scholarly journals Nonslipping Contact Between a Mismatch Film and a Finite-Thickness Graded Substrate

2015 ◽  
Vol 83 (2) ◽  
Author(s):  
Chen Peijian ◽  
Chen Shaohua ◽  
Yao Yin
Keyword(s):  
Failure Modes ◽  
Finite Thickness ◽  
Interfacial Shear Stress ◽  
Modulus Ratio ◽  
Transform Method ◽  
Mismatch Strain ◽  
Elastic Film ◽  
Potential Failure ◽  
The Fourier Transform ◽  
Film Substrate

The contact behavior of an elastic film subjected to a mismatch strain on a finite-thickness graded substrate is investigated, in which the contact interface is assumed to be nonslipping and the shear modulus of the substrate varies exponentially in the thickness direction. The Fourier transform method is adopted in order to reduce the governing partial differential equations to integral ones. With the help of numerical calculation, the interfacial shear stress, the internal normal stress in the film and the stress intensity factors are predicted for cases with different material parameters and geometric ones, including the modulus ratio of the film to the substrate, the inhomogeneous feature of the graded substrate, as well as the profile of the contacting film. All the physical predictions can be used to estimate the potential failure modes of the film–substrate interface. Furthermore, it is found that the result of a finite-thickness model is significantly different from the prediction of a generally adopted half-plane one. The study should be helpful for the design of film–substrate systems in real applications.

scholarly journals Multimodal Surface Instabilities in Curved Film–Substrate Structures

2017 ◽  
Vol 84 (8) ◽  
Author(s):  
Ruike Zhao ◽  
Xuanhe Zhao
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Numerical Simulation ◽  
Period Doubling ◽  
Tubular Structures ◽  
Modulus Ratio ◽  
Future Design ◽  
Mismatch Strain ◽  
Curved Structures ◽  
Film Substrate

Structures of thin films bonded on thick substrates are abundant in biological systems and engineering applications. Mismatch strains due to expansion of the films or shrinkage of the substrates can induce various modes of surface instabilities such as wrinkling, creasing, period doubling, folding, ridging, and delamination. In many cases, the film–substrate structures are not flat but curved. While it is known that the surface instabilities can be controlled by film–substrate mechanical properties, adhesion and mismatch strain, effects of the structures’ curvature on multiple modes of instabilities have not been well understood. In this paper, we provide a systematic study on the formation of multimodal surface instabilities on film–substrate tubular structures with different curvatures through combined theoretical analysis and numerical simulation. We first introduce a method to quantitatively categorize various instability patterns by analyzing their wave frequencies using fast Fourier transform (FFT). We show that the curved film–substrate structures delay the critical mismatch strain for wrinkling when the system modulus ratio between the film and substrate is relatively large, compared with flat ones with otherwise the same properties. In addition, concave structures promote creasing and folding, and suppress ridging. On the contrary, convex structures promote ridging and suppress creasing and folding. A set of phase diagrams are calculated to guide future design and analysis of multimodal surface instabilities in curved structures.

Deformation and failure of a film/substrate system subjected to spherical indentation: Part II. Prediction of failure modes in a thin TiN film deposited on a compliant elastic substrate

2006 ◽  
Vol 21 (3) ◽  
pp. 783-790 ◽  
Author(s):  
S. Math ◽  
V. Jayaram ◽  
S.K. Biswas
Keyword(s):  
Film Thickness ◽  
Failure Modes ◽  
Normal Load ◽  
Real Life ◽  
Plastic Substrate ◽  
Spherical Indentation ◽  
Elastic Substrate ◽  
Transform Method ◽  
Deformation And Failure ◽  
Elastic Film

We have demonstrated previously, using nanoindentation, that the film thickness and substrate plasticity, the important two external variables in the film layer, control the failure of the film in a mutually exclusive way. In this work, we used a non-iterative Hankel transform method to analyze the stresses in an elastic film bound to an elastic substrate by a no-slip boundary condition and subjected to a Hertzian traction. We vary the substrate compliance by two orders of magnitude to generate interfacial mismatch stresses, which mimic the corresponding changes found in a real-life elastic film on an elastic-plastic substrate when the hardness of the substrate is changed. The analysis is found to reproduce faithfully the experimental trends, which showed that normal load and interfacial stresses generated by strain mismatch drive different modes of fracture depending on the film thickness in a mutually exclusive way. This validation paves the way for this theoretical technique to be used to design multilayered film structures.

scholarly journals Surface Contamination by Antineoplastics in Hospitals: An Observational Study for Mapping of Potential Contamination Associated with Handling Excreta of Babies through Diaper Management

2020 ◽  
Vol 4 (3-4) ◽  
pp. 119-125
Author(s):  
Marie Palamini ◽  
Geneviève Mercier ◽  
Jean-François Bussières
Keyword(s):  
Bone Marrow ◽  
Exploratory Study ◽  
Research Team ◽  
Failure Modes ◽  
Hospital Setting ◽  
Marrow Transplant ◽  
Mother And Child ◽  
Potential Failure ◽  
Key Steps ◽  
Hazardous Drugs

AbstractBackgroundIn the hospital setting, trace contamination with hazardous medications comes primarily from the manipulation of containers used in preparing and administering drugs. However, some traces of medications also come from the excreta of patients.MethodsThis descriptive exploratory study involved direct observation and discussion. The aim was to map potential contamination associated with handling babies’ excreta through diaper management. The study was conducted at CHU Sainte Justine (Montréal, Québec, Canada), a 500-bed mother and child facility with 38 beds for hematology-oncology and bone marrow transplant. A list of key steps related to the management of diapers by a parent or caregiver on a pediatric unit was established by the investigators. A data collection grid was then developed and reviewed by a member of the research team.ResultsA total of six diaper changes, by six distinct individuals, were observed in August and September 2019. Transport of a soiled diaper for weighing outside the baby’s room by an additional caregiver was also observed and recorded. In total, 25 individual steps in diaper management and 28 potential failure modes were identified through mapping.ConclusionsChanging a baby’s diaper involves many individual steps, which are subject to numerous failure modes that can contribute to contamination with traces of hazardous drugs. A good understanding of these process steps and failure modes is desirable to better train caregivers and parents to reduce trace contamination with hazardous drugs.

A Systematized FMEA Practice for Magnet Relays

2010 ◽  
Vol 146-147 ◽  
pp. 757-769
Author(s):  
Ching Ming Cheng ◽  
Wen Fang Wu ◽  
Yao Hsu
Keyword(s):  
New Product Development ◽  
Failure Modes ◽  
New Product ◽  
Risk Priority Number ◽  
Detection Model ◽  
Regulation Function ◽  
Potential Failure ◽  
Weighting Rule ◽  
Rating Criterion

The Design Failure Modes and Effects Analysis (DFMEA) are generally applied to risk management of New Product Development (NPD) through standardization of potential failure modes and effect-ranking of rating criterion with failure modes. Typical 1 to 10 of effect-ranking are widely weighed the priority of classification, that framing effects and status quo senses might cause decision trap happening thus. The FMEA follows considerable indexes which are including Severity, Occurrence and Detection, and need be associated with difference between every two failures individually. However, we suspect that a more systematic construction of the analysis by which failure modes belong is necessary in order to make intellectual progress in this area. Two ways of such differentiation and construction are improvable effect-ranking and systematized indexes; here we resolve for attributes of failures with classification, maturity and experiance of indexes according to an existing rule. In Severity model, the larger differentiation is achieved by separating indexes to the classification of the Law & Regulation, Function and Cosmetic. Occurrence model has its characteristic a reliable ranking indexwhich assists decisionmakers to manage their venture. This is the model most closely associate with product maturity by grouping indexes to the new, extend and series product. Detection model offers a special perspective on cost; here the connections concerned with phase occasion of the review, verification and validation. Such differentiations will be proposed and mapped with the Life Cycle Profile (LCP) to systematize FMEA. Meanwhile, a more reasonable Risk Priority Number (RPN) with the new weighting rule will be worked out for effect-ranking and management system will be integrated systematiclly

scholarly journals Interaction between line cracks in an orthotropic layer

2002 ◽  
Vol 29 (1) ◽  
pp. 31-42 ◽  
Author(s):  
Subir Das
Keyword(s):  
Fourier Transform ◽  
Stress Intensity ◽  
Finite Thickness ◽  
Intensity Factors ◽  
Orthotropic Layer ◽  
Finite Hilbert Transform ◽  
Crack Tips ◽  
The Fourier Transform ◽  
Analytical Expressions ◽  
Elastostatic Problem

We deal with the interaction between three coplanar Griffith cracks located symmetrically in the mid plane of an orthotropic layer of finite thickness2h. The Fourier transform technique is used to reduce the elastostatic problem to the solution of a set of integral equations which have been solved by using the finite Hilbert transform technique and Cooke's result. The analytical expressions for the stress intensity factors at the crack tips are obtained for largeh. Numerical values of the interaction effect have been computed for and results show that interaction effects are either shielding or amplification depending on the location of each crack with respect to each other and crack tip spacing as well as the thickness of the layer.

scholarly journals Apparent Variation of v sin i and Rotational Modulation in Be Stars

2004 ◽  
Vol 215 ◽  
pp. 93-94
Author(s):  
C. Neiner ◽  
S. Jankov ◽  
M. Floquet ◽  
A. M. Hubert
Keyword(s):  
Fourier Transform ◽  
Magnetic Dipole ◽  
Be Stars ◽  
Line Profiles ◽  
Transform Method ◽  
Rotational Modulation ◽  
Be Star ◽  
Apparent Variation ◽  
The Fourier Transform ◽  
First Time

v sin i was determined by applying the Fourier transform method to the line profiles of two classical Be Stars. A variation is observed in the apparent v sin i which corresponds to the main frequencies associated to nrp modes. Rotational modulation is observed in wind sensitive UV lines of the Be star ω Ori and is associated with an oblique magnetic dipole which is discovered for the first time in a classical Be star.

Bleustein-Gulyaev Waves in an Inhomogeneous Layered Piezoelectric Half-Space

2006 ◽  
Vol 306-308 ◽  
pp. 1223-1228
Author(s):  
Fei Peng ◽  
Hua Rui Liu
Keyword(s):  
Fourier Transform ◽  
Phase Velocity ◽  
Half Space ◽  
Electric Potential ◽  
Piezoelectric Layer ◽  
Field Equations ◽  
Transform Method ◽  
Coupled Field ◽  
Coupled Field Equations ◽  
The Fourier Transform

The propagation of Bleustein-Gulyaev (BG) waves in an inhomogeneous layered piezoelectric half-space is investigated in this paper. Application of the Fourier transform method and by solving the electromechanically coupled field equations, solutions to the mechanical displacement and electric potential are obtained for the piezoelectric layer and substrate, respectively. The phase velocity equations for BG waves are obtained for the surface electrically shorted case. When the layer and the substrate are homogenous, the dispersion equations are in agreement with the corresponding results. Numerical calculations are performed for the case that the layer and the substrate are identical LiNbO3 except that they are polarized in opposite directions. Effects of the inhomogeneities induced by either the layer or substrate are discussed in detail.

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