【作者】 杨多和；

【导师】 安伟光；

【作者基本信息】 哈尔滨工程大学 ， 固体力学， 2009， 博士

【摘要】 由于压电材料结构系统具有很多不确定的因素,例如载荷的不确定性；结构中用的材料物理性能数据可能与提供的有所差异；名义尺寸也可能与实际结构不完全一致。因此,对压电材料结构进行随机分析并评价其可靠性就显得非常有必要。本课题应用可靠性理论,进行表面贴有压电片的桁架结构系统的静力可靠性、稳定可靠性、动力可靠性及基于神经网络的可靠性分析。主要有以下几个方面1)对表面贴有压电片的压电主动杆单元组成的桁架结构,建立其有限元分析模型,其中包括静力分析有限元模型,稳定分析有限元模型和动力分析有限元模型,计算结构在机电耦合作用的内力响应。2)研究压电杆元的破坏机理,在静力和动力可靠性分析过程中,给出压电杆单元破坏的判断准则,分别写出压电杆基体屈服失效、压电片断裂破坏、胶合层破坏和击穿破坏引起的安全余量表达形式；在稳定可靠性分析中给出了由载荷系数构成的安全余量表达形式,以及不同工况下压电桁架结构系统稳定可靠性分析方法。3)把压电杆元基体的屈服强度、杆元截面面积和压电片的断裂强度、损伤电场强度、外载荷等为随机变量,研究了安全余量对其求偏导运算公式,采用Taylor展开随机有限元法,给出了安全余量可靠性指标的计算方法；运用可靠性的基本理论,结合压电桁架结构的力学特点,进行压电桁架结构系统的可靠性分析,采用PNET法求出压电桁架结构系统的可靠性指标。4)借助了神经网络具有较强的函数映射关系,采用正交表的方法设置样本,结合Monte Carlo随机抽样,产生极限状态函数值,进行了基于神经网络的压电桁架结构系统的可靠性分析。5)编制程序,计算和分析了机电耦合效应和外加电压,对压电片桁架结构系统在静力、稳定和动力方面的可靠性影响,说明了压电桁架结构系统的可靠性优于普通的桁架结构系统,同时也分析压电元件的优化配置对系统可靠性的影响。更多还原

【Abstract】 For piezoelectric structure system, there are a lot of uncertainty factors, for example, the loads which act on the structure are indeterminate; material data and dimension data provided may be not consistent with that of real structure; Therefore, it is necessary for piezoelectric structure to make stochastic analysis and evaluate its reliability. Static strength reliability, stable reliability, dynamic reliability and reliability based on Neural Networks are analyzed by using the theory of reliability for truss structure with piezoelectric patches affixed to its surface in this paper. The main research works of the paper are as following1) For the truss structure comprised of piezoelectric active-member with piezoelectric patches affixed to its surface, the finite element model is founded, which includes static force models, stabile models and dynamical models. The responses of internal force under Mech-Electric coupling are calculated.2) The failure mechanism of the piezoelectric member is discussed. In the process of statics and dynamic reliability analysis, the failure criterion of the piezoelectric member is proposed, safety margin functions of failure modes which are caused by yield failure of piezoelectric elementary body, fracture damage of piezoelectric patches, clue layer destroying and electrical breakdown are established separately, In the process of stabile reliability analysis, safety margin functions which are composed of load coefficient are established and stable reliability analysis method of piezoelectric truss is proposed in different condition.3) By considering the yield strength of piezoelectric elementary body, area of section, fracture strength and breakdown electric field intensity of the piezoelectric member, loads as stochastic variables, the formula of partial derivative of the safety margin functions is studied, the method of reliability of safe margin is given by adopting Taylor expansion SFEM; Then adopting basic theory of reliability, combining the mechanical character of piezoelectric truss structure, the reliability analysis of piezoelectric truss structure is discussed. At last, the reliability index of piezoelectric truss structure system is got by PNET.4) By means of Neural Networks which has strong ability of function mapping and using orthogonal table as sample set, combining with Monte Carlo stochastic sampling, the function values of limit state are obtained. Reliability analysis of piezoelectric truss structure based on Neural Network is discussed also.5) For program compiling, the static force, stabile and dynamical reliability effect of Mech-Electric coupling and external voltage on piezoelectric truss structure are analyzed. The results indicates the reliability of piezoelectric truss structure is better than common structure, and the effect of optimum distribution of piezoelectric member to the reliability of structural system is analyzed.更多还原