Delamination from edge flaws

1994 ◽  
Vol 447 (1930) ◽  
pp. 271-279 ◽  
Keyword(s):  
Thin Films ◽  
Stress State ◽  
Failure Mechanism ◽  
Crack Front ◽  
Failure Mechanisms ◽  
Different Types ◽  
Laminated Material ◽  
Localized Failure

The mechanics of delamination from an edge flaw in a laminated material is presented. Two different types of failure mechanism have been identified: uniform delamination along the crack front and localized delamination which can be initiated if the laminate buckles above the debonded portion of the interface. Depending on the stress state within the bonded portion of the laminate, this localized failure can initiate the formation of blisters which grow by a mechanism of buckling-driven delamination and can cause general failure of the laminate. There are conditions under which this class of buckling-assisted delamination occurs at loads lower than would be predicted for uniform delamination. It may, therefore, have important implications in the design against failure for thin films, composites and other laminated systems. Experimental observations of the different failure mechanisms are presented and the factors governing the transitions between them are discussed.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

1989 ◽  
Vol 47 ◽  
pp. 592-593
Author(s):  
J.B. Posthill ◽  
R.P. Burns ◽  
R.A. Rudder ◽  
Y.H. Lee ◽  
R.J. Markunas ◽  
...  
Keyword(s):  
Thin Films ◽  
Wide Band ◽  
Deposition Process ◽  
Heteroepitaxial Growth ◽  
Electron Microscopic ◽  
Wide Band Gap ◽  
Lattice Matching ◽  
Different Types ◽  
Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

Comparative Study on Electrical Properties of Three Different Types of Graphene-Based Thin Films

2013 ◽  
Vol 53 (14) ◽  
pp. 1-9
Author(s):  
X. Wang ◽  
J. Yu ◽  
H. Dong ◽  
F. Jiang ◽  
Q. Zhu ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Comparative Study ◽  
Different Types

Different types of ferrite thin films as magnetic cantilever coating for magnetic force microscopy

2010 ◽  
Vol 322 (9-12) ◽  
pp. 1697-1699 ◽  
Author(s):  
M.R. Koblischka ◽  
M. Kirsch ◽  
R. Pfeifer ◽  
S. Getlawi ◽  
F. Rigato ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Force Microscopy ◽  
Different Types ◽  
Ferrite Thin Films

Acceleration Factors and Life Predictions

2020 ◽  
Vol 2020 (1) ◽  
pp. 000100-000105
Author(s):  
P.E. Chris South
Keyword(s):  
Failure Mechanism ◽  
Confidence Level ◽  
Failure Mechanisms ◽  
Software Tool ◽  
Acceleration Factor ◽  
Accelerated Life Test ◽  
Time To Failure ◽  
Confidence Bounds ◽  
Life Predictions ◽  
Equivalent Field

Abstract Acceleration factors (AF) are key to designing an effective accelerated life test (ALT). They represent the ratio of the time in field to the time in test for a particular event to occur (typically a failure event related to a specific failure mechanism). Time to failure for a device generally correlates with the amount of stress applied (the higher the stress, the quicker the device will fail), and failure models exist to mathematically define that correlation for various failure mechanisms. This allows for use of a higher stress in test than in the field, thereby providing an acceleration factor that shortens the time in test to demonstrate a failure-free time period. ALT can take the form of qualitative or quantitative testing. The latter is used to determine the life characteristics of the device with some reliability and confidence level. Usage rate acceleration and higher stress acceleration can be used. It is important to consider the design limits of the device based on its specification and material properties, and limit the stress levels in test so as not to induce failure mechanisms that the device would not otherwise have experienced in the field. ALT results are used to make life predictions for the device tested. With no failures, the test results demonstrate the required reliability and confidence level metrics for the failure mechanism of interest. With several failures, a reliability software tool can be used with the appropriate analysis method, rank method, and confidence bounds method chosen in order to extrapolate to an expected life in test. The equivalent field life is based on multiplying the expected life in test by the AF. If the field stress and/or test stress are not constant, there are multiple acceleration factors to utilize. As a result, an equivalent acceleration factor needs to be calculated and used as the AF when predicting equivalent field life.

Failure mechanisms in two-layer undrained slopes

2020 ◽  
Vol 57 (10) ◽  
pp. 1617-1621
Author(s):  
Shuangfeng Guo ◽  
D.V. Griffiths
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Slope Angle ◽  
Strength Ratio ◽  
The Finite Element Method ◽  
Stability Analyses ◽  
Shallow Failure ◽  
Insight Into

This note presents results of stability analyses of two-layer undrained slopes by the finite element method. The study focuses on the circumstances under which either deep or shallow failure mechanisms occur, as a function of the strength ratio of the layers, slope angle, and foundation depth ratio. Improved knowledge of the location of the critical failure mechanism(s) in two-layer systems will give engineers better insight into where to focus their attention in terms or remediation or reinforcement to preserve stability.

scholarly journals Modeling of macroscopic quantum states in functional properties of the laser-induced 4D-topological nanoclusters in thin films on solid surface

2019 ◽  
Vol 220 ◽  
pp. 01002
Author(s):  
S.M. Arakelian ◽  
A.O. Kucherik ◽  
T.A. Khudaberganov ◽  
D.N. Bukharov
Keyword(s):  
Thin Films ◽  
Lattice Structure ◽  
Wave Length ◽  
Spatial Period ◽  
Nanoparticle Distribution ◽  
De Broglie Wave ◽  
Different Types ◽  
Quantum Behavior ◽  
New Type ◽  
Coherent Tunneling

Nanocluster structures can be easily modified in necessary direction and by controlled way in femtonanophotonics experiments. The variation of the key topology parameters can result in new type of the quantum correlation states/size effect for charged particles. In our earlier experiments we studied laser-induced topological nanoclusters structures of different types in thin films with unique phenomena in electrophysics and optics (see [1-3]). A simple 2-steps mechanism for enhancement of quantum behavior (e.g. in electroconductivity) exists for different conditions. First, when inelastic length linelastic > acluster we have no incoherent electron-phonon (e-ph) scattering, i.e. the coherent process takes place. Second, when de Broglie wave length λdB ≡ ℓcoh < Λ, (acluster – cluster size , Λ – spatial period of nanoparticle distribution) the coherent tunneling without loss occurs, and a long-range order with interference of the states takes place in the medium due to lattice structure.

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