Maidenmob Pdr 2011

8/12/2019 Maidenmob Pdr 2011

1/15

Maiden Mob


2/15

PAGE 1 :

Every design aspect and parameter mentioned in the rule book serves as bench mark for thedesign and selection of various components and subsystems of the vehicle.

The material used for the entire required roll cage members must be:(i) Circular steel tubing with an outside diameter of 2.5 cm (1 inch) and a wall

thickness of 3.05 mm (.120inch) and a carbon content of at least 0.18%.(ii) Steel members with at least equal bending stiffness and bending strength to 1018

steel having a circular cross section with a 2.54 cm (1 inch) outer diameter and awall thickness of 3.05 mm (.120 inch)

The following elements of the roll cage are designed based upon rules mentioned incorresponding points.

(i)Rear Roll Hoop (RRH) Rule 31.2.2

(ii)Roll Hoop Overhead Members (RHO) Rule 31.2.4

(iii)Front Bracing Members (FBM) Rule 31.2.7

(iv)Lateral Cross Member (LC) Rules 31.2.4 and 31.2.5

The drivers helmet to be 15.24 cm (6 inches) away from a straightedge applied to anytwo points on the cockpit of the car, excluding the drivers seat and the rear driver safetysupports

The drivers torso, knees, shoulders, elbows, hands, and arms must have a minimum of7.62 cm (3 in) of clearance from the envelope created by the structure of the car. Driver must be able to exit from either side of the vehicle within 5 seconds. A firewall between the cockpit and the engine and fuel tank compartment is mandatory. It

must cover the area between the lower and upper lateral cross member. This firewallmust be metal, at least .508 mm (.020inch) thick, and must completely separate theengine compartment and fuel tank from the cockpit.

The vehicle must have at least two independent hydraulic braking systems that act on allwheels and is operated by a single foot and in case of a leak or failure at any point in thesystem; effective braking power shall be maintained on at least two wheels.

Teams are free to use any transmission such that maximum speed of the vehicle on aplain terrain is recommended to be no more than 60 km/hr in top gear

Any muffler whose back pressure does not exceed 450 mm of Water Column may beused.


3/15

Vehicle specifications

Track width : 64 inches

Wheel base : 72 inches

Approx weight : 300 kgs

:

.

D : 65 ( , ) =(130,0)

E & : 55 ( , ) = (182.5,0)

E : Lombardini LGA 340 11 hp engine

: 338 * C : 8:1* : 8 @ 4400 * M : 19 N @ 3000 * B : 84 64 , , A C * E : 30.5

: . 4 1 M&M A

1 ----- 31.48:1

2 ----- 18.70:1

3 ----- 11.40:1

4 ----- 7.35:1

R ----- 55.08:1


4/15

'

, , . ,

F ,

. D ,

. I

. I C.G . C.G ,

.

, . A . D , , ,

K .

A . C .A

. D , 20 .


5/15

: /2 + / ( )

: 4.23

K B . I

. K .

F (G )= * G. *10200/( * G )

G = .

= N.

G. = .

= ( ) .

RR = Rolling resistance expressed in percentage grade.

R = Rolling resistance Newtons per hundred kilograms vehicle weight

For a soft gravel track,

R=40N, RR = 4%

50% .

0.50 1 .

: 60

: 1.38 / 2 ( 100 )


6/15

B :

( ) = /2 g

= =60

= 0.6

A = 9.81 /

d = 23.6m

Ground clearance: 300mm

Suspension parameters:

Gross vehicle weight = 370kgs.

Unladen Weight = 300kgs

Suspension travel: 8cm (jounce), 2 cm (droop)

Spring wire diameter: 9.5 mm

Coil diameter: 65mm

Spring Index: 6.8

Sprung mass = 230kg

Unsprung mass: 70kg.

Tires:

As the type of tyre chosen should satisfy traction and torque made available by theengine, a good MT texture tyre would do the job. A 12 inch diameter rim for all fourwheels is opted so as to facilitate stub axle, hub and calipers setup in it, and avoidingusage of spacers.

Emissions:

The emissions being designed to achieved optimum emission control and for this a catalyticconverter is being adopted which enables the vehicle to be upgraded to the latest emission


7/15

norms(BSIV/ EURO IV).also attempts are being made to make the vehicle eco friendly usingdegradable and eco friendly materials and products.

PAGE 4 :

ROLL CAGE:

Roll cage design is an important parameter for the fabrication of an efficient buggy. The rollcage is the frame which envelopes the driver and its design is of utmost importance consideringthe safety of the driver, design and analysis of the roll cage is done. The roll cage design consistsof the three different bays.

1. Front bay for which serves as impact member and suspension a-arm mounting.

2. Center bay for driver cabin

3. Rear bay for the engine mounting .

Improvisation:

During the design of roll cage team main concentration was driver ergonomics, aesthetic looksand weight reduction. Rule book served as the basis for the design of the roll cage. The roll cagewhich was made for Baja 2010 used the material mild steel seamless pipe with a carbon

percentage of 0.18 which about the 55 kgs. For the weight reduction factor material with highstrength and less weight is required.

The geometry is also limited by industry standards. It is important to utilize commonly availabletubing sizes and materials. Tubing is available in standard fractional sizes to the 1/8th of an inch:1 to 1.5 inch. Also the wall thicknesses available are: 0.035, 0.049, 0.058, 0.065, 0.083 and 0.120inches.

The available materials for the tubing are 1018 Mild Steel and 4130 Chromyl Steel. The benefitof the chromoly steel is that 17.5% stronger than the 1018 mild steel the modulus of elasticityand density are same for both the materials. Keeping the weight reduction and strength factors inmind chromoly is considered as the efficient material for the roll cage fabrication.

Material aggregates:

Outer diameter : 2.54 cm (1 inch)

Wall thickness : 0.305cm (0.120inch)

Yield stress : 360.6 M.pa

Youngs modulus : 190-210 G.pa


8/15

Impact strength : 61.7 J (izod)

Carbon percentage : 0.3%

Ergonomics:

Ergonomics considered to be important for BAJA , ,

. F 4 5

110 , . 25 35 .

40 45 , 40 45 5 8 . 75 80 ( )

7 7.5

AGE 5 :

Structural analysis:

SOLID WORKS 9.0 and ANSYS 10 workbench were used for the design and analysis. Thestructural analysis consists of three impact scenarios which help in analysis of the stressesdeveloped in the roll cage. They are

1. F 2. 3.

Front impact:

To approximate the worst case scenario that the vehicle will see, research into the forces thehuman body can endure was completed. The literature survey that the human body will pass outat loads much higher than 9 times the force of gravity or 9 Gs. A value of 10 Gs was set as thegoal point for an extreme worst case collision.

In this case, a deceleration of 10 G was the assumed loading which is equivalent to 30KN byassuming the weight of the complete buggy about 300kgs. After the analysis of impact the valueof deflection, with proper bracing & the FACTOR OF SAFETY comes to be > 1.5 which isacceptable. Fig. 2 show the loads applied on the impact member of the roll cage and theconstraints given.


9/15

Fig 3. Shows the stresses developed in the members during the impact

PAGE 6 :

Side impact:

As a side impact is most likely to occur with the vehicle being hit by another vehicle, the forcewas assumed to be half that of head on collision with a fixed object of deceleration of 5 Gs. Thisvalue is an extreme overestimation, but will allow the ability to account for a blown shockabsorber. The next step in the analysis was to analyze a side impact with a 5 G load which is

equivalent to 15kN as shown in fig 4.

After the analysis of impact the value of deflection, with proper bracing & the FOS comes to be> 2.5 which is acceptable which is shown is fig 5.

Roll over impact:

The final step in the analysis was to analyze the stress on the roll cage caused by roll over with a2.5 G load on the cage. This is equivalent to a loading force of 7.5 KN. The fig.6 shows the pointof application for the loading on the roll cage the load was chosen to be on a single corner as thiswould be the worst case scenario roll over.

After the analysis it is found out that the factor of safety is > 2.5 which is acceptable. Hence thedesign is left unaltered as shown in fig .7

The final 3d views of roll cage with complete bracing members are shown in figure fig.8 andfig.9

PAGE 7 :

steering full lock the tie rods and the suspension components must not scrub the wheel on full lock

brakes test : There must be no leakage in the brake fluid containers and the brake hose.

Testing Resource :practically putting the components in water and checking for AIR bubbles which showsthe leakage.

steering full lock : The tie rods and the suspension components must not scrub the wheel on full lock


10/15

Testing resource :By steering the vehicle to the extremes

electrical components: A l the components must switch on or off when the corresponding switch is On orOff.

owing test: The vehicle frame must not show any yield during the test

Testing resource :By physically lifting the vehicle using a pulley mechanism

Manoeuvrability : The vehicle must be able to easily manoeuvre the sharp turns.

Testing Resource: At one of the GO karting race tracks

Fig.1


11/15

Fig.2

Fig.3


12/15

Fig.4

Fig.5


13/15

Fig .6

Fig.7

3-dViewsofthevehicle:


14/15


15/15

Documents

Maidenmob Pdr 2011