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Cleveland State University SAE Baja Car Design Report Cleveland State University SAE
ABSTRACT The following report details the specifications and design aspects used in manufacturing of an off-road Baja vehicle. Some alternatives were also discussed throughout the design process. The vehicle is meant to be accepted for manufacturing and compete in the 2014 Baja SAE Auburn competition. Rules and standards for the vehicle design are set forth by the 2014 Baja SAE rules.
enthusiast. The vehicle must be safe, easy to transported, easy to maintain, and most importantly fun to drive. Rough terrain and adverse weather conditions should not be a problem for the vehicle. The Baja vehicle should be attractive to consumers because of its aesthetics, performance, reliability and low cost of maintenance. Lastly, it should be able to be manufactured using predominantly semi-skilled labor and standard machine tools.
CUSTOMER REQUIREMENTS INTRODUCTION The Baja SAE competition is yearly facilitated by The Society of Automotive Engineers (SAE) in order to provide students with a hands-on educational opportunity to engineer and build a prototype off-road vehicle. It provides the teams with a project involving the planning and manufacturing tasks found when introducing a new product to the consumer industrial market. The competition goals reflect the “real world” demand for a balance between performance and cost. Simultaneously, the focal point of the project will be centered on the engineering process and the methodology behind the design components. A fictitious firm evaluates the design teams on many different levels. The firm assesses the individual concepts, manufacturing processes, and cost effectiveness to determine how well each teams’ solutions fall within the preset regulations. The team assessments are compared to the performance of its car. Each team has the individual goal to function as one well-knit unit which will design and build a prototype proof of concept. This prototype must be developed within the official rules and guidelines described by the SAE officials.
ENGINE—The Baja car must utilize an unmodified, ten horsepower, air cooled, four-cycle, OHV Intek Model 205332 Type 0036-F1 engine made by Briggs & Stratton. Other acceptable engine models include: Model 205432 Type 0536-E9 , Model 205332 Type 0536-E9 or Model 205332 Type 0536-B1. No modifications may be made except for the relocation of muffler, intake air filter, and fuel tank. Only the single fuel tank supplied must be used.
Figure 1—Briggs & Stratton Intek Model 20
The design team is competing to have its design accepted for manufacture by a fictitious firm. This “firm” judges each Baja vehicle on its design goals and if each goal has been accomplished. The team functions as one to design, build, test, and compete within the requirements set by the 2014 Baja SAE Series officials.
Muffler—Any rerouting of the muffler must use 1.25 inch inside diameter tube, and still use original muffler.
The purpose of the competition is to design and build a prototype of a rugged, single seat, off-road recreational vehicle. The target market for the vehicle is geared toward the non-professional, weekend, off-road
Fuel Tank—The fuel tank may be repositioned as long as the fuel lines are not larger than the stock lines supplied (i.e. ½” outer diameter and ¼” inner diameter).
Air Filter—If air filter relocation is chosen, remote kit 792349 can be used, along with choke shaft 695329 and base 699960, all from Briggs & Stratton.
ROLL CAGE—The purpose of the roll cage is to allow minimal space surrounding the driver in order to prevent the driver from being seriously injured during regular operational usage. In the event of an accident the roll cage must remain structurally sound.
guards and safety. Specific details regarding these design components will be discussed further in latter sections of this report.
Other requirements are: Sharp edges are strictly prohibited on any part of the roll cage and should be shielded or padded; Minimum of 41 inches above the seating surface to the bottom of the roll cage tubes; Material for the cage must have bending stiffness and strength that is greater than or equal to the standard of one inch outside diameter 1018 steel tubing with a wall thickness of 0.120 inch; Material must have at least 0.18% carbon content. The aforementioned is stipulated in the 2014 Competition Rules.
The Baja vehicle will undergo several dynamic and static tests in the competition. The points earned in these tests, or events, will determine how well the vehicle was designed and performed. The goal is to place the highest in as many events as possible. The best team receives a small cash prize along with a fictitious contract for the manufacturing of their Baja car.
COCKPIT— “The cockpit must be designed to (1) protect the driver and (2) permit easy driver exit in an emergency.” (2014 Baja SAE Rules, B9.1). Firewall—The use of a firewall is required. The firewall must be made of sheet metal at least 0.020 inch thick and separate the cockpit from the engine compartment (B9.3). Belly Pan—A belly pan must extend the entire length of the cockpit so that the operator of the vehicle is not exposed to the ground or miscellaneous debris. Exceptions for the belly pan include: Expanded metal, Fabric, Perforated panels (B9.8). Body Panels—Body panels must also be mounted on the sides of the vehicle to prevent debris from hitting the driver. No gap larger than 0.25 inch can exist between the panel and frame. Body panels must be made of plastic, fiberglass, metal or similar material (B9.7). Fire Extinguisher—The cockpit must be equipped with a fire extinguisher with a minimum UL rating of 5 B-C. To add safety to the driver, all steering and suspension links must be shielded in case of failure. Foot pedals must be mounted and positioned to avoid the possibility of the driver getting his or her foot trapped in any position. BRAKING SYSTEM—The braking system on the Baja car must include a single pedal hydraulic system that provides braking to all four wheels. This braking system consists of two independent hydraulic systems, one for two front wheels, and the other for the two rear wheels. The Baja vehicle must also have a functioning brake light that is SAE “S” or “U”, which is a standard used for lighting identification. OTHER COMPONENTS—Other components that must be designed are the steering, suspension, and power transmission systems. SAE does not put forth specific requirements for these components, with exception of
DESIGN CRITERIA
DYNAMIC EVENTS—Each Baja car must participate in these five dynamic events: acceleration, traction, maneuverability, endurance, and a specialty event. The maximum scores possible are shown in Table 1 below: Dynamic Event
Points (Maximum)
Acceleration
75
Hill Climb
75
Maneuverability
75
Suspension
75
Endurance
400
Table 1--Dynamic Scoring With 1,000 points possible for the entire competition (including static events). Acceleration—The acceleration event will take place on either a 100-foot or 150-foot long flat course. The vehicle will be given two attempts to achieve its fastest acceleration and top speed. The two factors taken in to consideration when designing the vehicle for acceleration were a lightweight frame and an effective drive train gear ratio Hill Climb—This event tests the vehicle’s ability to use its traction to accomplish various tasks. This event will be either a hill climb or pulling event at the organizer’s discretion. This year’s event will be a pull event. Points will be received based on completion time if course is completed, or distance traveled if the course is not completed. Maneuverability—The Baja vehicle’s suspension, handling, and steering are all tested through the maneuverability event. This event is specifically designed to have tight turns, ruts, bumps, rocks, inclines, and pylon maneuvers. The vehicle will be given two attempts in this one-lap course, with the vehicle receiving the highest points for the fastest time completing the course.
Endurance—The objective of the endurance race is to assess the vehicle’s ability to function continuously over rough terrain in any weather condition. Some obstacles that drivers have to tackle are the rocky paths, mud pits, water holes, tight turns, and hills. The scoring for the endurance race is based on laps of completion within a four-hour period, without failure. Specialty Event—This event is unique to each competition location and makes use of anything that may be available at the site. A rock crawl or mud bog are not unusual elements thrown at the Baja vehicle. This year the specialty event will be some sort of pull.
RESEARCH ON PAST DESIGNS Inquiries have been made to previous teams who have designed Baja SAE vehicles. Questions have been raised about various configurations used in earlier cars: power transmission, front suspension setup, rear suspension setup, frame material and design, etc. The research is necessary to avoid past mistakes and to improve upon the successes of previous teams. FRAME— The frame constitutes the largest amount of weight of the vehicle, steel tubing material selection is most critical to reduce the weight The main focus was to reduce the weight of the frame as much as possible, while still fulfilling the strength requirements set out in the Baja SAE Rules. The selection of material for the frame has varied from design to design. An aluminum frame from approximately 10 years prior was evaluated. This frame weighs less than 60 lbs and met all the stiffness and strength guidelines in the SAE Rule Book from that year. In the 2008-2009 school year, the MiniBaja team used the standard tubing, thus not choosing a stronger nor lighter material. In the 2010 school year, the Baja design used 1.0” OD x 0.083” thick 4130 steel. This choice was not lighter than the standard, but was approximately 62% stronger than the same dimensions in 1018 grade steel. In 2011, the design team used 1.25” OD x 0.049” thick 4130 grade steel. This tubing was light when compared to the standard tubing set forth in the SAE Consolidated Rules, was 30% stronger, 70% stiffer, but almost 25% lighter in weight. However, current rules require steel tubing with a minimum carbon content of 0.18%. In this year’s design, the rules have changed by increasing the size of the frame to offer more safety to the driver of the vehicle. This means that the roll cage will be larger than before thus making one of the heaviest. Cleveland State has been fortunate enough to have some of the frames from previous years still in operation condition. They are currently being used for driving practice as well as a visual timeline of concepts both good and bad. REAR SUSPENSION— Another main design aspect that varied from year to year is the rear suspension setup. In the 2010 and 2011 competitions, the rear suspension was independent. That is, each wheel acted independently from one another when going over bumps. The Mini-Baja vehicles built for the 2009 and
2010 competitions had a solid rear axle. All four vehicles have been driven and tested to see which rearend setup offers the best performance. The solid rear axle was liked due to the durability and reduced number of components, but is somewhat unstable in cornering. The independent suspension is preferred due to better handling around corners and over rough terrain. The independent axle all so offered a shortened overall wheel base and very positive handling characteristics. The weight of each setup is almost equal. POWER TRANSMISSION— The power train region was looked at next for the design of the Mini-Baja. For many years, the designs have used a Continuously Variable Transmission (CVT). This type of transmission automatically adjusts the speed/torque output of the drive train depending on the load imposed on the system. For flat terrain the CVT allows the vehicle to obtain the top speed by continually decreasing the amount of gear reduction. When a steep grade or obstacle is encountered the CVT holds on to the maximum gear reduction to maximize torque output while the obstacle is being cleared. Meaning it functions like an automatic transmission making it easy for anyone to drive. The other type of transmission used in some designs was a conventional manual transmission. This choice is attractive because of its high efficiency. However, after reviewing the results from the 2010 Midwest Competition it was found to have poor performance, excessive weight, and a complicated setup. The Idea 2010 car’s manual transmission has yet to be reused. Furthermore with the use of the CVT in the regional Dayton Competition we were fortunate enough to place first.
DESIGN OF CAR #16 An overall specification sheet is located in Appendix A. The specification sheet includes information on the wheelbase, transmission, curb weight and other information pertaining to car #16. FRAME DESIGN—Baja SAE enforces many rules with regards to designing the frame. Minimal variations are allowed in order to maximize driver and spectator safety. Frame Material—According to the rules set forth in the 2014 Baja SAE Rules, any steel tubing can be used for the frame and roll cage that has a minimum carbon content of 0.18%, and greater than or equal to bending strength and stiffness to that of 1020 steel with a 1-inch outside diameter and a wall thickness of 0.120”. Bending strength and stiffness were calculated for various grades of steel tubing while considering several different outside diameter and wall thickness combinations. In order to effectively compete in the events, a lightweight but durable frame is needed. The current roll cage is made of 1.25” OD x .065” thick 1020 steel. Other parts of the Baja vehicle use 1.25” OD x .035” thick 1020 steel for parts of the front end. After careful analysis of the rules, it was discovered that more than one size of tubing could be used for the frame. This
fact allows us to save weight in the frame while adhering to the rules. Calculations showing the bending stiffness and bending strengths of other types of steels used to determine the frame material can be seen in Appendix B. The standard tubing of 1018 steel, 1.00” OD x 0.120” wall 3 has a bending strength of approximately 3,500 psi-in 4 and a bending stiffness of roughly 970,000 psi-in . The tubing that was selected for the frame has a bending 3 strength of about 3,660 psi-in and a bending stiffness of 4 roughly 1,260,000 psi-in .
Figure 3—Roll Cage Members (in blue) meet rule 31.2. based on the geometry of 2012's car. The weak members that experienced minor deformations due to repeated abuse are being replaced with stronger tubing in the new design. Confidence in the frame structure was manifest after stress analysis was performed. In Figure 4, one can see very few stress concentration areas exist.
Figure 2—Main Roll Cage Members (in red) meet rules 31.2. For the engine cage and other supporting members of the frame the same material of 1020 cold rolled was selected. SAE does allow the design to use smaller size tubing for these members per rule B8.3.12. The minimum requirement for these members is 1018 1” steel tubing with a wall thickness of 0.035”. For these members 1.25” 1020 steel tubing with a wall thickness of 0.035” was selected. A weight reduction of 27.9% was found in changing the steel tube sizes and wall thicknesses. The minimum wall thickness was used for these members in order to use as light as possible tubing for the frame and allow for easy manufacturing. The 1.25” O.D. x 0.035” wall thickness Is the preferable tubing for additional members because it allows for one size of tube (outside diameter) throughout vehicle and it is the lightest weight and strongest alternative for this application. Figure 3 shows the roll cage support members and engine cage that meet this criterion. Frame Analysis—The frame was designed using the 3D modeling program SolidWorks, making sure that it adhered to all of the rules. This year’s 3D model was then analyzed using COSMOS Works 2008, which is a finite element analysis program that comes with the SolidWorks package. The geometry of 2014's car is
Figure 4— Example of FEA Stress Analysis Program (not current car) POWER TRAIN DESIGN—Use of the continuously variable transmission (CVT) type of power train was decided upon after previous successes. This decision was mainly based on the great performance, and the persistent success of CVT based cars. The CVT is fully automatic and finds the best gear ratio for any given terrain. Therefore, there is no need to monitor the engine’s revolutions per minute (RPM) or gear selection. The CVT uses infinite gearing for the correct power band at any given moment that the vehicle is in motion. Also, the maintenance of a CVT is very simple due to the fact that only the belt requires periodic replacement or tuning of the springs and weights. The only drawback to the CVT is the estimated power loss of 15% from flywheel of the engine, to the actual wheel horse power.
A manual locking differential is also a vital part of the power train design. Transmission—The choice for this vehicle was the Comet 500 Series CVT. Its tuneability and durability were the key factors for choosing this CVT, although some modification is required to properly work with the engine and the rest of the drive train. The drive clutch and driven clutch for the Comet CVT can be seen in Figures 5 and 6, respectively. Figure 7—Honda Foreman Differential
Figure 5—Comet 500 Series Drive Clutch
Figure 6—Comet 500 Series Driven Clutch
Differential—Utilization of a Honda Foreman ATV’s proprietary Cam and Pawl style differential allows the car to operate with locked wheels under the application of torque for maximum traction while also allowing for easy navigation of turns when a sufficient speed difference occurs between the inner and outer wheels results in open differential behavior. Only one extra gear reduction is needed between the driven part of the CVT and the differential to obtain the optimal gear ratio. The gear ratio of 10:1 after the CVT provides the torque needed for quick accelerating and hill climbs while allowing the vehicle to reach a maximum speed of 30 mile per hour. SUSPENSION—An important aspect in determining suspension geometry is the ratio between the wheel travel and spring compression. Variations in a-arm length, shock absorber length, mounting position, and mounting angle will yield different wheel travel and spring deflection ratios. The suspension system can be optimized by selecting the proper configuration to produce maximum wheel travel while utilizing full travel that is allowable by the shock absorbers. The longer
distance the shock absorber travels will allow for better energy dissipation and lower load transfer to the unsprung mass of the vehicle. Ideally, the ride height should remain relatively level for the first increment of wheel travel so that tire compliance and shock absorption are achieved under normal conditions, and then gradually become stiffer as the load is increased. Therefore, greater wheel travel results in greater resistance. This affect is produced by using progressive springs which increases suspension resistance at higher deflections thereby preventing the suspension system and vehicle from bottoming out. Front Suspension—The universal (identical left and right) double A-arm suspension was selected for use in the front suspension (see Figure 8). This system was chosen for its high quality, low cost, and relative simplicity when compared to other setups. The front suspension was designed to minimize the range in camber and toe while the vehicle is in motion. In order to minimize these two suspension aspects, graphical analysis of extreme positions of the tire, in jounce and rebound, are performed. Since this is an off-road vehicle, the suspension must be designed to provide maximum travel with quick response and return. By using the same graphical analysis the wheel travel of the Baja car was determined to be 12 inches. The response and return of the suspension system will be determined by springs and dampers that are purchased according to shock mounting points, overall weight of the vehicle, and un-sprung weight. The castor angle is set at 10° which makes the vehicle easier to drive in a straight line. The built in castor angle also assists the vehicle in tackling all extreme terrain conditions. The camber is set to negative 2° at static ride height. The combination of these two makes the vehicle more stable while driving in a straight line and over rough terrain. This set up also creates a good contact patch when steering. The toe set to 0, will make steering more responsive.
Figure 8—Front Suspension A-arms Rear Suspension—The suspension chosen was a 3-link or Trailing arm / Radius Rod combination. This type of independent suspension yields a great degree of terrain navigation as the forward mounted pivot point allows the rear of the car to easily roll over obstacles. The independent rear suspension setup also gives the ability to achieve the greatest amount of ground clearance while keeping the engine relatively low for a low center of gravity. This type of suspension also allows for use of a differential which gives the car a tight turning radius.
Figure 9—Polaris RZR 3-Link Suspension Comparison Shocks—Almost any ATV shock can be tuned to function properly with this size and weight vehicle. The shocks chosen were the Carrera Coil-Over shocks (front) and the King 2.0 24” nitrogen emulsion shocks (rear). These shocks are light weight and the King shocks allow for stiffness adjustability based on internal nitrogen pressure while the Carrera shocks allow ride height and stiffness adjustment based on spring rate and preload.
Figure 10—Rear King 2.0 Air Shocks BRAKING SYSTEM—The braking system for the Baja car has to meet a number of performance parameters that have been determined through consideration of the operating environment. The braking setup must generate a sufficient amount of braking force to stop the vehicle. The components of the system must also be able to withstand the maximum operating pressures generated during braking. The brake rotors must also be able to absorb the kinetic energy associated with the vehicle traveling at its maximum velocity and dissipate the energy effectively. The braking system is designed not only to meet these minimum requirements but also to be reliable, lightweight, serviceable, and easy to operate. The maximum braking torque was calculated by determining all the vertical forces on the tires at maximum deceleration. The maximum deceleration of the vehicle can be determined from the coefficient of friction between the tire and road, which is assumed to be 0.8 for rubber on dry pavement, since the rules require that the tires lock up on dry pavement. The stopping power is greatly exceeded because full-size racing master cylinders by Wilwood, coupled with single piston 2002 Yamaha Raptor calipers in front and 2007 Polaris Ranger braking system in the rear are being used. The braking system is one of the most important safety features next to the roll cage. The designed braking system provides adequate braking in any situation. TIRES & WHEELS—Tire tread and size play a large role in how well the car can grip the riding surface. A superior tire tread selected for the front and rear offer reliable performance and excellent results on dry, wet, and muddy terrain.
Wheels—The front rims selected are 10"x5" with a 0.160” wall, heavy-duty rolled lip aluminum racing wheels. The selected wall thickness offers a compromise of strength and weight. In the rear, standard 12"x7" with a lip 0.125” thick wheels are used to clear brake calipers.
of the engine or CVT, if needed. Also added this year is a removable engine and CVT cradle that allows for quick and easy repairs. All components are fastened with lock nuts or safety wire ensuring that vibration will not cause a failure in any system.
Tires—Rotating mass becomes an increasing issue with high quality tires. Finding a quality tire that is still light weight was a challenging task. The goal for tire choice was a lightweight tire that was also cost effective while maintaining quality. These tires each weigh 11 pounds which keeps rotating mass to a minimum for ultimate acceleration.
Minimizing the number of parts in the assembly of the vehicle created fewer areas to fail. This in turn makes repair a simple task of replacing the damaged or worn out system. Since the entire vehicle is designed symmetrically along the vertical mid-plane, this allows for faster assembly.
IMPROVEMENTS FROM PREVIOUS DESIGNS Front Tires—Maxxis Front Pro Tires 23"x7"-10" are being used in the front. According to 4WheelParts.com, "The Maxxis Front Pro provides positive precision steering. Its reinforced elongated knobs maintain positive directional stability. angled lateral knobs increase steering precision in straight line tracking, as well as cornering and braking."
Wheelbase—A major improvement from last year's design is a shortened wheelbase. In shortening up the wheelbase of the vehicle, it will allow for a tighter turning radius. This turning radius will demonstrate itself in the maneuverability course and on the endurance course.
Rear Tires—In the rear, Maxxis Ceros Radial Tires 23"x8"-12" are being used. These are specifically built to handle extreme abuse. It allows for the driver to maintain precise handling at high speeds. The smoothrolling directional tread pattern creates predictable braking. Front and rear tires are shown in Figure 11.
Weight Distribution—In the previous years, the car tended to be front heavy so every jump would result in a nose dive causing high stresses to the car, loss of momentum, and great discomfort to the driver. This year the engine and transmission are position as low as possible and pushed back over the rear axle. Lighter front tire and wheel combination further facilitate level landings from jumps. Engine & Transmission—With the ideal gear ratio coupled with the CVT, the vehicle will have no problem negotiating rough terrain while still having a substantial top speed. This year's car added a new engine and CVT cradle that allows the engine and CVT to be removed from the car as one unit. Simple disconnection of the chain and removal of a handful of bolts is all it takes. This is integral for engine and/or CVT swaps, or maintenance on either part.
Figure 11—Front Tire (left) & Rear Tire (right)
MANUFACTURING AND SERVICEABILITY The goal of the 2014 Baja team was to design a car that was simple to manufacture while producing a product that was pleasing to the eye. The drive train has a minimal number of components. This minimized the amount of brackets needed for mounting the engine and transmission allow for a clean look and less hardware. All gears and chains are contained in an enclosed housing for cleanliness and safe operation. All of the suspension mounts for the front and rear A-arms are identical. The vehicle with its simple and open design makes service a simple task. The entire engine and drive train area is wide open, allowing for quick and easy access. The engine cage and the transmission guards are made to be removable. This will allow for ease of replacement
Frame—The choice of using two different size steel tubing allow for a lighter, but stronger frame. Fabrication of more components throughout the vehicle allow for lower the cost and also help to reduce weight by using other types of materials instead of the standard metals used. A-arms—The front and rear are now outfitted with universal A-arms. This allows for fewer differentiated manufactured parts. Now, the front upper and lower aarms can be switched for either side, respectively; likewise for the rear upper and lower. Body Panels—The team's body panels have been modified to be easier to install and remove. This includes simplified body panels for the front and sides, along with fewer and better placed fasteners. In the front is just one panel instead of three. The sides now can be removed without tampering with the front
suspension. These improvements allow for easy replacement of damaged panels. Steering—New placement of steering wheel and rack allow for better control and less fatigue of driver's arms. Differential Lock—Innovative design and new location of the manual differential lock handle assembly gives the driver greater ability to activate/deactivate. Electrical—A dual battery box permits longer drives between charges.
CONCLUSION The 2014 Baja team selected to concentrate on reducing the gross vehicle weight while maintaining durability and overall vehicle stability. Final configurations of the Baja design include a more comfortable cockpit, refined front suspension, fully independent suspension, lightweight frame, a low center of gravity, and desirable jumping characteristics. Thorough research, a dedicated design team, and solid construction will bring a very competitive vehicle to this year’s Baja SAE Competition in Greenville, South Carolina. We are certain that the Baja prototype will perform well. Excitement is rapidly growing about applying the knowledge and skills developed during the manufacturing for next year's brand new design! The team relied on perspectives from all students involved, including our Business major and amateur firstyear members.
REFERENCES 1. 2. 3. 4. 5.
2014 Baja SAE Rules,< http://www.sae.org/students/mbrules.pdf> Babbitts Sports Center--Polaris OEM Parts, Building an Offroad Go Kart, ATV Tire Finder, Norton, Robert L. Design of Machinery: An Introduction to the Synthesis and Analysis of rd Mechanisms and Machines. 3 ed. Boston: McGraw-Hill, 2004.
6. Milliken, Douglas L., William F. Milliken. Race Car Vehicle Dynamics. New York: SAE International, 1995. th
7. Riley, William F. et al. Mechanics of Materials. 5 ed. New York: John Wiley and Sons, 1999.
8. Shigley, Joseph, et al. Mechanical Engineering th Design. 7 ed. New York: McGraw-Hill, 2003. 9. Smith, Carol. Engineer to Win. SAE International, 1984.
APPENDIX A
ENGINE Type 4-stroke, OHV, Briggs & Stratton Displacement 305 cc Power 10 HP Torque 14.50 ft-lb DRIVE TRAIN Transmission Comet 500 Series CVT Reduction 11:1 Gearbox Reduction 3.7:1 Final Drive Reduction 43.8:1 CHASSIS/SUSPENSION Chassis Type 1020 steel, tubular frame Overall Length 90 in. Wheelbase 65 in. Overall Width 62 in. Front Suspension Double A-arm Rear Suspension 3-Link Trailing Arm/Radius Rod Ground Clearance 14 in. Shocks King 2.0 and Carrera Coil-Over Front Travel 14 in. Rear Travel 12 in. Weight 501 lbs. WHEELS/TIRES Front Tires Maxxis Front Pro Tire, 23"x7"-10" Front Wheels 10"x5" Rear Tires Maxxis Ceros Radial Tire, 23"x8"-12" Rear Wheels 12"x7"
APPENDIX B
H = height of simulated vehicle drop G = acceleration due to gravity T = time to impact KE = kinetic energy absorbed in impact Table 2 - List of Steel Sizes and Calculations V = impact velocity
Bending _ Strength
yield I
M = mass
router
W = weight of vehicle
Wall _ thickness OD ID Moment _ of _ Inertia ( I )
ro4 ri 4 4 Modulus _ of _ Elasticity ( E ) 29,700ksi Yield _ Strength ( y ) Given _ per _ material Bending _ Stiffness E I Bending _ Strength
y I ro
Weight _ per _ foot Given Bending _ Stiffness material Stiffer Bending _ Stiffness 1018 Stronger Heavier
Bending _ Strength material Bending _ Strength1018
Weight _ per _ foot material Weight _ per _ foot1018
F = impact force S = deflection of shock and/or tire
