Inhomogeneous isoparametric elements for stress analysis of composites

The concept of inhomogeneous element is proposed and the formulations of the inhomogeneous isoparametric elements for stress analysis of four kinds of problems are derived. As an example of applications of the inhomogeneous elements, the stress distribution in a cone-like composite syntheticrope termination is calculated.

Stress analysis of ZrO2/SiO2 multilayers deposited on different substrates with different thickness periods

The effects of repeating thickness periods on stress are studied in ZrO2/SiO2 multilayers deposited by electron-beam evaporation on BK7 glass and fused-silica substrates. The results show that the residual stress is compressive and decreases with an increase of the periods of repeating thickness in the ZrO2/SiO2 multilayers. At the same time, the residual stress in multilayers deposited on BK7 glass is less than that of samples deposited on fused silica. The variation of the microstructure examined by x-ray diffraction shows that microscopic deformation does not correspond to macroscopic stress, which may be due to variation of the interface stress. (c) 2005 Optical Society of America.

Stress analysis of ZnO film with a GaN buffer layer on sapphire substrate

A 5.35-mu m-thick ZnO film is grown by chemical vapour deposition technique on a sapphire (0001) substrate with a GaN buffer layer. The surface of the ZnO film is smooth and shows many hexagonal features. The full width at half maximum of ZnO (0002) omega-rocking curve is 161 arcsec, corresponding to a high crystal quality of the ZnO film. From the result of x-ray diffraction theta - 2. scanning, the stress status in ZnO film is tensile, which is supported by Raman scattering measurement. The reason of the tensile stress in the ZnO film is analysed in detail. The lattice mismatch and thermal mismatch are excluded and the reason is attributed to the coalescence of grains or islands during the growth of the ZnO film.

Thermal stress analysis for GaInAsP multiple quantum well wafer chemically bonded to Si (100)

An n-InP-based InGaAsP multiple-quantum-well wafer was bonded with p-Si by chemical surface activated bonding at 70 degrees C, and then annealed at 450 degrees C. Different thermal expansion coefficients between InP and Si will induce thermal stresses in the bonded wafer. Planar and cross-sectional distributions of thermal stress in the bonded InP-Si pairs were analyzed by a two-dimensional finite element method. In addition, the normal, peeling, and shear stresses were calculated by an analytic method. Furthermore, x-ray double crystalline diffraction was applied to measure the thermal strain and the strain caused by the mismatching of the crystalline orientation between InP (100) and Si (100). The wavelength redshift of the photoluminescence (PL) spectrum due to thermal strain was investigated via the calculation of the band structure, which is in agreement with the measured PL spectra.

Stress analysis of silica-based arrayed waveguide grating by a finite element method

The stress distribution in silica optical waveguides on silicon is calculated by using finite element method (FEM). The waveguides are mainly subjected to compressive stress along the x direction and the z direction, and it is accumulated near the interfaces between the core and cladding layers. The shift of central wavelength of silica arrayed waveguide grating (AWG) on silicon-substrate with the designed wavelength and the polarization dependence are caused by the stress in the silica waveguides.

Stress analysis of CR superferric magnet

Finite Element Method is used in this article to analyze the stress of CR superferric magnet. Magnetic force and the stress caused by this force are calculated. The thermal stress and strain of the coil caused by cooling down is also analyzed. The result will be taken as a check for the design of the coil and coilcase, and also as a reference for the optimization of further design and quench protection.

Super-FRS超导磁体失超瞬态热应力分析；Quench transient thermal stress analysis of super-FRS dipoles

国际反质子与离子大科学工程(FAIR)项目是一个大型的国际合作项目,其中Super-FRS超导二极磁体由中国科学院近代物理研究所研制。利用ADINA有限元程序对项目中的超导Super-FRS磁体线圈的失超过程进行了模拟分析。利用C程序对ADINA程序进行二次开发以便对有限元求解器的调用和载荷的控制。分析结果显示:在失超过程中产生的最大热应力为26 MPa,可能产生的声波频率在35 Hz左右。

Stress Analysis of the Superconducting Magnet of LPT

The superconducting magnet of the LPT (Lanzhou Penning trap) consists of nine coaxial coils. The maximum magnetic field is 7 T and thus results in a large magnetic force. In order to assure the mechanical stability, it is necessary to do the stress analysis of the magnet system. The 3D Finite Element Analysis of thermal and mechanical behavior was presented in this paper. For the numerical simulation and analysis of the phenomena inside the structure, the ADINA and TOSCA code were chosen right from start. The ADINA code is commonly used for numerical simulations of the structure analysis [1] and the TOSCA code is professional software to calculate the magnetic field and Lorentz Forces. The results of the analysis were evaluated in terms of the stress and deformation.

Structure analysis of the SECRAL superconducting magnet system

An advanced superconducting ECR ion source named SECRAL has been constructed at Institute of Modern Physics of Chinese Academy of Sciences, whose superconducting magnet assembly consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamp. In order to investigate the structure of sextupole coils and to increase the structural reliabilities of the magnet system, global and local structural analysis have been performed in various operation scenarios. Winding pack and support structure design of magnet system, mechanical calculation and stress analysis are given in this paper. From the analysis results, it has been found that the magnet system is safe in the referential operation scenarios and the configuration of the magnet complies with design requirements of the SECRAL.

复合材料飞轮的三维应力分析

高速旋转的飞轮在给定外径和质量的情况下，轮缘采用先进的碳纤维缠绕，提高飞轮的转速，从而增大飞轮的储能密度，解决了飞轮轮缘因高速旋转而断裂破坏的问题。本文采用三维实体元分析计算复合材料飞轮工作时的应力分布，为安全合理设计复合材料飞轮提供依据。

纤维束张紧力缠绕复合材料飞轮的预应力简化分析

在纤维束缠绕时施加张紧力，使得固化成型后的飞轮内部形成一定的预加径向压应力，这是提高飞轮径向强度的有效方法之一。基于过盈配合的思想建立了计算张紧力缠绕导致的复合材料飞轮内部预应力和变形的简化模型和方法。通过算例分析发现：等张力缠绕产生的环向应力在半径方向上先减小后增大，径向压力应力不断变小；变张力缠绕过程中，张紧力由小逐渐变大时，飞轮的径向压应力增大，径向强度提高；飞轮设计中仅仅依靠张紧力缠绕是不够的，还必须和固化成型后的厚壁筒之间的过盈套装一起来设计合理的径向预加压应力。

Strain evolution in GaN layers grown on high-temperature AlN interlayers

The strain evolution of the GaN layer grown on a high-temperature AlN interlayer with GaN template by metal organic chemical vapor deposition is investigated. It is found that the layer is initially under compressive strain and then gradually relaxes and transforms to under tensile strain with increasing film thickness. The result of the in situ stress analysis is confirmed by x-ray diffraction measurements. Transmission electron microscopy analysis shows that the inclination of edge and mixed threading dislocations rather than the reduction of dislocation density mainly accounts for such a strain evolution. (c) 2006 American Institute of Physics.

SUPER-FRS/CR超导磁体力学性能分析

中国签订了为德国FAIR国际大科学工程加工SUPER-FRS/CR超导二极磁铁样机的合作备忘录。该超导二极磁铁属于常温铁芯、低温线圈的超导磁铁，该磁铁的磁场强度0.15～1.6T，偏转角度15°，偏转半径8125mm，磁场精度要求±1×10-4，磁铁总重量约50吨。磁铁铁芯采用0.5mm的硅钢片叠压成型，由中科院近代物理研究（IMP）所计算、设计制造，线圈采用4.2K液氦浸泡式超导线圈，由合肥等离子体所设计制造（IPP）。 超导磁体的力学性能分析一直是超导磁体的基础问题。本文利用有限元分析方法，借助有限分析工具ANSYS、ADINA、OPERA等，分析了超导磁体的电磁场，着重模拟计算了SUPER-FRS/CR超导二极磁铁的电磁力作用；模拟了降温过程，计算了杜瓦、线圈热应力的作用；并对SUPER-FRS/CR超导线圈进行地震载荷作用的模拟。对以上不同的受力作用所遵循的不同的机械设计准则，进行不同的分析，最后计算结果证明设计的结构是安全、可靠的。由于超导线圈的结构复杂，导致在线圈拐角的地方应力有些集中，但是并不影响结构的可靠性。 本文还介绍了超导实验线圈的一些工艺设计，例如超导线圈的绕制，低温材料的选择，电流引线的设计工艺，以及VPI工艺。并对实验磁体进行了一系列的低温性能测试，例如短样测试、降温实验等，获得了一些重要的低温实验参数。这些参数将为以后超导磁体的研制提供宝贵的依据

松辽盆地南部腰英台区块低渗透储层整体压裂改造技术研究

The Yaoyingtai Block is located within the northeastern Changling Depression of southern Songliao Basin, where the reservoir sandstones are petrophysically characterized by very low permeability, which results in the low success probability of artificial fracturing, and the low oil yield by water injection in the course of oil production. In order to improve the situations as stated above, this research aims to work out an integral fracturing technology and strategy applicable to the low permeable reservoirs in Yaoyingtai Block. Under the guidance of geological theory, reservoir engineering and technology, the subsurface occurrences of natural and hydraulic fractures in the reservoirs are expected to be delineated, and appropriate fracturing fluids and proppants are to be optimized, based on the data of drilling, well logging, laboratory and field experiments, and geological data. These approaches lay the basis of the integral fracturing technology suitable for the low permeable reservoir in the study area. Based on core sample test, in-situ stress analysis of well logging, and forward and inversion stress field modeling, as well as fluid dynamic analysis, the maximum in-situ stress field is unraveled to be extended nearly along the E-W direction (clustering along N85-135°E) as is demonstrated by the E-W trending tensional fractures. Hydraulic fractures are distributed approximately along the E-W direction as well. Faulting activities could have exerted obvious influences on the distribution of fractures, which were preferentially developed along fault zones. Based on reservoir sensitivity analysis, integrated with studies on rock mechanics, in-situ stress, natural fracture distribution and production in injection-production pilot area, the influences of primary fractures on fracturing operation are analyzed, and a diagnostic technology for primary fractures during depressurization is accordingly developed. An appropriate fracturing fluid (hydroxypropyl guar gum) and a proppant (Yixing ceramsite, with a moderate-density, 0.45-0.9mm in size) applicable to Qingshankou Formation reservoir are worked out through extensive optimization analysis. The fracturing fluid can decrease the damage to the oil reservoir, and the friction in fracturing operation, improving the effect of fracturing operation. Some problems, such as sand-out at early stage and low success rate of fracturing operations, have been effectively solved, through pre-fracturing formation evaluation, “suspension plug” fracturing, real-time monitoring and limited-flow fracturing. Through analysis of fracture-bearing tight reservoir with variable densities and dynamic analysis of influences of well patterns on fracturing by using numerical simulation, a fracturing operation scheme for the Qingshankou Formation reservoir is proposed here as being better to compress the short factures, rather than to compress the long fractures during hydraulic fracturing. It is suggested to adopt the 450m×150m inverted 9-spot well pattern in a diamond shape with wells placed parallel to fractures and a half fracture length of 60-75m.