APPLICATION OF NUMERICAL METHODS FOR CRASHWORTHINESS INVESTIGATION OF A LARGE AIRCRAFT WING IMPACT WITH A TREE
Chao Zhang, Wieslaw K. Binienda, Frank E. Horvat, Wenzhi Wang (Department of Civil Engineering, University of Akron, 302 Buchtel Common, Akron, OH, 44325, USA, School of Aeronautics, Northwestern Polytechnical University, Xian, Shaanxi 710072, China)
Paper type: Research paper
Published: March 30, 2022
This paper demonstrates the application of a numerical methodology for a full-scale aircraft impact crashworthiness investigation. We studied the impact of an aircraft wing with a tree using LS-DYNA and ANSYS CFX. In particular, a detailed finite element model of the wing structure was represented as a box structure containing skin, spars and ribs, and fuel was represented as a distributed mass. We utilized several material models and verified them using leading-edge bird strike and wood bending experiments. Wood model Mat 143 with material parameters developed based on the wood bending test was found to be the most accurate in comparison with the experiment. We used the commercially available Computational Fluid Dynamics (CFD) software of ANSYS CFX to calculate the aerodynamic pressure distribution on the overall surface of the wing. The algorithm utilized the full three-dimensional Navier-Stokes equations for steady-state compressible fluid. LS-DYNA finite element model included aerodynamic pressures on the wings surfaces. Parametric studies showed that the tree model cannot destroy the lifting surface of the wing except the fragment of the leading edge. In every simulation scenario, the first spar of the wing cut through the tree and the upper part of the tree fell in the direction of the movement of the airplane.
Full-scale modeling, Finite Element Method, crashworthiness, nonlinear wood model, Mat 143, Johnson-Cook material model, fluid dynamics, aircraft, wing, tree
Click on the thumbnails below to view screen dumps from the detectors used to examine the wreckage and seats from the Polish president's plane crash in Smolensk. An "X" denotes the presence of the detected explosive substance and its type. The underlined Polish word "Probka" or "probka" in the screen dump 1 and 2, means "Sample"
Why did they all fly on the same plane?
Synopsis: January 12, 2013, Toronto, Canada. The wife of the late Deputy-Minister of Culture Tomasz Merta: "What I am about to tell you now, are suspicions - and not even my own - but, rather the [suspicions of the] individuals in the inner-circles of the [Polish] military... I heard a statement that was made - but, I am not taking any responsibility for how credible, or not credible it is. [I heard that] had the generals and journalists' not been re-assigned to different aircraft, it wouldn't have been the Tupolev [Tu-154M], but rather the Casa [transport aircraft] that would have been taken out.
Because the Generals were no longer onboard the Casa, there was no reason for it to get airborne. And for this reason it was the Yak[-40] that flew off to Smolensk. This Casa [transport aircraft] was never examined in any way. It was not subject to any examination. Aside from a single note in the deposition given to the military, no one was interested why this aircraft didn't fly [to Smolensk]. Perhaps, this is someones crazy phantasy, but perhaps it isn't.
Some [Polish] military personnel had suggested, that it [the Casa] had to stay behind at the Okecie military [tarmack], so that the explosives could be removed from it - because they were no longer needed [...] I am only repeating what I was told."
"Disarming" Explosives ...
It is worth for us to retrace the entire process of "disarming" the case of explosive substances at the crash site. It all started with the publication of Cezary Gmyz in "Rzeczpospolita" on October 30, 2012, and information that the detectors, which were used by experts in Smolensk (in late September and October) showed traces of TNT and nitroglycerine.
As it turned out, the journalist was also reporting about the indication of Hexogen. The storm broke. The prosecution denied the publication, and ultimately, the editor-in-chief of "Rzeczpospolita," Cezary Gmyz and two other journalists lost their jobs. The entire editorial staff of one of Poland’s most popular weeklies, "Uważam Rze", was also silenced.
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