Energy Absorption Mechanisms and Crash Analysis of Helicopter Seats

2018 ◽  
Author(s):  
Gülce Özturk ◽  
Altan Kayran
Keyword(s):  
Plastic Deformation ◽  
Energy Absorption ◽  
Strain Curve ◽  
Rigid Wall ◽  
Absorption Mechanism ◽  
Dynamic Simulations ◽  
Explicit Finite Element ◽  
Energy Absorbing ◽  
The Impact ◽  
Aluminum Material

In this paper, a crushable absorber system is designed to analyze the dynamic behavior and performance of a helicopter seat. The mechanism of the absorption system makes use of the crash energy to plastically deform the aluminum material of the seat legs. Seat structure is composed of a bucket, two legs and two sliding parts on each leg. Seat legs are made of aluminum and and the sliding parts of the seat are steel. During the impact event, the heavier sliding parts move down and crash the aluminum material for the purpose of deforming the aluminum material under the sliding parts and reduce the crash energy. The designed helicopter seat is analyzed using the explicit finite element method to evaluate how the seat energy absorbing mechanism works. Dynamic simulations are performed in ABAQUS by crashing the seat to a fixed rigid wall. To simulate the plastic deformation, true stress-strain curve of the aluminum material of the seat leg has been used. Time response results are filtered to calculate the meaningful g loads which incur damage to the occupants. Analyses are performed with and without the energy absorption mechanism in order to see the effectiveness of the energy absorption mechanism on the human survivability by comparing the g loads on the seat bucket with the acceptable loads specified by EASA. This study is a preliminary study intended to check the effectiveness of the damping mechanism based on the plastic deformation of the aluminum legs of the seat in the event of a crash.

Energy Absorption of an Re-Entrant Honeycombs with Negative Poisson’s Ratio

2011 ◽  
Vol 148-149 ◽  
pp. 992-995 ◽  
Author(s):  
Shu Yang ◽  
Chang Qi ◽  
Dong Ming Guo ◽  
Dong Wang
Keyword(s):  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Structural Response ◽  
Rigid Wall ◽  
Geometrical Model ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Explicit Finite Element ◽  
Good Ability ◽  
Negative Poisson's Ratio

In the present paper, we have investigated a negative Poisson’s ratio structure with regular re-entrant cell shape to study its structural response under crush by rigid wall. Firstly, we created the geometry of cellular material in HYPERMESH. The developed geometrical model is imported into LS-DYNA. Then we use commercially available nonlinear explicit finite element code LS-DYNA to simulate the NPR material under uniformly distributed load. The deformation modes and energy absorption characteristics of NPR material were analyzed. Numerical results indicate that this NPR material have good ability of energy absorption.

A multiscale approach for modelling impact on woven composites under consideration of the fabric topology

2018 ◽  
Vol 52 (21) ◽  
pp. 2859-2874 ◽  
Author(s):  
Martin Schwab ◽  
Melanie Todt ◽  
Heinz E Pettermann
Keyword(s):  
Total Energy ◽  
Energy Absorption ◽  
Temporal Distribution ◽  
Woven Composites ◽  
Multiscale Approach ◽  
Stress Concentrations ◽  
Damage Mechanisms ◽  
Explicit Finite Element ◽  
Impact Behaviour ◽  
The Impact

A computationally efficient multiscale modelling approach for predicting impact damage within fabric reinforced laminated composites is presented. In contrast to common ply-level approaches, the topology of a multi-layered fabric reinforced laminate is resolved at tow-level for a sub-domain embedded in a shell layer with homogenised representation of the laminate. The detailed sub-domain is entirely modelled using shell elements, where material nonlinearities such as damage and plasticity-like behaviour of the tows, inelastic behaviour of unreinforced resin zones up to failure and delamination between plies are accounted for. To exemplify the capabilities of the approach, an explicit finite element simulation of a laminated plate consisting of eight carbon fabric reinforced epoxy plies with eight harness satin weaving style in a drop weight impact test setup is conducted. The spatial and temporal distribution of intra- and inter-ply damage is predicted and the total energy absorption by the plate, as well as the contributions of individual damage mechanisms are evaluated. The predictions show very good agreement with corresponding experimental data from the literature and give insight into the impact behaviour of the laminate beyond the capability of usual experiments. The new approach allows to resolve the stress concentrations due to fabric topology in detail. Compared to common ply-level approaches this is reflected in different predicted energy absorptions per mechanism although, the total energy absorption hardly differs. This is especially important when the post impact behaviour of laminates is predicted as it is strongly influenced by the extent of the individual damage mechanisms.

Numerical and Experimental Investigation on the Energy Absorption Capability of a Full-Scale Composite Fuselage Section

2019 ◽  
Vol 827 ◽  
pp. 19-24 ◽  
Author(s):  
Donato Perfetto ◽  
Giuseppe Lamanna ◽  
M. Manzo ◽  
A. Chiariello ◽  
F. di Caprio ◽  
...  
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Load Condition ◽  
Element Model ◽  
Full Scale ◽  
Research Centre ◽  
Fe Method ◽  
Explicit Finite Element ◽  
Crashworthiness Design ◽  
The Impact

In the case of catastrophic events, such as an emergency landing, the fuselage structure is demanded to absorb most of the impact energy preserving, at the same time, a survivable space for the passengers. Moreover, the increasing trend of using composites in the aerospace field is pushing the investigation on the passive safety capabilities of such structures in order to get compliance with regulations and crashworthiness requirements. This paper deals with the development of a numerical model, based on the explicit finite element (FE) method, aimed to investigate the energy absorption capability of a full-scale 95% composite made fuselage section of a civil aircraft. A vertical drop test, performed at the Italian Aerospace Research Centre (CIRA), carried out from a height of 14 feet so to achieve a ground contact velocity of 30 feet/s in according to the FAR/CS 25, has been used to assess the prediction capabilities of the developed FE method, allowing verifying the response under dynamic load condition and the energy absorption capabilities of the designed structure. An established finite element model could be used to define the reliable crashworthiness design strategy to improve the survival chance of the passengers in events such as the investigated one.

Dynamic Energy Absorption Performances of Rain Forest Vehicle (RFV) under Frontal Impact

2014 ◽  
Vol 67 (3) ◽  
Author(s):  
M. S. Othman ◽  
Z. Ahmad
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Loading ◽  
Rain Forest ◽  
Experimental Testing ◽  
Rigid Wall ◽  
Crash Analysis ◽  
Frontal Impact ◽  
Frontal Section ◽  
The Impact

This paper treats the crash analysis and energy absorption response of Rain Forest Vehicle (RFV) subjected to frontal impact scenario namely impacting rigid wall and column. Dynamic computer simulation techniques validated by experimental testing are used to carry out a crash analysis of such vehicle. The study aims at quantifying the energy absorption capability of frontal section of RFV under impact loading, for variations in the load transfer paths and geometry of the crashworthy components. It is evident that the proposed design of the RFV frontal section are desirable as primary impact energy mitigation due to its ability to withstand and absorb impact loads effectively. Furthermore, it is found that the impact energy transmitted to the survival room may feasibly be minimized in these two impact events. The primary outcome of this study is design recommendation for enhancing the level of safety of the off-road vehicle where impact loading is expected.   

Dynamic Energy Absorption Performances of Rain Forest Vehicle (RFV) under Frontal Impact

2014 ◽  
Vol 69 (3) ◽  
Author(s):  
M. S. Othman ◽  
Z. Ahmad
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Loading ◽  
Rain Forest ◽  
Experimental Testing ◽  
Rigid Wall ◽  
Crash Analysis ◽  
Frontal Impact ◽  
Frontal Section ◽  
The Impact

This paper treats the crash analysis and energy absorption response of Rain Forest Vehicle (RFV) subjected to frontal impact scenario namely impacting rigid wall and column. Dynamic computer simulation techniques validated by experimental testing are used to carry out a crash analysis of such vehicle. The study aims at quantifying the energy absorption capability of frontal section of RFV under impact loading, for variations in the load transfer paths and geometry of the crashworthy components. It is evident that the proposed design of the RFV frontal section are desirable as primary impact energy mitigation due to its ability to withstand and absorb impact loads effectively. Furthermore, it is found that the impact energy transmitted to the survival room may feasibly be minimized in these two impact events. The primary outcome of this study is design recommendation for enhancing the level of safety of the off-road vehicle where impact loading is expected.   

FINITE ELEMENT ANALYSIS OF HONEYCOMB IMPACT ATTENUATOR

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1417-1422
Author(s):  
SEUNG-YONG YANG ◽  
SEUNG-KYU CHOI ◽  
NOHYU KIM
Keyword(s):  
Finite Element ◽  
Rigid Wall ◽  
Honeycomb Structure ◽  
Student Group ◽  
Safety Requirement ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
University Of Technology ◽  
Deformation Behaviors ◽  
The Impact

To participate in Student Formula Society of Automotive Engineers (SAE) competitions, it is necessary to build an impact attenuator that would give an average deceleration not to exceed 20g when it runs into a rigid wall. Students can use numerical simulations or experimental test data to show that their car satisfies this safety requirement. A student group to study formula cars at the Korea University of Technology and Education has designed a vehicle to take part in a SAE competition, and a honeycomb structure was adopted as the impact attenuator. In this paper, finite element calculations were carried out to investigate the dynamic behavior of the honeycomb attenuator. Deceleration and deformation behaviors were studied. Effect of the yield strength was checked by comparing the numerical results. ABAQUS/Explicit finite element code was used.

Study on Ballistic Energy Absorption of Laminated and Sandwich Composites

2006 ◽  
Vol 306-308 ◽  
pp. 739-744 ◽  
Author(s):  
Xiao Dong Cui ◽  
Tao Zeng ◽  
Dai Ning Fang
Keyword(s):  
Energy Absorption ◽  
Impact Response ◽  
Sandwich Composite ◽  
Sandwich Composites ◽  
Ballistic Resistance ◽  
Honeycomb Sandwich ◽  
Honeycomb Sandwich Composite ◽  
Improved Model ◽  
Energy Absorbing ◽  
The Impact

The impact response and energy absorbing characteristics of laminated, foam sandwich and honeycomb sandwich composites under ballistic impact have been studied in this investigation. An improved model is proposed in this paper to predict the ballistic property of the laminated composites. In this model, the material structures related to fiber lamination angles are designed in terms of their anti-impacting energy absorption capability. The ballistic limit speed and energy absorption per unit thickness of the three composites under different conditions are calculated. It is shown that honeycomb sandwich composite has the best ballistic resistance capability and energy absorption property among the three composites.

Experimental analysis on the axial crushing and energy absorption characteristics of novel hybrid aluminium/composite-capped cylindrical tubular structures

2019 ◽  
Vol 233 (11) ◽  
pp. 2234-2252 ◽  
Author(s):  
A Praveen Kumar
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Cylindrical Tube ◽  
Tubular Structures ◽  
Aluminium Composite ◽  
Specific Energy Absorption ◽  
Cylindrical Tubes ◽  
Impact Crushing ◽  
Energy Absorbing ◽  
The Impact

In recent years, aluminium-composite hybrid tubular structures, which combine the stable and progressive plastic deformation of the aluminium metal with light-weight composite materials, are obtaining increased consideration for meeting the advanced needs of crashworthiness characteristics. This research article presents the experimental outcomes of novel aluminium/composite-capped cylindrical tubes subjected to quasi-static and impact axial loads. The influence of various capped geometries in the aluminium segment and three different fabrics of the composite segment in the cylindrical tube are investigated experimentally. The outcomes of the impact crushing test are also correlated with the quasi-static results of the proposed aluminium/composite-capped cylindrical tubes. The overall outcomes revealed that the crashworthiness characteristics of crushing force consistency and specific energy absorption of the aluminium-composite hybrid tubes are superior to those of the bare aluminium tubes. When the glass fabric/epoxy composite is wrapped to aluminium cylindrical tubes, the specific energy absorption increases about 23–30%, and the wrapping of hybrid glass/kenaf fabrics increases the specific energy absorption of almost 40–52%. Such a hybrid tubular structures would be of huge prospective to be used as effective energy-absorbing devices in aerospace and automotive applications. A further benefit of the composite-wrapping approach is that the composite might be retro-fitted to aluminium tubes, and the energy absorption capability is shown to be significantly enhanced by such utilization.

scholarly journals A Study of Multi-Objective Crashworthiness Optimization of the Thin-Walled Composite Tube under Axial Load

Vehicles ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 438-452
Author(s):  
Mohammad Reza Seyedi ◽  
Abolfazl Khalkhali
Keyword(s):  
Failure Mechanism ◽  
Energy Absorption ◽  
Failure Modes ◽  
Matrix Material ◽  
Load Condition ◽  
Fe Model ◽  
Absorption Mechanism ◽  
Multi Objective ◽  
Thin Walled ◽  
The Impact

In recent decades, thin-walled composite components have been widely used in the automotive industry due to their high specific energy absorption. A large number of experimental and numerical studies have been conducted to characterize the energy absorption mechanism and failure criteria for different composite tubes. Their results indicate that the energy absorption characteristics depend highly on the failure modes that occur during the impact. And failure mechanism is dependent on fiber material, matrix material, fiber angle, the layout of the fibers, as well as the geometry of structure and load condition. In this paper, first, the finite element (FE) model of the CFRP tube was developed using the Tsai-Wu failure criterion to model the crush characteristics. The FE results were validated using the published experimental. Then, a series of FE simulations were conducted considering different fiber directions and the number of layers to generate enough data for constructing the GMDH-type neural network. The polynomial expression of the three outputs (energy absorption, maximum force, and critical buckling force) was extracted using the GMDH algorithm and was used to perform the Pareto-based multi-objective optimizations. Finally, the failure mechanism of the optimum design point was simulated in LS-DYNA. The main contribution of this study was to successfully model the CFRP tube and damage mechanism using appropriate material constitutive model’s parameters and present the multi-objective method to find the optimum crashworthy design of the CFRP tube.

Influence of the Cross Section Shape on Energy Absorbing Component of Bumper Subjected to Low Speed Crash

2013 ◽  
Vol 477-478 ◽  
pp. 3-6
Author(s):  
Yan Jie Liu ◽  
Lin Ding
Keyword(s):  
Energy Absorption ◽  
Cross Section ◽  
Peak Load ◽  
Low Velocity Impact ◽  
Fe Model ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross ◽  
Energy Absorbing ◽  
The Impact

Energy absorbing component of bumper equipped at the front end of a car, is one of the most important automotive parts for crash energy absorption. It usually was made a mental thin walled tube. In the paper, automobile energy absorbing component at low-velocity impact was studied by using Finite Element Method. The FE model of the tube was builded by comparing the five cross section shape . Results show that the impact peak load and maximum energy absorption have certain effect to energy-absorbing component with different the cross section shape.

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