轴对称横观各向同性浅球壳受物体撞击的非线性动力响应分析

基于非线性扁壳理论和弹性接触力学,建立了横观各向同性浅球壳在其顶部受集中载荷作用的非线性运动微分方程,根据Hertz定律,考虑撞击物与浅球壳之间的弹性接触效应,确定了壳体顶部所承受的冲击力,它与撞击物的质量、初始速度、壳体的几何和物理性质等因素相关.对此非线性动力问题,采用正交配点法与时间增量法求解.算例中,讨论了撞击物的冲击速度、壳体的厚度及中曲面曲率半径对壳体所受冲击载荷及其位移响应的影响.     

基于CDM的黏弹性薄板压屈失效分析

研究黏弹性薄板的压屈失效问题.基于连续介质损伤力学与Schapery对应原理,得到耦合各向异性蠕变损伤的黏弹性本构模型,构造板的分层模型以考虑损伤演化的空间特征,建立具初挠度板的非线性压屈控制方程与边界条件,并进行空间与时间域上的数值离散和迭代求解.计算结果与实验曲线的对比表明本文的分析方法是有效的,黏弹性材料的蠕变损伤将导致结构刚度不断削弱,在一定应力水平下,板发生变形快速增加的压屈失效.     

轴对称压电圆板的非线性动力响应

基于Von Karman板理论和压电材料力学,考虑横向剪切变形,建立了轴对称压电圆板的非线性运动方程,提出了相应的力学与电学边界条件.求解时,首先应用Galerkin方法,将非线性偏微分运动方程转化为仅含时间变量的非线性常微分方程.然后,应用Newmark-β方法将时间函数离散,整个问题应用Newtoni迭代法求解.算例中,求得了压电圆板线性振动基频,验证了方程和求解方法的可靠性,讨论了压电效应、几何非线性、结构尺寸、力学和电学荷载等因素对板非线性动力响应的影响.     

Nonlinear active control of damaged piezoelectric smart laminated plates and damage detection

Considering mass and stiffness of piezoelectric layers and damage effects of composite layers, nonlinear dynamic equations of damaged piezoelectric smart laminated plates are derived. The derivation is based on the Hamilton＇s principle, the higher- order shear deformation plate theory, von Karman type geometrically nonlinear straindisplacement relations, and the strain energy equivalence theory. A negative velocity feedback control algorithm coupling the direct and converse piezoelectric effects is used to realize the active control and damage detection with a closed control loop. Simply supported rectangular laminated plates with immovable edges are used in numerical computation. Influence of the piezoelectric layers＇ location on the vibration control is in- vestigated. In addition, effects of the degree and location of damage on the sensor output voltage are discussed. A method for damage detection is introduced.     

NONLINEAR VIBRATION FOR MODERATE THICKNESS RECTANGULAR CRACKED PLATES INCLUDING COUPLED EFFECT OF ELASTIC FOUNDATION

IntroductionThe moderate thickness plates on elastic foundation are a kind of important structure instructural engineering. The mechanic characters of the plates on elastic foundation withdifferent boundary conditions have been received considerable atten…     

单轴转动截锥扁壳的全局分岔与混沌

考虑－受横向周期载荷作用下单轴转动的截锥扁壳，利用Melnikov方法讨论了该动力系统的同宿轨分岔，次谐分岔；并用数值方法进行模拟，研究该系统的混沌运动，从所得出的相平面图，时间历程图和庞加莱映射图业看，在一定参数组合下，该系统确实存在混沌运动。     

弹性地基上间断中厚矩形板的非线性静力分析

研究弹性地基上带传力杆的间断中厚矩形板的非线性静力特性。荷载在传力杆中的传递由竖向弹簧模拟,其弹簧刚度取决于传力杆的特性以及杆与板间的相互作用。根据能量变分原理,考虑地基耦合效应,建立了双参数地基上带传力杆的间断矩形中厚板的非线性静力控制方程。构造出一组满足所有边界条件的试探函数,应用伽辽金法对该组非线性方程进行求解。数值算例中,讨论了传力杆参数、板的结构参数及地基参数对弹性地基上间断矩形中厚板的非线性静力特性的影响。     

Delamination growth for composite laminated cylindrical shells under external pressure

The delamination growth may occur in delaminated cylindrical shells under external pressure.This will lead to failure of structure.By using the variational principle of moving boundary and considering the contact effect between delamination regions,in this work,the delamination growth was investigated for cylindrical shells under the action of external pressure.At the same time,according to the Griffith criterion,the formulas of energy release rate along the delamination front were obtained.In the numerical calculation,the delamination growth of axisymmetrical laminated cylindrical shells was analyzed,and the effects of delamination sizes and depths,the geometrical parameters, the material properties,and the laminate stacking sequences on delamination growth were discussed.     

考虑损伤效应的开孔浅球壳的非线性动力响应与动力屈曲

研究损伤对开孔浅球壳非线性动力响应与动力屈曲的影响.基于Talreja张量内变量损伤模型,建立了纤维增强复合材料板壳弯曲问题的损伤本构关系,导出了考虑损伤效应的具轴对称变形正交各向异性开孔浅球壳的非线性运动控制方程.对未知函数在空间域采用正交点配置法离散,时间域采用Newm ark-β方法离散.数值结果表明,由于损伤导致结构刚度不断削弱,结构振幅增大而频率减小,结构的动力临界屈曲载荷降低.     

正交各向异性材料的弹塑性损伤本构关系

基于弹塑性力学和损伤理论,建立了一个与应力球张量有关的正交各向异性材料的混合硬化屈服准则,该准则无量纲化后与各向同性材料的Mises准则同构,在此基础上,进而建立了混合硬化正交各向异性材料的增量型弹塑性损伤本构方程,并以具局部损伤的正交各向异性矩形薄板为例,采用Galerkin法和迭代法,对其弹塑性屈曲问题进行了分析,讨论了局部损伤对正交各向异性矩形薄板弹塑性屈曲临界应力的影响.