Mechanical Modeling of Multilayered Films on an Elastic Substrate—Part I: Analysis

1990 ◽  
Vol 112 (4) ◽  
pp. 309-316 ◽  
Author(s):  
F. Erdogan ◽  
P. F. Joseph
Keyword(s):  
Interfacial Crack ◽  
Strain Energy Release ◽  
Interfacial Zone ◽  
Stress Concentrations ◽  
Elastic Substrate ◽  
Multilayered Films ◽  
Elastic Continuum ◽  
Modeling And Analysis ◽  
Film Substrate ◽  
Homogeneous Temperature

In this paper the basic residual stress problem for multilayered or multiple films on an elastic substrate is considered. The stresses may be caused by a homogeneous temperature variation or slow thermal cycling and by far field mechanical loading. The films are approximated by orthotropic membranes and the substrate is assumed to be an elastic continuum. The interfacial zone is modeled by either an ideal interface or a homogeneous shear layer. The primary interest in the paper is in examining stress concentrations or singularities near the film ends. For the two interface conditions considered, this is done by varying the film/substrate contact angle. Also studied are strain energy release rate for the propagation of an interfacial crack and the direction and the magnitude of the maximum cleavage stress for a possible crack initiation in the substrate. The basic modeling and analysis are considered in Part I. Part II of the paper is devoted to the presentation and discussion of the results.

Mechanical Modeling of Thin Films and Cover Plates Bonded to Graded Substrates

2008 ◽  
Vol 75 (5) ◽  
Author(s):  
Mehmet A. Guler
Keyword(s):  
Thin Films ◽  
Stress Intensity ◽  
Interfacial Shear Stress ◽  
Contact Problems ◽  
Stress Concentrations ◽  
Elastic Continuum ◽  
Temperature Changes ◽  
Initiation And Propagation ◽  
Axial Normal Stress ◽  
Cover Plates

In this study, the contact problems of thin films and cover plates are considered. In these problems, the loading consists of any one or combination of stresses caused by uniform temperature changes and temperature excursions, far field mechanical loading, and residual stresses resulting from film processing or welding. The primary interest in this study is in examining stress concentrations or singularities near the film ends for the purpose of addressing the question of crack initiation and propagation in the substrate or along the interface. The underlying contact mechanics problem is formulated by assuming that the film is a “membrane” and the substrate a graded elastic continuum, and is solved analytically by reducing it to an integral equation. The calculated results are the interfacial shear stress between the film and the graded substrate, the Mode II stress intensity factor at the end of the film, and the axial normal stress in the film. The results indicate that grading the material properties of the substrate helps to decrease the film stresses and the stress intensity factors at the free edges and to lower the axial normal stresses at the midsection where the film is most likely to crack.

Numerical Analysis on the Wrinkling Instability of a Stiff Film Adhering to an Elastic Substrate with a Graded Coating

2019 ◽  
Vol 11 (02) ◽  
pp. 1950015 ◽  
Author(s):  
Feng Gao ◽  
Wang Guo ◽  
Peijian Chen ◽  
Chengzheng Cai ◽  
Guangjian Peng
Keyword(s):  
Flexible Electronics ◽  
Critical Strain ◽  
Present Finding ◽  
Elastic Substrate ◽  
Material Parameters ◽  
Numerical Result ◽  
Graded Coating ◽  
Inhomogeneous Coating ◽  
Graded Properties ◽  
Film Substrate

The wrinkling instability of a stiff film adhering to a pre-strained inhomogeneous bi-layer substrate consisting of a homogeneous substrate and a graded coating is investigated in the present paper. The critical strain, wavelength and amplitude of the film/inhomogeneous substrate system are calculated numerically and analyzed comprehensively. Compared with the numerical result, a theoretical model is introduced to approximately predict the wrinkling responses of the system. The influence of various geometric and material parameters on the wrinkling behavior is mainly focused. The wrinkling responses are found to be highly related to the graded laws and the thickness of the inhomogeneous coating as well as the Poisson’s ratio. What is more, a proper choice of graded properties of a substrate can improve the wrinkling response of a film/substrate system. The present finding should be very meaningful to guide the design of various stretchable and flexible electronics.

scholarly journals Mechanics Of Interfacial Crack Propagation In Microscratching

1996 ◽  
Vol 436 ◽  
Author(s):  
Maarten P. de Boer ◽  
John C. Nelson ◽  
William W. Gerberich
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Grain Boundary ◽  
Interfacial Crack ◽  
Strain Energy Release ◽  
Linear Elastic ◽  
Interfacial Cracks ◽  
Bending Strain ◽  
Diamond Indenter ◽  
Boundary Fracture

AbstractA new probing technique has been developed to test thin film mechanical properties. In the Microwedge Scratch Test (MWST), a wedge shaped diamond indenter tip is drawn along a fine line, while simultaneously being driven into the line. We compare microwedge scratching of Zone 1 and Zone T thin film specimens of sputtered W on SiO2. Symptomatic of its poor mechanical properties, the Zone 1 film displays three separate crack systems. Because of its superior grain boundary strength, the Zone T film displayed only one of these - an interfacial crack system. Using bimaterial linear elastic fracture mechanics, governing equations are developed for propagating interfacial cracks, including expressions for strain energy release rate, bending strain, and mode mixity. Grain boundary fracture strength information may be deduced from the Zone 1 films, while adhesion may be inferred from the Zone T films.

scholarly journals Effect of geometric parameters and combined loading on stress distribution of tubular T-joints

Mechanika ◽  
2019 ◽  
Vol 25 (5) ◽  
pp. 350-356
Author(s):  
Samira Belhour ◽  
Hafida Kahoul ◽  
Ahmed Bellaouar ◽  
Sébastien Murer
Keyword(s):  
Axial Loading ◽  
Computation Time ◽  
Geometric Parameters ◽  
Combined Loading ◽  
Offshore Platforms ◽  
Tubular Structures ◽  
Stress Concentrations ◽  
Standard Samples ◽  
T Joints ◽  
Modeling And Analysis

Steel tubular structures are widely used in the construction of offshore platforms and T-type junctions are extensively used in this domain. The tubular members are welded, which generates significant stress concentrations at the edges. The stress levels reached in these critical places are used to assess lifetimes based on fatigue curves from tests conducted on standard samples. This study is devoted to the modeling and analysis of T-type welded tubular structures for the determination of hot spots stresses (HSS) at the chord/brace intersection, A numerical analysis was carried out to study the effect of a combined loading composed of an axial loading and a continuation of rational bending, that best assimilate real conditions, as well as the effect of normalized geometric parameters α, β, g on the distribution of stress concentration (area and values) of T-joints. The mechanical behaviour has been modeled in 2D using quadrangular and triangular thin-shell elements by the finite element method (FEM). It is the most appropriate approach because it considers all geometric complexities and singularities of the structure, while the efforts as well as the computation time are considerably reduced compared to an experimental study or to complex FE models implementing solid elements. In this study, we use the COMSOL-MULTIPHYSICS® software...

scholarly journals Manipulation of Nanorods on Elastic Substrate, Modeling and Analysis

Nanorods ◽  
10.5772/36355 ◽  
2012 ◽  
Author(s):  
A. H. ◽  
M. Moradi ◽  
S. Sadeghzadeh
Keyword(s):  
Elastic Substrate ◽  
Modeling And Analysis

Fracture Behavior of a Brittle Thin Film on an Elastic Substrate under Residual Stress and Uniaxial Tensile Loading

2012 ◽  
Vol 190-191 ◽  
pp. 487-490 ◽  
Author(s):  
Ban Quan Yang ◽  
Xue Jun Chen ◽  
Wei Hai Sun ◽  
Hong Qian Chen ◽  
Jing Wen Pan ◽  
...  
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Shear Stress ◽  
Fracture Behavior ◽  
Tensile Loading ◽  
Interfacial Shear ◽  
Uniaxial Tensile ◽  
Elastic Substrate ◽  
Uniaxial Tensile Loading ◽  
Film Substrate

The fracture behavior of a brittle thin film on an elastic substrate under residual stress and uniaxial tensile loading is investigated. It is assumed that the residual stress in the thin film is not large enough to cause the thin film to fracture. Using a mechanical model presented in this work, the analytical solutions for the distribution laws of the tensile stress developed in the thin film, the shear stress developed along the interface and the relationship between the crack density of the thin film and the applied strain of the substrate can be obtained. The results presented in this work can provide a new analytic solution to the interfacial shear stress for characterizing the interfacial shear strength of the thin film/substrate system when the uniaxial tensile test is adopted to evaluate the mechanical properties of the thin film/substrate system.

Stresses in Anisotropic Thin Films Bonded to Stiff Substrates

1987 ◽  
Vol 108 ◽  
Author(s):  
John C. Lambropculos ◽  
Shih-Ming Wan
Keyword(s):  
Film Growth ◽  
Elastic Anisotropy ◽  
Free Edge ◽  
Growth Direction ◽  
Numerical Techniques ◽  
Stress Concentrations ◽  
Elastic Symmetry ◽  
Material Parameters ◽  
Single Crystalline Film ◽  
Film Substrate

ABSTRACTNumerical techniques are used to calculate the stress concentrations arising near the interface of a single-crystalline film which is bonded to a stiff substrate. The film has cubic elastic symmetry, and it is characterized by the anisotropic constants A and H which show the deviation of the material frcm elastic isotropy. The normal to the film-substrate interface is taken to be along the 100, 111 or 110 directions. The inhomogeneous stresses near the free edge and the uniform stresses far from the free edge are calculated, and the effects of cubic elastic anisotropy and of film growth direction are established for material parameters typical of metallic and semiconducting films.

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