A.P.S.R.T.C- Bus body Fabrication.- Testing of new material for body structure. contact me at "singhvikas1993@gmail.com"

1. Name : VIKAS KUMAR
Project Industry Guide : Miss. Sharmila Asoka
( Asst. Workshop Manager)
Internal Guide : Mr. Prashant Kakade
(Manager & CMDC, CIRT, Pune)
Date : June 5, 2017
College : Vel Tech Dr. RR & Dr. SR Technical
University, Avadi, Chennai
BUS BODY FABRICATION –
Design & Analysis

2. Content
 Indian Scenario
 Importance of Correct Material selection and
Fabrication Method
 Bus Body Fabrication in A.P.S.R.T.C
 Design of Bus Body using CATIA V5
 Analysis of Bus Body Structure using
Different Materials
 Result
 Conclusion
 References

3. Indian Scenario
• Current production of buses in India is 54,000.
• MoUD estimate of urban bus requirement by 11th Five
Year Plan is 1,50,000 buses.
• Majority of buses built on drive-away truck chassis by
large number of bus body builders (>6000) in unorganized
sector.
• Only about 20 body builders and OEMs are in organized
sector.
• Capacity of the bus body building industry is very limited.
• Most of the designs developed by experience – not much
of engineering – only recently some designs of semi-low,
low floor of imported origin evolving.

4. However, Bus Accidents although fewer in numbers, attract
large attention because they can be catastrophic !
Accidents per year (based on
Modes of transport)

5. Today’s Expectations from Bus
Body Manufacturer
1) Consumer Demands
a) Looks and Ergonomics
b) Price- Performance
2) Competition
a) Reduced Lead Times
b) Reduced Cost
c) Improvised Quality
3) Government
a) Follow Standards – AIS: 052
b) Road Worthiness & Safety

6. Bus Manufacturer Expectations
 Body Design for assured safety and optimized body strength.
 Reduced fuel consumption achieved in terms of lesser
unladen weight and lower aero-dynamic drag.
 Assured passenger comfort in terms of dimensional and
seating requirements.
 Design for Noise Vibration and Harshness (NVH).
 Design for optimum HVAC.
 Internationally Competitive Design for specific applications

7. Importance of correct “Material
selection” and correct “Fabrication
Method”
So to obtain every one needs, as mentioned above either it is
Customer, Government or Manufacturer, it is very important to
choose correct material and fabrication method according to
material.
Because fabrication methods depend upon material used.
The structural design also varies on the basis of the
passenger capacity,
the types of usage,
 the nature of operation: urban/rural, long run/city run etc.
Based on above requirements the structural materials, the size
and shape of the structural member, the joint designs etc.

8. .
BUS BODY
FABRICATION IN
A.P.S.R.T.C
→

9. Classifications of Bus Bodies-
based on structures
1) M.S body (Steel sections)
2) All Aluminium body (Alu. Extruded sections)
3) Composite body (M.S Rolled sections filled with
Timber)
In practice all the three types of structures are used in varied
proportions to meet the individual requirement depending on
operating conditions.
 M.S structure is adopted for Hi- Tech and Super Luxury
Buses
 Aluminium structure is used in other types of bus bodies
such as- Luxury, Express, Ordinary and City buses.

10. THE MERITS AND DEMERITS OF DIFFERENT
TYPES OF BODIES ARE:
M.S Body
Merits
 Initial cost of the body is less when compared to all Aluminium body
 Ease of repairability in case of damages, accidents etc.
 Less rattling due to high structural rigidity.
De-Merits
 Relative weight of the body is high compared to all aluminium and
composite bodies hence result in more fuel consumption and tyre
wear.
 In coastal areas it is porne for corrosion.
 Lower salvage value compared to all aluminium body.
 Life span is less compared to all aluminium body on account of
corrosion.

11. All Aluminium Body
Merits
 Relatively lesser weight compared to M.S and composite bodies
and thereby savings in fuel and tyre.
 Suitable for operation in all types of atmospheric conditions.
 Higher salvage value compared to M.S and composite bodies.
 Longer life span compared to M.S and composite bodies.
 Lower repair and maintenance cost compared to M.S &
Composite bodies.
De-Merits
 Higher initial cost of fabrication compared to MS and Composite
bodies
 Rattling is more compared to MS bodies
( cont. )

12. Composite Body
Merits
 Initial cost of fabrication is low compared to all Aluminium and
MS Bodies.
De-Merits
 Lower resale value compared to all aluminium and MS
structures.
 Higher repair and maintenance cost compared to Alu. Body.
 Less life span compared to all Alu. Body due to corrosion.
 More weight compared to all Alu. Structures
 Not suitable for operation in coastal areas due to corrosion of
M.S components.
( cont. )

13. Compendium of Terms Pertaining to Bus
Body Structures

14. Sl No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Description
Cross Bearer
Pillars
Roof Longitudes
Roof Sticks
Skirt Rail
Cant Rail
Waist Rail
Crib Rail
Wheel Arch
Truss Panel
Grab Rail
Stanchions
Window Guard Rail
Parcel Racks
Luggage Carrier
Ladder
Driver Partition
Dash Board
Truss Panel
Anti sag bar
Out riggers
Material
Alu. Or M.S, 100*50*6 mm
Alu. Or M.S 40*40*3 mm
Alu. Or M.S 65*65*6 mm
Alu. Or M.S 40*40*3 mm
M.S 40*40*3 mm
Alu. Or M.S 40*40*3 mm
Alu. Or M.S 40*40*3 mm
Alu. Or M.S 40*40*3 mm
M.S Radius- 610mm
Alu. Sheet Or G.I Sheet
ERW steel tube, 25mm O.D, 2mm thick
ERW steel tube, 38mm O.D, 2mm thick
ERW steel tube, 20mm O.D, 1.6mm thick
CRCA sheet, 1mm thick
MS angles and Channels
ERW steel tube, 25mm O.D, 2mm thick
ERW tubes
MS angles, Alu. Or M.S sheet
Alu. Or G.I sheet
MS angles
MS angles, MS sheet

15. Main Dimensions (mm)
Sl.
No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
CHASSIS MODEL ->
DESCIPRTION
Wheel Base
Rear Overhang
Overall Length
Overall Width
Pillar Centers
Window sill (height
from cross bearer)
Waist Rail height from
skirt Rail
Interior Saloon min.
height
AL
222”WB
5639
2933 (52%)
10421
2590
1130
610
1160
1900
TATA
218”WB
5545
3050 (52%)
10370
2590
1130
610
1100
1900
EICHER
230”WB
5840
2920 (52%)
10660
2590
1130
610
1200
1900

16. Some Of The Bus Body Material
Specifications And Approved Sources
Description Specification Sources
Aluminium Materials
 Alu. Extruded sections Alu. alloy designation 64430 and
65032, condition WP( IS 733-1983)
 Alu. sheets Alu. alloy designation 31000, INDALCO/BALCO
Condition H3 of IS 737-1986 / HINDALCO
 Alu. 5-bar chequered Alu. alloy 65032 temper WP of
Plate IS: 737- 1986
 Alu. alloy solide Rivets Alloy designation 53000(NR-5)
Condition OD as per IS 740- 1977

17. M.S/ G.I Materials
i) Rolled sections IS 226 of 1975
IS 1079 of 1988 SAIL/ TISCO/ VSP
ii) CRCA Sheets IS 513- 1986
Bolts & Nuts
Bolts High tensile hexagonal TVS/ STL/ GKW/
bolts of fine thread conforming HINDUSTAN/ FAST
to property class of 8.8 of -NERS/ UNBRAKO
Nuts Antibrative type such as nyloc
Conforming to IS: 1364- 1983
U-bolts 45C-8 (EN8) as per
IS: 5517- 1978

18. Vehicle Replacement Policy in A.P.S.R.T.C
The vehicle replacement policy in APSRTC is as follows:-
 Special vehicles viz Express/ Luxury/ Hi-Tech will be replaced after
completion of 6.5/ 7.5/10 lakh kms Plus respectively
 Dist. Ordinary vehicles will be replaced after completion of 12.50 lakh kms.
Plus and based on physical condition.
 City vehicles will be replaced after completion of 13.00 lakh kms. Plus and
based on physical condition.
Replaced special buses are converted as City/ Ordinary/ Grammani buses at
Zonal Workshops and finally scrapped after completion of stipulated kms based
on the physical condition.

19. Stages in Bus Body Fabrication
There are 3 stages in Bus Body Fabrication in Zonal Workshop
Stage1
 Body interchange
 Vehicle Washing
 Removal of Panels
 Seat Removal
Stage2
 Structure Repair
 Flooring
 Cabin
Stage3
 Paneling
 Shutter frames
 Front Glasses
 Painting
 Seats

20. Body Interchange – Stage1

21. Vehicle Washing – Stage1

22. Removal of Panels – Stage1

23. Seat Removal – Stage1

24. Structure Repair – Stage 2

25. Flooring – Stage2

26. Cabin – Stage2

27. Paneling – Stage3

28. Shutter Frames – Stage3

29. Front Glass – Stage3

30. Painting – Stage3

31. Seats Fitting

32. Design
&
Analysis

33. DESIGN- CATIA V5
The three Dimensional model is modelled using CATIA software, according to
dimension of a “Express Bus” given in A.P.S.R.T.C specifications.
Overall Length 10093 mm
Overall Height 2375 mm
Overall Width 2590 mm

34. Front Rear
Left Hand Side Structure Right Hand Side Structure

35. Top
BUS BODY ASSEMBLY

36. Analysis of Bus Body
Structure – ANSYS
Modal analysis is the study of dynamic properties of structure under natural
vibration excitation, without applying any external load and gives us the
deformation of structure under natural vibration and equivalent stress
developed.
The Modal analysis of Bus Body is carried out by using three- materials:-
1) Mild Steel (used in Hi- Tech)
2) Alminium alloy 6351 (used in Ord./ Exp./ Lux.)
3) Aluminium alloy 6066- T651 (Testing material)

37. Mild Steel (used in Hi- Tech)
Composition:-
1) Carbon = 0.16 to 0.18%
2) Iron = 98.81 to 99.26 %
3) Manganese = 0.60 to 0.90%
4) Phosphorous ≤ 0.040%
5) Sulphur ≤ 0.050%
6) Silicon ≤ 0.40%
Properties:-
Ultimate Tensile Strength - 460 MPa
Density - 7.87 g/cc
Modulus of Elasticity - 250 GPa
Poisson's Ratio - 0.290

38. Aluminium alloy 6351 (used in
Ord./ Exp./ Lux.)
Composition:-
Aluminium = 97.8%
Silicon = 1%
Manganese = 0.6%
Magnesium = 0.6%
Properties:-
Ultimate Tensile Strength - 250 Mpa
Density - 2.7 g/cc
Modulus of Elasticity - 75 GPa
Poisson's Ratio - 0.033

39. Aluminium alloy 6066- T651
(Testing material)
Composition:-
Aluminium = 93 to 97%
Silicon = 0.9 to 1.8%
Magnesium = 0.8 to 1.4%
Copper = 0.7 to 1.2%
Manganese = 0.6 to 1.1%
Iron = 0 to 0.5%
Chromium = 0 to 0.4%
Zinc = 0 to 0.25%
Titanium = 0 to 0.2%
Residuals = 0 to 0.15%
Properties:-
Ultimate Tensile Strength - 393 Mpa
Density - 2.72 g/cc
Modulus of Elasticity - 68.9 GPa
Poisson's Ratio - 0.33

40. Modal Analysis
Meshing of Bus structure is done
 6- Modes are taken randomly to find subsequent random frequency, to
find:-
Deflection
Equivalent stress developed

41. Frequency
Modes Frequency (Hz)
1 6.5736
2 11.354
3 11.764
4 11.768
5 12.056
6 12.056

42. Mild steel structure Analysis
 Deflections (mm)
Mode1 Mode2
Mode4 Mode5

43. Mode 5 Mode 6
Frequency Deflection (mm)
6.5736 1.3814
11.354 1.336
11.764 67.313
11.768 67.345
12.056 68.873
12.056 68.865
Total 275.1134

44.  Equivalent Stress Developed
Stress developed in bus structure due to deflection is 0.47195 MPa

45. Aluminium alloy 6351
 Deflections (mm)
Mode1 Mode 2
Mode 3 Mode 4

46. Mode5 Mode 6
Frequency Deflections (mm)
6.8754 2.498
11.807 2.2428
12.291 114.63
12.295 114.68
12.606 117.33
12.606 117.31
Total 468.6908

47. Equivalent Stress developed
Stress developed in bus structure due to deflection is 0.53583 MPa

48. Aluminium alloy 6066- T651
 Deflections
Mode 1 Mode 2
Mode 3 Mode 4

49. Mode 5 Mode 6
Frequency Deflection (mm)
6.5736 2.502
11.354 2.256
11.764 114.38
11.768 114.44
12.056 117.02
12.056 117.01
Total 467.608

50. Equivalent Stress Developed due to deflection
Stress developed in bus structure due to deflection is 0.51577 MPa

51. Result
The structural Analysis is performed for Bus body structure , the model
is discretised in to 119484 elements and 230911 nodes.
Based on the Analysis results obtained by performing analysis on bus
body structure .The following discussions are written for different
materials are Mild steel structure, Aluminium alloy - 6351, and
Aluminium alloy- 6066 T651.
Materials Total Deflection Equivalent Stress
(mm) (Mpa)
 Mild Steel structure 275.1134 0.47195
 Aluminium alloy 6351
structure 468.6908 0.53583
 Aluminium alloy
6066- T651 structure 467.608 0.51577

52. Conclusion
According to the total Deflection and Equivalent Stress
developed of 3 materials, MS is best among the three.
But among Aluminium alloys 6351 & 6066- T651, the deflection
and equivalent stress developed of alloy 6066-T651 is lesser than
present used alloy 6351 extrusions.
So I suggest A.P.S.R.T.C to consider Aluminium 6066- T651
alloy and do research on this, so that it can be used in future, to
increase the life of Bus Body Structure.

53. References
 CMVR -1989 Rules
 AIS for Buses
 AIS- 052
 Strength of Material (Text book)- Dr. R K Bansal.
 Engineering Materials & Metallurgy (Text book)- R.K Rajput
 http://www.dexcraft.com/articles/carbon-fiber-composites/aluminium-vs-carbon-
fiber-comparison-of-materials/
 s://www.metalsupermarkets.com/7-things-consider-choosing-aluminum-grade/
 Wikkipedia
 http://apsrtc.gov.in/profile.aspx
 http://itsmyblogvbe.blogspot.in/2015/09/bus-body.html
 Prasannapriya. Chinta, Dr.L.V.Venugopal Rao, IOSR Journal of Mechanical and
Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume
11, Issue 5 Ver. I (Sep- Oct. 2014), PP 39-47
 Rajesh S.Rayakar - INTERNATIONAL JOURNA L FOR RES EARCH IN AP PL I
ED SC IENC E AND ENGINEERING TECHNOLO GY (I JRAS ET) Vol. 2 Issue
VII, July 2014 ISSN: 2321-9653.
 Satosh.B PRECEDING OF COMPUTIME Sep 16-17-2015,Natinal conference on
Computational Methods in Mechanical Engineering,Deparartment of Mechanical
Engineering Osmania University Hyderabad.
 Mahesh Haldankar, A. M. Shirahatti- International Journal of Engineering and