Determination of the Interlaminar Fracture Toughness of Glass-Fiber-Reinforced Plastics on Ring Segments

A method is developed which allows one to estimate the fracture toughness G _{I c} of fiber-reinforced plastics using ring segment specimens. It is shown that this method reduces to the so-called angle method. The approach developed was tested on segments of glass-fiber-reinforced plastic (GFRP) rings based on an EDT-10 epoxy matrix and RVMPN 10-1200-14 glass fibers. The crack was set by a polyimide film placed in the specimen midlayer at the winding stage. The ring thickness was 1 to 4.5 mm. The fracture toughness G _{I c} was also calculated from force F-displacement D diagrams. It was found that the values of G _{I c} determined by both methods agreed well. For 2 mm thick segments with long (L 30 mm) cracks, G _{I c} was practically independent of L and , and, for the GFRP examined, it could be regarded as a material constant.     

The Influence of Carbon/Glass/Epoxy Hybrid Interfacial Adhesion on the Mode II Delamination Fracture Toughness

Mechanics of Composite Materials - The incorporation of two different reinforcements in the same matrix introduces distinct physical, mechanical, and chemical characteristics into it, which need to...     

非线性梁方程的渐近吸引子

研究了一类非线性梁方程的渐近吸引子.即利用正交分解法构造一个有限维解序列.首先用数学归纳法证明了该解序列不会远离方程的整体吸引子,其次证明了它在长时间后无限趋于方程的整体吸引子,并给出了渐近吸引子的维数估计.     

Numerical Analysis of the Fracture Toughness of Low-Density Open-Cell Voronoi Foams

Mechanics of Composite Materials - In this study, the geometry of open-cell foams is simulated using a model based on Voronoi tessellations. The fracture toughness of open-cell foams with Voronoi...     

三维变形状态下Ⅰ型裂纹裂尖应力场结构的有限元分析*

本文用ADINA(Automatic Dynamical Incremental Nonlinear Analysis)有限元程序计算了三维变形条件下,幂硬化材料紧凑拉伸(CT)试样的应力应变场,并根据计算结果分析了Ⅰ型裂纹裂尖应力场的结构,发现在厚度方向的任一平面上,裂尖应力场的表达式都可写成r,θ坐标变量分离的形式,从而r的函数部分可展成罗朗级数,且三个正应力分量具有相同的数量级.这两个结论为从理论上求解Ⅰ型裂纹裂尖应力场的数学表达式提供了两个有根据的假设条件,可大大减化求解过程.     

利用模糊滑模控制的非线性不确定系统模型到达控制

研究了一类非线性不确定系统的模型到达控制问题。控制机构中采用了动态补偿器和模糊滑模控制律,并且在解模糊中采用了双二次函数插值算法。模糊滑模控制的应用,抑制了抖振,保证了系统的快速性和鲁棒性,模糊数模型和双二次函数插值解模糊算法,大大减少了计算量。仿真验证了本文的方法的有效性。     

On the Existence of a Periodic Mode in a Nonlinear System

Differential Equations - We consider a nonlinear control system with a bang-bang hysteresis control, which is a simplified model of a thermal energy harvester. We obtain conditions on the...     

Quasi-periodic Solutions of the General Nonlinear Beam Equations

In this paper,one-dimensional (1D) nonlinear beam equations of the form utt - uxx + uxxxx + mu = f(u)with Dirichlet boundary conditions are considered,where the nonlinearity f is an analytic,odd funct...     

一维非线性梁方程的摄动解

对于两端固定的一维非线性梁方程的初边值问题,用多重尺度法求得近似解的首项,并用能量方法结合非线性Gronwall不等式得出了近似解首项的误差的一致性估计.     

Determination of the Transverse Shear Stress in an Euler-Bernoulli Beam Using Non-Admissible Virtual Displacements

The point of view that a beam can be considered as a three-dimensional continuum with a constrained position field (cf. [1]) together with the virtual work principle and the concept of perfect constraint stresses, leads to a systematic way to reduce the equilibrium equations of the continuous body to an ordinary differential equation describing the constrained displacement field of the beam. Using virtual displacements, being non-admissible with respect to the constrained beam kinematics, together with the solution of the boundary value problem, allows us to analytically determine the constraint stresses and consequently the total stresses of a beam up to a certain indeterminacy. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

用Adomian分解法求解分数阻尼梁的解析解

利用Adomian分解法, 得到了由任意阶分数微分描述的具有阻尼特性的黏弹性连续梁的解析解．解中包含了任意的初始条件和零输入．为了更明确的分析, 假定初始条件是奇次的,输入受力是针对某种特定梁的特殊过程．分别考虑了两种简单情况下梁的响应:阶跃激励和脉冲激励．然后在系统的不同组参数条件下绘制了梁的位移图,并且讨论了梁在不同微分阶数下响应情况．     

On the Accuracy of the Galerkin Method for a Nonlinear Dynamic Beam Equation

The paper deals with the boundary value problem for a nonlinear integro‐differential equation modeling the dynamic state of the Timoshenko beam. To approximate the solution with respect to a spatial variable, the Galerkin method is used, the error of which is estimated. Copyright © 2011 John Wiley & Sons, Ltd.     

弹塑性状态下Ⅰ型裂纹前缘应力应变场的奇异性分析

本文从弹塑性力学的三维基本方程出发,分析了幂硬化材料Ⅰ型裂纹前缘应力、应变场的奇异性,发现,裂尖附近诸应力、应变分量的奇异性沿厚度不变;六个应力分量的奇异性不完全相同,六个应变分量的奇异性也不完全相同.     

Isolation of the Trivial Part of a Nonlinear Control System by Factorization: I

The problem of constructing aggregated systems (quotient systems) of the simplest kind for nonlinear control systems is considered. With the help of this factorization, the original control system is reduced to a decomposition that allows one to reduce the dimension of control problems.     

非线性悬臂梁方程的正解存在定理

研究了非线性悬臂梁方程u^（4）（t）=f（t,u（t）,u′（t））,0相似文献   

Global Dynamics of a Nonlinear Beam Equation with Strong Structural Damping

In this paper, the global attractor, exponential attractor and flat inertial manifold are obtained for a nonlinear beam equation with strong structural damping.     

On the Toughness of a Graph

Abstract

In this paper, general results on the toughness of a graph are considered. Firstly the link between toughness and connectivity is explored and then results linking toughness and the parameters binding number and integrity are given. Further, the toughness of product graphs is discussed including general results for the lexicographic product. The paper concludes with some observations on toughness and hamiltoni-city.