Crashworthiness Study of Helicopter Skid Landing Gear System Equipped With a Magnetorheological Energy Absorber

2017 ◽  
Author(s):  
Muftah Saleh ◽  
Ramin Sedaghati ◽  
Rama Bhat
Keyword(s):  
Energy Absorption ◽  
Landing Gear ◽  
Civil Aviation ◽  
Soft Landing ◽  
Damping Force ◽  
Dimensional Solution ◽  
Energy Absorber ◽  
Passive Damper ◽  
Skid Landing Gear ◽  
The Impact

The present study concerns with the performance of a skid landing gear (SLG) system of a rotorcraft impacting the ground at a vertical sink rate of 5.0 m/s. The impact attitude is per chapter 527 of the Airworthiness Manual (AWM) of Transport Canada Civil Aviation and FAR Part 27 of the U.S. Federal Aviation Regulation. A single degree of freedom helicopter model is investigated under two rotor lift factors 0.67 and 1.0. Three Configurations are evaluated: a) A conventional SLG; b) SLG equipped with a passive viscous damper and c) SLG incorporated with a magnetorheological energy absorber. The non-dimensional solutions of the helicopter model show that the passive damper system could reduce the maximum acceleration experienced by the helicopter occupants by 21% and 19.8% in comparison to the undamped system for the above rotor lift factors, respectively. However, the passive damper fails to constrain the non-dimensional energy absorption stroke of the damper within the given 18 cm maximum stroke and a bottoming out of the damper piston was noticed. Therefore, the alternative and successful choice was to employ a magnetorheological energy absorber (MREA). To improve the MREA controllability and to resettle the payload with no oscillations, i.e. in one cycle, two different Bingham numbers for compression stroke and rebound stroke were defined in the non-dimensional solution. Several simulations were conducted for different values of Bingham numbers. Among these numerical simulation results, the solution that implemented the optimum Bingham numbers was found to be the only one feasible solution. In this case the MREA with optimum Bingham number for compression could utilize the full energy absorption stroke to attain soft landing. In the rebound stroke, the generated optimal on-state damping force successfully controls the bounce of the payload until the payload settles down to its original equilibrium position with no oscillations.

scholarly journals A smart passive MR damper with a hybrid powering system for impact mitigation: An experimental study

2021 ◽  
pp. 1045389X2098808
Author(s):  
S. Jin ◽  
L. Deng ◽  
J. Yang ◽  
S. Sun ◽  
D. Ning ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Mr Damper ◽  
Damping Force ◽  
Softening Effect ◽  
Impact Speed ◽  
Impact Mitigation ◽  
Passive Damper ◽  
Comparison Results ◽  
Wide Range ◽  
The Impact

This paper presents a smart passive MR damper with fast-responsive characteristics for impact mitigation. The hybrid powering system of the MR damper, composed of batteries and self-powering component, enables the damping of the MR damper to be negatively proportional to the impact velocity, which is called rate-dependent softening effect. This effect can keep the damping force as the maximum allowable constant force under different impact speed and thus improve the efficiency of the shock energy mitigation. The structure, prototype and working principle of the new MR damper are presented firstly. Then a vibration platform was used to characterize the dynamic property and the self-powering capability of the new MR damper. The impact mitigation performance of the new MR damper was evaluated using a drop hammer and compared with a passive damper. The comparison results demonstrate that the damping force generated by the new MR damper can be constant over a large range of impact velocity while the passive damper cannot. The special characteristics of the new MR damper can improve its energy dissipation efficiency over a wide range of impact speed and keep occupants and mechanical structures safe.

scholarly journals Robust Adaptive Control for an Aircraft Landing Gear Equipped with a Magnetorheological Damper

2020 ◽  
Vol 10 (4) ◽  
pp. 1459 ◽  
Author(s):  
Quoc Viet Luong ◽  
Dae-Sung Jang ◽  
Jai-Hyuk Hwang
Keyword(s):  
Hybrid Control ◽  
Sliding Mode ◽  
Landing Gear ◽  
Robust Adaptive Control ◽  
Magnetorheological Damper ◽  
Parametric Uncertainties ◽  
Active System ◽  
Damping Force ◽  
Passive Damper ◽  
Robust Adaptive

A landing gear of an aircraft is required to function at touchdown in different landing scenarios with parametric uncertainties. A typical passive damper in a landing gear has limited performance in differing landing scenarios, which can be overcome with magnetorheological (MR) dampers. An MR damper is a semi-active system that can adjust damping force by changing the amount of electric current applied to it. This paper proposes a new robust controller based on model reference sliding mode control and adaptive hybrid control to improve the efficiency of absorbing landing impact energy, not only considering the variables of aircraft weight and sink speed but also managing uncertainties, such as ambient temperature and passive damping coefficient. To verify the effectiveness of the proposed controller, comparative numerical simulations were performed with a passive damper, a skyhook controller, and the proposed controller under various landing scenarios. The simulation results show that the proposed controller improves the total energy absorber efficiency by up to 10% higher than that of the skyhook controller. In addition, the proposed controller is demonstrated to have better adaptability and robustness than the other control algorithms in the differing landing scenarios and parametric uncertainties.

A Constant Stroking Load Regulator for Shock Absorption

2011 ◽  
Author(s):  
Gang Wang ◽  
Gregory Hiemenz ◽  
Wei Hu ◽  
Norman M. Wereley
Keyword(s):  
Impact Velocity ◽  
Input Parameter ◽  
Control Input ◽  
Soft Landing ◽  
Shock Absorption ◽  
Energy Absorber ◽  
Seat Suspension ◽  
Drop Tests ◽  
Payload Mass ◽  
The Impact

The goal of this study is to provide shock mitigation in an active (or semi-active) shock absorption system, typically comprising of a spring, and an adjustable stroking load element, such as an adaptive energy absorber (EA) or semiactive damper element, in which the stroking load can be electronically adjusted in real-time. Typically, there is a maximum limiting stroking load that can be accommodated by a payload. Thus, a Constant Stroking Load Regulator (CSLR) is developed that accepts sensor feedback, and then selects control gains that result in the energy absorber (EA) providing the required controllable stroking load. A key benefit of this regulator is that it is capable of adapting to a varying range of payload mass, impulse types, and impulse excitation levels. The payload mass is measured and used as a control input parameter. The measured impact velocity is used to determine the impulse acceleration level by assuming an impulse profile, which tends to be application-specific. Finally, the required constant stroking load is determined using a physics-based model. The CSLR is designed to achieve a “soft landing” such the payload comes to rest when the available stroke is used completely, in order to minimize the stroking load and thereby minimize the potential for payload damage. The CSLR methodology was then experimentally validated for a representative occupant protection system consisting of a seat suspension with an adaptive stroking element, which in this case was a magnetorheological energy absorber (MREA). A MREA was used as the stroking element because its stroking load can be adjusted electronically. To validate the CSLR strategy, experimental drop tests were conducted for two different payloads. The impact velocity was 10.3 ft/s (3.15 m/s) and the acceleration profile was a 50 ms duration half-sine pulse. The constant stroking load was pre-calculated as a function of payload mass and initial velocity. During each drop test, the required stroking load was supplied to the MREA in order to achieve a “soft landing.” The CSLR was successfully demonstrated under laboratory conditions. These tests demonstrated feasibility of using the CSLR, in conjunction with a MREA as the stroking element.

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.

A Numerical Model to Study the Effects of Aluminum Foam Filler on the Dynamic Behavior of a Steel Tubular Energy Absorber Using a Multi-Node Displacement Evaluation Procedure

2014 ◽  
Vol 9 (3) ◽  
Author(s):  
Vinícius Veloso ◽  
Pedro Américo Almeida Magalhães ◽  
Janes Landre
Keyword(s):  
Numerical Model ◽  
Dynamic Behavior ◽  
Energy Absorption ◽  
Great Influence ◽  
Constant Load ◽  
Absorption Efficiency ◽  
Evaluation Procedure ◽  
Energy Absorber ◽  
Energy Absorption Efficiency ◽  
The Impact

Tubular energy absorbers are usually found in the structures of cars, trains, and other means of transportation. They can absorb high levels of impact energy by plastic deformation during axial folding. The key advantages of this type of energy absorber are the compact dimensions, simple manufacturing, and good energy absorption efficiency. The dynamic behavior of the tube during collapse has a great influence on the total energy absorbed and, consequently, the force transmitted during folding. The optimization of this process may lead to improved energy absorption efficiency, allowing us to reduce the dimensions and costs of the component or improve the crashworthiness of pre-existing structures. Foam materials are used in most applications to improve the impact absorption of structures due to its constant load pattern during crushing. They are used, in most cases, as fillers inside empty absorbers such as tubes. In this paper, a numerical model was developed in order to study the possible interactions of foam and tube walls, providing information onhow this relation can influence the deformation modes of the tube. The obtained results showed a direct influence of the foam interaction with the tube walls under the energy absorption and load transmitting characteristics of the component.

Crashworthy Landing Gear Design Using a Composite Tube by Extra Energy Absorber

2014 ◽  
Author(s):  
Tae-Uk Kim ◽  
Sung Joon Kim ◽  
Seunggyu Lee
Keyword(s):  
Energy Absorption ◽  
Shock Absorber ◽  
Numerical Solutions ◽  
Landing Gear ◽  
Relief Valve ◽  
Composite Tubes ◽  
Additional Energy ◽  
Energy Absorber ◽  
Composite Tube ◽  
Extra Energy

Landing gear is the one of the key components for improving aircraft crashworthiness because its primary function is the energy absorption. But, in general, the shock absorbers are designed to have best efficiency for normal landing cases and can be ineffective when faced with very high sink speed. Thus special design and implementation are necessary for landing gear to have crashworthiness. For this purpose, various concepts have been studied and put to practical use such as structural pin, pressure relief valve and additional energy absorbing devices, etc. In this paper, the composite tube is investigated as an extra energy absorber and adopted to landing gear to increase shock absorbing performance in case of crash. To do this, first the quasi-static and impact test of composite tubes are conducted and the analysis model is tuned to explain the test results. During the correlation process, the failure modes and the specific energy absorption of the composite tubes are analyzed and the optimal configurations are searched. The overall performance of landing gear including the composite tube is analyzed by developing a simplified dynamic model. Each force-stroke relation of oleo-pneumatic shock absorber, tire and composite tube are modeled as spring and damper, then the equation of motion is solved to obtain the crash responses. In this model, after the bottoming of shock absorber, the crushing of composite tube is activated for additional energy absorption. Numerical solutions show that the enhanced shock absorbing capability in case of crash when the composite tube adopted. For practical use, the landing gear performance should be verified by drop tests and this is author’s future research project.

Optimization Analysis of Maximum Energy Absorption Properties of Metallic Honeycomb and an Application in Designing Arresting Mechanism for Landing Gear Drop Testing

2004 ◽  
Author(s):  
V. Aaron ◽  
A. H. Adibi-Sedeh ◽  
B. Bahr
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Landing Gear ◽  
Regression Equations ◽  
Absorption Properties ◽  
Cell Parameters ◽  
Structural Applications ◽  
Honeycomb Cell ◽  
The Impact ◽  
Absorption Characteristics

Metallic honeycomb possess excellent kinetic energy absorption properties which can be used as an impact resistance members in structural applications. In order to design energy absorption systems in effective manner using honeycomb material, the various parameters affecting the energy absorption characteristics of the honeycomb should be evaluated. Parameters affecting the honeycomb will be evaluated using analytical methods and finite element analysis. Validated finite element models are used to study the parameters namely honeycomb width, mass of impact and dynamic load factor affecting the energy absorption characteristics of metallic honeycomb. Mathematical models are used to study the half wavelength of the buckling of the honeycomb cell and the factors affecting the dynamic crush strength. Sensitivity analysis is performed using response surface methods to determine the performance effect of the honeycomb cell parameters namely cell size, gauge thickness and inner-edge angle affecting the energy absorption properties. Regression equations are obtained to determine the optimized values of the honeycomb parameters. Guidelines will be provided for the designer to select appropriate honeycomb cell parameters for optimized energy absorption properties. As an application, these honeycombs models are used to design the arresting mechanism for landing gear drop tower for absorbing the impact energy and to protect the structural members and load cells in the event failure of the landing gear during the drop testing. On a whole this research will provide an insight of the energy absorption properties of metallic honeycomb affected by various parameters.

scholarly journals Parameters Optimization and Energy Absorption Evaluation of the Steel Ball Friction Energy Absorber

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Bin Gong
Keyword(s):  
Energy Absorption ◽  
Contact Force ◽  
Column Height ◽  
Load Factor ◽  
Column Diameter ◽  
Impact Frequency ◽  
Energy Absorber ◽  
Ball Diameter ◽  
The Impact ◽  
Dynamic Load Factor

The energy absorber is used to simulate the reaction of a working piece subjected to a vibration stimulus, by which the consistent and repeatable reactions to the tool’s vibration inputs could be achieved. According to the proposed coupling simulation model by using commercial software RecurDyn and EDEM, the energy dissipated by the energy absorber and the contact force between the drill rod and the piston are evaluated under different load conditions such as the impact frequency and impact stroke. Moreover, the effects of the ball diameter, ball column height, and diameter on the energy absorption characteristics are also studied. The results show that the impact frequency and stroke influence the energy absorber by changing the impact force; the energy absorption is more obvious under higher impact frequency and long impact stroke. The filling ball diameter influences the energy reflectivity by changing the porosity, which is negatively correlated to the energy reflectivity, and a 6 mm filling ball diameter is suggested. The energy reflectivity is inversely proportional to the ball column height and diameter, and the suggested ball column diameter and height are 160 mm and 600 mm, respectively, with energy reflectivity of 0.045. Even when the increase in impact frequency and stroke will increase the contact force, the dynamic load factor decreases. The contact force and dynamic load factor are inversely proportional to the ball column height, but they are not influenced by the ball diameter and the ball column diameter.

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