Study on applicability of modal analysis of thin finite length cylindrical shells using wave propagation approach

INTRODUCTION Vibrations of cylindrical shells are of consider-able importance as they are extensively used in in-dustry,flight structures and marine crafts.The naturalfrequencies and mode shapes are important sources ofinformation for understanding and controlling thevibration of these structures,so many papers on theprediction of the natural frequencies of cylindricalshells have been published over the past years.Many shell theories have been developed andvarious solution methods have bee…     

Three-dimensional analysis of a thick FGM rectangular plate in thermal environment

The thermal behavior of a thick transversely isotropic FGM rectangular plate was investigated within the scope of three-dimensional elasticity. Noticing many FGMs may have temperature-dependent properties, the material constants were further considered as functions of temperature. A solution method based on state-space formulations with a laminate approximate model was proposed. For a thin plate, the method was clarified by comparison with the thin plate theory. The influences of material inhomogeneity and temperature-dependent characteristics were finally discussed, through numerical examples. Project (No. 10002016) supported by National Natural Science Foundation of China     

弯曲共振法测量金属材料高温弹性模量探讨

对弯曲共振法测量金属材料高温弹性模量的相关问题进行了探讨。结合铝合金高温弹性模量的测量,分析了弯曲共振法测量高温弹性模量中的各种影响因素对结果的影响;总结了弯曲共振法测量中的难点,列出了多种判别虚假共振峰的方法;采用频谱分析对动态法中判定共振频率的方法进行了改进并结合软件采用扫频技术将弹性模量测量自动化。成功应用于国产6061-T6系列铝合金高温弹性模量的测量。     

Three-dimensional analysis of a thick FGM rectangular plate in thermal environment

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微分求积法求解不可压二阶粘弹性流体和热迁移模型中的稳态流动

1IntroductionAlthoughthe computation of the fluid mechanics hasgreat development during the last decades,due to themodel in nonlinear fluid mechanics is very complicat-ed,the more efficient techniques for solvingthis prob-lemstill attract the interest of many researchers.Thedifferential quadrature method(DQM)introduced byBell man,et al.[1,2]is an efficient numerical methodfor solving partial differential equations.In recentyears,the DQMhas been widely used for solving theproblems of enginee…     

Fatigue tests of composite beam by steel fiber reinforced self-stressing concrete in the hogging bending

Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete （SFRSC） as the composite beam in the composite layer was studied under the hogging bending. The tests simulated composite layer tensile strain under the hogging bending of inverted loading composite beams, giving the relationship under the different fatigue stress ratios between fatigue cycles and steel bar’s stress range, crack width, stiffness loss and damage, etc., in composite layer. This article established fatigue life equation, and analyzed SFRSC reinforced mechanism to crack width and stiffness loss. The results show that SFRSC as the composite beam concrete has excellent properties of crack resistance and tensile, can reinforce the fatigue crack width and stiffness loss of composite beams, and improve the durability and in normal use of composite beams in the hogging bending zone.     

Analysis of structural response under blast loads using the coupled SPH-FEM approach

A numerical model using the coupled smoothed panicle hydrodynamics-finite element method （SPH-FEM） approach is presented for analysis of structures under blast loads. The analyses on two numerical cases, one for free field explosive and the other for structural response under blast loads, are performed to model the whole processes from the propagation of the pressure wave to the response of structures. Based on the simulation, it is concluded that this model can be used for reasonably accurate explosive analysis of structures. The resulting information would be valuable for protecting structures under blast loads.     

Relationship of public preferences and behavior in residential outdoor spaces using analytic hierarchy process and principal component analysis—— a case study of Hangzhou City, China

INTRODUCTION Nowadays, as a large number of residential blocks and college campuses are being constructed nationwide in China, improvement in the quality of residential community becomes a rising issue of city policy and urban planning. Layouts of open spaces in residential areas are predicated on their ability to deliver both a mechanism to maintain the viability of citizens’ outdoor lives and a treatment to alleviate the high-density of urban constructions. What kinds of residential o…     

Finite element model analysis of thermal failure in connector

Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was investigated. It was found that the contact resistance increased due to the Joule heating, and that increased contact resistance produced more Joule heating; this mutual action causes the connector to lose efficiency. The thermal distribution in the connector was analyzed using finite element method (FEM). The failure mechanism is discussed. It provides basis for improving the structure. The conclusion was verified by experimental results.     

Towards fully automatic modelling of the fracture process in quasi-brittle and ductile materials: a unified crack growth criterion

Fully automatic finite element （FE） modelling of the fracture process in quasi-brittle materials such as concrete and rocks and ductile materials such as metals and alloys, is of great significance in assessing structural integrity and presents tremendous challenges to the engineering community. One challenge lies in the adoption of an objective and effective crack propagation criterion. This paper proposes a crack propagation criterion based on the principle of energy conservation and the cohesive zone model （CZM）. The virtual crack extension technique is used to calculate the differential terms in the criterion. A fully-automatic discrete crack modelling methodology, integrating the developed criterion, the CZM to model the crack, a simple remeshing procedure to accommodate crack propagation, the J2 flow theory implemented within the incremental plasticity framework to model the ductile materials, and a local arc-length solver to the nonlinear equation system, is developed and implemented in an in-house program. Three examples, i.e., a plain concrete beam with a single shear crack, a reinforced concrete （RC） beam with multiple cracks and a compact-tension steel specimen, are simulated. Good agreement between numerical predictions and experimental data is found, which demonstrates the applicability of the criterion to both quasi-brittle and ductile materials.     

高等几何中完全四点(线)形的调和性质应用于初等几何中某些问题的初探

本文对高等几何中的安全四点（线）形的调和性质进行了归纳整理，并从初等几何与高等几何之间的本质联系出发，主要讨论了高等几何中的完全四点（线）形的调和和性质应用于初等几何中某些问题的作用，以达到化难为易，拓广解题思路，并进一步获得某些初等几何命题的推广，以更加充实和完善初等几何的内容。     

Application of causality diagram in system safety analysis

Causality Diagram （CD） is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper, and the Minimal Cut Set, the Minimal Path Set and the Importance were introduced to develop the methodology. These concepts are employed to analyze the influence each event has on the top event - the gas explosion, so as to find out about the defects of the system and accordingly help to work out the emphasis of the precautionary work and some preventive measures as well. The results of the safety analysis are in accordance with the practical requirements; therefore the preventive measures are certain to work effectively. In brief, according to the research CD is so effective in the safety analysis and the safety assessment that it can be a qualitative and quantitative method to predict the accident as well as offer some effective measures for the investigation, the prevention and the control of the accident.     

Magnetic field and performance analysis of a tubular permanent magnet linear synchronous motor applied in elevator door system

A novel elevator door driven by tubular permanent magnet linear synchronous motor （TPMLSM） is presented. This TPMLSM applies axial magnet array topology of the secondary rod, air-cored armature windings and slotless structure of the forcer to improve the stability of the thrust. The influence of two major dimensions, the pitch and radius of the permanent magnet （PM）, on magnetic field was studied and the best values were given by the finite element analysis （FEA）. The magnetic field, back EMF and thrust of the motor were analyzed and the PM size was optimized to reduce the harmonic components of the magnetic field and improve the performance of the motor. Predicted results are validated by the experiment. It is shown that the performance of the motor and the novel elevator door system is satisfying.     

Use of stochastic simulations to investigate the power and design of a whole genome association study using single nucleotide polymorphism arrays in farm animals

This paper presents a quick, easy to implement and versatile way of using stochastic simulations to investigate the power and design of using single nucleotide polymorphism (SNP) arrays for genome-wide association studies in farm animals. It illustrates the methodology by discussing a small example where 6 experimental designs are considered to analyse the same resource consisting of 6006 animals with pedigree and phenotypic records: (1) genotyping the 30 most widely used sires in the population and all of their progeny (515 animals in total), (2) genotyping the 100 most widely used sires in the population and all of their progeny (1102 animals in total), genotyping respectively (3) 515 and (4) 1102 animals selected randomly or genotyping respectively (5) 515 and (6) 1102 animals from the tails of the phenotypic distribution. Given the resource at hand, designs where the extreme animals are genotyped perform the best, followed by designs selecting animals at random. Designs where sires and their progeny are genotyped perform the worst, as even genotyping the 100 most widely used sires and their progeny is not as powerful of genotyping 515 extreme animals.     

电导法测定298K时NdCl3在DMF和H2O中的活度系数

应用电导法在298K时测定了稀土氯化盐NdCl3在混合溶剂(DMF-H2O)中的电导率;利用公式计算了NdCl3的摩尔电导率;应用Kohlraush经验规则,使用Origin软件进行线性拟合,外推得到298K时NdCl3在混合溶剂(DMF-H2O)中的无限稀释摩尔电导率λ0 =300.01 (S*cm2 *mol-1);应用Debye-Hücker 和Osager-Falkenhangen公式计算了NdCl3在混合溶剂(DMF-H2O)中的活度系数,并讨论了在298K时浓度对稀土盐NdCl3溶液活度系数的影响,随稀土氯化盐溶液浓度的增加,稀土盐溶液的活度系数降低.