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61.
G. V. Galatenko 《International Applied Mechanics》2007,43(7):745-753
The generalized Dugdale crack model is used to formulate two-parameter failure criteria for the cases of quasibrittle state
and developed plastic zones at a mode I crack tip. The failure criteria relate the fracture strength characteristics and the
stress mode at the crack tip through the plastic constraint factor. The critical state of bodies with cracks under uni-and
biaxial loading is analyzed in the cases of plane stress and plane strain using the Tresca and von Mises yield criteria. A
small-scale yield criterion, which is an analytic relation between the critical stress intensity factor and T-stresses, is established
__________
Translated from Prikladnaya Mekhanika, Vol. 43, No. 7, pp. 47–57, July 2007. 相似文献
62.
T形型钢混凝土柱正截面承载力的计算方法探讨 总被引:3,自引:0,他引:3
在总结了型钢混凝土(SRC)柱承载力计算一般方法的基础上,针对T形型钢混凝土柱,
结合中国现行规范,分析了此种柱的受力特点和破坏模式,提出T形型钢混凝土柱正截面极
限承载力的计算方法,并采用该方法对一T形型钢混凝土柱的承载力进行验算. 结果表明与
试验数据吻合较好,说明本文方法具有较好的精确度和适用性. 相似文献
63.
64.
We explore recent contributions to research in Econophysics, switching between Macroscopic complexity and microscopic modelling, showing how each leads to the other and detailing the everyday applicability of both approaches and the tools they help develop. Over the past decades, the world underwent several major crises, leading to significant increase in interdependence and, thus, complexity. We show here that from the perspective of network science, these processes become more understandable and, to some extent, also controllable. 相似文献
65.
在反平面剪切载荷及侧压力共同作用下引起的裂纹及裂纹扩展导致的层间界面失效,是岩土工程层间界面及砌体结构中界面层上典型的失效方式.运用弹性力学和断裂力学的理论原理,提出了能够反映上述层间界面断裂失效问题力学特性的剪切梁模型.文中采用具有应力软化特性的“粘性裂纹”(内聚力裂纹)模型来表述层间裂纹前方损伤过程区的本构行为.对通过粘性层结合在一起的两个弹性板,在反平面剪切载荷及侧压力共同作用下的力学行为作了解析分析计算,研究了层间界面裂纹扩展规律. 相似文献
66.
Well‐controlled ATRP of 2‐(2‐(2‐azidoethyoxy)ethoxy)ethyl methacrylate for high‐density click functionalization of polymers and metallic substrates
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The combination of atom transfer radical polymerization (ATRP) and click chemistry has created unprecedented opportunities for controlled syntheses of functional polymers. ATRP of azido‐bearing methacrylate monomers (e.g., 2‐(2‐(2‐azidoethyoxy)ethoxy)ethyl methacrylate, AzTEGMA), however, proceeded with poor control at commonly adopted temperature of 50 °C, resulting in significant side reactions. By lowering reaction temperature and monomer concentrations, well‐defined pAzTEGMA with significantly reduced polydispersity were prepared within a reasonable timeframe. Upon subsequent functionalization of the side chains of pAzTEGMA via Cu(I)‐catalyzed azide‐alkyne cycloaddition (CuAAC) click chemistry, functional polymers with number‐average molecular weights (Mn) up to 22 kDa with narrow polydispersity (PDI < 1.30) were obtained. Applying the optimized polymerization condition, we also grafted pAzTEGMA brushes from Ti6Al4 substrates by surface‐initiated ATRP (SI‐ATRP), and effectively functionalized the azide‐terminated side chains with hydrophobic and hydrophilic alkynes by CuAAC. The well‐controlled ATRP of azido‐bearing methacrylates and subsequent facile high‐density functionalization of the side chains of the polymethacrylates via CuAAC offers a useful tool for engineering functional polymers or surfaces for diverse applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1268–1277 相似文献
67.
Cascades with coupled map lattices in preferential attachment community networks 总被引:2,自引:0,他引:2
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In this paper, cascading failure is studied by coupled map lattice (CML) methods in preferential attachment community networks. It is found that external perturbation R is increasing with modularity Q growing by simulation. In particular, the large modularity Q can hold off the cascading failure dynamic process in community networks. Furthermore, different attack strategies also greatly affect the cascading failure dynamic process. It is particularly significant to control cascading failure process in real community networks. 相似文献
68.
A two dimensional plane-stress finite-element type of analysis is presented to predict the behaviour of geogrids embedded
in sand under pullout loading conditions. In the analysis the interactions between soil and geogrid are simulated by non-linear
springs. The stiffnesses of the springs can be determined from simple tests in a specially designed pullout box. The proposed
finite element (FE) analysis is applied to interpret test results from a large scale pullout test rig. The predicted behaviour
of the geogrid under pullout load agrees well with the observed data including the load-displacement properties, the displacement
distribution along the longitudinal direction and the mobilisation of the frictional and bearing resistance. 相似文献
69.
Sheldon M Ross 《Stochastic Processes and their Applications》1976,4(2):167-173
Consider an n-component reliability system having the property that at any time each of its components is either up (i.e., working) or down (i.e., being repaired). Each component acts independently and we suppose that each time the ith component goes up it remains up for an exponentially distributed time having mean μi, and each time it goes down it remains down for an exponentially distributed time having mean υi. We further suppose that whether or not the system itself is up at any time depends only on which components are up at that time. We are interested in the distribution of the time of first system failure when all components are initially up at time zero. In section 2 we show that this distribution has the NBU (i.e., new better than used) property, and in Section 3 we make use of this and other results to obtain a lower bound to the mean time until first system failure. 相似文献
70.