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法国科学院AlainPierreLeger教授讲学通知
发布人:管理员LI  发布时间:2016-05-17   浏览次数:35

应我校航天学院非线性动力学研究中心曹庆杰教授的邀请,国际著名非线性力学专家、法国科学院AlainPierreLeger  教授将于514日到26日来我校访问讲学。欢迎广大师生参加。学术讲座信息如下:讲座一题目:“IntroductiontoNon-SmoothDynamics”时间:5月15日上午9:00—11:00地点:正心楼1103内容:Taking contact  and friction conditions into account in the mechanics of continuous media leads  to open and very difficult problems. But as far as simple models are chosen  conveniently, they might allow some qualitative investigation which would not be  possible for continuous bodies. This lecture will present the basic features of  the dynamics in presence of contact and friction in the case of a very simple  model: a mass-spring system moving over a plane obstacle. This lecture shall  first show that the equations of the motion should be understood as equalities  between measures, which changes all the classical results of the theory of  ordinary differential equations.讲座二题目:“Qualitative  investigation ofasimplesystemwithcontactandfriction”时间:5月17日上午9:00—11:00地点:正心楼1103内容:This lecture  shall show the qualitative dynamics of a simplemass-spring system involving non  regularized unilateralcontact and Coulomb friction and submitted to an  oscillating external force. The period-amplitude plane of theexcitation appears  to be essentially divided into two rangesof sliding solutions. At each point of  the lower range thereexist infinitely many equilibrium points  and all the trajectories go to equilibrium in finite time. In  the upper range,there no longer exist equilibria. Different kinds of  periodicsolutions are shown to exist in different zones and thetransitions  between these zones are explicitly computed.The upper boundary of this range,  where the mass loosescontact, is also computed and special attention is paid  tothe dependence of this upper boundary with respect to theperiod of the  excitation.讲座三题目:“Unilateralproblemsinthemechanicsofstructure:theobstacleproblemforshallow  shells时间:5月19日上午9:00—11:00地点:正心楼1103内容:A  three-dimensional equilibrium problem for a linearly elastic shallow shell of  constantthickness subjected to unilateral contact constraints is studied in  curvilinear coordinates.The main result establishes that the three-dimensional  equilibrium problem converges,when the thickness tends to zero, towards a model  of shallow shell in unilateral contactwith an obstacle. Because the unilateral  contact conditions involve a non-penetrabilityinequality which couples the three  covariant components of the displacements, it isshown that, nevertheless, these  components can be uncoupled and the resulting contactconditions include only the  transverse covariant component of the displacement.讲座四题目:“Dynamicsofelasticbodiesbondedbyathinlayer时间:5月21日上午9:00—11:00地点:正心楼1103内容:This lecture  extend the study of Licht et al. devoted to the dynamic response of a structure  made of two linearly elastic bodies connected by a thin soft adhesive layer made  of a Kelvin–Voigt-type nonlinear viscoelastic material to the case of a  generalized standard material with a positive definite quadratic density of free  energy. A concise formulation in terms of an evolution equation in a Hilbert  space of possible states with finite energy makes it possible to identify the  asymptotic behavior, when some geometrical and mechanical parameters tend to  their natural limits, like the response of the two bodies connected by a  mechanical constraint. Its law has the same structure as that of the adhesive  but with coefficients accounting for the relative behavior of the  parameters.AlainPierreLeger  教授简介:AlainPierreLeger  教授是是国际著名的非线性动力学理论与应用专家,长期从事非线性动力系统理在工程中的应用研究。主要研究领域涉及结构力学,非光滑动力系统问题,如接触,碰撞等以及分叉问题及其在力学中的应用,已发表高水平学术论文200余篇。AlainPierreLeger  教授的主要研究兴趣如下:1、结构力学的理论及分析方法;2、非光滑动力学分析及控制理论;3、碰撞、摩擦作用下的非光滑动力系统的定性分析;4、向量场分叉理论;5、非线性动力系统的理论、数值方法与应用。