Numerical approach to a reverse problem using LS-DYNA3D analysis: collision of an airplane door with the ground
Menglong Ding and Wieslaw K. Binienda, Department of Civil Engineering, The University of Akron, Akron, OH, USA
Published: March 30, 2022
ABSTRACT
Nonlinear finite element analysis (FEA) with LS-DYNA3D is used to determine the initial conditions needed for aircraft components to become damaged as observed after impact with the ground. Determining initial conditions of aircraft or components—impact velocity, orientation with respect to the ground before impact, and average soil properties—could reproduce the damage observed at the final state and reveal the condition of the structures immediately prior to collision with the ground. Predictive methods using FEA require detailed reverse engineering modeling of components, highly accurate material model characteristics and multiple numerical simulations for unknown parameters in order to identify average soil properties and initial conditions of components such that the numerically generated final results will agree with the condition observed following impact. A case study is presented in which various scenarios are considered for the impact of the door of a large passenger aircraft with soil at the crash site.
ARTICLE HISTORY
Received 26 June 2018 Accepted 12 November 2018
KEYWORDS
Impact; airplane; damage; reverse engineering; numerical simulation; inverse problem
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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