【作者】 滑广军；

【导师】 吴运新；

【作者基本信息】 中南大学 ， 机械工程， 2013， 博士

【摘要】 摘要：混凝土泵车是将用于泵送混凝土的泵送机构和用于布料的臂架系统集成在汽车底盘上的专用车辆,具有工作效率高、浇筑质量好、机动灵活等优点。由于工作环境恶劣、维护难度大,以及材料老化、环境侵蚀、疲劳等长期效应与突变等灾害因素相互作用,混凝土泵车结构损伤及故障既有渐变性,又有突发性。如操作不当、维护不及时,均有可能造成重大经济和生命安全问题。本文在国家高技术研究发展计划(863计划)项目“远程监控及维护关键技术及单元系统研究”(2008AA042801)及“混凝土泵车远程监控及维护应用系统研制”(2008AA042802)资助下,以理论研究、仿真分析、实验分析为研究手段,围绕混凝土泵车臂架结构健康监测关键技术问题-结构健康监测方法、传感器布置、监测信号采集处理、特征参数提取、健康状态评价等进行研究。主要研究工作如下：对混凝土泵车结构及载荷特点进行了分析,对其结构故障进行了统计,采取仿真分析、实验分析方法对泵车臂架结构动静态特性进行研究,提出了基于应变参数的混凝土泵车臂架结构健康监测策略。对频谱分析、幅值分析及损伤分析的采样频率问题进行了研究。推导了幅值分析及损伤分析误差与采样频率的关系,提出了基于误差控制的应变信号采样策略。将该方法运用到泵车臂架结构健康监测应变信号采样频率的确定,通过实例验证该采样频率满足损伤分析精度要求,能够减少采集的数据量、节省存储空间并提高数据处理及分析的效率。利用小波多分辨率分析理论和方法,对混凝土泵车臂架结构监测应力信号进行了分析处理,对监测信号进行了降噪和奇异值剔除处理,并分析了各种尺度响应信号的分布特征。提出了基于综合评价法的监测应变传感器优化布置方法。该方法首先根据混凝土泵车臂架结构、工作环境、损伤特点及健康监测内容等确定了影响测点布置的因素集；利用层次分析法(AHP)确定各因素的权重；利用各待选测点应变信号的相关系数构建了模糊支持度矩阵,计算了各待选测点的综合支持度以表征传感器覆盖能力；基于模糊数学的方法和思想,将因素集中的待选测点应力水平、传感器安装难易程度、测点安全性、应力梯度因素进行了分级及标准量化；最后利用加权平均综合评价方法对某泵车臂架待选测点进行了优化布置。对疲劳累积损伤理论及损伤特征参数提取方法进行了研究。基于疲劳损伤理论,研究了信号分段影响宽带随机应力疲劳损伤计算精度的机理。提出了基于实时监测数据的泵车臂架结构载荷谱提取方法。该方法能够减小长周期应力循环的截断及信号频繁重组,提高了载荷谱的提取精度及疲劳损伤计算准确度。建立了基于损伤的臂架结构健康状态评价体系,将疲劳损伤引入到结构运行工况健康状态评估、结构周期性点检及寿命评估,为泵车臂架结构健康维护及管理提供依据。将疲劳损伤作为评价指标,结合小波多分辨率分析理论和方法,对臂架结构不同尺度应力响应进行了累积损伤分析,揭示了不同尺度应力响应对臂架结构损伤的影响。更多还原

【Abstract】 Abstract:Concrete pump truck is a specialty vehicle with the pump transport mechanism used for pumping conceret and boom used for distributing conceret integrated on automobile chassis. It has the advantages of high efficiency, good pouring quality and high flexibility. Due to the interaction of the poor working conditions, difficult to maintenance, materials aging, environmental erosion, fatigue, other long-term effects and disaster factors, the structural damage and failure of concrete pump truck has the propoety of gradient and sudden. Improper operation and not timely maintenance are likely to cause significant economic and life-safety issues.The work in this thesis was supported by the National "863" Plan essential project of China "Remote Monitoring and Maintenance of Key Technologies and Unit System"(2008AA042801) and "Concrete Pump Truck Remote Monitoring and Maintenance Application System Development"(2008AA042802). Using theoretical studies, simulation modeling and experimental analysis as research tools, the key technology of health monitoring for concrete pump truck structure, such as structural health monitoring method, sensor optimal placement, monitoring signal acquisition and processing, characteristic parameter extraction and health status evaluation method are studied in this thesis. The main contents are as follows:The structure and load characteristics of concrete pump truck was described. The statistics analysis of the common failure of the concrete pump truck structural was done. The static and dynamic characteristics of concrete pump truck boom structure were studied by simulation and experimental analysis. The health monitoring strategy of concrete pump truck boom structure based on strain parameter was proposed.The determination of sampling frequency in spectrum analysis, amplitude analysis and damage analysis was studied. The relationship between sampling frequency and damage analysis accuracy was deduced. A signal sampling strategy based on error contral was proposed. This method was applied to the strain signal sampling frequency determination of pump truck boom structure health monitoring. By examples, it is verified the sampling frequency can not only met the accuracy requirements of damage analysis, but also save data storage and increase the data treatment efficiency. Based on theory and methods of wavelet multi-resolution analysis, the noise reduction and abnormal value elimination of the structure monitoring strain signal were processed, and the distribution characteristics and the cumulative damage of different scale response signal was analyzed.Based on comprehensive evaluation method, a method of optimal monitoring strain sensor placement was proposed. According to the characteristics of concrete pump truck boom structure, working environment, damage and health monitoring content, the factor set affecting sensor placement was determinded. And the weight of each factor was determined based on Analytical Hierarchy Process (AHP). The fuzzy support matrix was constructed by using the correlation coefficient of strain signal of the proposed measuring points, and the comprehensive support degree of each proposed measured points was also calculated. Based on fuzzy mathematics methods, factors such as the stress level, the measuring point security, the sensor installation performance and the stress gradient, were classified and standardized. At last, the selected monitoring points of a concrete pump truck boom were optimized according to comprehensive evaluation method.The cumulative damage theory and the method of damage characteristic parameter extraction were researched. Based on fatigue damage theory, the influence mechanism of signal segment on the damage calculation accuracy was studied. A optimal load spectrum extraction method based on the real-time monitoring data of pump truck boom structure was proposed. The method can reduce the truncation of long-time stress cycles and frequent signal reorganization, which can improve the accuracy of load spectrum extraction and fatigue damage calculation.Based on damage index, the health evaluation system of boom structural was established, which introduced the fatigue damage into structure health status assessment of running condition, structure periodical check and life assessment. The evaluation result can provide the basis for health maintenance and management of the pump truck boom structure. Using fatigue damage as the evaluation index, and combining with wavelet multi-resolution analysis theory and method, the cumulative damage of different scale stress response was analyzed. The study reveals the influence of different scale stress response on the boom structure damage.更多还原