带脱层的复合材料层板屈曲分析中的接触问题

用基于Mindlin板理论的有限元方法进行了带脱层损伤复合材料层板的屈曲载荷分析．为了处理在屈曲模态中上下脱层之间的接触问题，我们提出了一种有效的算法．在这种算法中，首先用一阶灵敏度分析和二次规划方法相结合的选代算法算出接触区域的虚拟力，然后将这种虚拟力转化成一些假想弹簧的刚度系数，并对原始刚度矩阵进行修正．数值算例表明本算法可以有效地克服屈曲模态中上下脱层之间的相互贯穿．同时，还对脱层的大小，形状和位置对屈曲载荷的影响进行了研究．     

八十书怀

 八十居幽燕,故园齐楚间.欲临秦隘险,一睹汉关严.炮火出林上,钻研茀树间.鲁直每不羁,容恕亦释然.     

An iterative parallel algorithm of finite element method

In this paper, a parallel algorithm with iterative form for solving finite element equation is presented. Based on the iterative solution of linear algebra equations, the parallel computational steps are introduced in this method. Also by using the weighted residual method and choosing the appropriate weighting functions, the finite element basic form of parallel algorithm is deduced. The program of this algorithm has been realized on the ELXSI-6400 parallel computer of Xi'an Jiaotong University. The computational results show the operational speed will be raised and the CPU time will be cut down effectively. So this method is one kind of effective parallel algorithm for solving the finite element equations of large-scale structures.     

利用色散关系计算单个粒子的格林函数

本文利用核子与反核子散射振幅的解析性和么正性导出单个虚介子的格林函数。在计算中不需要进行重正化手续     

基于复合式团队两阶段道德风险模型的担保企业评委激励机制

学术界将团队道德风险与两阶段道德风险模型结合构建复合式模型成为激励理论新研究的趋势.然而,这种复合式模型对团队成员间协作,业务两阶段间努力的影响以及代理人的行为因素考虑不足.以担保企业的评委团队在评议会和评审会两阶段的道德风险为研究对象,运用经济学激励理论和最优理论与算法,构造了团队两阶段道德风险复合模型,并通过数值仿真揭示了评委团队在不同规模人数下,团队成员的业务两阶段的努力影响因子,评委团队协作度、两阶段评委道德敏感度与激励强度的关系.主要研究结果表明:在业务评议会阶段,评委团队为3~5人规模,且两阶段努力影响因子偏小或评委道德敏感度偏大时,对该阶段评委团队应施加高激励;而当评委间的协作度为中等或高水平时,随着评委间协作度的增加,对该阶段评委团队的激励强度应递减.在业务评审会阶段,随着评委人数的增加且评委两阶段的努力影响因子减小,对该阶段评委团队应施以较强的正激励;随着评委道德敏感度的减小或评委的协作度增加,对该阶段评委应强化正激励.     

土壤源热泵在合肥地区的应用研究

介绍了土壤源热泵的工作原理,探讨了土壤源热泵空调应用于中央空调系统的设计方法,以及其主要部件地埋换热器的埋管方式、结构、管材、运行等特点。实验研究了合肥地区夏季不同运行模式下地埋换热器的换热性能以及换热器周围温度场的变化情况,最后利用有限元分析软件ANSYS对地埋换热器运行一个夏季后周围土壤温度场进行了模拟。     

高能物理剀进展

本文概述了高能物理实验和理论方面的进展,近几年来实验对QCD和弱电统一理论的重要验证,用电子、正电子碰撞对量子电动力学在高能极限的验证,及以高能强作用喷射时的实验结果,报告还讨论了对强子质量谱的唯象处理。     

Microcrack localization using a collinear Lamb wave frequency-mixing technique in a thin plate

A novel Lamb wave frequency-mixing technique is proposed for locating microcracks in a thin plate,which does not require the resonance condition of Lamb wave mixing and can accurately locate the microcracks through only one-time sensing.Based on the bilinear stress-strain constitutive model,a two-dimensional finite element(FE)model is built to investigate the frequency-mixing response induced by the interaction between two primary Lamb waves and a microcrack.When two primary Lamb waves of A0 and S0 modes with different frequencies excited on the same side of the plate simultaneously impinge on the examined microcrack,under the modulation of the contact acoustic nonlinearity,the microcrack itself can be deemed as the secondary sound source and it will radiate the Lamb waves of new combined frequencies.Based on the time of flight of the generated A0 mode at difference frequency,an indicator named normalized amplitude index(NAI)is defined to directly locate the multi-microcracks in the given plate.It is found that the number and location of the microcracks can be intuitively visualized by using the NAI based frequency-mixing technique.It is also demonstrated that the proposed frequency mixing technique is a promising approach for the microcrack localization.     

模拟长纤维增强树脂层合板冲击损伤的数值方法

建立了一套模拟树脂层合板低速冲击下损伤过程的方法.该方法采用Mindlin板模型并考虑板的大变形,使用以前提出的一种修正的Newmark时间积分方案进行层板的动态分析,全面考虑了复合材料的脱层破坏、基体开裂和纤维断裂等破坏形式及其相互作用.还建立了一种适合于 Mindlin板的计算应变能释放率的方法;构造了一种连续的罚函数来动态加人弹簧约束以考虑脱层间的接触效应;证明了球板之间的冲击过程是刚性系统,应使用A（α）稳定的数值方法求解;实现了模拟过程中的自适应分析.使用所开发的软件NBHULI完成了长纤维增强碳/环氧复合材料层板在低速冲击下损伤过程的模拟,取得了一些重要的结果.