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三维非均匀脆性材料破坏过程的数值模拟 总被引:32,自引:1,他引:32
采用有限元方法模拟了三维均匀固体材料在宏观等效力学性质和破坏过程。首先采用格形(lattice)方法把试件离散成三维均匀网格,在每个单元格中将材料按照均匀处理,根据给定的统计规则来确定不同单元格中的材料常数以反映材料的非均匀性。然后对非均匀脆性材料选用简单的本构关系与断裂准则,采用自适应选取载荷步长对试件进行加载,通过非平衡迭代技术对刚度矩阵进行不断修正,实现了非均匀脆性材料的弹性行为及破坏过程的数值模拟。在此基础上,通过数值计算研究了材料的非均匀分布对宏观等效力学性质和破坏过程的影响,给出了破坏全过程的非线性载荷-位移曲线以及不同载荷阶段的三维损伤破坏的演化图。 相似文献
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Synchronization of the fractional-order generalized augmented Lii system and its circuit implementation 下载免费PDF全文
In this paper, the synchronization of the fractional-order generalized augmented Lti system is investigated. Based on the predictor--corrector method, we obtain phase portraits, bifurcation diagrams, Lyapunov exponent spectra, and Poincar6 maps of the fractional-order system and find that a four-wing chaotic attractor exists in the system when the system pa- rameters change within certain ranges. Further, by varying the system parameters, rich dynamical behaviors occur in the 2.7-order system. According to the stability theory of a fractional-order linear system, and adopting the linearization by feedback method, we have designed a nonlinear feedback controller in our theoretical analysis to implement the synchro- nization of the drive system with the response system. In addition, the synchronization is also shown by an electronic circuit implementation for the 2.7-order system. The obtained experiment results accord with the theoretical analyses, which further demonstrate the feasibility and effectiveness of the proposed synchronization scheme. 相似文献
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类前缘防热层流场与热响应耦合计算研究 总被引:1,自引:0,他引:1
本文在以往对类前缘防热层热响应计算分析基础上,进一步研究实现了外流场高超音速NS方程数值计算表面气动加热与防热层结构热响应的耦合计算,这对于常用的非耦合计算方法来说是一进步,也为进一步开展外流场/结构热响应/热应力全耦合一体化计算研究和防热层表面吹气强化传热问题的场协同研究打下了基础。 相似文献
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多孔介质中热对流的分叉机理研究 总被引:3,自引:1,他引:3
本文利用解析分析方法研究了数值模拟发现的多孔介质层中出现的对流分叉机理,指出控制方程中的Rayleigh数,是决定流动的特征参数。当Rayleigh数小于临界数值时,多孔介质内流动处于静止传热状态,并且这种状态是稳定的。如果Rayleigh数大于临界数值,非线性方程出现分叉解,文中指出,存在多个使平凡解失稳而分叉的临界Rayleigh数,当Rayleigh数由小到大经历这些临界数值时,其由平凡解发展起来的分叉解的流态,依次由单回流区转变为双回流区及三回流区。理论分析给出了分叉解和分叉解的振幅方程,阐明了分叉的机理,其结论和数值结果定性一致. 相似文献
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CHAOTICBEHAVIOUROFFORCEDOSCILLATORCONTAININGASQUARENONLINEARTERMONPRINCIPALRESONANCECURVESPeiQin-yuan(裴钦元)(ChangshaRailwayUni... 相似文献
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The spin polarization phenomenon in lepton circular accelerators had been known for many years.It provides a new approach for physicists to study the spin feature of fundamental particles and the dynamics of spin-orbit coupling,such as spin resonances.We use numerical simulation to study the features of spin under the modulation of orbital motion in an electron storage ring.The various cases of depolarization due to spin-orbit coupling through an emitting photon and misalignment of magnets in the ring are discussed. 相似文献
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