Transient thermal stresses of a bimaterial specimen with interface cracks, under uniform cooling by convection, are analyzed by photothermoelasticity and a coupled temperature-displacement, finite element scheme. The stress intensity factors of the interface crack are determined by a multiparameter overdeterministic system of equations in a least-squares sense using the experimental data and by J-integral, numerically. The study showed that a normal temperature variation can lead to significant stresses due to the mismatch of thermal expansion coefficients. © 2009 by ASME.

Krishnamurthi Ramesh

Department of Applied Mechanics

Bi-material

BI-MATERIAL INTERFACES

Experimental data

FINITE ELEMENT SCHEMES

Interface crack

J integral

Least Square

Multiparameters

SIF EVALUATION

System of equations

Temperature variation

Thermal expansion coefficients

TRANSIENT THERMAL LOADING

TRANSIENT THERMAL STRESS

Cracks

Numerical analysis

Stress intensity factors

Thermal load

Thermal stress

Thermoelasticity

Thermal expansion

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IIT Madras

Digital Photothermoelastic and Numerical Analysis of Transient Thermal Stresses in Cracked Bimaterial Interfaces

Journal of Applied Mechanics, Transactions ASME

Transient thermal stresses of a bimaterial specimen with interface edge cracks subjected to heating along an edge is analysed by refined three-fringe photoelasticity (RTFP). Whole-field, noise-free, fringe order estimation using a single colour image is made possible using RTFP combined with colour adaptation. The stress intensity factors (SIFs) of the interface crack are determined through a multiparameter overdeterministic system of equations by a least-squares approach using experimental data collected automatically. The transient SIFs are found to peak to a higher value than in steady state, and the opening mode is found to be dominant. An increase in thermal load causes the crack to propagate, and this is easily visualized on the basis of quantitative fringe order data available for the whole field. The SIFs of a propagating crack are found to be low. The study shows that the crack propagates easily when the opening mode is dominant. © 2009 IMechE.

Fulltext

Journal of Strain Analysis for Engineering Design

Transient thermal stress intensity factors of bimaterial interface cracks using refined three-fringe photoelasticity

A novel approach to plot photoelastic fringe contours from three-dimensional finite element results is presented. Plotting of fringe contours from 3D FE models requires the calculation of secondary principal stresses along the light path. The definition of secondary principal stresses and the calculation of relevant photoelastic data for fringe plotting are discussed. The plotting scheme uses a scanning approach and the evaluation of total fringe order is achieved by combining a file structure and subsequent sorting of these data to enable integration along the light path. The methodology is validated for the problem of a cantilever beam with an edge load. The usefulness of the methodology to verify 3D FE modelling and for experimentalists to design their experiments is indicated. Copyright © 2006 John Wiley & Sons, Ltd.

Communications in Numerical Methods in Engineering

Development of photoelastic fringe plotting scheme from 3D FE results

Photoelastic evaluation of the stress intensity factor (SIF) for a crack in a bimaterial tangential to the interface is hitherto confined to the use of only a singular stress field equation. In this paper, the multi-parameter stress field equations of Deng are simplified for use by experimentalists to evaluate the stress field parameters by digital photoelasticity using an overdeterministic least-squares technique. A bimaterial Brazilian disc with a central interface crack is selected as the model for study as different mode mixities could be easily simulated by changing the crack orientation angle. The use of SIF evaluation based on a singular stress field equation is found to be inadequate for the problems considered. On the other hand, the use of a multi-parameter stress field equation is quite successful in evaluating the stress field for various mode mixities and for two values of bimaterial constant. It is shown that the new procedure allows data collection from a larger zone, which helps to simplify data collection from experiments. © IMechE 2005.

Evaluation of stress field parameters for an interface crack in a bimaterial by digital photoelasticity

The Journal of Strain Analysis for Engineering Design

Re-examination on thermal stresses of bonded structures

Experimental Mechanics

Interfacial transient thermal fracture of adhesively bonded dissimilar materials

Material properties in thermal-stress analysis

Digital photothermoelastic and numerical analysis of transient thermal stresses in cracked bimaterial interfaces

Journal	Journal of Applied Mechanics, Transactions ASME
ISSN	00218936
Open Access	No