四边固支球面扁壳的解析解

本文用解析法四边固支球面扁壳的在均布荷载作用下的内力和挠度进行了计算。     

用泰勒级数法求解横观各向同性球壳的轴对称弯曲问题

本文采用泰勒级数法分析横观各向同性球壳轴对称弯曲问题。将位移沿厚度方向展开成泰勒级数,利用三维弹性方程求得级数中的各阶导数。对于边值问题,用特征函数法满足球面齐次边界条件,并用最小二乘配点法满足端部条件。     

Einsatz von DMS- und Piezomeßtechnik zur direkten Schubspannungsermittlung in der Kapillarrheometrie

Zusammenfassung Der Stand der Kapillarheometrie mit den Vor- und Nachteilen der einzelnen Systeme und Meßverfahren wird dargestellt. Ausgehend von diesem Stand werden zwei alternative Meßverfahren, nämlich Piezo-Einzelkraftund DMS-Meßverfahren, zur direkten Schubspannungsermittlung besprochen und eine nach diesem Prinzip konzipierte Versuchsdüse vorgestellt. Die mit dieser Düse erhaltenen Meßergebnisse zeigen im Vergleich zu konventionell, d. h. unter Anwendung des Bagley-Verfahrens, ermittelten Fließkurven im Falle der Einzelkraftmessung gute Übereinstimmung. Das Problem der Einlaufdruckkorrektur ist bei diesem Konzept von vornherein nicht vorhanden, und der ununterbrochene Fließkanal erlaubt, bei entsprechender Erweiterung auf zwei Kraftaufnehmer, einen unproblematischen Einsatz im On-line- oder sogar im In-line-Betrieb in der Polymerverarbeitung.Schlüsselwörter Rheometrie; Kapillarrheometrie; Schubspannungsermittlung; Piezokraftmessung; DMS-Anwendung; Kunststoffschmelzen; On-line-Rheometrie

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The state-of-the-art of capillary rheometry, especially the advantages and disadvantages of different systems, is presented. Two measuring methods, a piezo single-force transducer, and a strain-gauge device combined in a testing die are compared. The strain gauges are fixed at the outside of a small capillary to detect the resulting wall shear stress between inner surface of the die and polymer flow by measuring the axial strain in the wall of the die. The single force method uses an elastic section of the die which uncouples the die from the supporting structure without changing the cross-section of the flow. The uncoupled part of the die is supported by a stiff, piezo-force transducer that detects the integral effect of wall shear stress. The resulting flow curves compare well with those using the Bagley method. With the novel die no entrance pressure-loss correction is needed. In principle, it also could be used as an on-line device for polymer processing.

Vortrag, gehalten auf der Jahrestagung der Deutschen Rheologischen Gesellschaft, TH Darmstadt, 19.–21. April 1989.     

Thermoconductivity and thermoelasticity of thin isotropic shells heated by a moving heat pulse

The paper presents a solution to the problem of thermal conduction and thermoelasticity for a thin shallow spherical shell heated by a concentrated or local impulsive heat source moving over the shell surface. It is assumed that temperature is linearly distributed across the shell thickness and that the shell, on its sides, exchanges heat with the environment in accordance with Newton’s law of cooling. The Fourier and Laplace transforms are used to find an analytic solution. The dependence of the temperature field and stress/strain components on the type of heating and the form of heat source is studied __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 11, pp. 85–92, November 2006.     

Scaled-boundary method in electroelasticity of thin plates

The paper discusses the scaled-boundary method as applied to electroelastic problems. As an example, the stress-intensity factor is calculated for a thin rectangular piezoelectric plate with an edge crack __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 124–134, July 2006.     

含压电层的功能梯度柱壳的自由振动分析

基于三维弹性理论，导出了带有压电层的圆柱形梯度壳的动力学方程以及相应的边界条件，用幂级数展开法得到了求解该圆柱形梯度壳自由振动的三维精确公式．通过实例模型求解了该壳体的自由振动的固有频率；分析了不同电学边界条件对壳体的振动频率的影响。结果可评估各种近似理论解和数值解的正确性。     

T-STRESS IN PIEZOELECTRIC SOLID

The non-singular and bounded terms for stresses near the crack tip were investigated. The crack problem in a transversely isotropic piezoelectric solid for the plane problem was dealt with. The principle of superposition and the Plemelj formulation were introduced. The non-singular terms are given by solving Rieman-Hilbert problem. It is shown that the non-singular terms are influenced by the elastic and electric constants.     

静压气体球轴承支承球形转子的干扰力矩分析

中心小孔供气单向受载球面气体轴承可以用于球形转子的静平衡测量。对作用于转子上的干扰力矩进行估算是平衡装置设计的重要部分。本在一定假设条件下推导了由粘性剪切应力和气膜支撑力引起的作用于转子上的干扰力矩。干扰力矩以轴承包角、中心气室张角、气膜压力、转子转速、转子旋转轴位置、失中度、转子非球表示。以干扰力矩最小为准则分析了这些参数的影响，结论有助于静平衡装置的优化设计以及对精度的进一步分析。     

基于高阶位移模式的压电层合板动力有限元模型

建立了含压电片层合板的有限元动力学模型。以位于压电层上下表面处的电场强度和层间电压为未知量,给出了三次函数的电势分布模式,采用Reddy的高阶剪切理论描述板的位移场,假设板厚度方向的正应力为零给出了减缩的本构方程,采用有限元方法,基于Hamilton原理导出结构的动力学方程,然后用静态缩聚的方法压缩掉电场自由度和次要的位移自由度。最后用四边形矩形单元求解了一对称铺层和非对称铺层悬臂板的固有频率,并与ANSYS结果对比验证了本文模型的精确性。     

Global structural behaviour of thin and moderately thick monoclinic spherical shells using a mixed shear deformation model

Summary The static and dynamic responses of anisotropic spherical shells under a uniformly distributed transverse load are investigated. Analytical solutions using the mixed variational formulation are presented for spherical shells subjected to various boundary conditions. Numerical results of a refined mixed first-order shear deformation theory for natural frequencies, critical buckling, center deflections and stresses are compared with those obtained using the classical shell theory. A variety of simply-supported and clamped boundary conditions are considered and comparisons with the existing literature are made. The sample numerical results presented herein for global structural behaviour of monoclinic spherical shells should serve as references for future comparisons.