NASA Scientific and Technical Aerospace Reports

Program (NCHRP) Report 350 test 3-11. The TX DOT F411 bridge rail performed acceptably according to the evaluation
criteria of NCHRP Report 350. However, the T77 design failed to perform acceptably with the pickup truck. The objective
of this project was to modify the TX DOT T77 bridge rail to perform as an aesthetically pleasing and crashworthy bridge rail.
TT1 and TX DOT worked cooperatively to modify the design to make the rail perform satisfactorily. Researchers performed
full-scale crash tests in accordance with NCHRP Report 350. The T77 bridge rail was modified so it would perform in
accordance with the evaluation criteria for NCHRP Report 350 test 3-11.
NTIS
Rails; Transportation
20040070719 NASA Langley Research Center, Hampton, VA, USA
Global-Local Finite Element Analysis of Bonded Single-Lap Joints
Kilic, Bahattin; Madenci, Erdogan; Ambur, Damodar R.; April 15, 2004; 13 pp.; In English; 45th AIAA/ASME/ASCE/AHS/
ASC Structures, Structural Dynamics, and Materials Conference, 19-22 Apr. 2004, Palm Springs, CA, USA; Original contains
color illustrations
Contract(s)/Grant(s): 762-55-LE
Report No.(s): AIAA Paper 2004-1559; Copyright; Avail: CASI; A03, Hardcopy
Adhesively bonded lap joints involve dissimilar material junctions and sharp changes in geometry, possibly leading to
premature failure. Although the finite element method is well suited to model the bonded lap joints, traditional finite elements
are incapable of correctly resolving the stress state at junctions of dissimilar materials because of the unbounded nature of the
stresses. In order to facilitate the use of bonded lap joints in future structures, this study presents a finite element technique
utilizing a global (special) element coupled with traditional elements. The global element includes the singular behavior at the
junction of dissimilar materials with or without traction-free surfaces.
Author
Adhesive Bonding; Bonded Joints; Lap Joints; Finite Element Method; Stress Analysis
20040070761 NASA Langley Research Center, Hampton, VA, USA
Application of Non-Deterministic Methods to Assess Modeling Uncertainties for Reinforced Carbon-Carbon Debris
Impacts
Lyle, Karen H.; Fasanella, Edwin L.; Melis, Matthew; Carney, Kelly; Gabrys, Jonathan; March 05, 2004; 11 pp.; In English;
8th International LS-DYNA Users Conference, 2-4 May 2004, Dearborn, MI, USA; Original contains color and black and
white illustrations; Copyright; Avail: CASI; A03, Hardcopy
The Space Shuttle Columbia Accident Investigation Board (CAIB) made several recommendations for improving the
NASA Space Shuttle Program. An extensive experimental and analytical program has been developed to address two
recommendations related to structural impact analysis. The objective of the present work is to demonstrate the application of
probabilistic analysis to assess the effect of uncertainties on debris impacts on Space Shuttle Reinforced Carbon-Carbon
(RCC) panels. The probabilistic analysis is used to identify the material modeling parameters controlling the uncertainty. A
comparison of the finite element results with limited experimental data provided confidence that the simulations were
adequately representing the global response of the material. Five input parameters were identified as significantly controlling
the response.
Author
Carbon-Carbon Composites; Finite Element Method; Structural Analysis; Space Shuttle Orbiters; Impact Damage; Panels;
Monte Carlo Method
20040070811 NASA Marshall Space Flight Center, Huntsville, AL, USA
Development of a Fatigue Crack Growth Coupon for Highly Plastic Stress Conditions
Allen, Phillip A.; Aggarwal, Pravin K.; Swanson, Gregory R.; July 24, 2003; 9 pp.; In English; 45th AIAA/ASME/ASCE/
AHS/ASC Structures, Structural Dynamics and Materials Conference; No Copyright; Avail: CASI; A02, Hardcopy
This paper presents an analytical approach used to develop a novel fatigue crack growth coupon for a highly plastic 3-D
stress field condition. The flight hardware investigated in this paper is a large separation bolt that fractures using pyrotechnics
at the appointed time during the flight sequence. The separation bolt has a deep notch that produces a severe stress
concentration and a large plastic zone when highly loaded. For this geometry, linear-elastic fracture mechanics (LEFM)
techniques are not valid due to the large nonlinear stress field. Unfortunately, industry codes that are generally available for
fracture mechanics analysis and fatigue crack growth (e.g. NASGRO (11) are limited to LEFM and are available for only a
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