The chassis acts as a support for attaching all the systems (braking, suspension etc) for the vehicle so it has to be strong. While designing the chassis various factors to be considered which includes compact design, ergonomics, durability, ease while manufacturing and light weight. It is a specially engineered and constructed frame built in (or sometimes around, in which case it is known as an exo cage) the passenger compartment of a vehicle to protect its occupants from being injured or killed in an accident, particularly in the event of a rollover.
Some of the major points which are considered for designing the off road vehicle –
- Safety and ergonomics
- Market availability
- Costs of the components
- Safe engineering practice.
The main objectives behind our project are as followed:
To design a safest vehicle for the driver.
To design in accordance with the Rulebook.
To design for the driver’s compatibility.
For optimum stability of the vehicle.
To reduce the weight and maintain a desired centre of gravity.
To maintain stability in turns.
For prevention from front collision, rear collision, side collision and rolling.
Design of Chassis:-
In order to avoid from bending which is more worst then compression and tension, tubes should be arranged to form triangles with the major loads applied at the intersection of tubes. In comparison to straight tubes, bent tubes have more chances to get buckled.
as to cover and enclose the rider’s area. The frame work is use able with or without the cover for roll over protection and also provides a means to deflect branches and similar hazards awaythe rider by virtue of the design of the front portion
Load Impact Calculation:-
After finalizing the frame along with its material and cross section, it is very essential to test the rigidity and strength of the frame under severe conditions. The frame should be able to withstand the impact, torsion, roll over conditions and provide almost safety to the driver without undergoing much deformation.
Following tests were performed on the roll cage.
- Front impact
- Rear impact
- Side impact
- Longitudinal Torsion
- Front Impact Analysis-
Generally in the case of pure elastic collision in frontal impact the linear velocity remains at 60Kmph according to ENCAP (The European new car assessment program).Hence the value of force is calculated by mass moment equation that is-F = P×∆T.
- Rear Impact Analysis-
The rear impact force is also calculated in the same way as remaining two. In this case the velocity of collision was taken 72kmph or 20 m/s by the calculations and also as according to the ENCAP standards.
- Side Impact Analysis-
Using the projected vehicle-driver mass of 300 kg, the impact force was calculated base on a G-load of 2.We apply 6000 N from the side for the test of side impact of the roll cage structure of the vehicle for determining strength at the time of side collision.
- Longitudional Impact Analysis-
The torsion analysis is done by constraining base and applying loads in opposite directions on front and rear ends. Loading F=6000N on opposite directions on front and rear ends applied .
A good strength material is important in a chassis because the chassis needs to absorb as much energy as possible to prevent the roll cage material from fracturing at the time of high impact. This AISI 4130 STEEL gains hardness and strength with heat treatment. This carbon steel is a commonly used plain carbon steel. It has a good combination of strength and ductility. The chassis is the component in charge of supporting all other vehicle’s subsystems with the plus of taking care of the driver safety at all time. The chassis design need to be prepared for impacts created in any certain crash or rollover. It must be strong and durable taking always in account the weight distribution for a better performance. The chassis was mainly designed through CAD software.
S.No Properties Values
- Density 7.87g/cm3
- Ultimate Tensile Strength 560Mpa
- Yield Strength 350Mpa
- Modulus of Elasticity 210Mpa
- Shear Modulus 80Gpa
- Poisson’s Ratio 0.29
The seat in our quad bike is also designed to be very light it is very simple made of plastic material and is attached to the chassis by two points only and can be adjusted in angle of back rest according to the requirement of the drivers comfort the back side angle of the seat is at 180 degrees which is the good position of the drivers body rest according to the ergonomics point of view .the seat implemented in our quad bike provides a good combination of weight reduction and ergonomics. Ergonomically the quad-bike is building up with proper dimensions as given by the rule book. The driver seat is well cushioned. Alignment of the driver seat/driver sitting direction is parallel to vehicle’s longitudinal axis.