scholarly journals Modeling the Fracture of a Sandwich Structure due to Cavitation in a Ductile Adhesive Layer

2000 ◽  
Vol 68 (1) ◽  
pp. 93-100 ◽  
Author(s):  
S. Zhang ◽  
K. J. Hsia
Keyword(s):  
Fracture Resistance ◽  
Virtual Work ◽  
Exact Analytical Solution ◽  
Cavity Growth ◽  
Adhesive Layer ◽  
New Method ◽  
Strain Hardening Exponent ◽  
Stress Separation ◽  
The One ◽  
Strength And Durability

The strength and durability of adhesively bonded sandwich structures often depend on the mechanisms of fracture, which in turn depend on the properties of the adhesive and the microstructures of the interface. When the thin adhesive layer is ductile, cavitation either within the layer or along the interface is often the dominant failure mechanism. In the present paper, fracture due to cavity growth in a thin ductile layer is analyzed. A new method utilizing fluid mechanics solutions is developed. Solutions of fluid flow field are used to approximate the plastic deformation field in the corresponding solid body with a cavity. The equilibrium condition is satisfied by using the principle of virtual work rate. Stress-separation curves due to cavitation in the thin layer can thus be obtained. The method is validated by reevaluating the one-dimensional problem of cavity growth in a sphere—a problem for which an exact, analytical solution exists. A two-dimensional plane strain cavitation problem is analyzed using the new method. The stress-separation curves and the fracture resistance due to this mechanism are obtained. The results show that both the stress-separation curves and the fracture resistance are sensitive to the strain-hardening exponent and the initial void size, but not the yield strength of the material. The new method has clear advantages over numerical methods, such as the finite element method, when parametric studies are performed.

A TWELFTH-ORDER FOUR-STEP FORMULA FOR THE NUMERICAL INTEGRATION OF THE ONE-DIMENSIONAL SCHRÖDINGER EQUATION

2003 ◽  
Vol 14 (08) ◽  
pp. 1087-1105 ◽  
Author(s):  
ZHONGCHENG WANG ◽  
YONGMING DAI
Keyword(s):  
Schrödinger Equation ◽  
Numerical Integration ◽  
Schrodinger Equation ◽  
Numerical Test ◽  
New Method ◽  
Step Method ◽  
One Dimensional ◽  
The Stability ◽  
The One ◽  
Order Four

A new twelfth-order four-step formula containing fourth derivatives for the numerical integration of the one-dimensional Schrödinger equation has been developed. It was found that by adding multi-derivative terms, the stability of a linear multi-step method can be improved and the interval of periodicity of this new method is larger than that of the Numerov's method. The numerical test shows that the new method is superior to the previous lower orders in both accuracy and efficiency and it is specially applied to the problem when an increasing accuracy is requested.

A Fast Method for Solving Contact Plasticity in a Half Space

2011 ◽  
Author(s):  
Zhanjiang Wang ◽  
Xiaoqing Jin ◽  
Shuangbiao Liu ◽  
Leon M. Keer ◽  
Jian Cao ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Residual Stresses ◽  
Fast Fourier Transform ◽  
Half Space ◽  
Three Dimensional ◽  
New Method ◽  
Fast Method ◽  
Discrete Convolution ◽  
Influence Coefficients ◽  
The One

This paper presents a new method of contact plasticity analysis based on Galerkin vectors to solve the eigenstresses due to eigenstrain. The influence coefficients relating eigenstrains to eigenstresses thus can be divided into four terms the one due to the eigenstrains in the full space, others due to the mirrored eigenstrains in the mirror half space. Each term can be solved fast and efficient by using the three-dimensional discrete convolution and fast Fourier transform (DC-FFT) or the three-dimensional discrete correlation and fast Fourier transform (DCR-FFT). The new method is used to analyze the contact plastic residual stresses in half space.

scholarly journals Comparison between the Cauchy problem and the scattering problem for the Landau damping in the Vlasov-HMF equation

2021 ◽  
pp. 1-24
Author(s):  
Dario Benedetto ◽  
Emanuele Caglioti ◽  
Stefano Rossi
Keyword(s):  
Cauchy Problem ◽  
Asymptotic Behavior ◽  
Scattering Problem ◽  
New Method ◽  
Landau Damping ◽  
The Cauchy Problem ◽  
The One ◽  
Perturbative Result

We analyze the analytic Landau damping problem for the Vlasov-HMF equation, by fixing the asymptotic behavior of the solution. We use a new method for this “scattering problem”, closer to the one used for the Cauchy problem. In this way we are able to compare the two results, emphasizing the different influence of the plasma echoes in the two approaches. In particular, we prove a non-perturbative result for the scattering problem.

A Method of Constructing Quaternary Periodic Complementary Sequence Sets for Suppression of Multiple Access Interference in CDMA Communication Systems

2014 ◽  
Vol 543-547 ◽  
pp. 2323-2328
Author(s):  
Fan Xin Zeng ◽  
Zhen Yu Zhang ◽  
Lin Jie Qian
Keyword(s):  
Communication System ◽  
Communication Systems ◽  
Multiple Access ◽  
Binary Sequence ◽  
Multiple Access Interference ◽  
New Method ◽  
Complementary Sequence ◽  
The One ◽  
Spreading Sequences

For suppressing multiple access interference (MAI) in a CDMA communication system, complementary sequence sets are employed as spreading sequences in such system. In this paper, we present a method for constructing a family of quaternary periodic complementary sequence sets, which arises from the conversion of the existing binary periodic complementary sequence sets with odd period of sub-sequences. The period of sub-sequences in the proposed sequence sets is twice as long as the one of the binary sequence sets employed, which is a drawback in the proposed method. Finally, some examples are given in order to illuminate the validity of the new method.

Optimal Camera Placement in a Virtual Environment

2021 ◽  
pp. 247-260
Author(s):  
Hocine Chebi
Keyword(s):  
Real Time ◽  
Virtual Environment ◽  
The Other ◽  
New Method ◽  
Camera Placement ◽  
Virtual Camera ◽  
Clear Vision ◽  
Transmission Of Information ◽  
The One ◽  
Visual Properties

Camera placement in a virtual environment consists of positioning and orienting a 3D virtual camera so as to respect a set of visual or cinematographic properties defined by the user. Carrying out this task is difficult in practice. Indeed, the user has a clear vision of the result he wants to obtain in terms of the arrangement of the objects in the image. In this chapter, the authors identify three areas of research that are relatively little covered by the literature dedicated to camera placement and which nevertheless appear essential. On the one hand, existing approaches offer little flexibility in both solving and describing a problem in terms of visual properties, especially when it has no solution. They propose a flexible solution method which computes the set of solutions, maximizing the satisfaction of the properties of the problem, whether it is over constrained or not. On the other hand, the existing methods calculate only one solution, even when the problem has several classes of equivalent solutions in terms of satisfaction of properties. They introduce the method of semantic volumes which computes the set of classes of semantically equivalent solutions and proposes a representative of each of them to the user. Finally, the problem of occlusion, although essential in the transmission of information, is little addressed by the community. Consequently, they present a new method of taking into account occlusion in dynamic real-time environments.

Complexity Factors in Networked and Virtual Working Environments

2010 ◽  
pp. 1346-1354
Author(s):  
Juha Kettunen ◽  
Ari Putkonen ◽  
Ursula Hyrkkänen
Keyword(s):  
Applied Sciences ◽  
Working Conditions ◽  
Virtual Work ◽  
Working Environment ◽  
Data Networks ◽  
Working Environments ◽  
Cultural Spaces ◽  
Information And Communication ◽  
Ict Tools ◽  
The One

Working environments are changing from the traditional model. An increasing amount of work takes place in networked and virtual environments which are not tied to one place and time. The work environment is defined “virtual,” when the employee uses information and communication technology (ICT) for collaboration (Vartiainen, 2006). The planning of working conditions becomes challenging task for managers and ICT tool developers, because there is a lack of understanding the consequences of emerging virtual work. The capacity of workers to percept and process information is burdened with the complexity and high demands of working life. Knowledge of the complexity factors of the overall work system is essential for an in depth understanding of human working capabilities and limitations (Kleiner, 2006). The complexity of work is usually considered as a factor related to the task. At the one end the task is creative and demanding and at the other end it is simple and routine-like. The expanded complexity concept also takes into account the working environment that can be different combinations of physical, virtual, social and cultural spaces. The purpose of this article is to present a framework to analyse the complexity factors in networked and virtual working environments. The approach developed in this article is intended to be generic in order to be applicable to various kinds of organisations and networks for the purpose of management. It is important that the working conditions of workers can be planned in advance to provide workers with appropriate ICT tools and data networks to enable efficient cooperation in networks in a way that the workload can be limited to a sustainable level. The described framework is assessed using the case of the Turku University of Applied Sciences (TUAS).

Kansas Water-Cement Ratio Meter: Preliminary Results

1996 ◽  
Vol 1532 (1) ◽  
pp. 73-79
Author(s):  
Mustaque Hossain ◽  
James Koelliker ◽  
Hisham Ibrahim ◽  
John Wojakowski
Keyword(s):  
Fresh Concrete ◽  
Accurate Determination ◽  
Hardened Concrete ◽  
Cement Slurry ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Concrete Mix ◽  
Predominant Factor ◽  
The One ◽  
Strength And Durability

The water-cement ratio of fresh concrete is recognized as the one factor that affects the strength and durability of an adequately compacted concrete mix. Although water-cement ratio is the predominant factor affecting strength of hardened concrete, currently no widely used, reliable method is available for measuring water-cement ratio in the field. A prototype device has been developed to measure the water-cement ratio of a plastic concrete mix. The method is based on the measurement of turbidity of water-cement slurry separated out of a concrete mixture by pressure sieving. Consistent results were obtained for air-entrained and non-air-entrained concrete. Statistical analyses of the test results have shown that this meter can measure the water-cement ratio of fresh concrete with an accuracy of ±0.01 on the water-cement ratio scale for a single test at a 90 percent confidence interval. The equipment will cost less than $10,000. If the method works as well in the field as it does in the laboratory, accurate determination of water-cement ratio could dramatically improve the ability of the concrete industry to ensure the quality of concrete construction.

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