Fracture Analysis of Adhesively Bonded Cracked Panels

1978 ◽  
Vol 100 (1) ◽  
pp. 10-15 ◽  
Author(s):  
T. Swift
Keyword(s):  
Air Force ◽  
Complex Stress ◽  
Intensity Factors ◽  
Adhesively Bonded ◽  
Stiffened Panels ◽  
Aircraft Fuselage ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Shear Distortion ◽  
Using Data

An analysis procedure is presented for predicting crack tip stress intensity factors, adhesive stiffener stresses and strains, and the residual strength of adhesively bonded stiffened panels containing cracks equally spaced between stiffeners. The approach considers the cracked skin as a linear elastic fracture mechanics problem but accounts for the effects of plasticity on both adhesive and stiffener. The solution is based on displacement compatibility between the cracked sheet and the stiffener, accounting for shear distortion of the adhesive. Displacements in the cracked sheet are determined using the Westergaard complex stress function approach. The analysis was correlated with test using data from a cracked panel, simulating typical aircraft fuselage construction, previously tested during the Air Force Primary Adhesive Bonded Structures Technology (PABST) Program.

Parametric damage tolerance design of metallic aeronautical stiffened panels

2012 ◽  
Vol 116 (1182) ◽  
pp. 815-831 ◽  
Author(s):  
G. Molinari ◽  
I. Meneghin ◽  
M. Melega ◽  
E. Troiani
Keyword(s):  
Parametric Analysis ◽  
Damage Tolerance ◽  
Propagation Rate ◽  
Design Guidelines ◽  
Analytical Tool ◽  
Elastic Analysis ◽  
Adhesively Bonded ◽  
Stiffened Panels ◽  
Linear Elastic ◽  
Elastic Fracture

Abstract On the basis of well-known literature, an analytical tool named LEAF (linear elastic analysis of fracture) was developed by the authors to predict the damage tolerance (DT) proprieties of aeronautical stiffened panels. The tool is based on the linear elastic fracture mechanics and the displacement compatibility method. By means of LEAF, an extensive parametric analysis of stiffened panels, representative of typical aeronautical constructions, was performed to provide meaningful design guidelines. The effects of riveted, integral and adhesively bonded stringers on the fatigue crack propagation performances of stiffened panels were investigated, as well as the crack retarder contribution using metallic straps (named doublers) bonded in the middle of the stringers bays. The effect of both perfectly bonded and partially debonded doublers was investigated as well. Adhesively bonded stiffeners showed the best DT properties in comparison with riveted and integral ones. A great reduction of the skin crack growth propagation rate can be achieved with the adoption of additional doublers bonded between the stringers.

Boundary Element Formulations in Fracture Mechanics

1997 ◽  
Vol 50 (2) ◽  
pp. 83-96 ◽  
Author(s):  
M. H. Aliabadi
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Boundary Element ◽  
Growth Analysis ◽  
Review Article ◽  
Boundary Element Methods ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Transient Problems ◽  
Elastic Fracture

This article reviews advances in the application of boundary element methods (BEM) to fracture mechanics which have taken place over the last 25 years. Applications discussed include linear, nonlinear and transient problems. Also reviewed are contributions using the indirect boundary element formulations. Over this period the method has emerged as the most efficient technique for the evaluation of stress intensity factors (SIF) and crack growth analysis in the context of linear elastic fracture mechanics (LEFM). Much has also been achieved in the application to dynamic fracture mechanics. This review article contains 289 references.

scholarly journals Evaluation of the criticality of cracks in ice shelves using finite element simulations

2012 ◽  
Vol 6 (5) ◽  
pp. 973-984 ◽  
Author(s):  
C. Plate ◽  
R. Müller ◽  
A. Humbert ◽  
D. Gross
Keyword(s):  
Stress Intensity ◽  
Configurational Forces ◽  
Intensity Factors ◽  
Physical Processes ◽  
Ice Shelf ◽  
Critical Crack ◽  
Ice Shelves ◽  
Various Boundary Conditions ◽  
Linear Elastic ◽  
Elastic Fracture

Abstract. The ongoing disintegration of large ice shelf parts in Antarctica raise the need for a better understanding of the physical processes that trigger critical crack growth in ice shelves. Finite elements in combination with configurational forces facilitate the analysis of single surface fractures in ice under various boundary conditions and material parameters. The principles of linear elastic fracture mechanics are applied to show the strong influence of different depth dependent functions for the density and the Young's modulus on the stress intensity factor KI at the crack tip. Ice, for this purpose, is treated as an elastically compressible solid and the consequences of this choice in comparison to the predominant incompressible approaches are discussed. The computed stress intensity factors KI for dry and water filled cracks are compared to critical values KIc from measurements that can be found in literature.

Application of Fracture Mechanics to Arch Dam Analysis

2004 ◽  
Vol 261-263 ◽  
pp. 57-62 ◽  
Author(s):  
Shui Cheng Yang ◽  
Li Song ◽  
Hong Jian Liao
Keyword(s):  
Fracture Mechanics ◽  
Three Dimensional ◽  
Arch Dam ◽  
Mixed Mode Fracture ◽  
Analysis Method ◽  
Intensity Factors ◽  
Arch Dams ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
The Stability

The authors present a procedure for the analysis of the stability and propagation of cracks in arch dams based on linear elastic fracture mechanics. A finite element method was used to calculate the stress intensity factors(KⅠ, KⅡ and KⅢ) of crack in the concrete arch dam, and fracture analysis for arch dams was carried out, which based on the criterion of three-dimensional mixed mode fracture of concrete from the experiment. The analysis method can be applied to evaluate the safety of the arch dam and improve the design for arch dam.

Propagation of Fatigue Cracks Emanating from Sharp Notches under Different Loading Direction

2007 ◽  
Vol 348-349 ◽  
pp. 461-464
Author(s):  
Matteo Benedetti ◽  
M. Beghini ◽  
L. Bertini ◽  
V. Fontanari
Keyword(s):  
Stress Intensity ◽  
Applied Load ◽  
Fatigue Cracks ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Notched Specimens ◽  
Loading Direction ◽  
Al 7075 ◽  
Elastic Fracture ◽  
Edge Cracks

The present paper is aimed at investigating the behaviour of fatigue cracks emanating from sharp V-shaped notches. To this purpose, several tests has been conducted on Al-7075-T651 notched specimens using a servohydraulic machine by changing the directions and levels of the applied load. The crack growth have been interpreted on the basis of a linear elastic fracture mechanics approach by adopting a weight function derived by the authors for the calculation of the stress intensity factors (SIFs) of inclined edge-cracks emanating from V-shaped notches.

Examination of Ellipticity and Stress Intensity Factors by Photoelastic and Caustic Methods

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1898-1903
Author(s):  
Tsutomu Ezumi ◽  
Katsunao Suzuki
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Experimental Methods ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Freezing Method ◽  
Elastic Fracture ◽  
Caustics Method

In the field of linear elastic fracture mechanics, the stress intensity factor approach has been widely accepted as a valid means for predicting the behavior of a material in the presence of a crack or flaw. To optimize their dimension and to ensure their safety in service, a practical study of the strength under centrifugal force is important. In this paper, it is investigated that the stress intensity factors K_ and K_ on the rotating elliptic disks having outside cracks by means of combining the photoelastic freezing method and the caustics method. Stress intensity factors K and K were determined by using two experimental methods, as a function of ellipticity of the elliptic disk and at two different velocities. The results of these experimental methods was nearly agreement, and attracted the interest.

scholarly journals Two-Dimensional Stress Intensity Factor Analysis of Cracks in Anisotropic Bimaterial

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Chia-Huei Tu ◽  
Jia-Jyun Dong ◽  
Chao-Shi Chen ◽  
Chien-Chung Ke ◽  
Jyun-Yong Jhan ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Numerical Technique ◽  
Intensity Factors ◽  
Straight Crack ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Anisotropic Bimaterials

This paper presents a 2D numerical technique based on the boundary element method (BEM) for the analysis of linear elastic fracture mechanics (LEFM) problems on stress intensity factors (SIFs) involving anisotropic bimaterials. The most outstanding feature of this analysis is that it is a singledomain method, yet it is very accurate, efficient, and versatile (i.e., the material properties of the medium can be anisotropic as well as isotropic). A computer program using the BEM formula translation (FORTRAN 90) code was developed to effectively calculate the stress intensity factors (SIFs) in an anisotropic bi-material. This BEM program has been verified and showed good accuracy compared with the previous studies. Numerical examples of stress intensity factor calculation for a straight crack with various locations in both finite and infinite bimaterials are presented. It was found that very accurate results can be obtained using the proposed method, even with relatively simple discretization. The results of the numerical analysis also show that material anisotropy can greatly affect the stress intensity factor.

scholarly journals Analysis of Multiple Fatigue Cracks—Part II: Results

1992 ◽  
Vol 114 (3) ◽  
pp. 462-468 ◽  
Author(s):  
M. C. Dubourg ◽  
M. Godet ◽  
B. Villechaise
Keyword(s):  
Load Transfer ◽  
Fatigue Cracks ◽  
Interfacial Crack ◽  
Frictional Resistance ◽  
Mode I ◽  
Crack Interaction ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Crack Faces

A semianalytical model of multiple fatigue crack analysis in sliding contact is developed. Linear elastic fracture mechanics is applied. Frictional resistance between crack faces is taken into account. Five crack interaction mechanisms have been identified. Load transfer between cracks can cause both significant increases and drops in stress intensity factors both in mode I and II. The interaction depends on the distance between cracks, their relative position with respect to the loading zone, and the interfacial crack coefficient of friction.

scholarly journals Stress intensity factors for multiple cracks in thick-walled cylinder

2015 ◽  
Vol 3 (2) ◽  
pp. 207
Author(s):  
Krunal G. Girase ◽  
Navneet K. Patil ◽  
Dinesh Shinde ◽  
Kanak Kalita
Keyword(s):  
Stress Intensity ◽  
Crack Size ◽  
Diameter Ratio ◽  
Multiple Cracks ◽  
Intensity Factors ◽  
Structural Geometry ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Walled Cylinder ◽  
Good Agreement

<p>The stress intensity factor (SIF) is the linear elastic fracture mechanics parameter that relates remote load, crack size and structural geometry. It predicts very accurately the stress state. In this work, cylinders with multiple cracks are considered. The following parameters are varied during the analysis of the cylinders: the number of cracks, (the variation in number of cracks ultimately led to a variation in the inter-crack spacing), the crack length to cylinder thickness ratio (a/t), the diameter ratio of the cylinders. Very good agreement between the finite element stresses and the theoretical stresses is seen.</p>

Finite Element Analysis for the Fatigue Behavior of Steel Plates Strengthened with CFRP Plates

2006 ◽  
Vol 324-325 ◽  
pp. 359-362 ◽  
Author(s):  
Zheng Yun ◽  
Lie Ping Ye ◽  
Xin Zheng Lu ◽  
Qing Rui Yue
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Fatigue Behavior ◽  
Steel Plates ◽  
Intensity Factors ◽  
Element Analysis ◽  
Linear Elastic ◽  
Paris Law ◽  
Numerical Predictions ◽  
Elastic Fracture

The experimental research on six steel plates strengthened with CFRP plates, loaded in tension, shows that their fatigue lives can be greatly increased compared with un-strengthened specimens. Linear elastic fracture mechanics (LEFM) is adopted to explain the mechanism of CFRP plates strengthening. The stress intensity factors of the steel plates are calculated with finite element method (FEM), and Paris law on crack propagation is used to predict the fatigue life of strengthened specimens. The comparison between experimental results and numerical predictions shows good agreements on the fatigue crack propagation.

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