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针对螺栓联接状态监测问题,提出了基于压电阻抗解耦技术的螺栓松动监测技术。建立相应的实验装置,检测螺栓在不同预紧力下的导纳信号,将所采集的压电导纳信号,剔除导纳信号的被动部分后对所得到的导纳信号主动部分采用阻抗解耦算法,获得新的测点结构阻抗信息。以解耦得到的测点结构阻抗信号的实部定义了RMSD(Root Mean Square Deviation均方根偏差)损伤指标,识别螺栓联接状态(表现为螺栓轴向预紧力变化)。试验表明:导纳实部损伤指标能反映螺栓的联接状态;将解耦得到的机械阻抗实部作为监测螺栓联接状态的指标,较之常用的直接采用导纳信号实部定义的RMSD损伤指标,该方法所得的损伤指标明显提高,能更加有效的识别螺栓联接状态。 相似文献
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《机械设计与制造》2015,(9)
针对工程结构中的螺栓连接件易松动的问题,进行了基于压电阻抗技术(EMI)的螺栓松动监测实验。实验将锆钛酸铅压电陶瓷材料(PZT)直接粘贴在螺栓和螺母上,通过万能试验机对螺栓施加不同的拉力来模拟螺栓预紧力的变化,采用精密阻抗分析仪提取不同螺栓和螺母上压电材料的导纳信号,引入基于电导纳的均方根偏差(RMSD)损伤指标,建立螺栓松动程度和预紧力之间的对应关系。试验结果表明,不同型号的螺栓和螺母上安装的压电材料都可以感知预紧力的变化;得到了损伤指标(RMSD)和预紧力之间的定量对应关系;通过分析损伤指标和预紧力之间的关系可得到螺栓的松动情况,并且可直接定位松动的螺栓。研究表明基于压电阻抗技术的智能螺栓(智能螺母)可以实现松动自检测。 相似文献
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三角波信号波形参数的最小二乘评价 总被引:6,自引:0,他引:6
本文介绍了三角波信号时域波形参数的一种评价方法,通过使用波形测量手段和最小二乘直线拟合方法,对三角波信号的波峰,波谷,中值,幅度,频率,沿斜率,沿线性度,对称性等指标进行了精确评价,详细讨论了方法的实现过程以及有关技术问题,并对各项参数指标进行了误差分析,实验验证结果表明了该方法的有效性和实用性,该方法可应用到三角波信号源的性能指标评价中。 相似文献
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零部件表面经过硬化处理后,一般将形成由硬化层、过渡层和心部组织组成的三层结构,而硬化层深度是表面力学性能的重要评价指标。为将磁测法应用于硬化层深度的定量检测,建立了基于点状磁荷假设的多层结构磁滞模型,预测出三层结构微分磁导率曲线的双峰特性。双峰峰值、峰值比等参数与硬化层深度存在良好线性关系,由此提出一种硬化层深度的磁学无损检测新方法。对具有不同深度高频感应淬硬层的40Cr钢杆试样进行磁滞回线试验测试,分析结果表明:相比矫顽力,微分磁导率曲线的双峰峰值比更适用于硬化层深度的定量表征,其重复测试结果的变异系数小于1%,与硬化层深度的线性拟合确定系数高于0.95。建立的多层结构磁滞模型可为硬化层深度的磁测法提供理论依据,基于微分磁导率双峰曲线的硬化层深度检测方法可推广至平面或曲面构件。 相似文献
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This paper is aimed at the system evaluation problem of mechanical equipment caused by various factors including the multiplicity of structure, close relevancy, and complex operating environment. From functional hierarchy viewpoint of mechanical equipment, a quantitative evaluation model for mechanical equipment state is developed on the basis of fuzzy set synthesis evaluation and analytic hierarchy process (AHP). Considering the concept of human health and the equipment running parameters such as reliability, maintenance, and technical performance, the mechanical equipment health state and its evaluation hierarchy model are discussed. The health value is employed to quantitatively describe the running state degree of mechanical equipment. The weighted vectors of all evaluation hierarchies are discussed by using the AHP method with experiences of expert. Applied fuzzy set evaluation theory, a type of subordinate function of positive and negative indicators, is presented, and evaluation matrix is discussed as well as fuzzy transformation algorithm operators. The valuation model for mechanical equipment's multi feature parameters health state based on fuzzy AHP can be developed. The health value of subsystems can be obtained by the means of “from bottom to top”. Therefore, health value database of whole mechanical equipment can be established. Based on the database, the health state of mechanical equipment is explicit, which provides us with theoretical guide for seeking further optimization maintenance strategy. Finally, a health state evaluation of rotary kiln used in cement industry is taken as an example to verify the validity and feasibility of the proposed model. 相似文献
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五自由度并联机械腿静力学性能评价与优化设计 总被引:4,自引:0,他引:4
为了对一种六足机器人的五自由度并联机械腿进行静力学性能评价和优化设计,提出了一种同时考虑约束力映射关系和驱动力映射关系的腿部机构静力学分析方法,并基于此方法对机械腿进行了优化设计.首先,通过分析腿部机构的驱动、约束映射关系,分别建立了腿部机构的驱动雅可比矩阵和约束雅可比矩阵;应用虚功原理建立了腿部机构的驱动静力传递平衡方程,在定义驱动静力学评价指标的基础上绘制了评价指标分布图,得出了结构参数与驱动静力评价指标之间的关系曲线.然后,采用同样的方法建立了腿部机构的约束静力传递平衡方程,定义了约束静力学性能评价指标,得出了结构参数与约束静力评价指标之间的关系曲线.最后,基于驱动、约束静力学性能评价指标,采用蒙特卡罗法对结构参数进行了优化设计.计算表明,固定平台结构参数a为200mm、运动平台结构参数b为80 mm,UPU支链长度l1min,l3max分别为500mm、900mm时,腿部机构的静力学综合性能最好. 相似文献
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机械设计专家系统中设计方案的评价与决策子系统的研究 总被引:1,自引:0,他引:1
评价与决策是机械设计专家系统的重要组成部分。提出建立集评价、决策及反馈于一体的机械设计专家系统中设计方案的评价与决策子系统。详细阐述了该评价与决策子系统的基本结构、功能及各部分关键技术。 相似文献
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机械传动系统设计方案的模糊综合评判 总被引:6,自引:0,他引:6
针对机械传动系统方案设计的复杂性,探讨运用模糊设计理论和机械设计理论,在方案的评价体系中引入因素子集、因素、因素等级三层结构,对方案作三级模糊综合评判,找出最优方案。对一实例进行分析计算,结果表明该评价方法的效果是显著的。 相似文献
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介绍为机械产品的强度设计和结构设计而建立的数据库和强度评价方法及其程序系统。将机械强度与振动数据库分为四类,列出了已建立的数据表的中文表名,将强度评价方法分为:静强度评价、静刚度评价、疲劳强度评价、疲劳寿命估算、断裂强度评价。 相似文献
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J. H. Lee J. U. Cho G. Zhao C. Cho 《Journal of Mechanical Science and Technology》2016,30(10):4475-4478
Aluminum foam with its excellent physical and mechanical characteristics is a lightweight metallic material used with good quality in vehicle bumpers, internal shock absorbers on planes, as materials for vessel joints etc. On the contrary, when aluminum foam is used without sufficient investigation, there is the likelihood of damage or destruction of the machine or mechanical structure, and in extreme case it may cause to human casualties. This study aims to analyze the characteristics of adhesive structures with aluminum foam for the closed-type aluminum foam used primarily as shock absorbers. The fatigue analyses of the DCB test specimens at mode III with aluminum foam are verified through a fatigue experiment. As the analysis results, test specimen models with the thicknesses (t) of 35 mm, 45 mm and 55 mm showed the peak load occurrence approximately after the progress from 0 to 50 cycles. And afterwards the load gradually decreased as the cycles increased. The peak loads for each DCB test specimens were ±0.80 kN for the specimen thickness(t) of 35 mm, ±0.98 kN for the specimen thickness(t) of 45 mm and ±1.18 kN for the specimen thickness(t) of 55 mm. It is also shown that the peak load occurring on the specimen increased as specimen thickness increased. These study results are compared with the specimen thickness of 35 mm model as the basis. When the specimen thickness is increased as much as 10 mm, the peak load is increased approximately 1.25 times. When the specimen thickness is also increased as much as 20 mm, the peak load is increased 1.5 times. The analysis data and the real experiment data showed similar results each other. Therefore, it can be thought that the analysis data is applicable in real field. And it is estimated that the mechanical characteristics of the DCB test specimen at mode III during the fatigue load conditions can be systematically and efficiently analyzed. 相似文献
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六足步行机器人的并联机械腿设计 总被引:5,自引:0,他引:5
将并联机构用于六足步行机器人的腿部结构,以拓展六足步行机器人的应用领域.提出了一种基于(U+UPR)P+ UPS机构的并联机械腿,并对机械腿进行了结构参数设计.首先,对腿部机构进行了运动学分析,推导出了腿部机构的位置反解方程和速度传递方程;分析了腿部机构的工作空间并绘制了工作空间三维图,定义了工作空间性能评价指标,绘制了结构参数与工作空间性能指标的关系曲线.然后,对腿部机构进行了运动灵活性分析并绘制了雅克比矩阵条件数分布图,定义了运动灵活性评价指标,绘制了结构参数与运动灵活性指标的关系曲线.最后,基于工作空间性能指标和运动灵活性指标,采用蒙特卡罗法进行了结构参数分析,选取了一组性能较好的结构参数并考虑加工和装配工艺性,设计了一种新型3自由度并联机械腿的虚拟样机,为六足步行机器人的进一步研究奠定了基础. 相似文献