Active and Semi Active Suspension Systems

Bu tezin hazırlanması süresince destek olduğun ve beni hep ama hep sevdiğin için... Tüm aileme... Her zaman yanımda olan sevgili Hocam Doç. Dr. Ata MUĞAN´a… Moral desteklerini hiç esirgemeyen Gizem Öztimur ve Sena Cimilli`ye, İlker Altay ve Mesut Acar`a, İbrahim Günal ve Özgür Uyar`a Mesut Kırca`ya... Bu tezi yazarken yardımlarından dolayı, bir defa az olduğu için Gizem`e bir kez daha...

Magnetorheological (MR) shock absorbers have received remarkable attention in the last decade due to being a potential technology to conduct semi-active control in structures and mechanical systems in order to effectively suppress vibration. It is therefore vitally important to understand dynamic behavior of such devices whose nonlinear hysteresis is a complicated phenomenon. In the present paper, a MR shock absorbers has been designed, fabricated, tested and a fully-parametric modeling has been done using classical Bouc-Wen hysteretic model. Finally, the model has been verified against experimental data and excellent agreement has been observed between experimental and simulated data. Keyword: Magnetorhelogical shock absorbers, MR shock absorbers, MR devices, MR Fluid, Bouc-Wen model

This paper presents an experimental validation of a proposed Frequency Estimation-Based (FEB) controller for semi-active suspensions by using a Hardware-in-the-Loop (HiL) platform of a Quarter of Vehicle (QoV) model. The FEB approach is compared with three commercial On-Off controllers that have shown good results in comfort and road holding: Sky-Hook (SH), Groud-Hook (GH) and Mix-1-sensor (M1S). The comparison was done under the same experimental tests; the standards ISO-2631 and BS-6841 are used to evaluate the comfort and the Root Mean Square (RMS) index to quantify the road holding. The QoV model belongs to a front-left corner of a pick-up truck; the used experimental Magneto-Rheological (MR) damper is not symmetric and only hast 2 manipulation states. Experimental results show that the FEB controller has the best comfort performance at low frequencies (outperforms the benchmark controllers at 11.2%); while, for road holding, the improvement is slight; however, FEB controller works better for both goals simultaneously. By analyzing the suspension deflection, the FEB controller reduces up to 32.8% of motion respect to the GH controller. Additionally, the manipulation of the SH and GH controllers have several changes of actuation that do not allow the stabilization of the force in its desirable value; while FEB controller has a soft actuation defined on bandwidths.

Developing a reliable control algorithm for a mechatronic suspension can be tricky
because of the nonlinear nature of the system and the necessity to achieve a good trade-off
between the requirements of road handling ability and the comfort of passengers. This paper
assesses the performance of two control methods, the H-Infinity (H ∞) and linear quadratic
regulator (LQR), applied to an active suspension system. This suspension system uses
sensors and actuators in addition to the springs and dampers of the traditional suspension
system. It combines software, electrical, and mechanical parts to improve the car handling
and convenience of passengers on the road. A quarterly car automotive suspension model
consisting of 2 degrees of freedom (2 DOF) is proposed as the case study. The suspension
deviation, wheel displacement, and upward acceleration of the car frame are the
performance parameters considered in this research. The aim is to strike a perfect balance
while achieving minimum readings of car chassis acceleration and wheel deflection
demonstrated by each controller when steady state error approaches zero from the
suspension response. The body acceleration and wheel deflection affect the passenger
comfort and road handling, respectively. Time-based simulation is carried out in
MATLAB/Simulink environment to verify the effectiveness of the proposed control
mechanisms. The results of the simulation demonstrate the effectiveness and robustness of
the proposed control schemes.

The objective of this paper is to design and compare the performance of robust H 1 controllers for slow and fully active electromechanical suspension systems. H 1 controllers are synthesised based on half-car model dynamics. The criteria used for comparison are linear and angular body accelerations representing the ride comfort, tire compressions for handling, and actuator effort for energy consumption. It is shown that slow-active electromechanical suspension systems consume considerably less control energy relative to fully active electromechanical suspension systems, albeit with a slight decrease in performance.

Vehicle suspension is used to achieve good driving stability and passenger comfort regardless of road surface. The suspension system of an automobile or a vehicle is the arrangement or a device which not provide the cushioning but also prevents the vehicle‘s engine from the road surfaces by providing the sufficient desired distance. I this article it is discussed about the general review about the suspension system.

Despite the increased usage of composite materials, high-strength aluminum alloys maintain significance in airframe construction. Aluminum's attributes of being lightweight, relatively low-cost, heattreatable, and capable of withstanding high-stress levels contribute to its continued importance. These properties also reduce manufacturing and maintenance costs compared to other high-performance materials. Recent advancements in aluminum aircraft alloys have enabled them to compete effectively with modern composite materials. This study delves into the latest developments, focusing on improving the mechanical properties of aluminum alloys and utilizing high-performance joining techniques. Cu-Al-based alloys represent a new class of functional materials. Due to their unique thermoelastic martensite structure, their exceptional damping performance has garnered attention in materials science and engineering. However, challenges such as elastic anisotropy and larger grain sizes can lead to brittle fractures, impacting the material's mechanical properties. It is widely acknowledged that achieving a finer grain size is pivotal when creating Copper Aluminum alloys with exceptional mechanical attributes and effective damping characteristics. Smaller grain sizes allow for the combined use of fine grain strengthening and interfacial damping, resulting in alloys demonstrating exceptional overall characteristics. This paper presents several standard approaches for preparing Copper Aluminum alloys, subsequently examining research efforts dedicated to enhancing grain size through alloying and heat treatment. Moreover, nanomaterials are being investigated as potential agents for reinforcing Cu-Al-based alloys, leading to substantial improvements in their mechanical characteristics and damping capacities. The study aims to serve as a valuable reference for future research in developing structure-function integrated materials capable of simultaneously offering high strength and high damping characteristics.

Ternary Cu-12Al-4Mn and Cu-12Al-4Ni have been chosen for the present study and different alloying elements have been added in an attempt to further improve upon the shape memory properties in terms of the desired microstructure in the quenched condition. It has been observed that all compositions do not exhibit the martensitic structure on quenching and different types of martensitic phases are exhibited depending on the alloying constituents. Attempts have been made to roll the samples into thin sheets through multiple passes. It has been found that although the ternary base alloys can easily be rolled the quaternary alloys with both Mn and Ni make the sample brittle rendering it unsuitable for rolling. Also adding of Zn and Mg has not exhibited the desired microstructure for exhibiting the shape memory properties and also could not be rolled though these samples were not brittle. The ease of roll-ability has been compared between the alloys and correlated with the microstructure w...

Ternary Cu-12Al-4Mn and Cu-12Al-4Ni have been chosen for the present study and different alloying elements have been added in an attempt to further improve upon the shape memory properties in terms of the desired microstructure in the quenched condition. It has been observed that all compositions do not exhibit the martensitic structure on quenching and different types of martensitic phases are exhibited depending on the alloying constituents. Attempts have been made to roll the samples into thin sheets through multiple passes. It has been found that although the ternary base alloys can easily be rolled the quaternary alloys with both Mn and Ni make the sample brittle rendering it unsuitable for rolling. Also adding of Zn and Mg has not exhibited the desired microstructure for exhibiting the shape memory properties and also could not be rolled though these samples were not brittle. The ease of roll-ability has been compared between the alloys and correlated with the microstructure which helps in understanding which type of martensitic phase is useful in rolling the samples.

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.

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.

In this paper, a piezoelectric microrobot is modelled and simulated based on active force control (AFC) with a proportional (P) -type iterative learning algorithm (ILA) operating in a constrained environment for an in-pipe application. A mathematical model that represents the dynamic characteristics of microrobot has been developed considering the robot system subjected to different input excitations. The movement of the robot is based on an impact drive mechanism (IDM) strategy which causes the robot to move in a worm-like manner in the pipe. A dedicated feedback controller is integrated into this system that incorporates proportional-integral-derivative (PID) controller and active force control (AFC) with an embedded ILA. The primary objective of the scheme is to ensure a robust and accurate trajectory tracking control of the microrobot system is achieved. The performance of the proposed control system under different types of disturbances is evaluated through a rigorous simulation study. The obtained results clearly demonstrate an effective trajectory tracking capability of the worm-like microrobot in spite of the negative effects of the external disturbance conditions.

This paper discusses the research methodologies utilized for developing a suspension system for a four wheel-drive terrain vehicles. The main research methods can be identified as literature studies; design processes by applying CAD systems, numerical analyses methods, mathematical modeling and simulation, optimization of the mechanical systems, as well as the comparison, analysis, and evaluation of the obtained results. The proposed suspension system for the terrain vehicle was successfully derived at from a classic double wishbone control arm. Optimization of the suspension parameters for passive ones is performed by Multi Objective Genetic Algorithms, whilst for active damping force by employing Hooke-Jeeves non-linear programming method. On the basis of comprehensive analysis it is shown the active systems are more adequate. The proposed suspension design provides relatively small lateral wheel motion, zero camber angles, and effectively absorbs the vibrations caused by road exc...

Bu çalışma kara araçları için yol tutuşu ve yolcu konforu bakımından çok önemli bir yere sahip olan aktif süspansiyon sisteminin kontrolünü sunar. Kontrol sistemi için literatürde çeyrek taşıt modeli olarak bilinen ve aracın dörtte bir kütlesiyle tek teker sisteminden oluşan model kullanılmıştır. Öncelikle pasif ve aktif süspansiyon sistemlerinin matematiksel modelleri ortaya konulmuş ve aktif süspansiyon sistemi için kontrolörler tasarlanmıştır. Kontrolör tasarımları lineer matris eşitsizlikleri (LMI) ile optimizasyon yapılarak elde edilmiştir. Çalışmada lineer quadratik regülatör (LQR) kontrol ile lineer quadratik integral (LQI) kontrol tasarımları yapılmış ve yol bozucularına karşı performansları kıyaslanmıştır.

Bu calisma kara araclari icin yol tutusu ve yolcu konforu bakimindan cok onemli bir yere sahip olan aktif suspansiyon sisteminin kontrolunu sunar. Kontrol sistemi icin literaturde ceyrek tasit modeli olarak bilinen ve aracin dortte bir kutlesiyle tek teker sisteminden olusan model kullanilmistir. Oncelikle pasif ve aktif suspansiyon sistemlerinin matematiksel modelleri ortaya konulmus ve aktif suspansiyon sistemi icin kontrolorler tasarlanmistir. Kontrolor tasarimlari lineer matris esitsizlikleri (LMI) ile optimizasyon yapilarak elde edilmistir. Calismada lineer quadratik regulator (LQR) kontrol ile lineer quadratik integral (LQI) kontrol tasarimlari yapilmis ve yol bozucularina karsi performanslari kiyaslanmistir.

Bu çalışma kara araçları için yol tutuşu ve yolcu konforu bakımından çok önemli bir yere sahip olan aktif süspansiyon sisteminin kontrolünü sunar. Kontrol sistemi için literatürde çeyrek taşıt modeli olarak bilinen ve aracın dörtte bir kütlesiyle tek teker sisteminden oluşan model kullanılmıştır. Öncelikle pasif ve aktif süspansiyon sistemlerinin matematiksel modelleri ortaya konulmuş ve aktif süspansiyon sistemi için kontrolörler tasarlanmıştır. Kontrolör tasarımları lineer matris eşitsizlikleri (LMI) ile optimizasyon yapılarak elde edilmiştir. Çalışmada lineer quadratik regülatör (LQR) kontrol ile lineer quadratik integral (LQI) kontrol tasarımları yapılmış ve yol bozucularına karşı performansları kıyaslanmıştır.

In this work, four different semi-active controllers for a quarter of vehicle and full vehicles are evaluated and compared when used in internal combustion engine (ICE) vehicles vs electric vehicles (EVs) with in-wheel motor configuration as a way to explore the use of semi-active suspension systems in this kind of EVs. First, the quarter of vehicle vertical dynamics is analyzed and then a full vehicle approach explores the effectiveness of the control strategies and the effects of the traction in the vertical Control performances. Aspects like the relation between traction and suspension performances, and the resonance frequencies are also discussed.

This paper offers motivations for an active suspension system which provides for both additional stability and maneuverability by performing active roll and pitch control during cornering and braking as well as eliminating road irregularities, hence increasing both vehicle and passenger safety and drive comfort. Various technologies are compared to the proposed electromagnetic suspension system which uses a tubular permanent magnet (PM) actuator together with a passive spring. Based upon on-road measurements and results from the literature, several specifications for the design of an electromagnetic suspension system are derived. The measured on-road movement of the passive suspension system is reproduced by electromagnetic actuation on a quarter car setup proving the dynamic capabilities of an electromagnetic suspension system.

In preparing this thesis, I was in contact with many people, researchers, academicians, and practitioners. They have contributed towards my understanding and thoughts. In particular, I wish to express my sincere appreciation to my main thesis supervisor, Professor Madya Mustafa Yusof, for encouragement, guidance, critics and friendship. I am also very thankful to my co-supervisor Professor Dr. Roslan Abd. Rahman for his guidance, advice and motivation. Without their continued support and interest, this thesis would not have been the same as presented here. A special thank you also goes to Professor Madya Pakharuddin b. Mohd Samin for his help and guidance. My fellow postgraduate students should also be recognised for their support. My sincere appreciation also extends to all my colleagues and others who have provided assistance at various occasions. Their views and tips are useful indeed. Unfortunately, it is not possible to list all of them in this limited space. I am grateful to all my family members.

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.

The suspension was developed in order to annihilate the linear oscillations produced by the relative movements of the body car in relation to the wheels on the longitudinal and transversal direction and also the yaw oscillations. The main objective of this paper is to establish a correlation between comfort and energy consumption. The paper will present a new model of an active suspension using the AMESim program, in order to be compared with a standard suspension model. Using the numerical simulation with AMESim language, the authors have developed many models of suspension comparing active or semi-active suspensions with the passive ones.

In the paper a model is developed for a proposed eddy current damper using finite element analysis. Several damper configurations are studied and its characteristics are analyzed. The steady state performance for the configurations is compared to reach a design with an acceptable performance for the eddy current damper. Furthermore, the proposed designs performance are compared with the traditional damper performance. It was found that the best two designs to achieve the targeted performance were to have an iron core damper or an iron core with an aluminum sleeve. Those two designs are economical and simple while achieving acceptable performance when compared to traditional dampers and other electromagnetic damping systems.

Magnetorheological (MR) damper is one of the most advanced applications of semi active damper in controlling vibration. Its use is increasing day by day in the vehicle suspension system due to its continuous controllability in both on and off state. MR damper's damping force can be controlled by changing the viscosity of its internal magnetorheological fluids (MRF). Applying an external magnetic field viscosity of MRF can be controlled. Electromagnet such as solenoid coil is normally used as external magnetic field source. These coils are attached inside the damper's piston head. When the damper operates these coils create heat. That's why the conventional MR dampers normally face wide variations in temperature. This change of temperature results decay in MRF viscosity as well as post-yield damping of the damper. In this paper temperature effect on MR fluids viscosity and on MR dampers performance represented analytically and experimentally. Due to this temperature effect the deviation of MR dampers performance has shown here experimentally. Also a novel technique for solving the problem explained clearly. 

Explicit model predictive control (MPC) enhances application of MPC to areas where the fast online computation of the control signal is crucial, such as in aircraft or vehicle control. Explicit MPC controllers consist of several affine feedback gains, each of them valid over a polyhedral region of the state space. In this paper the optimal control of the quarter car semi-active suspension is studied. After a detailed theoretical introduction to the modeling, clipped LQ control and explicit MPC, the article demonstrates that there may exist regions where constrained MPC/explicit MPC has no feasible solution. To overcome this problem the use of soft constraints and combined clipped LQ/MPC methods are suggested. The paper also shows that the clipped optimal LQ solution equals to the MPC with horizon N = 1 for the whole union of explicit MPC regions. We study the explicit MPC of the semi-active suspension with actual discrete time observer connected to the explicit MPC in order to increase its practical applicability. The controller requires only measurement of the suspension deflection. Performance of the derived controller is evaluated through simulations where shock tests and white noise velocity disturbances are applied to a real quarter car vertical model. Comparing MPC and the clipped LQ approach, no essential improvement was detected in the control behavior. Keywords Explicit model predictive control • soft constraints • combined clipped LQ control/MPC • deterministic actual observer • passivity and saturation constraints • semi-active suspension • magneto-rheological (MR) damper.

This paper formulates a Linear Parameter Varying (LPV) model for a semi-active quarter of car (QoC). The formulation depends on a new MR damper model which is based on the measurement of the maximum deflection velocity. In this device, the saturation is dynamic and it depends on the maximum current to apply and the velocity deflection. One scheduling parameter includes the variation of the damping coefficient and the dynamic saturation of the MR damper decreasing the conservatism of the model. Open and closed loop frequency responses comparison of the proposed model and a nonlinear QoC are given. The results shows that the new structure for the model is feasible and the nonlinear saturation can be used to weight the controller's output. In both tests, the applied current always is kept realistic.

This paper deals with the modelling of a magneto-rheological damper as a component of a quarter-car model. The objective is to provide an analysis of the transient and frequency behavior of the suspension system in order to evaluate the inherent linearities of two identified models: a complex one and a control-oriented one. The models have a common structure but the effect of the current and the dynamic behavior has different principle. The results show that the design of experiments is a key issue in the identification process. A quarter of a vehicle which includes a control-oriented damper model is identified as well-suited for the synthesis of controllers that perform well in terms of accurate frequency response when compared with that of a quarter-car with a semi-active suspension simulated with experimental data.

A novel approach to design a road adaptive semi-active suspension is proposed. Two scheduling parameters are considered: the road frequency and the type of road. A single corner vehicle model with a nonlinear dynamic model of the semi-active damper is considered. The suspension deflection and its derivative are used as feedback signals. Nonlinear simulations show that an adaptive suspension controller: Frequency-Estimation-Based with road Adaptation (FEBA) provides better comfort and road holding over different types of road. The improvement of the performance ranges from 5-10 %.

A novel approach to design a road adaptive semi-active suspension is proposed. Two scheduling parameters are considered: the road frequency and the type of road. A single corner vehicle model with a nonlinear dynamic model of the semi-active damper is considered. The suspension deflection and its derivative are used as feedback signals. Nonlinear simulations show that an adaptive suspension controller: Frequency-Estimation-Based with road Adaptation (FEBA) provides better comfort and road holding over different types of road. The improvement of the performance ranges from 5-10 %.

This paper discusses the research methodologies utilized for developing a suspension system for a four wheel-drive terrain vehicles. The main research methods can be identified as literature studies; design processes by applying CAD systems, numerical analyses methods, mathematical modeling and simulation, optimization of the mechanical systems, as well as the comparison, analysis, and evaluation of the obtained results. The proposed suspension system for the terrain vehicle was successfully derived at from a classic double wishbone control arm. Optimization of the suspension parameters for passive ones is performed by Multi Objective Genetic Algorithms, whilst for active damping force by employing Hooke-Jeeves non-linear programming method. On the basis of comprehensive analysis it is shown the active systems are more adequate. The proposed suspension design provides relatively small lateral wheel motion, zero camber angles, and effectively absorbs the vibrations caused by road exc...

The paper presents a car suspension's behaviour on dynamic testing conditions through theoretical and mathematical simulation on specific model, on the single traction wheel, according to the real vehicle and by experiment on the test bench by reproducing the road's geometry and vehicle's speed and measuring the acceleration and damping response of the suspension system on that wheel. There are taking in consideration also the geometry and properties of the tyre-wheel model and physical wheel's properties. The results are important due to the suspension's model properties which allows to extend the theory and applications to the whole vehicle for improving the vehicle's dynamics.

The main objective of applying robust active control to base-isolated structures is to protect them in the event of an earthquake. Taking advantage of discontinuous control theory, a static discontinuous active bang-bang type control is developed using as a feedback only the measure of the velocity at the base. Moreover, due to that in many engineering applications, accelerometers are the only devices that provide information available for feedback, our velocity feedback controller could be easily extended by using just acceleration information through a filter. The main contributions of this paper are the development and application of (a) a static velocity feedback controller design, and (b) a dynamic acceleration feedback controller design, to a benchmark problem which is recognized as a state-of-the-art model for numerical experiments of seismic control attenuation. The performance indices show that the proposed controller behaves satisfactorily and with a reasonable control effort.

For Vehicle suspension systems, needs for high force density and ease of design made hydraulic actuating systems commercially viable but inefficient, with bandwidth requirement very small. With active electromagnetic suspension system, the lapse of providing adequate bandwidth is compensated. The governing differential equations of displacement interactions in both spatial and time domains were used and CEFLT algorithms employed in the stability analysis. An optimum for reduction of the electromagnetic actuating force acts as trade-off for given vehicle-road terrain parameters. System instability occurs when the value is decreased and stability is maintained when increased.

The field of the Electric Vehicles (EVs) is becoming a strategic laboratory for new solutions focused on the energy saving and/or the renewable energy sources. Regenerative brakes are well known and already applied in recent cars. In this paper, instead, the attention is focused on a regenerative Shock Absorber (SA), which converts its vibration-induced by the road roughness-in electrical energy. The vibration is transmitted to an electric generator through a mechanical component. Finally, the produced energy can be stored in a super capacitor for a future use. The paper proposes a Simulink-based model of this regenerative SA and compares the energy performance when the vehicle travels roads with different roughness, scientifically defined by means an index, said IRI.

This work has been carried out to bring an innovative approach to the difficulties encountered in the production of NiTi shape memory alloys by powder metallurgy (PM). For this purpose, new binder system, which was water soluble, was used for production of NiTi green parts. The green parts were sintered at 1200 • C for 60 min, and then red parts were deformed at 1000 • C for 40 and 50% deformation ratios. To observe the characterization of the microstructure and hot deformation effects, X-ray diffraction, scanning electron microscopy, mapping, microhardness and density measurements were applied to the samples. Experimental results show that the rhombohedral phase (space group R3), which was a lenticular disk-like morphology (disks), was detected at 1200 • C sintered PM parts. 551HV microhardness and 5.85 g/cm 3 density values could be achieved with the 50% hot deformation ratio. Furthermore, intermetallic components such as Ni 4 Ti 3 , Ni 3 Ti, NiTi and NiTi (B 19), which directly affect the shape memory, are beginning to form in the microstructure with deformation.

The main objective of applying active control forces to base-isolated structures is to protect them in the event of an earthquake. An LMI-based control design is proposed to attenuate seismic disturbances in base-isolated structures under saturation actuators. Using a simplified model of the structure system, a control algorithm design is offered. Performance evaluation of the controller is carried out in a simplified model version of a benchmark building system, which is recognized as a state-of-the-art model for numerical experiments of structures under seismic perturbations. Experimental results show that the proposed algorithm is robust with respect to model and seismic perturbations. Finally, the performance indices show that the proposed controller behaves satisfactorily and with a reasonable control effort.

This paper deals with a uniform cantilever Euler-Bernoulli beam subjected to follower and transversal force at its free end as a model for a pipe conveying fluid under electromagnetic damper force. The electromagnetic damper is composed of a permanent-magnet DC motor, a ball screw and a nut. The main objective of the current work is to reduce the pipe vibration resulting from the fluid velocity and allow it to transform into electric energy. To pursue this goal, the stability and vibration of the beam model was studied using Ritz and Newmark methods. It was observed that increasing the fluid velocity results in a decrease in the motion of the free end of the pipe. The results of simulation showed that the designed semiactive electromagnetic damper controlled by on-off damping control strategy decreased the vibration amplitude of the pipe about 5.9% and regenerated energy nearly 1.9 (mJ/s). It was also revealed that the designed semi-active electromagnetic damper has better performance and more energy regeneration than the passive electromagnetic damper.

In this paper, the electromagnetic damper (EMD), which is composed of a permanent-magnet DC motor, a ball screw and a nut, is considered to be analyzed as a passive damper. The main objective pursued in the paper is to determine the EMD characteristics in order to improve the vehicle performance. The effects of the EMD characteristics on ride comfort and road handling are investigated first, and then, the effect of a spring installed in series with the EMD to alter the EMD performance is observed. In order to study energy regeneration, the nonlinear equations of the modified passive electromagnetic suspension system (PEMSS) are extracted. The results of simulation show that the designed passive EMD maintains the desired performance while vibration energy from the road excitation can be regenerated and transformed into electric energy.

For Vehicle suspension systems, needs for high force density and ease of design made hydraulic actuating systems commercially viable but inefficient, with bandwidth requirement very small. With active electromagnetic suspension system, the lapse of providing adequate bandwidth is compensated. The governing differential equations of displacement interactions in both spatial and time domains were used and CEFLT algorithms employed in the stability analysis. An optimum for reduction of the electromagnetic actuating force acts as trade-off for given vehicle-road terrain parameters. System instability occurs when the value is decreased and stability is maintained when increased.

A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model) with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions. 

31 SIMULATION OF SUSPENSION SYSTEM WITH ADAPTIVE FUZZY ACTIVE FORCE CONTROL Priyandoko G. & Mailah M. Department of Applied Mechanics, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia E-mail: ...

Suspension system is an important part of the car design, because it influences both the comfort and safety of the passengers. In this paper an active suspension using linear electric motor is designed. This article is also focused on experiments with active suspension-developing an appropriate input signal for the test bed and evaluation of the results. Second important aspect of the active suspension design is energy demand of the system. Modification of the standard controller which allows changing amount of energy required by the system has been designed. Performance of the modification was verified taking various experiments.

This work has been carried out to bring an innovative approach to the difficulties encountered in the production of NiTi shape memory alloys by powder metallurgy (PM). For this purpose, new binder system, which was water soluble, was used for production of NiTi green parts. The green parts were sintered at 1200 • C for 60 min, and then red parts were deformed at 1000 • C for 40 and 50% deformation ratios. To observe the characterization of the microstructure and hot deformation effects, X-ray diffraction, scanning electron microscopy, mapping, microhardness and density measurements were applied to the samples. Experimental results show that the rhombohedral phase (space group R3), which was a lenticular disk-like morphology (disks), was detected at 1200 • C sintered PM parts. 551HV microhardness and 5.85 g/cm 3 density values could be achieved with the 50% hot deformation ratio. Furthermore, intermetallic components such as Ni 4 Ti 3 , Ni 3 Ti, NiTi and NiTi (B 19), which directly affect the shape memory, are beginning to form in the microstructure with deformation.

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...