Optical interferometry: Running crack-tip morphologies and craze material properties

2005 ◽  
pp. 215-261 ◽  
Author(s):  
R. Schirrer
Keyword(s):  
Material Properties ◽  
Crack Tip ◽  
Optical Interferometry ◽  
Craze Material

Analysis of Composite Plates Containing Cracks

1992 ◽  
Vol 114 (3) ◽  
pp. 358-363 ◽  
Author(s):  
Y. W. Kwon
Keyword(s):  
Stress Intensity Factor ◽  
Material Properties ◽  
Composite Plate ◽  
Crack Tip ◽  
Composite Plates ◽  
Unidirectional Composite ◽  
Matrix Crack ◽  
Fiber Breakage ◽  
Fiber Volume ◽  
Element Analysis

Effect of microcracks, such as local matrix crack and fiber breakage, on a macroscale crack in a unidirectional composite plate was studied for various fiber volume fractions, as well as different material properties of fiber and matrix materials. A finite element analysis was performed for this study. It showed that microcracks, located near a macroscale crack tip, resulted in a significant increase of stress intensity factor at the crack tip.

Material Properties Parameters Effect on Crack Threshold

2011 ◽  
Vol 243-249 ◽  
pp. 6026-6029
Author(s):  
Zhen Hua Yi
Keyword(s):  
Fatigue Crack ◽  
Research Methods ◽  
Test Data ◽  
Material Properties ◽  
Physical Meaning ◽  
Crack Tip ◽  
Displacement Fields ◽  
Existing Data

The research of fatigue crack threshold is an issue in fatigue research. Though there are many research methods, calculation formulae and test data, most of the formulae are evaluated by experiments and have test constants in them, which lead to inconvenient application. Based on displacement fields around crack tip and fatigue theory, A formula that can describe fatigue crack threshold related to material properties is proposed. Each parameters in the formula has definite physical meaning. And it is convenient to use this formula. Using this formula, the material threshold is primarily calculated before design. At last, using existing data to verify, it is shown that the formula is reliable.

A Simplified Method for Calculating the Crack-Tip Field of Functionally Graded Materials Using the Domain Integral

1999 ◽  
Vol 66 (1) ◽  
pp. 101-108 ◽  
Author(s):  
P. Gu ◽  
M. Dao ◽  
R. J. Asaro
Keyword(s):  
Finite Element ◽  
Functionally Graded Materials ◽  
Material Properties ◽  
Crack Tip ◽  
Functionally Graded ◽  
Crack Tip Field ◽  
Graded Materials ◽  
Fine Mesh ◽  
Domain Integral ◽  
Standard Domain

A finite element based method is proposed for calculating stress intensity factors of functionally graded materials (FGMs). We show that the standard domain integral is sufficiently accurate when applied to FGMs; the nonhomogeneous term in the domain integral for nonhomogeneous materials is very small compared to the first term (the standard domain integral). In order to obtain it, the domain integral is evaluated around the crack tip using sufficiently fine mesh. We have estimated the error in neglecting the second term in terms of the radius of the domain for the domain integration, the material properties and their gradients. The advantage of the proposed method is that, besides its accuracy, it does not require the input of material gradients, derivatives of material properties; and existing finite element codes can be used for FGMs without much additional work. The numerical examples show that it is accurate and efficient. Also, a discussion on the fracture of the FGM interlayer structure is given.

Effect of Voids on a Magistral Crack in Piezoelectric Brittle Materials

2015 ◽  
Vol 665 ◽  
pp. 233-236
Author(s):  
Jan Sladek ◽  
Vladimir Sladek ◽  
Slavomir Krahulec ◽  
Der Liang Young
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Value Problems ◽  
Material Properties ◽  
Crack Tip ◽  
Volume Element ◽  
Effective Material Properties ◽  
Piezoelectric Solid ◽  
Scaled Boundary Finite Element

A large (magistral) crack is analyzed in a voided piezoelectric solid. The representative volume element (RVE) is analyzed for determination of influence of voids on material properties. The whole domain is divided into two subdomains. At the crack tip vicinity it is considered a subdomain with the crack tip and circular voids. Material properties correspond to the piezoelectric skeleton there. The rest part of analyzed domain is modeled by effective material properties obtained from analyses on the RVE. The scaled boundary finite element method (SBFEM) is applied to solve all boundary value problems.

Mixed-Mode Dynamic Crack Growth in a Functionally Graded Particulate Composite: Experimental Measurements and Finite Element Simulations

2008 ◽  
Vol 75 (5) ◽  
Author(s):  
Madhu Kirugulige ◽  
Hareesh V. Tippur
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Material Properties ◽  
Mixed Mode ◽  
Crack Tip ◽  
Functionally Graded ◽  
Dynamic Crack ◽  
Cohesive Elements ◽  
Dynamic Crack Growth ◽  
Crack Paths

Mixed-mode dynamic crack growth behavior in a compositionally graded particle filled polymer is studied experimentally and computationally. Beams with single edge cracks initially aligned in the direction of the compositional gradient and subjected to one-point eccentric impact loading are examined. Optical interferometry along with high-speed photography is used to measure surface deformations around the crack tip. Two configurations, one with a crack on the stiffer side of a graded sheet and the second with a crack on the compliant side, are tested. The observed crack paths are distinctly different for these two configurations. Furthermore, the crack speed and stress intensity factor variations between the two configurations show significant differences. The optical measurements are examined with the aid of crack-tip fields, which incorporate local elastic modulus variations. To understand the role of material gradation on the observed crack paths, finite element models with cohesive elements are developed. A user-defined element subroutine for cohesive elements based on a bilinear traction-separation law is developed and implemented in a structural analysis environment. The necessary spatial variation of material properties is introduced into the continuum elements by first performing a thermal analysis and then by prescribing material properties as temperature dependent quantities. The simulated crack paths and crack speeds are found to be in qualitative agreement with the observed ones. The simulations also reveal differences in the energy dissipation in the two functionally graded material (FGM) cases. T-stresses and hence the crack-tip constraint are significantly different. Prior to crack initiation, larger negative T-stresses near the crack tip are seen when the crack is situated on the compliant side of the FGM.

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