Crash Energy Management of Rotorcraft Seat Based on Limit Load Curves and Corresponding Occupant Pelvic Load

2012 ◽  
Author(s):  
Rasoul Moradi ◽  
Tony Bromwell ◽  
Rohit Jategaonkar ◽  
Hamid M. Lankarani
Keyword(s):  
Impact Energy ◽  
Limit Load ◽  
Spine Injury ◽  
Military Aircraft ◽  
Two Stage ◽  
Energy Absorber ◽  
Load Limit ◽  
Effective Manner ◽  
Energy Absorbing ◽  
The Impact

In military aircraft and helicopter seat design, the seat system must be provided with an energy absorber (EA) to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between the seat stroke and the impact energy absorption. The available stroke must be used to prevent bottoming out of the seat, and also to absorb as much impact energy as possible to protect the occupant. In this study, the energy absorbing systems in civil and military aircraft seat design are evaluated and improved using a mathematical model of the occupant/seat system. Three load-limit design curves, namely, simple EA, two-stage EA, and two-stage EA with initial spike, are modeled, examined, and compared. A model of the load limiter is recommended to minimize the load sustained by the occupant by limiting the relative velocity between the seat pan and the occupant pelvis. Experimental responses of seat system and occupant from literature are utilized to validate the results from this study for civil and military helicopters. A modified energy-absorber/load-limiter is then implemented for the seat structure so that it absorbs the impact energy in an effective manner below the tolerable limit for the occupant and within a minimum stroke. Results from this study indicate that for a designed stroke, the occupant pelvic/lumbar spine injury level is significantly attenuated using the modified energy-absorber system.

scholarly journals Lumbar load attenuation for rotorcraft occupants using a design methodology for the seat impact energy-absorbing system

2012 ◽  
Vol 2 (4) ◽  
Author(s):  
Rasoul Moradi ◽  
Hamid Beheshti ◽  
Hamid Lankarani
Keyword(s):  
Impact Energy ◽  
Vertical Motion ◽  
Spine Injury ◽  
Energy Absorber ◽  
Effective Manner ◽  
Vertical Accelerations ◽  
Safety Considerations ◽  
Energy Absorbing ◽  
The Impact ◽  
Lumbar Load

AbstractAircraft occupant crash-safety considerations require a minimum cushion thickness to limit the relative vertical motion of the seat-pelvis during high vertical impact loadings in crash landings or accidents. In military aircraft and helicopter seat design, due to the potential for high vertical accelerations in crash scenarios, the seat system must be provided with an energy absorber to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between minimizing the stroke and maximizing the energy absorption. The available stroke must be used to prevent bottoming out of the seat as well as to absorb maximum impact energy to protect the occupant. In this study, the energy-absorbing system in a rotorcraft seat design is investigated using a mathematical model of the occupant/seat system. Impact theories between interconnected bodies in multibody mechanical systems are utilized to study the impact between the seat pan and the occupant. Experimental responses of the seat system and the occupant are utilized to validate the results from this study for civil and military helicopters according to FAR 23 and 25 and MIL-S-58095 requirements. A model for the load limiter is proposed to minimize the lumbar load for the occupant by minimizing the relative velocity between the seat pan and the occupant’s pelvis. The modified energy absorber/load limiter is then implemented for the seat structure so that it absorbs the energy of impact in an effective manner and below the tolerable limit for the occupant in a minimum stroke. Results show that for a designed stroke, the level of occupant lumbar spine injury would be significantly attenuated using this modified energy-absorber system.

Modeling and analysis of impact energy absorber by using ls dyna

2015 ◽  
Vol 12 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Adik Yadao ◽  
R. S. Hingole
Keyword(s):  
Impact Energy ◽  
Material Properties ◽  
Research Work ◽  
Cad Model ◽  
Post Processing ◽  
Passenger Compartment ◽  
Efficient Manner ◽  
Energy Absorber ◽  
Modeling And Analysis ◽  
Energy Absorbing

Today’s car is one of the most important things in everyone’s life .Every person wants to have his or her own car but the question that arises in each buyer’s mind is whether the vehicle is safe enough to spend so much of money so it is the responsibility of an mechanical engineer to make the vehical comfortable and at the Same time safer. Now a days automakers are coming with various energy absorbing devices such as crush box, door beams etc. this energy absorbing device s prove to be very useful in reducing the amount force that is being transmitted to the occupant. In this we are using impact energy absorber in efficient manner as compare to earlier. The various steps involved in this project starting from developing the cad model of this inner impact energy absorber using the CAD software CATIA V5 R19. Then pre-processing is carried out in HYPERMESH 11.0 which includes assigning material, properties, boundary conditions such as contacts, constraints etc. LS-DYNA971 is used as a solver and LS-POST is used for the post processing and results obtained are compared to the standards. By carrying out this idea it has been observed that there is a considerable amount of energy that is being absorbed by this energy-absorbing device. Along with this energy absorption, the intrusion in passenger compartment is also reduced by considerable amount. So for safer and comfortable car with inner impact energy absorber is one of the best options available. This will get implement by this research work.

scholarly journals The effects of gravel cushion particle size and thickness on the coefficient of restitution in rockfall impacts

2018 ◽  
Vol 18 (6) ◽  
pp. 1811-1823 ◽  
Author(s):  
Chun Zhu ◽  
Dongsheng Wang ◽  
Xing Xia ◽  
Zhigang Tao ◽  
Manchao He ◽  
...  
Keyword(s):  
Particle Size ◽  
Impact Energy ◽  
Coefficient Of Restitution ◽  
Open Pit ◽  
Test Results ◽  
Drop Tests ◽  
Damage Depth ◽  
The Stability ◽  
Energy Absorbing ◽  
The Impact

Abstract. Gravel cushions are widely used to absorb the impact energy of falling rocks in open-pit mines. A particularly important application is to enhance the energy-absorbing capacity of rockfall sheds. In this paper, we study how varying the thickness and particle size of a gravel cushion influences its energy-consumption and buffering effects. We performed a series of laboratory drop tests by dropping blocks from a fixed height onto cushions of different thicknesses and particle sizes. The results indicate that, for a given impact energy, the cushion thickness has a strong influence on the measured coefficient of restitution (COR) and therefore impact pressure. Additional tests were performed to study how the radius of the block and the height it is dropped from affect the measured COR. This showed that as the movement height of the block is increased the COR also increases, and blocks with larger radii exhibit a larger variability in measured COR. Finally, we investigated the influence of rockfall block radius, r, movement height, H, cushion thickness, h, and particle size, d, on the COR and the damage depth, L, of the cushion. The test results reveal that the cushion thickness is the primary design parameter, controlling not only COR, but also the stability of the cushion material. The results provide a theoretical and practical basis for the design of gravel cushions for rockfall protection.

scholarly journals Crashworthiness Characteristics of Multi-Cell Tubular Structures Subjected to Axial Impact

2019 ◽  
Vol 8 (4) ◽  
pp. 3911-3915 ◽  
Keyword(s):  
Impact Energy ◽  
Deformation Behaviour ◽  
Initial Period ◽  
Geometrical Parameters ◽  
Tubular Structures ◽  
Axial Impact ◽  
Thin Walled ◽  
Energy Absorbing ◽  
Impact Simulations ◽  
The Impact

To mitigate the impact forces in crash events, thin-walled tubular elements are employed as an energy absorbing attenuators in frontal part of the automotive vehicles. To develop more progressive deformation modes, at the initial period, and to absorb more impact energy at the final period of crash, it is significant to enhance the crashworthiness performance of the tube by modifying its geometrical parameters. Multi-cell tubular structures have recognized to own superior impact energy absorbing ability and lightweight effect in the modern automotive vehicles. This research article examines the deformation behaviour of thin walled aluminum alloy multi-cell tube with different stiffeners exposed to axial impact loading using numerical simulation. Nonlinear impact simulations were performed on multi-cell tubes using finite element ABAQUS/CAE explicit code. From the overall results obtained, the deformation behaviour of multi-cell tubes was compared. Furthermore, hexagonal tubes with stiffeners were retained as most prominent for better energy dissipation. This type of tube was found to be most efficient type to enhance the crashworthiness performance during axial impact.

Numerical and Experimental Study on Railway Impact Energy Absorption Using Tube External Inversion Mechanism at Real Scale

2006 ◽  
Vol 306-308 ◽  
pp. 315-320 ◽  
Author(s):  
Ign Wiratmaja Puja ◽  
A. Khairullah ◽  
Muhammad Agus Kariem ◽  
A.H. Saputro
Keyword(s):  
Experimental Study ◽  
Numerical Analysis ◽  
Energy Absorption ◽  
Contact Force ◽  
Impact Energy ◽  
Experimental Result ◽  
Energy Absorber ◽  
The Impact ◽  
Inversion Mechanism ◽  
Real Scale

Impact energy and deceleration at a certain time are the most influenced factor to passenger’s safety when collision between railway vehicles occurred. In this paper, forced external inversion mechanism is considered as impact energy absorber. This mechanism is selected due to its constant inversion load along uniform tube [5] and the impact force is reduced because of its inertia effect [7]. Material used as energy absorber is mild steel. Numerical analysis using finite element method is utilized to study the energy absorption capacity and deceleration characteristic of tube external inversion mechanism for complex transient problem of collision. The real scale experimental study is used to validate the numerical analysis by crashing a moving vehicle to static train series where the impact energy absorber module using external inversion mechanism is attached in the tip of static train series. Characteristic that consider in numerical and experimental study are deformation and contact force. The deformation differences between numerical and experimental study are under 9%. Whereas for contact force, the experimental result of contact force disposed under 8% of numerical result for velocity of moving train at 10 and 15 km/h.

scholarly journals Study on Mechanical Characteristics of Energy-Absorbing and Anti-Scour Bolts

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhi Tang ◽  
Hao Wu ◽  
Jinguo Lv ◽  
Zhuangzhuang Xin ◽  
Wenbo Zuo
Keyword(s):  
Impact Energy ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Energy Criterion ◽  
Energy Balance Equation ◽  
Surrounding Rock ◽  
Support Design ◽  
The Stability ◽  
Energy Absorbing ◽  
The Impact

In order to improve the impact resistance and mechanical performance of anchor rods and satisfy the requirements for supporting rockburst roadways, the energy balance equation of the energy-absorbing support and roadway surrounding rock system is established. Moreover, to effectively prevent rockburst disasters, the energy criterion for roadway instability is derived. From the perspective of an energy-absorbing support, a yield-absorbing anti-shock anchor composed of a rod body, tray, constant resistance energy-absorbing device, and special-shaped nut is designed and developed; compared with ordinary anchor rods, this rod has stronger mechanical properties for resisting impact. Theoretical and numerical simulation studies show that the energy-absorbing device has a repeatable deformation failure mode and a constant yield force. The paper also presents the principle involved in the design of anti-shock bolt supports. The energy-absorbing support not only effectively guides and controls the release and conversion of impact energy but also consumes the impact energy in the buffering process of the anchor to ensure the stability of surrounding rock and support protection system. This study aims to provide reference for roadway support design and to improve rock bolts used in rockburst roadways.

scholarly journals Impact Loads on the Occupant under the Protection of an Inversion Tube Energy Absorber during a Helicopter Crash

2018 ◽  
Vol 167 ◽  
pp. 03009
Author(s):  
Yunhua Luo ◽  
Mengqi Wang ◽  
Tao Yan ◽  
Lingjie Wang
Keyword(s):  
Numerical Simulation ◽  
Vertical Direction ◽  
Impact Loads ◽  
Vertical Acceleration ◽  
Energy Absorber ◽  
Occupant Protection ◽  
Occupant Injury ◽  
Energy Absorbing ◽  
The Impact ◽  
Head Neck

The objective of this paper is to investigate the impact loads on the occupants’ head, neck, and spine under the protection of an inversion tube energy absorber during a helicopter crash landing. Due to the high vertical acceleration, the head, neck and spine are the most vulnerable parts of a body, so that an energy absorber is needed to dissipate the kinetic energy of the occupant and the seat to minimize the impact loads. In this paper, an inversion tube was adopted as an energy-absorbing device. The occupant injury conditions were evaluated by a numerical simulation. The result indicates that the impact loads on occupant’s head, neck and spine are below the regulated thresholds under the protection of the energy absorber when the helicopter crash at a speed of 12.81m/s in vertical direction. As a consequence, the design of the occupant protection system has been proven reliable.

Novel Design of Impact Attenuator for an 'Eco Challenge' Car

2012 ◽  
Vol 165 ◽  
pp. 237-241 ◽  
Author(s):  
Amir Radzi Ab Ghani ◽  
Ramlan Kasiran ◽  
Mohd Shahriman Adenan ◽  
Mohd Haniff Mat ◽  
Rizal Effendy Mohd Nasir ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
High Energy ◽  
Absorption Capacity ◽  
Flat Plates ◽  
Final Design ◽  
High Energy Absorption ◽  
Energy Absorbing ◽  
Long Stroke ◽  
The Impact

Thin-walled metallic tubular structures are generally used as impact energy absorber in automotive structures due to their ease of fabrication and installation, high energy absorption capacity and long stroke. However, unlike a normal passenger car where the impact energy can be distributed throughout the whole structure, the impact energy absorbing system of an Eco-Challenge car is confined within a limited space on the front bulkhead. The challenge is to develop an impact attenuator system that can effectively absorb the impact energy within the given space and fulfil the specified rate of deceleration. This new design utilized the standard Aluminium 6063 circular tubes, cut and welded into specific configurations i.e. stacked toroidal tubes with central axial tube sandwiched between two flat plates. Two configurations were investigated; circular and square toroids. Explicit non-linear FEA software was used to determine the impact response i.e. energy absorption, impact force and rate of deceleration. Both configurations showed promising results but the configuration that can be readily fabricated was chosen as the final design.

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