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Development of Advanced Numerical Tools for Aircraft Crash Analysis.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Development of Advanced Numerical Tools for Aircraft Crash Analysis./
Author:	Ding, Menglong.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
Description:	177 p.
Notes:	Source: Dissertations Abstracts International, Volume: 82-05, Section: B.
Contained By:	Dissertations Abstracts International82-05B.
Subject:	Aerospace engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28186555
ISBN:	9798678159380

Development of Advanced Numerical Tools for Aircraft Crash Analysis.
Ding, Menglong.

Development of Advanced Numerical Tools for Aircraft Crash Analysis. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 177 p.

Source: Dissertations Abstracts International, Volume: 82-05, Section: B.

Thesis (Ph.D.)--The University of Akron, 2020.

This item must not be sold to any third party vendors.

The study aims to explore advanced tools for air crash analysis with universal meaning in air-crash analysis and uses the crash of Tu-154M large transport airplane in Smolensk, Russia on April 10, 2010, as an example. The crash was initiated by the impact of the left wing into a large birch tree according to the Russian investigation report. Nevertheless, some facts caused the attention and suspicion to this explanation. The research is devoted to investigate how far the wing has to be damaged for the airplane to lose balance, how a pilot can compensate the degraded aerodynamic performance of the aircraft, how to reconstruct the trajectory of a fall of major debris separated from the airplane in the air are critical in the air-crash analysis, what the most possible mechanism of airplane door is to end up one meter deep and perpendicular berried in the ground, and what the most possible outcome of the airplane wing impact into the birch tree. First of all, the aircraft in landing configuration with various wingtip damage on the left wing was under consideration while the no-damaged case was also studied as the baseline. Wind tunnel test results with a 1:100 scale model were correlated using CFD simulations. The variations of lift force, drag force, and asymmetric rolling moment with respect to the angle of attack and sideslip were investigated for different damage situations. The methods to compensate for the lift force and the asymmetric rolling moment were also investigated for the possibility of a safe landing.Secondly, estimating the trajectory of separated objects after disintegration caused by the impact will be useful in crashes analysis of airplane, especially in the circumstance when the impact condition cannot be determined. Since the motion of an airplane’s fragments in the air is highly affected by the aerodynamic loads, computational fluid dynamics with an automated unstructured tetrahedral mesh approach using spring-based smoothing and remeshing are employed. Three-dimensional compressible Navier-Stokes equations and six-degree of freedom (6-DOF) rigid body motion equations are solved by Euler solver coupled with the 6-DOF time integration module. Numerical simulations are performed under various initial conditions. The trajectory of the store structure results is validated with published data and found to be in good agreement. Thirdly, A study was undertaken to establish, demonstrate, and apply a methodology for the dynamic characterization and implementation of a material model for birch wood for the nonlinear explicit finite element (FE) code, LS-DYNA. Several static and impact tests were conducted, and the results were correlated with FE simulation results. The patterns of damage induced during the impact process as well as the energy dissipation were also analyzed. A robust numerical material model that incorporates the strain rate effect for the green birch tree was developed and validated. Good agreement was demonstrated between the simulation results and the experimental results over a wide range of impact velocities and specimen diameters, showing that it is possible to predict the damage and energy dissipation under various impact velocities. The new material model can be utilized for the prediction of impact results for crashworthiness analysis and/or accident reconstruction for collisions involving birch trees, and the methodology described in this study can be used to develop material models for the wood of other tree species.In addition, 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 the 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.Finally, assessment of the crashworthiness of the aircraft structure like the wing is important. Nowadays the finite element (FE) analysis is widely used in this area. Also, the numerical simulation can aid air crash investigation to exclude some unreasonable reasons. In this work, finite element models of the wing and slat structures are generated including skin, spars, stringers, and ribs. In every scenario with various fidelity of the mesh of the wing, material model of the birch, and the impact location, the front 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. The damage to the wing is localized on the leading edge and front spar while the structural integrality of the wing is maintained. The impact with the birch tree cannot cause significant damage to the wing.

ISBN: 9798678159380Subjects--Topical Terms:

686400
Aerospace engineering.
Subjects--Index Terms:

Aircraft crash analysis

Development of Advanced Numerical Tools for Aircraft Crash Analysis.
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506 $a This item must not be sold to any third party vendors.
520 $a The study aims to explore advanced tools for air crash analysis with universal meaning in air-crash analysis and uses the crash of Tu-154M large transport airplane in Smolensk, Russia on April 10, 2010, as an example. The crash was initiated by the impact of the left wing into a large birch tree according to the Russian investigation report. Nevertheless, some facts caused the attention and suspicion to this explanation. The research is devoted to investigate how far the wing has to be damaged for the airplane to lose balance, how a pilot can compensate the degraded aerodynamic performance of the aircraft, how to reconstruct the trajectory of a fall of major debris separated from the airplane in the air are critical in the air-crash analysis, what the most possible mechanism of airplane door is to end up one meter deep and perpendicular berried in the ground, and what the most possible outcome of the airplane wing impact into the birch tree. First of all, the aircraft in landing configuration with various wingtip damage on the left wing was under consideration while the no-damaged case was also studied as the baseline. Wind tunnel test results with a 1:100 scale model were correlated using CFD simulations. The variations of lift force, drag force, and asymmetric rolling moment with respect to the angle of attack and sideslip were investigated for different damage situations. The methods to compensate for the lift force and the asymmetric rolling moment were also investigated for the possibility of a safe landing.Secondly, estimating the trajectory of separated objects after disintegration caused by the impact will be useful in crashes analysis of airplane, especially in the circumstance when the impact condition cannot be determined. Since the motion of an airplane’s fragments in the air is highly affected by the aerodynamic loads, computational fluid dynamics with an automated unstructured tetrahedral mesh approach using spring-based smoothing and remeshing are employed. Three-dimensional compressible Navier-Stokes equations and six-degree of freedom (6-DOF) rigid body motion equations are solved by Euler solver coupled with the 6-DOF time integration module. Numerical simulations are performed under various initial conditions. The trajectory of the store structure results is validated with published data and found to be in good agreement. Thirdly, A study was undertaken to establish, demonstrate, and apply a methodology for the dynamic characterization and implementation of a material model for birch wood for the nonlinear explicit finite element (FE) code, LS-DYNA. Several static and impact tests were conducted, and the results were correlated with FE simulation results. The patterns of damage induced during the impact process as well as the energy dissipation were also analyzed. A robust numerical material model that incorporates the strain rate effect for the green birch tree was developed and validated. Good agreement was demonstrated between the simulation results and the experimental results over a wide range of impact velocities and specimen diameters, showing that it is possible to predict the damage and energy dissipation under various impact velocities. The new material model can be utilized for the prediction of impact results for crashworthiness analysis and/or accident reconstruction for collisions involving birch trees, and the methodology described in this study can be used to develop material models for the wood of other tree species.In addition, 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 the 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.Finally, assessment of the crashworthiness of the aircraft structure like the wing is important. Nowadays the finite element (FE) analysis is widely used in this area. Also, the numerical simulation can aid air crash investigation to exclude some unreasonable reasons. In this work, finite element models of the wing and slat structures are generated including skin, spars, stringers, and ribs. In every scenario with various fidelity of the mesh of the wing, material model of the birch, and the impact location, the front 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. The damage to the wing is localized on the leading edge and front spar while the structural integrality of the wing is maintained. The impact with the birch tree cannot cause significant damage to the wing.
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