chassis design for Solar operated vehicle
Updated: May 28, 2020
This report presents about the frame design structure for solar car. Solar car has been invented to find an alternative energy that can be replaced the common energy that being used right now which is fuel energy. The condition to design for this frame design is lightweight in term of weight, low displacement on frame when accident due to tensile strength of the material and the high natural frequency of that design.
The design of the final model will be done by using CATIA software which is suitable for making the 3D model of the car.
Then the design will included into ANSYS 14.5 software to analyses about natural frequency and also the roll bar testing and got the results that the third chassis of the solar car is the best chassis that can be use inside the solar car to optimize the solar energy used.
Basically chassis is considered as a framework to support the body, engine and other parts which make up the vehicle. Chassis lends the whole vehicle support and rigidity. Chassis usually includes a pair of longitudinally extending channels and multiple transverse cross members that intersect the channels. The transverse members have a reduced cross section in order to allow for a longitudinally extending storage space. The chassis has to contain the various components required for the race car as well as being based around a driver’s cockpit. The safety of the chassis is a major aspect in the design, and should be considered through all stages. Generally, the basic chassis types consist of backbone, ladder, Spaceframe and monocoque. Different types of chassis design result the different performance.
Space frame chassis
In this study, it is decided that tubular space frame chassis is used for the urban car. Since ladder chassis is not strong enough, motor racing engineers have developed a 3-dimensional design which known as tubular space frame. Tubular space frame chassis employs dozens of circular-section tubes (some may use square section tubes for easier connection to the body panels though circular section provides the maximum strength), position in different directions to provide mechanical strength against forces from anywhere. These tubes are welded together and form a complex structure. For higher strength required by high performance sports cars, tubular space frame chassis usually incorporate a strong structure under both doors. Tubular space frame chassis also very strong in any direction compared with ladder chassis and monologue chassis of the same weight
example of space frame chassis is given
OBJECTIVES of project
The design objectives for chassis are :
i. To evaluate current chassis
ii. To redesign car chassis
iii. To analyse in term of structure failure using software.
iv. to design proper ergonomics and safe chassis
i. This car is designed for Solar Vehicle Championship.
ii. Design stage for this project using CATIA V5 software.
iii. ANSYS 14.5 software is used to analyse the stress at the car chassis.
Different chassis materials can reduce the weight of the vehicle, improving the vehicle power to weight ratio. Material selection can also provide advantages by reducing member deflection, increasing chassis strength and can determine the amount of reinforcement required.
AISI 1018 mild/low carbon steel has excellent weldability and produces a uniform and harder case and it is considered as the best steel for carburized parts. AISI 1018 mild/low carbon steel offers a good balance of toughness, strength and ductility. Provided with higher mechanical properties.
As material with the carbon percentage of 0.18% is required hence the 1018 material is selected.
THE DESIGN PROCESS
Conceptual Design by using CATIA V5
By using sketches, as guideline, the conceptual chassis design can be using Catia. In this step, the best dimensions need to make the design to be draw symmetry and have logic concept. Figure 1.6 shown drawing perform using CATIA. The design shown that the design shape is monocoque type. Consist cross shape beam under the driver compartment to support weight of driver and the chassis designed with tow tire at front and one tire at the rear or back.
The scenario which everyone tries to avoid is having an accident. During a car accident on a road there is more emphasis put on decelerating a vehicle through structural deformation absorbing the impact with crumble zones. An accident on the track is more concerned with having a very rigid enclosure with devices attached to dissipate the energy. A driver is also very securely connected to the chassis through multipoint harnesses and head restraints like the Hans Device. There is a difference in philosophy and the focus here will be on the latter.
A simulation works includes various necessary testing which are basics, such as:
· Frontal impact test.
· Side impact test
· Rear impact test
In following all the test we had taken two tests , those are –
1. Total deformation
2. Equivalent (von-mises) stress..
Frontal Impact Test
The frontal impacting force is calculated by Newton’s second low.
For the frontal collision considering m as mass of the vehicle and u, v as the initial and final velocities respectively is taken as Collision time.
F = (m*(v-u))/t
In automotive industry, the impact time is of the range 0.15 to 0.2 s. Taking time of impact as
t = 0.18
F =250*(12.5-0)/0.18……..by taking velocity 45 kmph
F =17361.11 N
Maximum deformation in case of frontal impact is seen as 13.006 mm & Maximum Stress is 32305 Mpa. So drivers cabin safe in case of frontal impact driver will be safe.
In rear impact, forces are considered as per Newton’s second law. Deformation is seen 20.54 mm & 332.97 stress is Mpa
In side impact, forces are considered as per Newton’s second law. Deformation is seen 3.1052 mm and stress is 332.97 Mpa.
From overall tests conducted on ANSYS software for total displacement and von-mises stress the chassis design selected is safe.
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