ANALYSIS OF TIE ROD :
As that of theoretical study of tie rod is done. The overall purpose if tie – rod is to transmit the motion from steering arm to steering knuckle and sustain the forced vibrations caused by bumps from tires due to uneven road surfaces the main task is to find the deformation and stresses induced in the tie rod and optimising it for various material combinations. The 3-D model is prepared for Tie-Rod of AISI 1020 material is assigned and analysis is carried out using ANSYS14.0.
Total Torque to drive the wheel =
TF + TR = 1656.3x0.2413 + 403.18x0.2286
= 491.83 Nm
For Front Drum brake–
For Rear disc brake –
As that of theoretical study of tie rod is done. The overall purpose if tie – rod is to transmit the motion from steering arm to steering knuckle and sustain the forced vibrations caused by bumps from tires due to uneven road surfaces the main task is to find the deformation and stresses induced in the tie rod and optimising it for various material combinations. The 3-D model is prepared for Tie-Rod of AISI 1020 material is assigned and analysis is carried out using ANSYS14.0.
FEM OF TIE ROD FOR MAX. DEFORMATION
FEM OF TIE ROD FOR TIE ROD FOR MAX. STRESS TIE ROD DETERMINATION :-
Tie rod length was found virtually in CATIA VSR20 by assuming the position of tie rod to be fixed on knuckle and extending wishbone axis to meet at the instantaneous centres and with the help of steering angle, geometrically we found tie rod
Graph :
Effect of the w/l on the Ackermann condition for the front-wheel steering vehicles:-
Bump and roll steer
Steer with ride travel is very common in all terrain scenarios.steer with ride travel is undesirable because if the wheel steers when it runs over a bumps or when the car rolls in a turn the car will travel on a path that a driver did not select intentionally.
Ride/Bump and roll steer are a function of the steering geometry . If the tied rod is not aimed at the instant axis of the motion of the suspension system then the steer will occur with ride because the steering and suspension are moving about different centres. If the tie rod is not of the correct length for its location then it will not continue to point at the instant axis when the suspension travelled in ride. Thus the choice of the tie rod location and length is important. If the tie rod height and angle are adjustable it is usually possible to tune most of the ride steer out of a suspension.
Curved ride/bump steer as shown in figure are to be avoided because they result in a net change in toe with ride and the steer effect changes from under steer to over steer depending on the wheel ride position. If ride steer plot is curved then a possible solution is to raise both the ends of the tie rod to move it closer to the shorter, upper A arm with the tie rod angle also be adjusted.
Braking system
Objective –
The purpose of the braking system is to increase the safety and maneuverability of the vehicle. In order to achieve maximum performance from the braking system, the brakes have been designed to lock up all four wheels at the same time. It is desired from a quad bike that it should have effective braking capability to negotiate rigid terrains.
Design –
The braking system is composed of both internal expanding drum brakes and disc brakes. The drum brakes are installed at the two front wheels and a single rotor is mounted on the rear axle to satisfy the braking requirements of our quad bike such as terrain of the track, speedlimits, driver ergonomics and other rulebook constraints.
The front drum brakes are mounted on each wheel of internal radius 2.5 inches having a brake lining width of 3 mm. The distance between the pivot point of both the brake shoes and the cam is 3.93 inches.
At the rear axle we are using disc brake due to fact that we require a effective braking at the rear. It is also to our advantagethat even if the front brakes fail in the worst case scenario, braking power is still available to the driver. The Rear brake is composed of 5 inch diameter disc and dual piston 1.5 inch diameter calliper.
FEM OF BRAKE DISK ( CUSTOMISED ) :
The role of FEA analysis in disk brake helps us to ascertain the importance of holes in the design of disks.
TYPE of Element used : PLANE 55
Since the thickness of disk is very small (4mm) when it is compared to its diameter, hence the analysis in 2-D. for this reason, the plane element is chosen in place of solid element in case of 3-D analysis.
BOUNDARY CONDITION :
The boundary condition is that the temperature of outer edge is 40C and of the inner edge also 40C.
THERMAL LOAD :
The temperature of the contact patch is assumed to be 700C. It is assumed to be annular region.
ANALYSIS OF RESULT :
By using 8 holes of 10mm diameter in the disk the temperature of the disk is reduced and more area is under reduced temperature. Hence by using holed disk the life of the disk can be improved from thermal degradation.
Calculations–
The total weight of the vehicle along with a average weight of driver ( 70 kg ) was estimated to be 260 kg. The weight distribution for the quad bike was estimated to be approximately 45:55 from the front to the rear. The static weight distribution of the vehicle is 117 kg at the front and 143 kg at the rear.
Stopping Distance (SD) = (Vmax)2/2μg
= (16.662/2 x 0.75 x 9.81 = 18.72 m
Deceleration rate (Dx) = (Vmax)2/2 SD
= 16.662/2 x 18.72 = 7.36 m/sec2
Dynamic weight transfer (ΔW) = Dxx W x Hc.g/gxl
=7.36 x 280 x 0.406 / (9.81 x 1.193) = 71.49 kg
TF + TR = 1656.3x0.2413 + 403.18x0.2286
= 491.83 Nm
For Front Drum brake–
Initial Data-
Driver effort 25 lbs
Lever Ratio 6.3:1
Coefficient of friction () 0.5
Internal Radius of Drum (r) 2.5 inches
Width of Brake Lining (b) 3 mm
Pivot point to cam distance (l) 3.93 inches
θ1 30
Θ2 150
Braking Torque( Tb )
= μp1br2 ( cosθ1– cos Θ2 )
= 0.5 x 16.427 x 106 x 0.003 x (0.63)2
= 169.386 N-m
Braking Torque for both the wheels (TBF)=2 x Tb
= 2 x 169.386 = 338.772 N-m
For Rear disc brake –
Initial data –
Drive Effort (DE) 80 lbs
Pedal Ratio ( RP ) 4.66:1
I.D of Master Cylinder ( IDmc ) 14.043 mm
I.D of Calliper (IDc) 38.23 mm
μ between Disc Pad & Rotor 0.4
Diameter of Rotor 5 inches
Pressure developed at master cylinder(Pmc)
= DE x RP / π/4 x (IDmc)2
= 10.09 x 106 N/m
Force of friction generated by brake pad (Ffri) = 2x Fcal x μ
= 9154.56 N
Torque at Rotor(Tr) = Ffri x Reff
= 9154.56 x 0.0508
= 465 N-m
Torque at Rear wheels(TBR) = Tr
= 465 N-m
Final Result-
Deceleration Rate 7.36 ms-2
Stopping Distance 18.72 m
Stopping Time 2.25 sec
Braking Force 3437 N
Dynamic mass Transfer 71.49 kg
Braking Efficiency 75%
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