Ductile tearing in thin aluminum panels: experiments and analyses using large-displacement, 3-D surface cohesive elements

被引:84
作者
Roychowdhury, S [1 ]
Roy, YD [1 ]
Dodds, RH [1 ]
机构
[1] Univ Illinois, Dept Civil & Environm Engn, Newmark Lab 2129, Urbana, IL 61801 USA
关键词
ductile tearing; quasi-static crack growth; finite deformation cohesive elements; CTOA; 2024-T3; aluminum; 3-D finite element analysis;
D O I
10.1016/S0013-7944(01)00113-8
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
This paper describes a large-displacement formulation for a 3-D, interface-cohesive finite element model and its application to predict ductile tearing in thin aluminum panels. A nonlinear traction-separation relationship defines the constitutive response of the initially zero thickness interface elements. Applications of the model simulate crack extension in C(T) and M(T) panels made of a 2.3 mm thick, Al 2024-T3 alloy tested as part of the NASA-Langley Aging Aircraft program. Tests of the M(T) specimens without guide plates exhibit significant out-of-plane (buckling) displacements during crack growth which necessitates the large-displacement, cohesive formulation. The measured load vs. outside surface crack extension behavior of high constraint (T-stress > 0) C(T) specimen drives the calibration process of the cohesive fracture model. Analyses of low constraint M(T) specimens, having widths of 300 and 600 mm and various a/W ratios, demonstrate the capabilities of the calibrated model to predict measured loads and measured outside surface crack extensions. The models capture accurately the strong 3-D effects leading to out-of-plane buckling and various degrees of crack front tunneling in the C(T) and M(T) specimens. Previous analyses of these specimens using a crack tip opening angle (CTOA) criterion for growth show good agreement with measured peak loads. However, without the ability of the interface-cohesive model to predict tunneling behavior, the CTOA approach overestimates crack extensions early in the loading when tunneling behavior dominates the response. (C) 2002 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:983 / 1002
页数:20
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