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581.
The paper is dedicated to the cracking analysis of FRP (Fiber-Reinforced Polymer)-reinforced concrete elements. A general nonlinear calculation procedure, based on the slip and bond stresses, is described and adopted for the prediction of the crack width and crack spacing in FRP-reinforced concrete beams. An analytical expression of the bond-slip law is estimated using the corresponding experimental results available in the literature. A numerical investigation is carried out and the influence of the mechanical and geometrical parameters of the material (bond-slip law, reinforcement ratio, concrete strength, diameter of rebars, etc.) on the crack formation is investigated. Referring to glass-FRP-reinforced concrete beams, a comparison between the theoretical predictions and experimental results is made. The results obtained are presented and discussed. 相似文献
582.
讨论壁面有引射的滑移边界条件的提法.利用Chapman Enskog速度分布函数,通过分析Knudsen层外缘和壁面处的质量、动量和能量等通量守恒,得到了有壁面引射的多组元气体有催化反应的壁面滑移边界条件方程组.利用粘性激波层方程和所得的边界条件对钝头体绕流驻点区的流场进行了计算,讨论了物面引射对边界上诸量及流场的影响 相似文献
583.
This paper reports experimental observations on the rheology and microstructure of concentrated oil-in-water emulsions stabilised
by macromolecular and low-molecular-weight emulsifiers. From the four different samples that were tested, certain general
trends were identified and the measured linear viscoelastic and non-linear viscoelastic properties were compared using a phenomenological
factored integral constitutive equation with a continuous relaxation spectrum. The self-consistency of the model was quite
good in two cases (vegetable protein and polyoxyethylene glycol non-ionic surfactant emulsifiers) with the general exception
of low steady shear rate data where the model overpredicted experimental stress measurements. It is shown that the fitting
of the experimental data is sensitive to a wide range of inter-relating factors. In addition, optical observations of the
sheared materials consistently showed low shear rate surface slip and this observation was correlated with the rheology miss
match. For some systems the optical microstructure studies reveal a range of behaviour for the emulsions dependent on emulsifier
composition. Wall slip, microdomain movement, chaining and changes in droplet size distribution were all observed under different
conditions and in some cases it has been possible to correlate these microstructure observations with the sample rheology.
Received: 10 November 1998 Accepted: 24 November 1998 相似文献
584.
周承倜 《应用数学和力学(英文版)》1984,5(2):1143-1150
In this paper, some current anisotropic failure criteria in the forms of tensor polynomials are investigated. In order to determine the interaction coefficients of the failure criterion, a non-linear optimization method is proposed. The results obtained by different theories as well as the optimization method are compared with the test data of some composite materials. The comparison shows that the optimization method is effective. 相似文献
585.
It has been noted in the present paper that the finite element method using linear elements for solving axisymmetrical shells
cannot be applied to the analysis of axisymmetrical shells with abrupt curvature change, owing to the fact that the influence
of the curvature upon the angular displacements has been neglected. The present paper provides a finite element method using
linear elements in which the influence of curvature is considered and the angular displacements are treated as continuous
parameters. This method has been applied to the calculation of corrugated shells of the type C, and compared with the experimental
results obtained by Turner-Ford as well as with the analytical solution given by Prof. Chien Wei-zang. The comparisons have
been proved that this theory is correct. 相似文献
586.
《Particuology》2023
In this paper, the squeeze flow between two rigid spheres with a bi-viscosity fluid is examined. Based on lubrication theory, the squeeze force is calculated by deriving the pressure and velocity expressions. The results of the normal squeeze force are discussed, and fitting functions of the squeeze and correction coefficients are given. The squeeze force between the rigid spheres increases linearly or logarithmically with the velocity when most or part of the boundary fluid reaches the yield state, respectively. Furthermore, the slip correction coefficient decreases with the increase in the velocity. The investigation may contribute to the further study of bi-viscosity fluids between rigid spheres with wall slip. 相似文献
587.
李龙元 《应用数学和力学(英文版)》1990,11(3):293-295
In this paper, a set of variational formulas of solving nonlinear instability critical loads are established from the viewpoint of variational principle. The paper shows that it is very convenient to solve nonlinear instability critical load by using the variational formulas suggested in this paper. 相似文献
588.
This work studies a mathematical model for the motion of a two mass–spring–damper system with friction, and has a two-fold purpose. The first is to start a mathematical study of the way detachment or slip waves, when the system transits from stick to slip motion, propagate in discrete and continuous systems. The introduction of friction changes the problems into systems of differential set-valued inclusions, which are mathematically interesting, but rather complex. The second is to use such a ‘simple’ system as an example of a very general existence and uniqueness theorem for systems described by set-valued pseudomonotone operators, Kuttler and Shillor (1999) and Andrews et al. (2020). 相似文献
589.
This paper reports on the microstructural changes occurring within molybdenum single crystals after shock treatment with an excimer laser‐system in a confined ablation mode with different number of impacts. Using different complementary investigation methods (optical microscopy, scanning electron microscopy and transmission electron microscopy) it is found that slip and twinning are active modes of deformation during the shock‐induced plastic deformation. After laser treatment with a single laser pulse slip bands on {112} planes containing several microscopic twins are the dominating microstructural feature, whereas further laser‐shock‐processing leads to the formation of a homogeneous arrangement of screw dislocations, tangles and loops. Deformation modes and microstructure in laser shocked samples prove to be quite similar to those of explosive shocked specimens although the laser‐induced peak pressure is about an order of magnitude lower than that during explosive loading.It is shown that the laser shock‐induced hardening increases with increasing number of impacts in the range from 1 to 6 impacts. This shock‐induced strengthening is correlated with the overall dislocation density. 相似文献