Shock Absorber Design

The wheelchair is one of the most commonly used assistive devices for enhancing personal mobility, which is a precondition for enjoying human rights and living in dignity and assists people with disabilities to become more productive members of their communities. For many people, an appropriate, well-designed and well-fitted wheelchair can be the first step towards inclusion and participation in society. When the need is not met, people with disabilities are isolated and do not have access to the same opportunities as others within their own communities. Providing wheelchairs that are fit for the purpose not only enhances mobility but begins a process of opening up a world of education, work and social life [1]. The development of national policies and increased training opportunities in the design, production and supply of wheelchairs are essential next steps. Every human being need to move from one place another to fulfill his requirements and to accomplish that requirements he wi...

A suspension system or shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. The shock absorber's duty is to absorb or dissipate energy. In a vehicle, it reduces the effect of traveling over rough ground, leading to improved ride quality, and an increase in comfort due to substantially reduced amplitude of disturbances. When a vehicle is traveling on a level road and the wheels strike a bump, the spring is compressed quickly. The compressed spring will attempt to return to its normal loaded length and, in so doing, will rebound past its normal height, causing the body to be lifted. The weight of the vehicle will then push the spring down below its normal loaded height. This, in turn, causes the spring to rebound again. This bouncing process is repeated over and over, a little less each time, until the up-and-down movement finally stops. If bouncing is allowed to go uncontrolled, it will not only cause an uncomfortable ride but will make handling of the vehicle very difficult. The design of spring in the suspension system is very important. In this project, a shock absorber is designed and a 3D model is created using solid works design software. Thus the model of two bikes splendor and Yamaha are modeled and structural analysis of both suspension springs is done in Ansys workbench by assigning two different materials such as alloy steel and chromium-vanadium steel.

A substructure technique is proposed to account for energy harvesting in vehicle suspension systems. In this study, two dynamic models are coupled: a classic 7-DOF full-car model and a 14-DOF double wishbone suspension model for a more reliable approach to energy harvesting predictions. In this context, a disk of piezoelectric material is introduced between the frame and the spring shock absorber assembly of each wheel. Additionally, wasted energy caused by undesired vibrations in the vehicle’s suspension system can be partially recovered and converted into useful electric energy. The converted energy is predicted by using a 14-DOF coupled substructure model, along with double wishbone suspension elements. Moreover, an approach using a linear piezoelectric model is applied. Simultaneous solution of the differential equations of motion for these dynamic systems is performed in the time domain, considering a bump as the input mode. Tests were conducted to obtain the responses of ceramic, polymer, and composite piezoelectric materials, focusing on their energy harvesting and mechanical strength. Despite the indication of the ceramic piezoelectric material’s potential for energy harvesting from wasted vibrations in this study, the composite piezoelectric material seems preferable due to its mechanical strength.

This paper is a review on design and modification of suspension in motorcycle. Appropriate suspension is needed for better handling and safety while reducing shock impulse. The commonly used suspension in front of motorcycle is telescopic forks which are replaced by mono suspension. The effects of modified suspension are better ride comfort, quality as well as safety even on rough road. Material of the spring is also important factor which affects the quality of the ride. In motorcycle steering system is connected with the front suspension so careful design is mandatory. In this review work, mono shock absorber and spring suspension are studied in detail.

The optimization of independent automotive suspension systems, which is one of the main pillars of the vehicle performance and comfort, is currently going through a revolutionary change due to the development of artificial intelligence and quantum computing. This paper aims to review the multi-objective optimization of suspension parameters including camber, caster, and toe to discuss the complex design issues that arise from geometric and dynamic considerations. Some of the most common computational methodologies, which are Genetic Algorithms, Particle Swarm Optimization, and Gradient Descent, are discussed in this paper along with the new quantum computing techniques such as Gate-Based quantum computing and Quantum Annealing (QA). In addition, this review incorporates information from the practice of automotive manufacturers who have incorporated the use of artificial intelligence and quantum computing in their suspension systems. However, there are still some issues remaining, such as the computational cost, real-time flexibility, and the applicability of theoretical concepts to actual engineering structures. Some potential future research directions are introduced in this paper, such as hybrid optimization approaches, quantum techniques, and adaptive materials, which are considered as potential directions for future development. This systematic review presents a conceptual framework for researchers and engineers to follow, stressing the importance of interdisciplinarity in the development of intelligent suspension systems with performance objectives that are capable of adjusting to various road conditions. The findings of this work underscore the growing importance of complex computational techniques in modern automotive industry and highlight their potential to shape future developments based on emerging trends and industry practices.

there are various suspension geometries that can be considered in formula SAE cars. The most common type of Independent suspension geometry is a double wishbone type. It is the most extensively used suspension geometry right from FSAE cars to professional sized formula cars. Since the double wishbone type of suspension system consists of several connected parts, the dimensions of each member play a vital role in the variation of steering and suspension angles. In this study importance has been given to optimization of suspension geometry and obtaining the optimum locations of the mounting points i.e. hard points of the suspension geometry. A double wishbone suspension (front suspension) with pushrod was analyzed in Lotus Shark software to obtain the most appropriate locations of the hard points. Steering knuckle being one of the important components of steering system is also analyzed in this study and emphasis has been given on alternate material for weight reduction. The knuckle was modeled in Solid Works and analyzed in ANSYS 15.0.

This paper presents a brief overview of research being conducted in the area of Seismic Hazards Mitigation. The focus of the study has been on the development of integrated model of a structure with controllable fluid damper. The damper is used with an objective of reducing the dynamic wave propagation potential in the structure, upon the structural excitation. Before its employability to serve the intended purpose, the system identification and the model validation are the pre-requisites for the optimal functioning of the damper. A phenomenological model of the controllable fluid damper-Magnetorheological damper is used along with other Smart materials in the experiments conducted under controlled conditions. The experimental results are used to verify the integrated system model. The experimental results obtained indicate that high performance can be attained with controllable fluid damper to meet the requirements associated with seismic response reduction in civil engineering structures.

The purpose of this paper is to analyze the influence of aircraft vertical landing speed (sink speed) and horizontal landing speed (approach speed) on amount of energy absorbed by shock absorber that equipped a landing gear with trailing arm. A landing gear multibody model was built by using Virtual Lab software which makes possible to simulate drop test runs in order to check the speeds effects. The model allows setting different initial conditions and computing the amount of absorbed energy from each run. Settings and results from each drop will be analyzed according to 2k Factorial Design in order to determine the factors (speeds) effects as well as the interaction between them.

Hydraulic shock absorbers are mechanical devices responsible of vibration damping. Although a high level of development and tuning has been carried on, in order to ensure high performance standards in almost every situation, some dynamic phenomenon affecting internal fluid may reduce the damping capacity. In hydraulic shock absorbers, the energy is dissipated forcing the internal fluid through calibrated orifices; this energy is converted in heat and dispersed outwards from the external walls. Hydraulic fluid has therefore a fundamental role for the proper functioning of the overall device, and the most important variations of its chemical-physical properties have to be considered. One of the most dangerous phenomena involving the internal fluid is cavitation, which could affect performances and generate structural damages of the internal components of the damper. The aim of this work is to diagnose the phenomenon of cavitation using experimental data from a prototype of monotube sh...

This paper examines the procedure adopted for the design of UAV landing gear. Aircraft landing gear serves as a mechanism to support weight of the aircraft during landing, take-off , taxiing and also provide a shock absorbing function. The design of landing gear for the Medium Altitude Long endurance unmanned Aerial Vehicle is simple and it is base on safe life and fail safe concept and at the same time, make optimum selection and used of high strength materials for the design.This design considerations for this landing gear are significantly different, but past design procedures were used as guide to this design .Various landing gear configurations and types are in used today. The most common landing gear use for UAV is the fixed tricycle arrangement with one nose wheel (NLG) and two main wheels (MLG) at the rear. The retractable tricycle type was adopted for this design. The most attractive feature for this design is the improve stability during braking and ground maneuvering. The...

This paper deals with the design and manufacturing of shock absorbers for ATVs (All-Terrain vehicles). For this dual rate coil spring shock absorbers, we have considered an independent type double Wishbone arrangement for required off-road conditions. The purpose of designing and manufacturing this Shock absorber is to optimize the wheel assembly and to manufacture it less expensive, light in weight, and strong as per the off-road condition are addressed. This paper summarizes the design calculation, Analysis of components of shock absorbers, and manufacturing process required for this Suspension System of an ATV.

This paper examines the procedure adopted for the design of UAV landing gear. Aircraft landing gear serves as a mechanism to support weight of the aircraft during landing, take-off , taxiing and also provide a shock absorbing function. The design of landing gear for the Medium Altitude Long endurance unmanned Aerial Vehicle is simple and it is base on safe life and fail safe concept and at the same time, make optimum selection and used of high strength materials for the design.This design considerations for this landing gear are significantly different, but past design procedures were used as guide to this design .Various landing gear configurations and types are in used today. The most common landing gear use for UAV is the fixed tricycle arrangement with one nose wheel (NLG) and two main wheels (MLG) at the rear. The retractable tricycle type was adopted for this design. The most attractive feature for this design is the improve stability during braking and ground maneuvering. The...

Suspension system is one of the major and indispensable subsystems for land vehicles and has functions of providing better road holding, handling, and ride comfort. There are many suspension system types used for automobiles, and MacPherson strut suspension is one of the most widely used suspension system type due to its favorable features like simplicity, low cost, and high performance. However, there exists a drawback of this suspension type; since the coil springs have no ability to absorb lateral forces, undesired dry friction effects on the damper may degrade the ride comfort. As remedy to this drawback, the most popular and contemporary application is the use of coil spring forms which are called side load springs.It is observed that, the vehicle drifts towards one side due to high weight of suspension system. This problem can be solved by implementation of banana-C shaped coil spring. A banana,C-shaped coil spring is designed in such a way that it, when fitted correctly, exer...

Numerical simulation procedures for landing dynamics of large transport aircraft are briefly presented. Developed numerical procedures allow for determination of dynamic response of landing aircraft for different flight and touch-down parameters. A non-linear dynamic model of landing aircraft, which serves as a basis for computational procedures, is synthesised by modelling of aircraft structural subsystems using a multibody dynamics approach. A dynamic model with variable kinematical structures includes discontinuous dynamics of landing gear oleo-pneumatic shock-absorber with friction and hydraulic/thermodynamic processes. Non-linear tire contact dynamics and unilateral dynamics of nose gear elastic leg assembly is modelled as well. The longitudinal and lateral aerodynamic loads are estimated by considering various aircraft system configurations (landing gears in “up’’ and “down’’ position, different control surfaces in active/inactive modes). A mathematical model is derived as a d...

Aircraft multibody model Dynamics of landing aircraft Non-linear landing gear dynamics Shock-absorber model Ključne riječi Dinamički model zrakoplova Dinamika zrakoplova pri slijetanju Model elastično-prigušnog elementa Nelinearna dinamika podvozja

Estimator designs only using relative displacement information for semi-active suspension system are investigated. Modified sensitivity method controls semiactive suspension directly using relative velocity and MR damper model without calculating absolute velocity and parameter estimator. The comfort evaluation parameters about the driver are presented and the mathematical models of skyhook and modified skyhook control suspension are simulated in Simulink. The comparison results of suggests that modified skyhook control could significantly improve riding comfort and provide more comfortable working conditions for passenger, which can be widely applied on car in the future.

Hydraulic shock absorbers are mechanical devices responsible of vibration damping. Although a high level of development and tuning has been carried on, in order to ensure high performance standards in almost every situation, some dynamic phenomenon affecting internal fluid may reduce the damping capacity. In hydraulic shock absorbers, the energy is dissipated forcing the internal fluid through calibrated orifices; this energy is converted in heat and dispersed outwards from the external walls. Hydraulic fluid has therefore a fundamental role for the proper functioning of the overall device, and the most important variations of its chemical-physical properties have to be considered. One of the most dangerous phenomena involving the internal fluid is cavitation, which could affect performances and generate structural damages of the internal components of the damper. The aim of this work is to diagnose the phenomenon of cavitation using experimental data from a prototype of monotube sh...

A gravity damper is a one-way valve, employed for regulating the airflow rate in ducts, generally constituted by a series of rectangular panels (closure sections), connected to an articulated quadrilateral synchronizing the movements. If the device needs to process large masses of high speed air, as common in the case of energy conversion systems, disadvantageous dynamic effects can occur. In this study, vortexinduced vibration (VIV), occurring on a gravity damper for high values of the Reynolds number, is investigated. The analysis of this work couples numerical methods (Computational Fluid Dynamics with Large-Eddy Simulation turbulence model and Finite Element Method) to experiments: a full-scale accelerometric measurement campaign is actually performed at the wind tunnel facilities of the University of Perugia. VIVs are diagnosed and quantified through the experimental vibration analysis, which is interpreted through numerical simulations. The large amplitude of VIV is interpreted as due to a tendency towards lockin because of the approaching of the vortex shedding frequency to a natural vibration mode of the system. The integrated numerical and experimental framework finally inspires two different design solutions for mitigating the amplitude of VIV: these strategies are tested at the wind tunnel and they are indeed shown to be effective.

Numerical simulation procedures for landing dynamics of large transport aircraft are shortly presented. Developed numerical procedures allow for determination of dynamic response of landing aircraft for different flight and touch-down parameters. Non-linear dynamical model of landing aircraft, which serves as a basis for computational procedures, is synthesised by modelling of aircraft structural subsystems using multibody dynamics approach. Dynamical model with variable kinematical structure includes discontinuous dynamics of landing gear oleo-pneumatic shock-absorber with friction and hydraulic/thermodynamic processes. Non-linear tire contact dynamics and unilateral dynamics of nose gear elastic leg assembly is modelled as well. The longitudinal and lateral aerodynamic loads are estimated by considering aircraft various system configurations (landing gears in "up" and "down" position, different control surfaces in active/inactive modes). Mathematical model is d...

The aircraft is a means of transportation that operates mainly in the air; however, it starts and ends its journey on the ground. Due to the aircraft’s structural complexity, simulation tools are used to understand and to predict its behavior in its movements on the ground. Simulation tools allow adjusting the observation parameters to gather a greater amount of data than real tests and explore interactions of the aircraft and their individual components with external objects such as pavement imperfections. This review aims to collect information on how to simulate the aircraft interaction with traffic-dependent energy harvesting systems. The specifications and framework to be met by a conceptual design are explored. The different configurations for simulating the aircraft configuration result in the selection of the two-mass-spring-damper model. For the components, especially the landing gear, a deployable element for on-ground movements, several existing models capable of translat...

One of the most important automotive systems is suspension. The primary purpose is to protect the driver from shocks from the road. In addition to providing proper wheel travel and load transfer, secondary functions also include lateral stability and ergonomics and driver comfort. Vehicles with all-terrain capabilities are built to tackle any surface. Stability, vehicle behavior, and driver comfort are the main issues because the vehicle is designed to operate on various types of terrain. The paper's primary goal was to develop and optimize the front suspension wishbone for a BAJA (ATV) vehicle. The purpose of this study is to analyze the entire suspension system of an ATV vehicle to enhance wheel handling and stability. The entire system was made to be strong enough to absorb shocks from the rough terrain that ATVs are typically used on. Calculations were used to design the springs, and SOLIDWORKS was used to design the components. The front and rear systems were simulated using Lotus software, and the components were examined using commercial FEA software from ANSYS. The steering and suspension system's pivot point, known as the steering knuckle, enables the steering arm to turn the front wheels. The knuckle is put to the test in a variety of loading conditions, including bump, cornering, and braking.

This paper deals with the design and analysis of a mechanism for a wheelchair which is propelled using the lever with our hands. The mechanism is placed on both sides of the wheelchair and is actuated independently with a lever on each side. The lever which is pivoted about an axis to the sides with help of bearing has to be pushed and pulled continuously to propel the wheelchair. Two sprockets and the lever of the mechanism are constrained to rotate together mounted over a bearing attached to the frame of the wheelchair on both sides. These two sprockets are each meshed with a freewheel which is coaxially placed with the axis of rotation of wheels of the wheelchair through cycle chains. One of the sprocket and freewheel on both sides is meshed in cross-over chain configuration. This enables the wheelchair to propel forward in both push and pull strokes of the lever.

Active suspension control system are used in today cars because of their ability to manage the compromise between ride comfort and vehicle road-handling. They constitute a typical example of distributed control systems. In this paper, the ride controller part of an ...

Tripod housing plays a major role in transmitting power from the transmission system to the drive wheel and hence it undergoes severe torsion and bending type of deformation. In this paper, a design of Tripod housing for an off-road vehicle was analyzed using a finite element analysis (FEA) and verified mathematically using the principle of impulse-momentum and maximum shear stress theory. For any mechanical component, Factor of Safety (F.O.S.) gives the degree of safeness of the component under consideration. Thus, the focus of concern of this paper was on the value of F.O.S. by FEA and its verification using analytical calculations.

The paper deals with study and analysis of the suspension parameters. The suspension design is very important to control the vehicle in motion. The automobile is moving machine it is not static machine. The vehicle while in motion encounters pitching, Rolling, Bouncing, yawing. These motions are initiated from the suspension system. In this paper double wishbone type of suspension system is considered for the analysis. we hierarchically structured design items from design variables that represent suspension geometry to evaluation criterion related to practical operation situations. Some of the crucial parameters are considered for the analysis and result is tabulated. Finally we showed that the optimal design solutions can be obtained.

The aircraft is a means of transportation that operates mainly in the air; however, it starts and ends its journey on the ground. Due to the aircraft’s structural complexity, simulation tools are used to understand and to predict its behavior in its movements on the ground. Simulation tools allow adjusting the observation parameters to gather a greater amount of data than real tests and explore interactions of the aircraft and their individual components with external objects such as pavement imperfections. This review aims to collect information on how to simulate the aircraft interaction with traffic-dependent energy harvesting systems. The specifications and framework to be met by a conceptual design are explored. The different configurations for simulating the aircraft configuration result in the selection of the two-mass-spring-damper model. For the components, especially the landing gear, a deployable element for on-ground movements, several existing models capable of translat...

Transportation has become an integral part of people's day to day life. At certain times, in large countries like India, people are forced to travel long distance from their work place to their place of residence. People with upper limb amputation and hands have difficulties in travelling and cannot travel these long distances. They use devices such as wheel chair, crutches and artificial limbs for mobility. These however cannot be used for long distance outdoor transportation Therefore, the aim of this project is to design and fabricate Foot operated system for armless people.The contents include a description of the design and selection process including all important information about the vehicle. Due to rapid industrialization and development of the economy the expectation of the customer and their ability and willingness to pay for the product has changed drastically.

This paper examines the procedure adopted for the design of UAV landing gear. Aircraft landing gear serves as a mechanism to support weight of the aircraft during landing, take-off , taxiing and also provide a shock absorbing function. The design of landing gear for the Medium Altitude Long endurance unmanned Aerial Vehicle is simple and it is base on safe life and fail safe concept and at the same time, make optimum selection and used of high strength materials for the design.This design considerations for this landing gear are significantly different, but past design procedures were used as guide to this design .Various landing gear configurations and types are in used today. The most common landing gear use for UAV is the fixed tricycle arrangement with one nose wheel (NLG) and two main wheels (MLG) at the rear. The retractable tricycle type was adopted for this design. The most attractive feature for this design is the improve stability during braking and ground maneuvering. The...

– Helical springs are mechanical parts used as shock Absorbers in various Engineering Designs. The design of Coil springs are fairly simple and they provide good suspension in mechanical machines. Various springs are used in Automobiles and other day to day devices. From clock to Aeroplanes, a spring is being used in almost every machine. The design of coil spring is slightly changed in order to obtain a Wave spring, which is also helically twisted and of same size and Material. In the present work a review is made on the the types of springs that have been used in the Engineering applications along the history. A thorough comparsion is made to find out different modes of failure of helical springs and how the design of helical coil spring evolved with time to fight against those modes of failures. The objective is to identify the best way to design a helical spring and to counter the modes of failure that the spring faces during its term of service.

This paper deals with the design and manufacturing of shock absorbers for ATVs (All-Terrain vehicles). For this dual rate coil spring shock absorbers, we have considered an independent type double Wishbone arrangement for required off-road conditions. The purpose of designing and manufacturing this Shock absorber is to optimize the wheel assembly and to manufacture it less expensive, light in weight, and strong as per the off-road condition are addressed. This paper summarizes the design calculation, Analysis of components of shock absorbers, and manufacturing process required for this Suspension System of an ATV.

Statistical techniques are extremely useful in system performance evaluation. Since any statistic cannot be guaranteed to give a close estimate for every sample, we must design statistics that will give good results on the average or in the long run. Despite of even higher performance computers, quantitative steady-state simulation of even a moderate complex system takes very long time, since to obtain reasonably stable results, that is, estimates with reasonably variances, very larges samples are usually necessary. Natural effort toward the reduction ...

The suspension system plays a major role in automobiles to improve passenger comfort, passenger safety and road handling. It isolates the body of a vehicle from road disturbances. The full vehicle would be subjected to disturbances from all four wheels or a full suspension model of the vehicle and, thus, a full-suspension model of the vehicle should be added to the idea of an enhanced control preview. The input data for the fuzzy logic controller (FLC) is the velocity and acceleration of the front and rear wheels. Controller outputs are considered to be active forces that improve driver comfort, safety and road handling characteristics. The objective of this work is to model and analyse an active full vehicle suspension. The model is optimized using advanced FLC to improve driver comfort, safety and road handling. The mathematical model for the active full vehicle suspension model has been derived. The necessary background for the Simulink fuzzy logic and FLC has been presented. All...

This paper gives an insight on the suspension dynamics of the two most widely used models for vehicle dynamics with their complete state space analysis, simulated by using Mat Lab platform. In this paper we investigate the responses of the quarter car and a half car model as the vehicle ride performance is generally assessed at the design stage by simulating the vehicle response to road excitation. This requires the development of a vehicle model to analysis its responses. The time responses and frequency responses of the sprung and unsprung masses have been studied. The optimal solution here is the damping, which has been optimized with the given set of fixed parameters.

This paper gives an insight on the suspension dynamics of the two most widely used models for vehicle dynamics with their complete state space analysis, simulated by using Mat Lab platform. In this paper we investigate the responses of the quarter car and a half car model as the vehicle ride performance is generally assessed at the design stage by simulating the vehicle response to road excitation. This requires the development of a vehicle model to analysis its responses. The time responses and frequency responses of the sprung and unsprung masses have been studied. The optimal solution here is the damping, which has been optimized with the given set of fixed parameters.

This paper gives an insight on the suspension dynamics of the two most widely used models for vehicle dynamics with their complete state space analysis, simulated by using Mat Lab platform. In this paper we investigate the responses of the quarter car and a half car model as the vehicle ride performance is generally assessed at the design stage by simulating the vehicle response to road excitation. This requires the development of a vehicle model to analysis its responses. The time responses and frequency responses of the sprung and unsprung masses have been studied. The optimal solution here is the damping, which has been optimized with the given set of fixed parameters.

Dynamic analyses of the landing gear are conducted to provide capabilities to forecast their behavior under hazardous conditions. This kind of investigation with numerical methods implementation is much easier and less expensive than stand tests. The major advantage of the presented numerical method is applicability to landing gear tests with artificially introduced flaws.

This paper shows the influence on dynamic behavior of the car when it is equipped with magneto-rheological dampers controlled by a feedback. The feedback is built up in two ways; the first is implemented by a switch on/off control that is characterized by the injection of magnetic field with a constant value. It happens when a certain value of relative speed between the sprung and unsprung mass is exceeded. The second feedback is characterized by the H-infinity control which is based on the relative displacement in order to vary the magnetic field signal in a continuous manner. At the same time the H-infinity control of vehicle is maintained by taking into account the exceeding of speed signal in order to consider the substantial differences with the switch on/off control. These differences are evaluated in terms of relative displacement and speed between the unsprung and sprung mass. The exogenous excitation is the road disturbances which are introduced as a square wave input in or...

This paper gives an insight on the suspension dynamics of the two most widely used models for vehicle dynamics with their complete state space analysis, simulated by using Mat Lab platform. In this paper we investigate the responses of the quarter car and a half car model as the vehicle ride performance is generally assessed at the design stage by simulating the vehicle response to road excitation. This requires the development of a vehicle model to analysis its responses. The time responses and frequency responses of the sprung and unsprung masses have been studied. The optimal solution here is the damping, which has been optimized with the given set of fixed parameters.

This paper examines the procedure adopted for the design of UAV landing gear. Aircraft landing gear serves as a mechanism to support weight of the aircraft during landing, take-off , taxiing and also provide a shock absorbing function. The design of landing gear for the Medium Altitude Long endurance unmanned Aerial Vehicle is simple and it is base on safe life and fail safe concept and at the same time, make optimum selection and used of high strength materials for the design.This design considerations for this landing gear are significantly different, but past design procedures were used as guide to this design .Various landing gear configurations and types are in used today. The most common landing gear use for UAV is the fixed tricycle arrangement with one nose wheel (NLG) and two main wheels (MLG) at the rear. The retractable tricycle type was adopted for this design. The most attractive feature for this design is the improve stability during braking and ground maneuvering. The...

A gravity damper is a one-way valve, employed for regulating the airflow rate in ducts, generally constituted by a series of rectangular panels (closure sections), connected to an articulated quadrilateral synchronizing the movements. If the device needs to process large masses of high speed air, as common in the case of energy conversion systems, disadvantageous dynamic effects can occur. In this study, vortexinduced vibration (VIV), occurring on a gravity damper for high values of the Reynolds number, is investigated. The analysis of this work couples numerical methods (Computational Fluid Dynamics with Large-Eddy Simulation turbulence model and Finite Element Method) to experiments: a full-scale accelerometric measurement campaign is actually performed at the wind tunnel facilities of the University of Perugia. VIVs are diagnosed and quantified through the experimental vibration analysis, which is interpreted through numerical simulations. The large amplitude of VIV is interpreted as due to a tendency towards lockin because of the approaching of the vortex shedding frequency to a natural vibration mode of the system. The integrated numerical and experimental framework finally inspires two different design solutions for mitigating the amplitude of VIV: these strategies are tested at the wind tunnel and they are indeed shown to be effective.

As one of the key components of the aircraft in terms of both operation and safety landing gears are of special interest of the aviation regulations. During the touch down landing gears need to dissipate as much of the energy as possible maintaining the lowest volume and weight as required by the aviation design restrictions. According to the aviation regulations landing gears have to be tested in order to prove the dissipation of the calculated landing energy and to evaluate actual loads acting on the fuselage via the mounting nodes of the landing gears. The tests need to replicate the real landing conditions as closely as possible – including the lift force (or lift) acting on the aircraft during landing. The lift force during landing is not sufficient to maintain the aircraft in flight but acts as the relief force to the aircraft weight resulting in lowering loads applied to the fuselage and decreasing landing energy needed to be dissipated. The lift force or lift has to be taken...

As one of the key components of the aircraft in terms of both operation and safety landing gears are of special interest of the aviation regulations. During the touch down landing gears need to dissipate as much of the energy as possible maintaining the lowest volume and weight as required by the aviation design restrictions. According to the aviation regulations landing gears have to be tested in order to prove the dissipation of the calculated landing energy and to evaluate actual loads acting on the fuselage via the mounting nodes of the landing gears. The tests need to replicate the real landing conditions as closely as possible – including the lift force (or lift) acting on the aircraft during landing. The lift force during landing is not sufficient to maintain the aircraft in flight but acts as the relief force to the aircraft weight resulting in lowering loads applied to the fuselage and decreasing landing energy needed to be dissipated. The lift force or lift has to be taken...

A new nonlinear model for a semi-active damper which describes a broad variety of hysteresis effects is presented in this paper. The novel part of the model is that the few parameters can be identified easily and cost effective for the automotive industry. Despite the few amounts of parameters, the validation of the model shows, that it describes the behavior of a real semiactive damper with strong hysteresis effects very well. Additionally, the influence of the unknown parameters is discussed in a detailed parameter study. In order to consider the hysteresis in the current control, the model is embedded in a dynamic feed-forward control structure.

Dynamic simulation, based on modelling, has a significant role during to the process of vehicle development. It is especially important in the first design stages, when relevant parameters are to be defined. Shock absorber, as an executive part of a semi-active suspension system, is exposed to thermal loads which can lead to its damage and degradation of characteristics. Therefore, this paper attempts to analyze a conversion of mechanical work into heat energy by use of a method of dynamic simulation. The issue of heat dissipation from the shock absorber has not been taken into consideration.

Hand-arm vibration (HAV) is vibration transmitted from a work processes into workers' hands and arms. It can be caused by operating hand-held power tools, hand-guided equipment, or by holding materials being processed by machines. Multiple studies have shown that regular and frequent exposure to HAV can lead to permanent adverse health effects, which are most likely to occur when contact with a vibrating tool or work process is a regular and significant part of a person's job. Hand-arm vibration can cause a range of conditions collectively known as hand-arm vibration syndrome (HAVS), as well as specific diseases such as white finger or Raynaud's syndrome, carpel tunnel syndrome and tendinitis. Vibration syndrome has adverse circulatory and neural effects in the fingers. The signs and symptoms include numbness, pain, and blanching (turning pale and ashen).so these vibration reduce by using viscous damper.

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is gen-erally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the pre-liminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Alt-hough based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was im-plemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

The Ratchet And Pawl, a very simple device which allows a shaft to turn only one way. The Pawl and Ratchet mechanism plays a vital role in providing one way transmission and safety against heavy loading conditions. Antiroll back mechanism has been analyzed using ANSYS software. The analysis results are concluded in detail.