Diploma project [306219]

Diploma project

Coordinator: Prof. Dr. Eng. Catalin ALEXANDRU

Graduate: Ioana Denisa TANASESCU

Specialization: Industrial Design

Group: ID 17221

Fișa lucrării de absolvire/ licență/ proiectului de diplomă/ lucrării de disertație

Modeling and simulation

of an integral steering system for automobiles

Coordinator: Prof. Dr. Eng. Catalin ALEXANDRU

Graduate: Ioana Denisa TANASESCU

Specialization: Industrial Design

Group: ID 17221

Contents

Introduction

Aims and objectives of the diploma project………………………………………………………………………11

Research & Documentation

Introduction …………………………………………………………………………………………………………………13

Front and rear axle steering box …………………………………………………………………………………….14

Types of steering………………………………………………………………………………………………………….16

Existing four wheel steering …………………………………………………………………………………………..19

Advantages and disadvantages of integral steering…………………………………………………………..22

Market overview solutions……………………………………………………………………………………………..24

Concept Generation

Brief …………………………………………………………………………………………………………………………..28

Concept solutions ………………………………………………………………………………………………………..29

Concept selection ………………………………………………………………………………………………………..32

Selection process calculus ……………………………………………………………………………………………33

[anonimizat] ……………………………………………………………………………………..37

Product Development

Material Selection ……………………………………………………………………………………………………….40

Slide mechanism ………………………………………………………………………………………………………..43

Development-CAD model …………………………………………………………………………………………….48

Finite element analysis ………………………………………………………………………………………………..52

MSC Development ……………………………………………………………………………………………………..55

Simulation ………………………………………………………………………………………………………………….60

Conclusion

Project conclusions ……………………………………………………………………………………………………..64

Personal contribution. ………………………………………………………………………………………………….66

V II. Bibliography

Books ………………………………………………………………………………………………………………………..68

Studies ………………………………………………………………………………………………………………………68

Websites……… …………………………………………………………………………………………………………..69

I. Introduction

Objectives

1.Smart approach of the existing solutions in order to create the best mechanism.

2.Modeling and simulation of an integral steering system for an automobile.

Activities

Analysis of existing solutions

Multi-criteria analysis to identify the optimal solution

CAD modeling

Modelling as multi- body system

Modeling & simulation environment MBS

II. Research & Documentation

Introduction

What steering is?

Steering is the collection of components, linkages, etc. which allows any vehicle (car, motorcycle, bicycle) to follow the desired course. An exception is the case of rail transport by which rail tracks combined together with railroad provide the steering function. The primary purpose of the steering system is to allow the driver to guide the vehicle.

The most conventional steering arrangement is to turn the front wheels using a hand–operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal, to allow it to deviate somewhat from a straight line. Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rear–wheel steering.

In conclusion

Steering purpose is to enable the driver to control movement / command vehicle through the steering wheel. The main component of this is the steering system that multiplies the effort at the wheel of leader – for cassettes front axle that provides high maneuverability and stability of the car the steering rear axle, used in integral steering.

Front axle steering box

Steering boxes can be constant or variable gear ratio also this may be assisted electrically or hydraulically. A disadvantage of the transmission ratio cassettes is that constant effort to increase driver at the wheel steering angle. The use a variable ratio steering boxes can reduce or eliminate this disadvantage, if cassettes strictly mechanical (without assistance).

Rear axle steering box

Much research in the past decade have reported that the steering system is one of 4WS the most effective active chassis control systems, which can increase significantly stability, vehicle handling. Car manufacturers have persisted in the development of a 4WS system to provide high vehicle handling and stability, easing parking maneuvers, cornering tight and driving stability when changing lanes and cornering at high speeds.

Today this system 4WS or AWS is known as the integral steering. For such a system when all the wheels are turning at the same time, the rear wheels are either in the same direction with the front end – increasing the vehicle's stability or are turned in the opposite direction of the front – Increasing maneuverability.

Types of steering

Rack and pinion, recirculating ball, worm and sector

1 steering wheel;

2 steering column;

3 rack and pinion;

4 tie rod;

5 kingpin

Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a linear gear that meshes with the pinion, converting circular motion into linear motion along the transverse axis of the car. This motion applies steering torque to the swivel pin ball joints that replaced previously used kingpins of the stub axle of the steered wheels via tie rods and a short lever arm called the steering arm.

The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel". A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.

Older designs use two main principles: the worm and sector design and the screw and nut.

Both types were enhanced by reducing the friction; for screw and nut it is the recirculating ball mechanism, which is still found on trucks and utility vehicles. The steering column turns a large screw which meshes with nut by recirculating balls. The nut moves a sector of a gear, causing it to rotate about its axis as the screw is turned; an arm attached to the axis of the sector moves the Pitman arm, which is connected to the steering linkage and thus steers the wheels. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the screw and the nut; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are "recirculated".

The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was originally limited to smaller and lighter ones; due to the almost universal adoption of power steering, however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars.

The recirculating ball design also has a perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be entirely eliminated because it will create excessive internal forces at other positions and the mechanism will wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage.

Power steering

Power steering helps the driver of a vehicle to steer by directing some of the its power to assist in swiveling the steered road wheels about their steering axes. As vehicles have become heavier and switched to front wheel drive, particularly using negative offset geometry, along with increases in tire width and diameter, the effort needed to turn the wheels about their steering axis has increased, often to the point where major physical exertion would be needed were it not for power assistance. To alleviate this auto makers have developed power steering systems, or more correctly power-assisted steering, since on road-going vehicles there has to be a mechanical linkage as a fail-safe. There are two types of power steering systems: hydraulic and electric/electronic. A hydraulic-electric hybrid system is also possible.

A hydraulic power steering (HPS) uses hydraulic pressure supplied by an engine-driven pump to assist the motion of turning the steering wheel. Electric power steering (EPS) is more efficient than hydraulic power steering, since the electric power steering motor only needs to provide assistance when the steering wheel is turned, whereas the hydraulic pump must run constantly. In EPS, the amount of assistance is easily tunable to the vehicle type, road speed, and even driver preference. An added benefit is the elimination of environmental hazard posed by leakage and disposal of hydraulic power steering fluid. In addition, electrical assistance is not lost when the engine fails or stalls, whereas hydraulic assistance stops working if the engine stops, making the steering doubly heavy as the driver must now turn not only the very heavy steering—without any help—but also the power-assistance system itself.

Speed sensitive steering

An outgrowth of power steering is speed sensitive steering, where the steering is heavily assisted at low speed and lightly assisted at high speed. Auto makers perceive that motorists might need to make large steering inputs while maneuvering for parking, but not while traveling at high speed. The first vehicle with this feature was the Citroën SM with its Diravi layout, although rather than altering the amount of assistance as in modern power steering systems, it altered the pressure on a centering cam which made the steering wheel try to "spring" back to the straight-ahead position. Modern speed-sensitive power steering systems reduce the mechanical or electrical assistance as the vehicle speed increases, giving a more direct feel. This feature is gradually becoming more common.

Existing four-wheel steering’s

Active four-wheel steering

In an active four-wheel steering system, all four wheels turn at the same time when the driver steers. In most active four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels. There can be controls to switch off the rear steer and options to steer only the rear wheels independently of the front wheels. At low speed the rear wheels turn opposite of the front wheels, reducing the turning radius by up to twenty-five percent, sometimes critical for large trucks or tractors and vehicles with trailers, while at higher speeds both

front and rear wheels turn alike, so that the vehicle may change position with less yaw, enhancing straight-line stability. The "snaking effect" experienced during motorway drives while towing a travel trailer is thus largely nullified

Four-wheel steering found its most widespread use in monster trucks, where maneuverability in small arenas is critical, and it is also popular in large farm vehicles and trucks.

Some of the modern European Intercity buses also utilize four-wheel steering to assist maneuverability in bus terminals, and also to improve road stability. The first rally vehicle to use the technology was the Peugeot 405 Turbo 16. Its debut was at the 1988 Pikes Peak International Hill Climb, where it set a record breaking time of 10:47.77. The car would go on to victory in the 1989 and 1990 Paris-Dakar Rally, again driven by Ari Vatanen.

Honda had four-wheel steering as an option in their 1987–2001 Prelude and Honda Ascot Innova models (1992–1996).

Mazda also offered four-wheel steering on the 626 and MX6 in 1988.

Nissan/Infiniti offer several versions of their HICAS system as standard or as an option in much of their line-up. A new "Active Drive" system is introduced on the 2008 version of the Renault Laguna line. It was designed as one of several measures to increase security and stability. The Active Drive should lower the effects of under steer and decrease the chances of spinning by diverting part of the G-forces generated in a turn from the front to the rear tires. At low speeds the turning circle can be tightened so parking and maneuvering is easier.

Crab steering

Crab steering is a special type of active four-wheel steering. It operates by steering all wheels in the same direction and at the same angle. Crab steering is used when the vehicle needs to proceed in a straight line but under an angle, or when the rear wheels may not follow the front wheel tracks.

Passive four-wheel steering

Many modern vehicles have passive rear steering. On many vehicles, when cornering, the rear wheels tend to steer slightly to the outside of a turn, which can reduce stability. The passive steering system uses the lateral forces generated in a turn and the bushings to correct this tendency and steer the wheels slightly to the inside of the corner. This improves the stability of the car, through the turn. This effect is called compliance understeer and it, or its opposite, is present on all suspensions. Typical methods of achieving compliance understeer are to use a Watt's link on a live rear axle, or the use of toe control bushings on a twist beam suspension. On an independent rear suspension it is normally achieved by changing the rates of the rubber bushings in the suspension. Some suspensions typically have compliance oversteer due to geometry, such as Hotchkiss live axles or a semi-trailing arm IRS, but may be mitigated by revisions to the pivot points of the leaf spring or trailing arm.

Passive rear wheel steering is not a new concept, as it has been in use for many years, although not always recognized as such.

Advantages and disadvantages of integral steering

Advantages

Superior cornering stability: – the vehicle cornering behavior become more stable and controllable at high speed as well as on wet slippery road surfaces.

Improved steering response and precision: – the vehicle response to steering input becomes quicker and more precise throughout the vehicle enter speed range.

High speed straight line stability: – the vehicle’s straight –line stability at high speed is improved. Negative effects of road irregularities and crosswinds on the vehicles stability are minimized.

Improved rapid lane-changing maneuvers: – this is stability in lane changing at high speed is improved. In high speed type operation become easier. The vehicle is less likely to go into a spin even in situations in which the driver must make a sudden and relatively large change of direction.

Smaller turning radius: – by steering the rear wheels in the duration opposite the front wheels at low speed, the vehicle’s turning circle is greatly reduced. Therefore, vehicle maneuvering on narrow roads and during parking become easier.

Disadvantages

4WD systems require more machinery and complex transmission components, and so increase the manufacturing cost of the vehicle and complexity of maintenance procedures and repairs compared to 2WD designs

4WD systems increase power-train mass, rotational inertia and power transmission losses, resulting in a reduction in performance in ideal dry conditions and increased fuel consumption compared to 2WD designs

The handbrake cannot be used to induce over-steer for maneuvering purposes, as the drivetrain couples the front and rear axles together. To overcome this limitation, some custom prepared stage rally cars have a special mechanism added to the transmission to disconnect the rear drive if the handbrake is applied while the car is moving.

Market available solutions overview

Electro-hydraulic Power Steering System

To provide steering assistance, an electric motor mounted to the side of the rack housing drives a ball-screw mechanism via a toothed rubber belt. The screw engages a spiral cut in the outside of the steering rack. A torque sensor attached to the pinion shaft signals a control computer when to provide assistance.

Pinion Shaft

Steering Torque Sensor

Rack-and-Pinion Housing

Electric Motor

Ball-screw Mechanism

Steering Rack

Drive Belt

Hydraulic Power Steering System

The steering gear's internal cavity is divided into two chambers by a sealed piston attached to the rack. Applying pressurized hydraulic fluid to one side of the piston while allowing fluid to return from the other side to a reservoir provides steering assistance. A valve attached to the pinion shaft controls the hydraulic-fluid flow.

Hydraulic Control Valve

Pinion Gear

Hydraulic Pressure/Return Lines

Hydraulic Piston

Rack Housing

III. Concept Generation

Brief

The next phase in the project is the ideation or concept generation. This implies brainstorming, sketching and selection of the concepts in order to come up with the best viable solution. Taking into account the research, it is time to come up with diverse solutions.

The concepts discussed in the next section have to comply with the URS. Furthermore, we will explore different shapes, technologies and mechanisms that can help us come up with a better product that will serve its purpose.

After initial description resulting in a single concept which will be moved into the development phase.

Concept 1 – Single contour mechanism for integral steering

The simple mechanisms with one contour from this figure, where crank 1 receives the movement from longitudinal shaft, can achieve a backward-and-forward motion of the central element 3, this mean that these mechanisms can be used for the rear steering box.

To achieve symmetry for left / right pivoting, these mechanisms should be designed so that – at the initial position- crank 1 is along the base OB, at going straight (namely

ϕ v = 0, θ f ,s = 0 ).

Concept 2 – Double contour slider mechanism with two cranks

Central slider is positioned by two cranks – driven by gears with different speeds (About 2: 1) , the joints A and B of the cranks in the positions represented 1 – 2 – 3 – 4 – 5 causing central position slider. This way point M through line 1 – 2 – 3 – 4 – 5 according to the type of law direction demanded full course requiring good correlation length cranks and report the transmission gear.

Compared to previous mechanism single contour, double contour mechanism presented has the advantage of linear trajectories point M, it can be ordered directly on the steering rack mechanism.

Concept 3 – Slide mechanism

Slide mechanism with defined parameters L1 and L0. The element leader (1) acts through the shoe (2) on the slider (3), located in rotating oscillating mechanism of the type crank – rocker (l1 < l0). If L1 > L0, element (3) execute and complete his rotation mechanism of the type double crank result. Movement is gathered from the slide (3) – intersecting angle.

Concept Selection

Methodology

After coming up with the above described and sketched solutions, it is necessarily to sort them and discard all but one which will be taken into the development stage.

This analysis will be conducted as following:

Choosing the criteria after which we will rate and classify the concepts. The main source of inspiration for this can be the previously made URS and to that general criteria such as aesthetics & costs can be added.

Assigning a weight factor for each criteria. This will be performed using the FRISCO formula.

Rating

Calculations of the overall score for each proposed concept solution

Review of the results and selection of the final concept.

Criteria:

Level of interaction required -LOIR

Durability – DU

Ease of Manufacturing – EOM

Ease of use – EOU

Versatility – VRS

Easiness of operation – EOO

Cost – COST

Aesthetics – AESTH

Determining the relative weight coefficient (wk) of the criteria

Concept selection calculus

Each criteria will receive an order number starting with LOIR (n=1) and ending with AESTH (n=8). In the left part of the table, we will compare the criteria with each other. The values of 0, 0.5 and 1 will be assigned as following.

If criterion a is more important than criterion b => 1

If criterion a is of equal importance as criterion b => 0.5

If criterion a is less important than criterion b => 0

Legend

k = 1…..n – the order number of the current criterion

Pk = the global grade of criterion k, which is the sum of grades from row k of the matrix n x n = 8 x 8

Lk = the place of the current based on the Pk column results

Sk = number of criteria whose global grades are inferior to the global grade of the current criterion k

Wk = Absolute coefficient of weight of the current criterion k, calculated using the below formula:

FRISCO formula

wk = the relative coefficient of weight of the current criterion k

Next, each concept will receive a mark N ranging from 1 to 10 for each of the criteria.

The mark depends on the degree of which the concept satisfies the requirement/criteria of selection.

The final selection takes place into the below table. The score will be evaluated by multiplying the relative weight coefficient with the specific grade given above.

The scores of all criteria for each concept will be summarized and the results compared.

Absolute coefficient of weight calculations

Relative coefficient of weight calculations

The winner is concept 3

Concept 3- Slide mechanism

The chosen type of mechanism is a slide mechanism, below is the constructive solution for the steering box with linkage mechanism.

How it will work?

IV. Product development

Material selection

In the design process, it is important that the designer has a general knowledge of materials, their general properties and when it is appropriate or better to use them. The material choice can make or break the success and efficiency of a product. Everybody has heard about products that break easily and that are unreliable or products that are very well made, efficient and are loved by the people.

Furthermore, the material choice has a big impact on the overall aesthetics of the product. A product made out of cheap materials will most likely not be appreciated by the majority of users.

The car industry uses a tremendous number of materials to build cars, including iron, aluminum, plastic steel, glass, rubber, petroleum products, copper, steel and others. These parts are used to create everything from those small things we don't think about, such as dashboard needles and wiring, to the big stuff, such as the engine block or the transmission gears.

These materials have evolved greatly over the decades, becoming more sophisticated, better built, and safer. They've changed as new automotive manufacturing technologies have emerged over the years, and they're used in increasingly innovative ways.

The chosen material is steel

Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steel's base metal is iron, which is able to take on two crystalline forms (allotropic forms), body centered cubic (BCC) and face centered cubic (FCC), depending on its temperature. It is the interaction of those allotropes with the alloying elements, primarily carbon, that gives steel and cast iron their range of unique properties.

In the body-centered cubic arrangement, there is an iron atom in the center of each cube, and in the face-centered cubic, there is one at the center of each of the six faces of the cube.

Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the crystal lattices of iron atoms

The carbon in typical steel alloys may contribute up to 2.1% of its weight. Varying the amount of alloying elements, their presence in the steel either as solute elements, or as precipitated phases, retards the movement of those dislocations that make iron comparatively ductile and weak, and thus controls its qualities such as the hardness, ductility, and tensile strength of the resulting steel. Steel's strength compared to pure iron is only possible at the expense of iron's ductility, of which iron has an excess.

Slide mechanism

We know: ;

We have to find: ;

1: Crank

2: Pin

3.Motion slot

Transmission Law

Contour equation: (1)

=

;

(2)

(3)

The speed function:

We derive the equation depending on :

(4)

We multiply the relation (4) with

Acceleration function:

In extreme positions slide stops and reverses the sign of movement; in this position the handle and slide are perpendicular.

Development

CAD model

Software

These days, CAD modeling is the industry standard for creating parts and technical drawings. In few situations, people still use the traditional methods for doing such things.

CATIA delivers the unique ability not only to model any product, but to do so in the context of its real-life behavior: design in the age of experience. Systems architects, engineers, designers and all contributors can define, imagine and shape the connected world.

For the purpose of this project, we will be using the 3D part & Assembly module. For showcasing how some of the components will be manufactured and FEA to show how the product will behave when used by the consumer.

Parts & Assembly – Steering system

Bevel Gears

The bevel gears were shaped like a right circular cone with most of its tip cut off. When the two bevel gears mesh, their imaginary vertices is occupying the same point. Their shaft axes also intersect at this point, forming an arbitrary non-straight angle between the shafts. The angle between the shafts can be anything except zero or 180 degrees. Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called miter gears.

The bevel gears in our situations needs to transmit the movement from the vertical plane to horizontal plan in order to activate the lever through rotation.

Crank

The crank is activated by the bevel gears. The crank is transmitting the horizontal motion to the pin and slot.

The crank is an important motion element created from steel with two insertion spaces that are designed in order to hold the two elements and also to stay strong enough, to create the necessary motion.

Pin

The pin is the element that transmit the movement from the lever to the slot in order to activate the rear axle.

The pin is making this through translational movement inside the slot.

It was created with two grooves and three stoppers.

Motion slot

The slot is one of the most important elements because he is the connection between all the pieces. In the upper part he got a whole that is attached on the car body. The longitudinal part is the actual slot, where the pin is attached and transmits the movement from the lever. The next two wholes will be connected to the rear axle.

Finite Element Analysis

During the product development stage, there are a number of tests and simulations performed on the components prior to manufacturing in order to ensure that the components successfully perform under loads or stresses. This reduces the amount of material and hours of manufacturing time wasted on parts that will under-perform or fail when put under stress.

Therefore, engineers test parts extensively and they only manufacture them when they are sure that the dimensions are correct and the part geometry is right in order to withstand the expected stresses.

Furthermore, the model was extensively simplified in order to speed up simulation calculus time. Components were studied individually in order to have the best result.

Bevel gears analysis in simulation.

The analysis was made on each element from the final assembly in order to put the 100N pressure on each element in the possible stress points, to test the resistance of the components.

In this kind of assembly is vital to have strong and in the same time, flexible elements, that can resist a lot of years without deformation or other problems.

After this test we can say that the components are strong and in some years there will exist some problems, but with them the mechanism will be functional.

The body enclosure was fixed on the ground and the hinge part of the lid was considered fixed geometry.

The bodies were defined as in contact with no penetration.

MSC Model

Software

As the world's most famous and widely used Multibody Dynamics (MBD) software, Adams improves engineering efficiency and reduces product development costs by enabling early system-level design validation. Engineers can evaluate and manage the complex interactions between disciplines including motion, structures, actuation, and controls to better optimize product designs for performance, safety, and comfort. Along with extensive analysis capabilities, Adams is optimized for large-scale problems, taking advantage of high performance computing environments.

Utilizing multibody dynamics solution technology, Adams runs nonlinear dynamics in a fraction of the time required by FEA solutions. Loads and forces computed by Adams simulations improve the accuracy of FEA by providing better assessment of how they vary throughout a full range of motion and operating environments.

For the purpose of this project, we will be using this program in order to simulate the efficiency of the integral steering box in a “real” environment.

3D virtual model development

The real appreciation of the dynamic behavior of the car is to be taken considering everything as a whole, including both systems running – guidance – suspension (front and rear), because of mutual influences between decks through body.

So to simulate vehicle movement with wheel steering (dynamic analysis) using virtual prototyping platform was designed a virtual prototype of the system rolling – guide – suspension being modeled using ADAMS software.

The dynamic driving system – guide (suspension / steering) used in vehicles. It is particularly complex, including cinematic elements / objects (body, bars, directions etc.), elastic and damping elements (springs, pads, tires, shock absorbers), and compliant links.

Front axle suspension subsystems, contains two mechanisms quadrilateral symmetrically disposed about the longitudinal plane (xz) of the car. The 12 bodies that component model are: lower suspension arms, upper suspension arm, steering stub, gear and rack, wheel, damper, steering wheel and steering column.

Box front axle steering subsystem that has compounds in type to a rack pinion – steering rack and transmission from the box.

The rear axle suspension is similar to that of the front axle suspension. The element that are different are the connectors that will offer support for the integral steering mechanism.

The steering assembly was imported from CATIA and mounted in the car assembly. As motion the steering wheel is commanding the moves and then the steering column give the motion to the gear and rack that are giving the motion to the second rack. This rack is transmitting the vertical rotational motion to the longitudinal transmission shaft. After this the bevel gear are activated. The bevel gears are transforming the motion from vertical rotational motion to horizontal rotational motion. After this the crank activate the slider that make the motion slut to command the power to the connectors that are activating the rear axle.

The car body was created in CATIA and imported in ADAMS. The car body was created only for a more relevant simulation.

Simulation

The objective of the simulation virtual wheel steering vehicle is to demonstrate that both stability and handling are improved by using such a system. tests concerned are: achieving specific law of motion and maneuver back of the car.

For virtual prototype testing with a rear box to obtain the proposed law specific direction of movement, whole car was considered at rest. By the restrictions cinematic (“Motion Generator”) applied torque from steering wheel body, it was simulated with a 540 rotation of the while a second.

The most important test is to manage to turn the car on a two-lane width when the integral steering system is mounted, otherwise the vehicle will collapse.

The car with integral steering will get a much higher performance than a with classical direction. Here was presented a car turning maneuver on a two-lane width. The integral steering is reducing the vehicle turning radius, giving a bigger possibility for tight maneuvers. As we can observe the classical steering is not turning because of the small turning radius and is crushing.

V. Product development

Project Conclusion

This research was focused on structures strictly mechanical steering box capable of providing variable gear ratios or complex laws of motion for the full direction. Although the mechanical structure of these boxes can contain any type of mechanism (articulated gears, cam), the research aimed types of gear boxes for steering axle front and types of gear boxes and other components for the rear axle.

The solution presented " slider mechanism" for constructive box, excel in terms of constructive simplicity and classic technology.

Research & Documentation conclusions

Valuable yet concerning information was gathered in the research and documentation phase. In here were studied all types of steering boxes that are used in this moment or that were used. Also, a series of already existent problems were analyzed in order to find out their strengths and weakness.

Diploma project aims at the study of strictly mechanical auto steering (without hydraulic assist or electric drive) so present work can find practice application on popular vehicles with lower cost price.

Concept generation conclusions

Using the information gathered, the concept generation phase included 3 possible solutions which ended with a single concept taken further into development stage after a concept selection calculus proved it is the best candidate for this.

Development conclusions

In the development phase, the initial sketch was turn into a CAD model which was generically split into several components. The majority of them were designed as steel parts as it made sense that steel in this case is the best material solution in terms of costs and. A FEA analysis was conducted on the lid in order to observe how much stress it would resist before cracking, and how the piece will be deformed in time.

After this the assembly together with the car body were imported in ADAMS where there were assembled together with the front axe and rear axle. After this all connectors, motion, forces and turning angles were added; and the mechanism was able to sustain a test with and without integral steering.

In conclusion, the project enabled me to put to good use knowledge, design research and techniques as well as skills that I have acquired during my 4 years of university. It now provides a starting point from which a future product can be designed and put on the market.

Personal Contributions

Even though it is nothing revolutionary, my project revolved around the comparison of existing similar solutions on the market, taking a look at their advantages and disadvantages and come up with a way to improve them. Furthermore, I considered a balance between technology, aspect, ease of use, durability, ease of manufacturing and costs. My focus was on the integral steering mechanism that will make a different in the market as cost and efficiency.

In order to select the best solution, I created a market research in order to understand clearly all the mechanisms and after this to select the best mechanical idea. The calculations for the mechanism created a big difference into the developing part.

The CAD development and the MAF analysis can show the element durability and efficiency. In the MSC development, the mechanism was connected with the front and rear axles in order to make the simulation that will tell if the system is a useful one or not.

In conclusion, I have achieved my initial goals with room for improvement in the majority of areas and I consider this a project that would increase its grad.

VI. Bibliography

Books

P. Alexandru, I. Visa, D.Talaba, C.Alexandru, Cs, Antonya (2015) Modelarea static-dinamica a mechanismelor de ghidare. Brasov. Ediduta Lux Libris Dorin DIACO

ESCU Mircea EAGOE Codruța JALIU Radu SĂULESCU (2010) Product’s conceptual design. Brasov. Editura Universitatii transilvania Brasov.

Studies

Alexandru, P. Macaveiu, D. LINKAGE MECHANISM FOR THE REAR AXLE STEERING BOX WITHIN THE INTEGRAL STEERING

Petre Alexandru, Dragos Macaveiu and Catalin Alexandru. Structure of Linkages and Cam Gear for Integral Steering of Vehicles – World Academy of Science, Engineering and Technology 56 2011

Arun Singh, Abhishek Kumar, Rajiv Chaudhary, R. C. Singh of 4 Wheel Steering Systems to Reduce Turning Radius and Increase Stability. Department of Mechanical Engineering, Delhi Technological University, Delhi, IndiaStudy

Websites

https://en.wikipedia.org/wiki/Steering#Four-wheel_steering

https://en.wikipedia.org/wiki/Automobile_layout

http://www.autoevolution.com/news/integral-steering-system-explained-20848.html

http://www.caranddriver.com/features/electric-vs-hydraulic-steering-a-comprehensive-comparison-test-feature

https://en.wikipedia.org/wiki/Steel

http://www.howacarworks.com/basics/how-the-steering-system-works

http://www.autoevolution.com/news/integral-steering-system-explained-20848.html

https://en.wikipedia.org/wiki/Gear

https://en.wikipedia.org/wiki/Bevel_gear