with non-probabilistic interval model. Probabilistic and non-probabilistic hybrid reliability method is put forward combining these two methods to calculate structure reliability.The probabilistic and non-probabilistic hybrid reliability model of hexagonal telescopic boom is build based on structure failure criterion, and the reliability of structure strength, stiffness, local stability and global stability is calculated respectively. Bayesian Network of hoist boom structure failure is build based on failure mechanism analysis. According to network inference to analyze the reliability under different failure reason combination and calculate the importance of every failure reason and failure form. To distribute structure reliability according to importance and correct buckling safety factor and strength factor in structure calculation and the reliability design method of crane structure based on hybrid reliability theory is developed.A QY15truck crane is the calculating sample and the reliability of its hoist boom is conducted to solve the probability interval of structure failure and the importance of every failure reason and form. After distributing the reliability, the reliability is calculated again and the results show that, buckling safety factor is1.62and strength factor is1.28. The calculating sample verifies the feasibility and validity of the reliability calculating method in this paper, which provides basis for reliability design of similar products.