NDLI: Interactive Failure in High Velocity Impact of Two Box Beams

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Xue, Liang Zheng, Li Wierzbicki, Tomasz
Copyright Year	2003
Abstract	The research reported in the present paper has been motivated mainly by the need of reconstructing the airplane impact damage of the WTC Towers. The initial phase of this catastrophic event was dominated by fracture, leading to breakup and fragmentation of the airplane and severance of a large number of external columns. However, the role of fracture has been de-emphasized in the recent attempt to reconstruct the 9/11 attack [1–3]. The objective of this paper is to raise the phenomenon of ductile fracture to the level of a main factor controlling the initial phase of the September 11th event. Our philosophy is similar to that employed by Lawver et al [4], but we are treating ductile fracture in a much more comprehensive way including the topics of material testing, calibration, validation and finite element implementation. A particular scenario considered is the impact of a corresponding section of the wing of the Boeing 767 into one external box column of a Twin Tower. Real dimensions are taken for the WTC column and the wing section is represented as a thin-walled box beam. Both members undergo extensive plastic deformation and fracture. In developing computer models, special attention was paid to the choice of the element type (shell vs. solid), contact algorithm, element removal (erosion) option, and above all the fracture criterion. Most calculations were done using LS-DYNA for several combinations of the equivalent strain to fracture of the aluminum alloy wing and the steel columns. In addition five ABAQUS runs were made with a newly developed criterion for ductile fracture with a cut-off value for negative triaxialities. Impact velocities considered ranged from 120 to 480 m/sec where 240 m/sec was the actual impact speed of the Boeing 767. It was found that the damage process is localized in the immediate velocity of the impact area. The fracture process initiates at the impacting flanges in the Mode III out-of-plane shear, continues down the webs as a combined shear/tension (tearing) and finally ends up as a tensile fracture of the rear flanges. While the airplane wing box was almost always completely cut, the WTC column was often partially penetrated for a wide range of the equivalent strain to fracture. It was also found that introducing a modified fracture locus changes the sequence of failure pattern as well as the mode of fracture.
Sponsorship	Applied Mechanics Division
Starting Page	23
Ending Page	31
Page Count	9
File Format	PDF
ISBN	0791837092
DOI	10.1115/IMECE2003-55112
Volume Number	Applied Mechanics and Biomedical Technology
Conference Proceedings	ASME 2003 International Mechanical Engineering Congress and Exposition
Language	English
Publisher Date	2003-11-15
Publisher Place	Washington, DC, USA
Access Restriction	Subscribed
Subject Keyword	Computers Materials testing Deformation Flanges Shells Aluminum alloys Dimensions Fracture (materials) Calibration Steel Fracture (process) Wings Algorithms Ductile fracture Tension Finite element analysis Damage Shear (mechanics) Aircraft Failure Erosion
Content Type	Text
Resource Type	Article

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