多节超长大跨度高压大流量悬臂输送系统动力学耦合规律及安全评价预测

Pump truck with overlenth arm longer than 100 meters will be given priority to be developed to satisfy the needs of some huge engineering . Dynamic actions become a key role on working quality and equipment safety due to the large size of the transfer arm.The lack of theories and methods to explain the dyanmic action and its effect on working process and safety has become bottleneck to the development and running safely of pump truck with overlenth arm longer than 100 meters. The dynamic characters of interaction between transfering pipe and concret of the cantilever transferring system with large Span will be studied according to the characters of structure and working modes under the constraints of varying angles,multi-surve and multi-spring support ac. A model will be put forward to exprees the the inverse dynamic tranfering law for the multi-body of the long arm. The degradation law of the safety performace at key section of the arm will be disgoveried under the ditributed excitation on much site at the same time. Monitoring and valuing of minute flaw are very important for large span cantilever arm due to it's damage are main caused mainly by high cycle fatigue.A Mass-Spring Damp(MSD)Model will be build to express the base of the safe performance on key section of the arm,and characterize methods for performance degrading of microstucture will be studied.The mapping relation between different working modes and modyfied S-N curve will be disclosured, and performance predition and safety evluation can be carried out based on the model. Theories and methohs will be provied to make the pump truck with overlenth arm longer than 100 meters working safely.

现代化大型工程的高效施工需求使百级超长臂架泵车成为今后发展重点，相对于传统泵车，动力学效应成为决定其作业质量和设备可靠性的不容忽视因素。多节柔性臂串联构成的大跨度柔性多体悬臂输送系统是超长混凝土泵车最为复杂和关键的部件，缺乏复杂动力学行为规律的揭示及其对作业行为和悬臂可靠性影响评价的理论和方法制约百米级超长臂架泵车设计开发及安全可靠运行。项目针对复杂结构及脉动变工况工作特性，研究大跨度悬臂输送系统在变姿态、多弯曲、多点弹性支撑等约束条件下的输送管流固耦合动力特性，建立超长柔性多体臂架的反向力学传递模型,揭示多点分布激励载荷对臂架关键部位微观性能衰退的影响规律。针对超长悬臂关键部位故障的高周损伤特性，构建关键部位基准微观性能的MSD模型，研究微观性能衰退的定量表征方法,建立工况模式历程与修正S-N曲线的映射关系, 实现性能预测与可靠性评估,为百米级超长悬臂泵车的安全可靠运行提供理论与方法。

1) 揭示了混凝土泵车臂架流固耦合的规律，从理论上为臂架结构危险工作点的确定提供了指导 .根据混凝土输送泵车臂架系统的工作原理和结构特点，基于多体运动学理论和 Hamilton 变分原理，推导出该模型流固耦合运动方程，并采用有限单元理论，对泵车臂架系统离散化，建立臂架系统流固耦合动力学方程，分析出混凝土流动与臂架结构振动的耦合作用。.2) 针对臂架等结构早期缺陷难以检测和评价的难题，采用PZT传感器，对基于机电耦合阻抗法的结构早期缺陷检测的微观多元建模、微弱信号及特征的提取、非线性特征发故障诊断进行了系列研究。.针对目前臂架结构缺陷检测单SMD模型不能解释耦合阻抗的多频协振现象。从PZT压电效应和主结构间的动力学耦合机理、机电结构类比入手，建立了PZT和主结构间微阵子多自由动力学模型及其等效电路模型，提供了高频微激励下的PZT与主结构的耦合响应提供了仿真手段。.针对目前EMI结构缺陷检测及性能评价的ＲＭＳＤ等评价指标对缺陷特征反应不够敏感，缺乏疲劳过程的微观解释，提出了瞬态ＲＭＳＤ评价指标，使PZT和被监测主结构的耦合电导、耦合导纳相位及导纳的瞬态方差在结构从健康到疲劳断裂过程中表现出很好的一致性，同时符合结构疲劳断裂过程的性能微观变化曲线。.PZT与主结构耦合信号中与结构损伤无关PZT本身结构参数影响检测精度，本研究从模型机理及试验现象两方面入手，分析了结构损伤无关的PZT参数与激励新号频率的线性相关及趋势项特性，提出了频域经验模式分解PZT与主结构耦合信号的趋势项剔除及有效特征提取方法，可有效便捷的去除耦合项中与结构缺陷无关的频率趋势项。.微观结构损伤往往伴随着微观结构之间的非线性行为，目前缺乏基于微观非线性特征的结构早期缺陷检测及性能评价，本研究用局部微观非线性特征进行结构缺陷检测及性能衰退评价，揭示了EMD经验模式分解前三阶模态包含了大部分缺陷特征信息，对EMD前三阶模态近似熵处理可以较好提取结构微观损伤特征。