【作者】 何洋洋；

【导师】 高崇仁；

【作者基本信息】 太原科技大学 ， 机械设计及理论， 2010， 硕士

【摘要】 桥式起重机(简称“桥机”)是使用最多的起重设备之一,同时安全事故发生的概率也较多,发生事故的原因之一是桥机的主要组成部分的金属结构存在疲劳问题。因此,起重机金属结构评估对于保障起重机械安全运行十分重要。然而,起重机结构评估的重要依据就是应力-时间历程数据,该数据量的多少是影响可靠性评估或疲劳寿命预测准确性的重要依据。此外,可靠度是评价结构的重要指标之一。传统的结构可靠性模型是直接运用应力与强度干涉理论进行积分运算求得结构可靠度,没有考虑到材料强度随时间的变化因素(称“剩余强度”)。由于起重机服役时间比较长,在其服役期间所受到载荷的作用通常是随机的,在进行起重机结构的可靠性计算时,忽略载荷作用时间和材料强度因素的影响会对结构可靠度计算造成影响。由于随机载荷的作用次数以及材料的强度随时间而变化,起重机在服役期间其结构的可靠度和失效率也应当是随时间而变化的。本文研究的内容主要包括以下几个部分:第一、阐述了应力时间历程数据对可靠性评估的影响,以及强度随时间变化因素对结构可靠性影响。第二、针对采集的桥机实时载荷及运行数据,应用力法和有限单元法对桥式起重机结构进行简化分析和编程实现快速求解应力的功能。第三、利用应力与强度的干涉模型和剩余强度理论,建立桥式起重机金属结构的可靠度随载荷作用次变化的模型,即动态可靠度。本文可以把大量的桥式起重机运行数据转换成应力数据,能够解决应力数据缺乏的难题,并对桥式起重机金属结构进行了动态的可靠性分析,建立了动态可靠性模型,为起重机的寿命评估和动态监测奠定了一定的理论基础,具有重要的工程实用价值,为合理制定维修计划具有一定的指导意义。更多还原

【Abstract】 Overhead travling crane is one of the most used lifting equipment, at the same time many safety misadventure has happen to it. One of the safty misadventure reason is the metal which is made up of crane exist fatigue. For this reason, it is very important to estimate the metal constructure of crane. To estimate the crane base on the data of stress, data volume is the basis which can impact accuracy of the satety evaluations.It is widely known that reliability is one of key indicators on safety evaluation. For crane metal structure, the traditional structural reliability calculation model is after the stress distribution and force distribution can be got. The Principle of Stress Strength Interference was directly used to calculate the reliability and obtain the structure reliability. But this method structural reliability of the stress cycle only can be calculated once or a specified number cycles. The reliability can’t be calculated at any time, and this method didn’t take into account the impacted by the strength degradation. So it will not essentially reflect the structural reliability are impacted by stress cycles and duration with stress increasing. However, the crane service time is always very long, and the structure often suffered a lot of repeated random stress cycles, and the affecting factors of the reliability such as stress cycles and the structure strength are often changing over time. In this case, when the reliability of the in service crane structure, it should also be changing over time. In the past, the force cycles time and the structural strength of metal degradation was ignored when the structure reliability had been calculated, it obviously affected the reliability of the crane. This text is based on the actual situation, considering the role of stress cycles and material strength changed over time to calculate the crane structure’s dynamic reliability.In this paper, the main component includes:First, it expounded the more data of stress is very important for satety evaluations, so as to the dynamic reliability. Second, according to the running data which has collected form overhead travling crane, use structure mechaniscs to analysis the structure of crane and coding the program to acculate the stress on the crane.Lastly, use of the model of Stress Streng Interference and strength degradation to set up of the dynamic reliability of crane.The plenty of running data of overhead travling crane can be translated to stress; the question of lacking stress data is being solved. A degradation model of dynamic reliability for the crane structures is established. A theoretical foundation on cranes dynamic monitoring and estimating the residual life for the structures have been laid. The research has a great practical in engineering and a significance for making certain maintenance and repairing plan on crane.更多还原