An emphasis is placed on the function and calculation of loads acting on oleopneumatic shock absorbers, which are the main type of shock absorber considered. A cylindrical oil chamber is separated by a movable orifice plate into high and lowpressure stages which are connected by a hollow metering pin passing through the orifice. The oleo pneumatic shock absorber has a high efficiency under dynamic conditions both in terms of energy dissipation and return to normal static conditions 1. Landing gear integration in aircraft conceptual design mad 96. A twostage oleopneumatic shock absorber incorporating two pneumatic air pressure chambers, a high air pressure chamber and a low. Ceska, montreal, canada 57 abstract a twostage oleo pneumatic shock absorber incor 75 inventor. The high gear and weight efficiencies associated with the oleopneumatic shock absorber make it the preferred design for commercial transports 2. Us4381857a programmed oleopneumatic shock absorber. An oleopneumatic shock absorber has both a gas charge, typically nitrogen or dry air is used, and a hydraulic oil. The most common shock absorber type is an oleopneumatic shock absorber.
Head is the direct contact part which is impacted by moving object and operated as a stopper to the body when cycle is. The shock absorber shown here is to model the leakage in the recoil chamber which is a common type of fault observed in most of the shock absorbers. This design cushions the impacts of landing and damps out vertical oscillations. The high gear and weight efficiencies associated with the oleo pneumatic shock absorber make it the preferred design for commercial transports 2. Energy storage, impact absorption, dampening of water hammer effect, transference of pressure between two different fluids, keeping the pressure in leaking circuits, to compensate the variations in the volume of a liquid due to its thermal dilatation, machine tools, etc. Optimization of an oleopneumatic shock absorber of an. Most landing gear use an oleopneumatic shock absorber which essentially consists of an oil damper and a gas spring.
Conceptual design of singleacting oleopneumatic shock. For any application involving a combination of high aircraft weight, high sink speed or minimum gear space an oleo pneumatic strut should be considered for its obvious gains in performance, small size and low weight. Please check the boxes for the options that you would like to add. The oleo pneumatic shock absorber of the present invention is shown operatively connected between the main support strut 14 and each wheel axle through a crank arm 15. No contact information is available for sachin barve. A shock absorber of the oleo pneumatic type comprising. A twostage oleopneumatic shock absorber incorporating two pneumatic air pressure chambers, a high air pressure chamber and a low pressure air chamber, separated by a hydraulic fluid oil pressure chamber. The force, which the aircraft structure is subject to, can be expressed in newtons 2nd law of physics f m a or force mass x acceleration. Multiphysics based simulations of a shock absorber subsystem. Landing gear model and an oleo pneumatic shock absorber a 2dof model shown in fig. The first innovation to the oleopneumatic shock absorbers was the metering pin, which modulated. The complete system is modeled within amesim using the thermohydraulic and pneumatic component design thcd and pcd to assess the sizing for each part of the device. This invention relates to oleo pneumatic shock absorbers such as those employed on mechanical equipment for example vehicles especially aircraft undercarriages, and more particularly to such a shock absorber wherein the rate of compression is programmed separately as for example in the case of aircraft landing gears for the landing impact and for rollout subsequent to the impact. Mar 10, 2016 oleo pneumatic shock absorber design 9 out of 10 based on 454 ratings.
Active control of a nonlinear landing gear system having. Strut assembly prices 1999 volvo s80 suspension strut and coil spring assembly position. The basic weight support function of the oleopneumatic shock struts, which have a high efficiency under dynamic conditions both in terms of energy absorption. The original oleo pneumatics shock absorber was developed from the vickers gun recuperative gear design which was first applied to an aeroplane by the french company breguet aviation. Young 2 presented the development of conventional landing gear with respect to the design, energy absorption characteristics, landing gear geometry and types from 1940 to the present. The basic structure of an oleo pneumatic shock strut is outlined in figure 7 below. An oleopneumatic strut is an airoil hydraulic shock absorber used on the landing gear of most large aircraft and many smaller ones. Each shock absorber is designated 16 since they are identical one to the other and the extension and retraction thereof serves to move each pair of associated wheels 12. Pneumatic and hydraulic shock absorbers are used in conjunction with cushions and springs. Based on the analysis procedure as outlined in this chapter, algorithms were developed to determine the required stroke and piston length to meet the given design conditions, as. The shock absorber 1 comprises an outer hollow metal cylinder 2 which is closed at its lower end and serves the dual function of acting as a load bearing structure and of containing. Parker pneumatic b shock absorbers actuator products shock absorbers shock absorbers shocks miniature shock absorbers mc 9 to mc 75 selfcompensating miniature shock absorbers mc 150, mc 225 and mc 600 selfcompensating heavyweight shock absorbers sc 300 and sc 650 soft contact and selfcompensating miniature shock absorbers sc 190 to sc 925.
Note that this model is presented to capture the first compressive stroke of the shock strut, i. The oleopneumatic shock absorber has a high efficiency under dynamic conditions both in terms of energy dissipation and return to normal static. Alex engineering design, gojan school of business and technology, redhills, chennai600 052 abstract. Swedish society of aeronautics and astronautics ftf. Request pdf active control of a nonlinear landing gear system having oleo pneumatic shock absorber using robust linear quadratic regulator approach this paper deals with the active control of. It is undesirable for an airplane to bounce on landingit could lead to a loss of control.
Optimization of an oleopneumatic shock absorber for main. Conceptual design of singleacting oleopneumatic shock absorber in landing gear with combined method nima ghiasi tabari. This project focuses on the design and analysis of an oleo pneumatic shock absorber strut for nose landing gear system for a lightweight aircraft. A twostage oleo pneumatic shock absorber incorporating an overload relief valve for instantaneous damping of transient loads. Cushioning components product range overview function type code version description area of application shock absorbers elastomer shock absorbers dyefy1 mechanical shock absorber with flexible rubber buffer cushioning stroke cannot be adjusted no fixed stop continuous mounting thread with internal hex mini slide dgsl. Head, piston rod, body, adjustment dial and lock nut. Including inerters in aircraft landing gear shock strut to improve the. These have a high damping to weight ratio and are used in most modern. Oleopneumatic shock absorber is considered the safest and the most efficient modern shock absorption type with efficiencies up to 90%.
These shock absorbers for having both fluid and gas flow can benefit from the advantages of both previous states. Inroduction a shock absorber or damper is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. Aircraft landing gear is a unique subsystem which is actuated to land the airframe without a depredation to the airframe. This project focuses on the design and analysis of an oleopneumatic shock absorber strut for nose landing gear system for a lightweight aircraft. Including inerters in aircraft landing gear shock strut to. Optimization of an oleopneumatic shock absorber of an aircraft during landing, journal of aircraft, vol. Shock absorber stroke torque ambient temperature collision speed impact object mass angle speed friction coefficient unit mm j j j n m s2 m kg m2 cycle min mpa m m n m c m s kg kg rad s 1 2 3 symbol corresponding mass of impact object shock absorber series rb rb individualx dx 3282rb. Nonlinear vibration analysis of oleo pneumatic landing gear at. Pdf design and analysis of modified oleo strut shock.
The active landing gears equipped with oleo pneumatic shock absorber are highly nonlinear systems. The oil chamber contains an orifice and metering pin, which orifice and metering pin control the rate of collapse of the low pressure air chamber. Catalog pdn2us shock absorbers parker pneumatic shocks. Design of a new magnetorheological damper based on passive.
Oleopneumatic shock struts are the most common type of shock absorber used on modern aircraft. Left and right abs sensor bracket may need to be swapped over on strut depending on position. Oleo pneumatic shock strut design the basic weight support function of the oleo pneumatic shock struts, which have a high efficiency under dynamic conditions both in terms of energy absorption and dissipation, is provided by a compressed cylinder of air and oil. The relief valve comprises a highpressure air chamber separated from the oil in the high.
Parker pneumatic industrial shock absorbers industrial shock. Applicable models can be selected depending on the operating speed. Nowadays, passive oleopneumatic shock absorbers are widely used in aircraft 3. Drop test of an oleopneumatic landing gear request pdf. The principles illustrated by the successful use of hydropneumatic suspension are now used in a broad range of applications, such as aircraft oleo struts and gas filled automobile shock absorbers, first patented in the u. An oleo strut is a pneumatic air oil hydraulic shock absorber used on the landing gear of most large aircraft and many smaller ones. The shock absorber analyzed in this thesis is the most current and modern type of shock absorber available. Compatible with the rb series in terms of mounting. Not only do oleo struts have a higher efficiency and dampingtoweight ratio than any other type of shock absorber, they also dissipate energy in a more optimal way, storing and releasing energy at controlled rates during the compression and. An automobile shock absorber contains springloaded check valves and orifices to control the flow of oil through an internal piston see below. Landing gear integration in aircraft conceptual design by sonny t.
An oleo strut is a pneumatic airoil hydraulic shock absorber used on the landing gear of most large aircraft and many smaller ones. Oleo pneumatic shock struts are the most common type of shock absorber used on modern aircraft. Nonlinear vibration analysis of oleo pneumatic landing gear. May 03, 1983 the oleo pneumatic shock absorber of the present invention is shown operatively connected between the main support strut 14 and each wheel axle through a crank arm 15. The primary purpose of the oleo strut, as you are probably already aware, is to absorb the landing loads on an aircraft. Design of a new magnetorheological damper based on passive oleopneumatic landing gear article in journal of aircraft 55207. Conceptual design of singleacting oleopneumatic shock absorber in. Programmed oleopneumatic shock absorber lockheed corporation. A twostage oleopneumatic shock absorber incorporating an overload relief valve for instantaneous damping of transient loads. One design consideration, when designing or choosing a shock absorber, is where that energy will go. Industrial shock absorber pneumatic end cushioning spring stroke s stopping time t v ms hydraulic dashpot t industrial shock absorber t selection of shock absorber type parker shock absorbers are available in two main types, to suit different applications and installation requirements.
Jun 15, 1982 the oleo pneumatic shock absorber 1 shown in the drawings is interposed between the body 18 of a vehicle and a wheel hub 5 and forms part of the wheel suspension. The basic structure of an oleopneumatic shock strut is outlined in figure 7 below. Multiphysics based simulations of a shock absorber sub. Optimization of an oleopneumatic shock absorber for main landing gear of. Oleo pneumatic shock absorber design struts and shocks. Apr 29, 2019 oleopneumatic shock absorber technology has continued to be refined, for example with us patent us2959410 a, jarry hydraulics, in 1960. Design and analysis of modified oleo strut shock absorber system in aircraft landing gear m. The mixture of oil and gas mode which is known as hydro pneumatic shock absorber, created a revolution in landing gear growth in the united states in 1950 bauer,2011. Conceptual design of singleacting oleo pneumatic shock absorber in landing gear with combined method nima ghiasi tabari, saeed mahdieh boroujeni department of mechanical engineering, dashtestan branch, islamic azad university, boushehr, iran manuscript received 18 jun. In this study, uncertain polytopic state space representation is developed by modelling the pneumatic shock absorber dynamics as a mechanical system with nonlinear stiffness and damping properties. The oleopneumatic accumulators have many generic applications.