cHaSsIs FrAmE fAbRiCaTeD...

Welcome guys!!!
We would like to inform with extreme delight and happiness that the frame of the chassis has been fabricated. Its length is basically 1.86m and width stands at around 1m.






The frame has been fabricated by means of hollow MS rods as was described and reasoned in the design statement some posts earlier.
Now that the chassis frame has been successfully fabricated, the next stage is the building and subsequent assembly of the steering and other mechanisms to complete the fabrication of the chassis.
We would like to inform you that our end-semester exams start in a couple of days time. As such there will be a temporary dwell period. We will resume work from the first week of December.
Till then keep smiling and do keep commenting...

FaBrIcAtIoN wOrK cOmMeNcEs!!!

The moment which we had been anticipating for the past few days is here. The nitcAMPHICAR is on its way as fabrication work has commenced.
As was stated, the design work was completed by 15th October but due to the festivities and the non-availability of work-space, a delay had to be incurred.
Nevertheless, the brain-storming sessions that accompanied the designing process is now bearing fruit as the first stage of fabrication is going on. The first stage of the fabrication process is the chassis, that is the basic frame on which the entire vehicle will rest. The pictures presented in this post illustrate how the bottom half skeleton will look like.
The outer frame is first welded and then the cross-bars are appropriately joined end to end. The material we are using for the chassis is 1.5 inch size 1018 hollow steel pipes. The reason we chose this material is that it is readily available and easily weldable with the prevalent and common arc welding process. Another reason for using circular pipe is that it offers better torsional resistance which is one of the primary resistances to be encountered by a perimeter frame, like ours.
With the first leap taken, the next step is to complete the chassis. This will involve completion of the chassis in the matter of a week. Hence, challenges are many and at times perturbing, but with all these done, the nitcAMPHICAR team is buoyant and roaring to go forward to overcome each and every challenge and obstacle that comes on the way.
In the coming days, the fabrication process of the chassis is sought to be accomplished. If time permits, we would like to move ahead of our framed schedule and look out for the wheels and the steering system. However, fabrication is a process with minimal margin of error and as such we have to be determined, focussed and at the same time patient in our endeavour of fabrication.
Without asking the readers to contemplate much on the following, we would like to sign off by saying that:
"ALL HUMAN WISDOM IS SUMMED UP IN TWO WORDS - wait and hope"

pRoPeLlEr HuNt !!!

Hello Everyone!
Nice to be back considering that the past few days were quite demanding. Just jostled through the second sessionals and the final hurdle in the design stage-the propeller mechanism is nearing completion.
As part of the process to overcome the final hurdle, the nitcAMPHICAR team visited Beypore. Beypore is a small town just on the outskirts of Calicut. Before that we went to a boating arena just to have a taste of the mechanism in practise. After a look at the man-powered propeller mechanism we set for Beypore.
The place is very beautiful and so are the people. We had a very fruitful conversation with a couple of fishermen. The process was however not going to be easy as communication gap is a major barrier. But then, when there is a will there is a way. We somehow interacted with them and got some insights into the engine and the propeller mechanism they are using.
The propeller is basically inbuilt in a 3litre Suzuki engine. They presented a live demo of the working and operation of the entire engine including the propellers. We got some contacts of the engine suppliers from these gentlemen.

Then we moved in search of these contacts and were fortunate enough to encounter a dock where an interceptor of the Indian Coast Guard was waiting to be inducted into the Indian Navy.
After some conversation with some of the persons there, we finally got the address of a mechanic who specializes in repairing the fishing boats. He is a person by the name of Ponappan and is the man seeked by every person with a boat in that region. Well the place he stays is called Chelliyar, a place on the opposite bank of the back water in the dock.
We were waiting for a steamer to take us to the other end. Then we met a person who volunteered as the interpreter between us and the boatman. From the conversation we came to know that Saturdays and Sundays are off-days for Ponappan. However, we got his contact number.
Well! There were many positives in spite of the fact that we could not find the mechanic. We got his contact and a basic idea about the propeller we will be going to use. Most importantly we came to know how beautiful the place is.
Next, we plan to meet our guide and make him informed about the work we have done. We also plan to have a telephonic conversation with Ponappan, the mechanic, through an interpreter.
We have set 15th Oct as the deadline for completion of the Design process and we are almost there.
We the enthusiam and energy level in the team and the guidance provided, we can confidently say that :
we will, we will rock you!!!
Signing off for the meoment...
Take care and be optimistic!!!

cRuIsInG sTaTe !!!

Well! After an opening burst to the 'mission' we can now afford to cruise a few paces ahead as most of the designing work has been accomplished and approved. However, keeping in mind that manufacturing demands a perfect design operation and analysis, we now intend to cross check our work with some experts in the field. Moreover, we need to get hold of the remaining sources of materials like the resin which may not be readily available in and around Calicut (Kozhikode). At this point we would like to admit that we are blessed to have Dr. Allesu K as one of our project guides who unlike other professors is more of an engineer in true sense and catches the nerve of a problem at its very root.
At present, we are analyzing a design on the bearings so as to calculate the optimum size of the axles (rear and front). In addition to this, we will also finalize our design of the propeller mechanism out of the two previously proposed designs in a matter of a week. By the end of this semester (end of October), we plan to complete the manufacturing of the chassis and the basic parts like the steering system as well as the wheel components.
So, in the next few days we plan to do two things. One, get the design of the propeller and the axles accomplished and approved. Another, sort out and enlist the probable sources from which we will be sourcing the materials for our project.
As such, there has to be constant communication and verification both among the group as well as between the group and the market. We thereby invite you to take initiatives and volunteer the effort in whichever manner possible. You can always contact us if you have something to offer (even a small piece of information or suggestion) and we are always ready to embrace your advice with our arms outstretched.
Last but certainly not the least, we would like to sign off by quoting The Mahatma
" Always aim a t complete harmony of thought and word and deed. Always aim at purifying your thoughts and everything will be fine."
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DESIGN sTaTeMeNt UnLeAsHeD !!!

Finally the design process is here. After a gruelling round of drawings, analysis and ‘debates’ we present before you the design process which we will be adopting in our endeavour towards the accomplishment of our AMPHIBIOUS VEHICLE.

NOTE: we have used some technical terms (hull,etc.) in this article which may cause some interpretation problems for non-technicians. This is intentional as we want the reader to search out these terms and experience the joy of learning through self discovery.

1. Engine Transmission: The engine to be incorporated in our vehicle is a Honda Street 100 engine. It is a 4 stroke engine with single cylinder and specifications as 97.2 cc, 6 bhp and a maximum rotational speed of 7500 rpm. The engine is fitted with an automatic centrifugal clutch with four forward speed. This engine will be used to provide a rear axle drive with the help of a chain and sprocket mechanism.

2. Steering System: Considering the vehicle weight, size, shape and driving conditions, we came up with the plan of using a steering which includes a Pitman arm with two tie rod ends. This mechanism will be a 100% Ackerman mechanism with an Ackerman angle of 24 degrees. If we consider a turning radius of 3 metres, then the rod ends travel is of 5 inches.

3. Braking System: We will be using Disc Brakes in our vehicle. We had a choice to make between Disc brakes and Rim brakes. Though Rim brakes are cheap, light, mechanically simple, easy to maintain, and powerful, they perform poorly when the rims are wet. Rim brakes require regular maintenance. Brake pads can wear down quickly, and have to be replaced. Over longer time and use, rims become worn. Rim brakes also heat the rim because the brake functions by converting kinetic energy into thermal energy. It is not a problem in light-weight vehicles but in case of a heavy-weight vehicle and tandems in mountainous regions, the heat build-up over a long descent can increase tire pressure so much that the tire blows off the rim causing serious accidents. For this reason, disc brakes are often fitted instead of rim brakes in this situation.

4. Wheel Specifications: The engine will provide the vehicle a top speed of about 80 km/hr. As the estimated kerb weight of the vehicles is 300 kg, the wheels we came up with have a wheel base of 55.5 inches and a wheel track of 50 inches. The tyre dimensions are 26 x 1.3/8 inches.

5. Material to be used for fabrication: We have decided upon to use 1018 steel pipes to use as our material for the chassis. The outer diameter of the pipes is 1 inch with a thickness of 0.07 inch. With such specifications, the total weight of the chassis is coming out to be 8.41 kg (only the tubular frame). The yield strength of this material is close to 386 MPa and the elastic modulus is in the range of 190-210 GPa. The reason we chose this material is that it is readily available and easily weld-able with arc welding.

6. FE Analysis of the chassis: In order to get an unbreakable frame, a proper analysis was done on ANSYS for different designs of the frame considering different loads. A frontal impact of 5-G force and a side impact of 3-G force were considered. After analysis, the points of maximum stress were checked suitable numbers of cross bars were added in the design to minimise the stress. With the above specified yield strength and elastic modulus of the material, a factor of safety of about 1.8 was achieved. As you might remember, the snapshots of the ANSYS analysis was posted a couple of days back and you can easily watch them simply scrolling down your mouse button.

7. Hull design: the role of the hull is important when the vehicle is in water. Considering the total weight of the vehicle, it was found that the depth of the vehicle inside water is 0.5 metres. So, the minimum volume of water to be displaced by hull came out to be 0.3cu.metres. Taking into account the factor of safety, the hull has been designed by taking this volume as 0.6cu.metres.

8. Propeller Design: the point where the axle containing the propeller system will be fixed to the chassis, can be decided after knowing the water level as the ideal position will be the centre of the propeller coinciding with the water level. Depending on the availability of propellers as well as the type that suits our need, we plan to devise the propeller system in the most satisfying manner for the vehicle.

Thus, this is the basic framework of our design and also the road map of our process. We will be glad to answer any quarry regarding our design from anyone and at the same time, will be enlightened to incorporate suggestions and corrections into our design in pursuit of perfection.

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Cheers!!!

CAD mOdEl...

As promised, we have come up with the initial CAD model of our work. We plan to work on this model further to enhance the features of our product.
The modeling was done on Pro E and was prepared exclusively by Sanjeev within an hour. This only makes us more determined to accomplish our goal. The design features of the project will be uploaded in a matter of days. Meanwhile, we would request you to post feedback and also contribute in our endeavour.

CHASSIS sTrEnGtH aNaLySiS on ANSYS !!!

3 g force=1652 lbf (3g is greater than required but for to be on the safer side
we choose 3g; 3g means 3 times the total weight of
the vehicle including the human weight)
1 pound force/square inch=6895 Pascal
in case of frontal impact,max stress=51863 pound force /square inch=357.59 MPa
This exceeds the yield stress of mild steel which is 250 MPa.
Hence, we provide an assembly of cross bars to further enhance the strength. After providing cross-bars, stress level reduces from 214mpa to 181.76mpa

factor of safetey from 1.16 to 1.5, which in simple terms, wow!!!
So we have virtually built the chassis and analyzed its strength and come to the conclusion that by providing adequate number of cross members at appropriate places, we can control the stress to be resisted by the frame, well below the failure stress...