Transcript
Preliminary Design Report:
Design and implementation of adjustable suspension for increased
vehicle performance
UVM Baja
Client: Mr. Floyd Vilmont and the UVM Baja team
Faculty Mentor: Dr. William Louisos
Design Team:
Sam Flinkström, ME
Owen Teetor, ME
Mackenzie Spencer, ME
15 December 2011
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Table of Contents:
2. Table of Contents
3.Working Problem Statement
4. Objective Analysis
Objective Tree
Figure 1: Performance
Figure 2: Adjustability
Figure 3: Weight
Figure 4: Cost
Discussion of objectives
Figure 5: Aggregate Ranking of objectives
Metrics
9. Function Analysis
10. Requirements
10.Design Options Comparison
14. Proposed Design
15. Analyses
21. Prior Art
22. Open Issues
22. Budget
23. Schedule
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Working Problem Statement
The purpose the problem statement is to clearly define the key objectives of which the
product being designed will satisfy. The problem statement is also a means by which to specify
specific and important limitations that the design must meet as well as note important attributes
and characteristics are to be included in the design. Beyond the scope of the design, the problem
statement is also used to clearly define who the user will be of the end product, and who the
product is being designed for, the client. The problem statement is a constantly changing aspect
of the design process and is updated continually to reflect the aforementioned goals and
characteristics of the design. It is therefore given the named „working‟ problem statement.
In the case of the design being considered in this report, the following working problem
statement has been developed over the course of the preliminary design process which has taken
place over the past fifteen (15) weeks.
The Mini Baja team needs a suspension that has been purposely designed for the unique
vehicle dynamics and exceptionally difficult course conditions it is put through. The
suspension has to be easily adjusted in order to remarkably perform in each of the
individual race events. The suspension needs to be designed with the goals of being
durable, lightweight and cost effective for a team with a limited budget.
Over the course of the last fifteen (15) weeks, this problem statement has evolved in a few major
ways. The original statement presented to us was very specific in nature and left no room for
innovative solutions to the problem to exist. The initial statement also included what was named,
“project tasks.” The project tasks were a list of implied solutions to the problem which were bias
towards a specific solution, again limiting design possibilities. After eliminating these
shortcomings of the original problem statement, we had our first working problem statement.
Throughout the remainder of the preliminary design period the statement incurred more subtle
refinements. These changes resulted from the formulation of the main objectives of the design
which are reflected in the current statement. The overall goal of the design, however, remains the
same as in the original statement – design an adjustable suspension of exceptional performance
in the baja race events.
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Objective Analysis
From the problem statement, many objectives that when satisfied will yield a successful
design can be brainstormed. The means by which to obtain useful objectives is to consider each
objective together with the others and rank them based on importance. After brainstorming
sessions where possible objectives were thought up, each of the preliminary objectives was
ranked by the design team members. The result of this ranking was a list of four high level
objectives which were to be considered in the design process. The remaining objectives were
either eliminated from contention, or placed on a lower level of importance.
From this brainstorming and ranking, a means of organizing this data, known as an
objective tree, was employed to more easily visualize these new goals. Beyond statement of the
four main objectives, the objective tree aids in defining various constraints to be considered in
the design as well. The final design objective tree is presented below in four (4) figures, each of
which represents a single main objective; Performance, Adjustability, Weight, and Cost.
Figure 1: Performance portion of objective tree
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Figure 2: Adjustability portion of objective tree
Figure 3: Weight portion of objective tree
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Figure 4: Cost portion of objective tree
The four objectives as presented in figures one (1) through four (4) represent the four
objectives chosen to be the key objectives of the suspensions design. Under each objective are
less important sub-objectives that fall under the main objective. These sub-objectives are not less
important to the design, per say, but instead help to further determine the success of each key
objective to the design. As one moves further down the pedigree to the right, the cells contain
more specific objectives and eventually constraints. With knowledge of the purpose behind this
design tool, the next few paragraphs attempt to explain each of the key objectives, why they were
chosen, as well as the associated constraints.
As mentioned on page four (4), a method of ranking was performed to quantify the
importance of each key objective to the overall design. Figure five (5) details the result of an
aggregate ranking method which was used to do this. In the table, each design team member
ranked each key objective to one another; giving ones (1) to the more important and zero (0) to
the less important. Cells with one-half (½) represent equal importance of objectives.
Figure 5: Aggregate ranking of key objectives
Performance
The performance objective is ranked the most important of all the objectives, this is
because the overall goal of our design is to come up with a suspension that will help our car
handle and perform better in our races, if our design cannot perform then it cannot be deemed
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successful on any level while with the others objectives while very important are less key to the
success or failure of the design.
Adjustment
Second to performance in terms of importance to design is adjustability, because our
design is going to be subjected to many different race conditions it is important that the geometry
can be easily and effectively adjusted under race conditions. This means that our adjustment
method has to be strong enough to with stand the forces the suspension is subjected to but also
must be easily accessed and have a fairly straight forward and simple method to enable effective
and speedy adjustment.
Weight
The weight of the overall design falls in the lower half of the key objectives in terms of
importance. The designs weight is important because the power of the vehicle is limited. The
weight of the design must not reduce the level of power available to drive the vehicle by any
significant amount. Simply, weight is never a desired characteristic to any vehicle design. This
is, however, not to be confused with a low center of gravity.
Cost
Lastly is the cost of the design. Because the UVM Baja team is working on a finite
budget, cost is of importance to the design and is a major constraint. Main factors affecting costs
appear in figure four (4) and include part choice (custom or off-the-shelf), complexity - reflected
in manufacturability, and amount of design testing (i.e. prototyping). The main constraint for
cost is the budget of the team.
The cost of the design is further an important objective due to the fact that the SAE Baja
static competition events include a cost report section. In this competition, the design of each
vehicle is examined and the marketability of the vehicle to consumers is judged. The cost to
manufacture the vehicle on a mass scale is one aspect of this competition.
Worth noting is the crossing between the cost objective and the other three key
objectives. Although maintaining significant independence from them, the following links can be
made. The more adjustable the design, the presumably more complex it will be and therefore
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more expensive. The lighter the material used, while maintaining strength, the more expensive
said material will be.
Constraints
Constraints for or project include that it has to complies with SAE Mini Baja standards for
material selection and hardware, the steering rack must be located within the frame of the vehicle
but the tie rods must be at an angle so that they don‟t interfere with the frame, and the overall
width of the vehicle with tires must be less than that of a full size truck bed.
Metrics
With each objective defined and explained, there need be a means of ranking the success
of the design in terms of each key objective. A scale on which the achievement of a design‟s
objectives can be measured is known as a metric. Many different types of metrics exist.
Examples include ordinal, ratio, interval and multidimensional scales. For each of the key
objectives of the design a metric is specified.
To gauge the performance of the design, timed trails will be performed on a race course
set up behind Centennial Field. The course will include obstacles which will test the suspension
systems durability, cornering capabilities, vehicle top-speed, vehicle braking power, and other
aspects of the suspension. Beyond these trails, the team‟s race results from the three national race
events will measure the suspensions performance in comparison to ninety-nine (99) other designs
by other Baja teams.
The adjustability of the suspension will be measured in numerous different ways. Each
means is defined by a specific degree of adjustment. Namely; castor, camber, camber gain, and
closeness to proper Ackermann geometry. Success will be judged also by the accuracy of the
vehicle suspension to the computer design. From the computer model, values of camber, camber
gain rate, and castor will be tabulated for numerous configurations of the suspension. From these
values, plots versus level of shock compression will be made. This is a highly multidimensional
way of measuring the adjustability of the suspension. The advantage of using this method is that
the geometry of the system will be known for many different configurations. Therefore, in a race
setting the system can be tuned to allow maximum performance in the given race setting. For
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example, for an event where the suspension will be making fast turns under medium shock load
such as in the „land maneuverability‟ event, from the estimated load and level of compression in
the shock we can adjust the suspension to, at that specific shock level and turning angle, have the
most desired geometry – camber, castor, and camber gain.
Weight of the suspension system is easily measured by a pound scale. It will also be
measured in comparison to the estimated weight given by the computer design analysis. The
weight will also be measured in how it is distributed from wheel to wheel. It is desired that the
design distributes the vehicles weight evenly from side to side as well as front to back.
Cost will be measured by how well the end design follows the set budget as well as on
the score received on the cost report section of the static competition mentioned previously.
Function Analysis
Black Box
A Black box is a useful tool which expresses the overall function for the design in terms
of the conversion of inputs to outputs. On the left side of our black box we have all of our inputs
that affect how our car drives and on the right side we have the complementing outputs that
describe how the car drives.
Car Turns
Steering wheel
Hits Bump
FUNCTION
Camber Shim is inserted
Car Drives
Shocks compress/rebound
Initial negative camber increased
Initial camber increase
A-Arm Bar moved down
Increase camber with turning angle
Castor shims moved back
Figure 6: Black Box
For the input of spinning the steering wheel, the output is the car will turn. When the
wheels hit a bump, the shocks will compress or rebound. When a camber shim is inserted, the
initial negative camber will be increased. For the input of the A-Arm bar moved down on the
mounting plate, the out put is the initial camber is increased. When the castor shims are moved
back, an increase in camber change with turning angle is accomplished.
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A more detailed description of our function can be seen in our sub-function tree diagram
shown below. This tree shows every intermediate step inbetween the initial input and the final
output. When the car hits a bump, first the tire will absorb some energy by compression. Next,
the A-arm will pivot about the connection with the frame. Then there will be frictional losses in
the bushings and bearings while the a-arm is flexing. The suspension shock will lastly compress
and hopefully absorb all remaining energy. When a castor shim moved back, first the upper aarms will move rearwards which will cause the castor angle to increase. This will increase the
camber change with the turning angle of the wheel.
Figure 7: Function means tree
A function-means tree is a useful tool for investigating possible means for each function.
When we made our function-means tree it was important that we formulated our means after
performing a functional analysis. We didn‟t want preconceived means to determine our design
or define the functions.
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FUNCTION
MEANS
Turn Car
Move steering wheel
Increase the camber gain
Move A-arm down
Increase the camber when turning
Move castor shims back
Maintain ground contact
Shocks
Increase initial negative camber
Insert camber shims
We performed an analysis on each function before determining the best possible means to
solve the problem. There are many ways and many different designs that can increase the initial
negative camber of the wheels. We studied the problem and determined that inserting a set
number of camber shims between the frame and the upper a-arm pivot bar was the simplest and
best solution.
Requirements
As seen in our Functions/Means Tree (figure 7) most of the functions presented have to
do with how the suspension geometry is adjusted which is a major factor in meeting one of our
main Design requirements which is for the suspension to provide good handling. Our other
requirements for our design include it being designed with large safety factors in all components
to ensure that it can survive the hardest hits it will take over the course of race, another
requirement that we placed on our design is that it be fairly low cost by utilizing some of the
shelf parts and be able to be manufactured in a way that is fairly straight forward (not require
specialized or expensive fabrication techniques) in order to make this an effective solution for
our team. Our last major requirement is that while we want our design to be rugged enough to
survive the races we want it to be as light as possible, this is desirable because a major factor in
determining how a vehicle handles is the amount of un-sprung weight and seeing as roughly half
of our design will be un-sprung there are handling advantages to be gained.
Design Options Comparison
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Creating Morphological and Pugh charts enabled us to decide which design we are
moving forward with. A morph chart is a way of comparing different solutions to different
problems. On the side column is a list of functions, attributes, or features that are essential to the
design. This list comes from our functional analyses and objectives list utilizing our aggregate
rank ordering results. For each feature we made a list of means. We used our function means
tree and brainstorming.
Features
Means
steering
hydraulic
Rack and pinion Lever arm
Handle bars
Steering
wheel
Shocks
Air/gas
spring
Oil
independent
Linked
geometry
Uneven
Lower A
Single A-arm
MacPherson
Multilink
Double
Upper I
wishbone
Joining to
welding
bolting
pinning
material
aluminum
steel
Carbon fiber
Location of tie
Behind
In front of
Above wheel
Below wheel
rods
wheel hub
wheel hub
axis
axis
Adequate
Length of
Wheel size
Shock travel
clearance
suspension
Bolts
Incremental
frame
arms
Speed of
Quick
adjustment
disconnect
Shim sets
shimming
Figure 9
This chart is very good at showing how many different design possibilities there really
are. The different features we focused on were steering system, shock type, geometry, how the
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system will be joined to the frame, what material will be used, the location of the tie rods, how to
achieve adequate ground clearance, and the fastest adjustment method. Just looking at the
location of the tie rods, we had four options for the means. We could either attach them behind
the wheel hub, in front of the wheel hub, above the wheel axis, or below the wheel axis.
The next step after making the Morph chart is making a Pugh chart. A Pugh chart is a
way of evaluating different optional designs relative to each other in a structured way. We used
a Best-of-class Pugh chart where we assigned an integer value to each design based on its ability
to meet each objective.
Constraints
and objectives
Horizontal
rigidity
Simplicity
Camber Gain
Unsprung
Weight
Ease of
adjustment
Totals
Uneven
Double
Wishbone
1
Lower A-arm
Upper I-Arm
Single A-arm
MacPherson
Multilink
2
3
2
1
2
1
2
2
1
2
1
4
1
3
3
3
4
1
2
1
1
2
2
3
7
8
11
13
11
In our Pugh chart we evaluated different designs for the suspension geometry. The
objectives we were looking for were horizontal rigidity, simplicity, camber gain, unsprung
weight, and the ease of adjustment. We looked at five different designs. For the horizontal
rigidity, an uneven double wishbone and multilink system were best with a single A-arm being
weakest. The simplest design was single A-arm and most complicated was multilink. The single
A-arm was the worst for camber gain but also had the lightest unsprung weight. All designs
could be easily adjusted except for the multilink system. Overall the best possible solution was
the uneven double wishbone. This was our original thought for our design and this Pugh chart
confirmed our decision.
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Proposed Design
For our design (Figures 11,12,13) we started out
Figure 11
with a basic symmetrical double wishbone
suspension. Some components in our design we
already have and have been used on past cars these
components include the hubs and spinals, the ball
joints and the bushings at the end of the A-arms.
Everything else we designed form the ground up,
the upper and lower A-arms are a fairly simple yet
effective design and will be constricted out of
cromoly tubing ( 1”x.065” for the lowers
and 3/4”x .12” for the uppers) and 3/8”
plate steel for the ball joint mounts. The
Figure 12
Part that had the most design work put
into it is the a arm Pivot bar (Figure 14)
and will be turned/milled from a single
piece of 1”x1” 4130 steel stock, this will
be bolted to the our mounting plate
(Figure 15) which will be constructed
from 1/4” steel plate stock. The function of
turning the car will be accomplished by the
tie rod acting on the backside of the hub
generating a moment that will rotate the hub
about the ball joints. The function of
increasing initial camber is accomplished
through the use of camber shims which are
inserted between the A-arm pivot bar and the
chassis mounting plate ( More for increased
camber less to decrease). The function of
Figure 13
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changing the camber gain rate is accomplished by
Figure 14
moving the A-arm pivot bar up and down on the bolt
holes located on the chassis mounting plate (move
down for increased rate, up for decreased rate). In
order to affect the rate of camber gain when the
steering wheel is turned you change the castor angle by
moving the shims in the A-arm pivot bar(move them forward
for more castor and thus more camber gain and vice versa).
Figure 15
Analysis
To ensure that our design would meet all our requirements, we conducted three analyses
on different components of our design. We analyzed the upper A-arm, the lower A-arm and the
mounts for supporting the shock. Based on our results we could determine the material needed,
the thicknesses required and other dimensions to ensure functionality of our design.
Analysis of upper A-Arm
To begin the analysis of the upper A-arm in our suspension system, the reaction forces at the
upper ball joint must first be calculated. To do this, the double wishbone suspension is modeled
in two-dimensions. It is possible to model the system this way due to the symmetry of the design
as well as the fact that most of the forces which will be acting on the system will be in either the
side-to-side or up-and-down direction. The up-and-down direction is defined as that which the
shocks majorly travel during compression. And side-to-side is the direction normal to the
straight-forward movement of the car. Beyond the assumption that most of the forces
experienced by the suspension is in these two dimensions, research on previous analyses of this
type of suspension shows that this is one of the best and simplest means of modeling such a
system. In this analysis, the camber gain on the car is zero degrees, the shock pressure at full
extension is 50 psi, and for the analysis are compressed five inches past full extension to
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simulate hitting an obstacle. From experience with this particular shock system these pressure
and displacement values are known to be plausible.
The diagram below is of the simplified double-wishbone system with rough dimensions
representing our current working design. Each dark triangle represents a pinned connection in the
system each connecting to the main frame of the car. Further, points (A), (B) and (C) are also
pinned connections. The upper A-arm extends from point (A), and the lower from point (B).
Between points (A&B) is the wheel hub. The large rectangle to the left is the car wheel/tire.
Point (G) represents the ground. At point (G) the connection is a roller (not pictured) with
vertical forces applied from below, and horizontal forces applied from the side of the tire at
ground level.
From this diagram, it is possible to now construct accurate free-body diagrams for the various
components of the system; namely, the upper and lower A-arms. The next section details the
analysis and results for the upper A-arm.
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Upper A-Arm Preliminary Analysis
Presented below is a free-body diagram for the rigid connections between the tire and wheel hub.
This body is allowed to pivot about point (B) in all directions via a ball joint at point (B). A
varying ground force is translated through the tire/wheel, into the wheel hub, and then into the
upper A-arm at point (A). Forces are represented as arrows, and the points are as defined in the
previous section of this assignment.
The input forces to this system are at point (G). The vertical
force represents the weight of the car and driver as well as any
impact force due to the car hitting an obstacle, e.g. a rock, log,
“carnage” from other cars, or landing on the ground after
becoming airborne. The horizontal force is mainly composed of
the force required to overcome inertia during turning, but also
from hitting obstacles as well or side swiping other cars.
In terms of numerical values for these forces, we have
estimated that they are 577 lbf in the vertical and 325 lbf in the
horizontal. The vertical force was estimated from the known
weight of the car with a driver as well as from the shock force
chart provided by the manufacturer of the shocks. The
horizontal force was approximated using a fixed velocity,
turning radius and mass in conjunction with the equation for
centripetal force. The result was divided by two to reflect the distribution between the left and
right front tires.
With the input forces known, a summation of moments is performed about point (B) to
find the reaction force at point (A). A coordinate system is chosen such that there is only one
unknown force, the other being in line with point (B), thus creating no moment.
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With the reaction force in the horizontal direction known, the next step is to find the vertical
reaction force. However, the geometry of the double wishbone suspension is such that the
vertical forces are small enough to neglect. This is due to the location of the shock on the system.
It is connected to the lower A-arm and absorbs all the vertical force. Therefore,
The input forces on the upper A-arm are now all known and the next step in the stress analysis of
the upper A-arm to isolate it in the diagram and perform another summation of forces to find the
reaction forces at the inboard side of the arm. The diagram below shows the upper A-arm with
the applied force at (A), and the reaction forces at (E).
The input force is decomposed into a normal and tangential component to the arm which is
inclined at 22 degrees from the horizontal, yielding the following equations of equilibrium.
The values just obtained are normal and tangent to the arm, making it possible to reorient the
diagram so it is horizontal with forces in a new xy-plane as seen in the diagram below. The arm
is modeled now as a simply supported beam for ease of calculation. Because the only force on
the arm act at the pins and it is assumed that the mass of the arm is negligible compared to the
input forces, the main concerns in the analysis are buckling and/or failure in compression from
the tangential forces. Therefore, these cases will be looked at in detail below.
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Material and cross-section of the A-arm are defined to be as follows. The member is
tubular with an outer diameter of 0.625” and wall thickness of 0.100”. The material of the A-arm
is AISI 4130 chromium-molybdenum steel with mechanical properties as defined by the table
below from efunda.com. These choices of material and shape are estimated to be significant for
our design from consideration of previous year‟s cars designs and their success. They are a
baseline for engineering this year‟s design.
Compression Analysis
To engineer the arm for the estimated load, we assume that the stress on the arm is a set amount.
Using the value of yield strength in the table and a factor of safety of 4, the desired stress is
then
. In conjunction with the known tangential force of
and the equation for normal stress,
the critical area of the arm is
Thus for a hollow tube with
,
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Buckling
In order to find an adequate diameter and wall thickness for the A-arm an analysis must be
performed to find the moment of inertia needed to resist buckling under the pure compressive
load. To perform this analysis the general equation for buckling is used.
Where (F) is the critical force needed for buckling to occur, (E) is the modulus of elasticity, (I) is
the moment of inertia, (K) is the column effective length factor, and (L) is the length of the free
column. Again using a safety factor of four, the critical force is then defined as:
Further,
. The moment of inertia is then solved for:
For a tube of inner and out diameter of
, respectively, the moment of inertia is equal to
Solving for I=91 yields
The two parameters for the design of the a-arm in terms of cross-section are now known. For the
design to be successful,
and
.
Therefore, if we retain the current designs outer diameter of 0.625” or 15.875 mm, the wall
thickness required is governed by the compressive strength of the material to be 0.005” or
0.127 mm. The materials resistance to buckling is greater than that of failure in compression.
Although a factor of safety of four has been built in to this analysis, the results may not be
adequate for our application due to other loading on the a-arm such as an impact force that is
experienced normal to the arm if the car were to hit a tree or a rock should fly up and hit the arm.
The next step in the mechanical analysis of this component is to do an impact/deflection analysis.
Another analysis that could be worth performing could be one that examines fatigue in the
material due to cyclic loading.
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Prior Art Review
The research we conducted earlier in the year on prior art was very helpful in designing
our suspension. We compared related products and articles to get a good understanding of what
is out there and could be used to help us. We also researched multiple patents regarding off-road
suspension design to ensure that we were not infringing upon anyone‟s ideas.
One of the best tools we use from our prior art review was a simple 2D suspension
modeling program that can be used to model a simple wishbone suspension geometry. We found
this program through racing development sites online at
http://www.racingaspirations.com/?p=286. This program was very helpful in determining the
length of our upper and lower A-arms. In the program we could adjust the upper arm‟s pivot
point and see how much camber would be gained through travel.
Existing patents are always helpful in designing your own product. One patent that was
of particular interest was titled “Variable camber suspension system.” The patent is a description
of a system that can adjust the camber of each wheel separately. It does this by extending or
retracting an actuator rod in and out which adjusts the position of the upper arm pivot point
giving the wheel less or more camber. Our design is similar in that we can adjust the camber of
each wheel by moving the upper arm‟s pivot point. The difference is that we are placing a
different number of shims in-between the frame and pivot point to move it in and out. The
patents design can adjust the camber very precisely using the rods while we are limited by
intervals of the thickness of our shims. The patents design can also be adjusted with no tools
while driving.
Many standards and regulations exist for design of our car. The main regulations come
from the SAE Baja rules which describe the overall dimensions of the vehicle. This affected
where our suspension mounting points would be and what length our a-arms could be to give
proper ground clearance and overall width.
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Open Issues
Open issues that we still have include finalizing the modifications we are going to make
to the frame to accept the new suspension design, we designed it on a simple jig in SolidWorks
and now just have to figure out the most effective way to incorporate it into our current frame
design. Another open issue is deciding how best to integrate the lower shock mount onto the
lower A-arm, we know the position that it should be located at relative to the ball joint but have
not finalized what method we will use to bridge the gap between the two A-arm tubes and
provide a location for suspension tabs to be mounted to. The last of our open issues and perhaps
the most challenging is that of correcting our Ackermann geometry, we have yet to decide what
we are going to do whether it be to extend the arms of the steering rack or by some other method.
Budget
Item #
Description
Size
Quantity
Unit Price Total Price
Mechant
Referance
1
4130 Bar stock for machining
A-Arm Pivot bars
1"x1"x12"
2
$
17.73 $
McMaster
6552K311
2
3
4
5
6
4130 Tubing for Lower AArms
4130Tubing for Upper AArms
4140 Plate Stock for Ball
Joint Fanges
1"x.065"x1"'
96
$
0.32 $
30.72 Chassis Shop 41-1-065
.625"x.12"x1"
96
$
0.59 $
56.64 Chassis Shop 41-58-120
.375"x3"x36"
1
$
51.60 $
51.60
McMaster
6554K233
Aluminum Plate for Shims
.5"x6"x12"
1
$
20.17 $
20.17
McMaster
8975K441
Steel Plate for Mounting
Brackets
.25"x3"x12"
1
$
18.91 $
18.91
McMaster
6554K151
Total Cost
35.46
$ 213.50
P r e l i m i n a r y D e s i g n R e p o r t – U V M B a j a | 23
Schedule
The important Milestones for our project are:
Frame complete 1/31/12- We want to have the major members that we have to
add to or frame bent and welded by the end of January so we can focus on the
other major fabrication aspects of our design
All Components Machined 3/19/12- We want all components of or design
machined by this date so that we can assemble the on the frame and perform some
preliminary tests before the frame is sent off for paint
Assembly Complete 4/9/12- We want to have our design assembled on the car by
this date to provide at least a week to test and fine-tune the suspension before our
first race.
Leave for Race 4/16/12- This is the date we depart for our first race the car must
be driving at this point .
P r e l i m i n a r y D e s i g n R e p o r t – U V M B a j a | 24