bus skeleton design

International Journal of Engineering & Technology IJET-IJENS Vol:12 No:04 113

I J E N S IJENS © August 2012 IJENS -IJET-8585-1213604

Computer Aided Bus Skeleton Design

(BUS-CAD)

H. M. A. Hussein and Alexander Harrich

Abstract— The designing and manufacturing of a new bus is a

process which need of a large number of technical labors and a

great consumption time, starting from designing operation until

full production process. Bus Industry in the Arab region realized

some success and is equivalent to their counterparts in Europe

and America. This makes the interest in reducing the time and

efforts spent in the design, planning and production processes in

the bus industry is an added value. The bus steel structure

(skeleton) building process is the starting base for all the

following manufacturing processes. Planning Department -based

on it – start writing the operating pages and determine the

required raw materials for the bus manufacture. The logistic

department starts to provide the necessary raw materials for the

bus construction. Tool department starts to design and

manufacture of production facilities, and main fixtures (drilling

and welding) for constructing the bus skeleton. The

administration department collects all the information’s to

estimate the bus cost and expect the profit from the

implementation of this product. The virtual world created by the

computer in nowadays our life puts a strong chance to simulate

many of the manufacturing processes before they occur, and this

was not available before. Bus skeleton design, planning and

manufacturing operation represent a good example can be

implemented entirely by using computer simulations. The

present paper discuss the basic lines for construction a program

to reduce the design, planning and manufacturing processes of

the bus structure. Objective of this proposed work is designing a

parametric program for the bus skeleton design (all types) with a

possibility in parametric design modification in the bus skeleton

– Automatic creation of technical documents – Bus welding

assembly fixture construction - determine the initial cost

estimation of the bus.

Index Term— Parametric design, Bus skeleton, CAD,

Concurrent engineering, Process Planning

I. INTRODUCTION

Bus and mini-bus in any country is a kind of industry which is

connected directly to the prosperity and the stability of this

state. It starts after two years of completion of the security and

sociality stability of the welfare state, but stopped immediately

in case of any defect in this stability. Begins, when the

industrial company owner demand for buses to transport his

H. M. A. Hussein, Author is with the Advanced Manufacturing Institute,

King Saud University, Riyadh, KSA., phone: 00966568775127

hhussein@ ksu.edu.sa

Alexander Heririch, Author is with Institute of Automotive Engineering,

Graz University of Technology, Inffeldgasse 11/1, A-8010 Graz, Austria

[email protected]

workers from and to his factories. When, Tourist company

owner demand for buses for tourist’s trip transport around the

country. When requested by state agencies for the buses, mini-

buses inside and outside of cities to transport citizens here and

there.

The design of the internal bus skeleton structure is the basis of

typical bus development of the bus industry. It contains of

framework of tubes with different cross sections, which

arranged in specified shapes based on the design philosophy.

This arrangement is used to be safe for occupants and to

sustain the extreme conditions can be matched on the road.

For this reason, several tests are made on the bus structure to

measure the durability. The most important is the impact and

the Roll-Over Tests. Time expected to complete the bus

structure design is more than 3 months and then followed by a

group of related industrial processes, such as; (1) covering the

bus body structure by panels, ―Sheeting‖. (2) Manufacture the

bus front and rear from fibreglass. (3) Process planning for

each bus components. (4) Cost Estimation for the complete

bus skeleton, which is a decision making support for the bus

company owner. (5) provide all the production facilities

requirements to complete the bus body. (6) Design and

manufacturing aspects of the assembly welding fixtures for the

six sub-assembly fixtures and finally the main Merry Jig. In

some industrial facilities, there is interest in the FEA

simulation programs to predict the durability of the structure

and the extent of its ability to withstand the shocks and the

coup. As well as simulate the thermal analysis of the body

structural related to the welding fixture to determine which

places may be exposed to the greatest welding deformation

operations. Then, consolidate and treatment of these regions

by more clamps. The means of installation that will maintain

the structure dimensions intact to ensure the safety of the next

related operations. Unfortunately, in many bus factories in the

Arab region neglects of the body skeleton FEA simulation and

depend only the on the past designer experience for added

more bus structure tubes, which increases the weight and cost

of the bus.

The bus or minibus body skeleton design represent the

bottleneck stage within the industrial facility, which once

completed successfully, the other company sectors starts to

work either parallel or sequential. Thus, an acceleration of this

process leads to a reduction of development time, which can

be consequently transferred into money. In this way the

industrial partner enhances its efficiency."

mailto:[email protected]



II. LITERATURE REVIEW

Process to accelerate of the bus structure completion design is

an urgent need within the industrial factories working in the

bus industry. The giant companies working in this area are

expecting to have their own programs for the bus structure

design. The information’s about this programs not reach us

except very little of these experiments are either considered

secrets of the industry or because they are completed within

companies so may not be publishing for research purposes in

this case.

From past experiences that have reached us is the experience

of El-Nasr for the cars manufacturer of in Egypt,‖NASCO‖

which carried out through The ―Automated Integrated

System‖ (1 and 2), through which the completion of the

program to build the structure of bus public transport (within

cities) using the AutoCAD program and AutoLISP language

linked to MS-Excel program. The coordinates were extracted

from a real bus skeleton from the former company products

called N966. It’s collected point by point from the blue printed

pages. The coordinate’s value then stored in Excel file. An

AutoLISP program constructed to build each layer of the pipe

through the pipe skeleton. The AutoCAD program also has

been linked to DCL, Dialogic Dialogue Box. Hundreds of

equations, computational relations and engineering rules

which related on the bus skeleton design have been used. All

those data are extracted from the company experts in bus

design. This expert rules data are stored into excel file to

construct the Knowledge Based Design. After full success of

Bus Skeleton design model, a Finite Element ―COSMOS‖

program is used to analyze the stresses on the structure and to

predict the extent of safety design structure. This work took

nearly 6 years starting in 1990. American University in Cairo

―AUC‖ and Azhar University are participated in the model

preparing project. The Mechanical Design Department in

Cairo University was participating in the stage of skeleton

stress analysis.

Researcher Majid Rasmy of Cairo University, progress of his

Master degree 2003 in reach an optimal design of the movable

tubes structure. This study was implemented in cooperation

with Ghabbour bus industry in Egypt. In this study, a movable

tube structure is simulated by computer and the stress analysis

is done using ―COSMOS‖ finite element program.

Researcher U.C. Tapici from Istanbul Technical University,

Turkey, 2006 (3 and 4) study the impact of appropriate clamp

selection in the process of tube welding used for bus structure

to reduce the dimensions distortions resulting from the arising

thermal stresses based on the welding operation. A

Programmable arc welding robot is used in this operation.

Researchers Lan, Chen, Lin (5) in Automotive Engineering

School in both of Jilin University in China and Birmingham

University in 2004 have a weight-loss study of the bus

structure to the permissible limit with using a stress analysis

program ―ANSYS‖. The study applied on 2 models, one of

those models before decreasing the weight, and the other after

decreasing the weight on the bus side wall. A comparison is

done between the 2 models to get ride off the unnecessary

tubes which have not a significant impact in the durability of

the structure.

The Researcher Vikas Yadav (6) in 2006 has studied the

impact action on the lower part of the bus by using the stress

analysis software, and similarly, the researcher Ganesh R.

Panneer (7) from the University of West Virginia in 1998 to

study the impact of trauma on the schools bus side.

The researcher PankajChandna et al, (8), as well as Rahul

Mahajan et al (9) have studied stress analysis on the bus

structure using Hypermesh and NASTRAN programs, the bus

structure model is build using the CATIA program.

In the current paper, a new parametric bus skeleton model will

build on both AutoCAD and CATIA program using tailor

made macros. The both macros controlled using visual basic

program, which connected with MS-Excel to extract the

coordinates for constructing the bus skeleton model. The

program is build to construct all the busses family groups,

such as mini_buses, city_buses, inter_city_buses, high deck,

super_high_deck. For each family of busses, the proposed

program will help in the Body skeleton model construction

module, bus skeleton modifier module, components process

planning module, cost estimations module, bus body sheeting

module, and Fixture design module.

In the first stage, the research work will focus on extracting

the co-ordinate data from the mini-bus crouser, which is one

of the Ghabbour-Egypt company products, as shown in Figure

1, to build the program main base. The co-ordinate data will

extract from a ready –made AutoCAD file for body drawing.

The extracting operation will need another tailor made

AutoLISP and VBA codes for this very long operation, but in

the same time it still need for extensive setup work and data-

entry work. The first stage work for constructing the bus body

model, will not focus on the design quality, but will focus only

on the time duration measurement in constructing the model.

Fig.1. Mini-bus crouser

III. RESEARCH OBJECTIVE

The main goal of this project is to introduce integrated

software in bus and mini-bus industry called BUSCAD.

BusCAD Program is to solve all the problems related to the all

types of buses in the bus industry. The types of busses could

be classified into MiniBus, CityBus, Intercity Bus, High Dick,

Super high Deck, School bus, ... etc as shown in Figure 2,

which shows the proposed program main menu. Each button

allows the user to access the selected type of buses. These



problems such as designing and building the bus skeleton

structure with the ability to re-design or modification in the

structure if necessary. The covering or sheeting of the desired

bus structure location. Designing and drafting of the interior

accessories bus design such as chairs, dashboard, the upper

shelves.... etc... Producing the full detailed process sheet for

every part of the bus components. Welding fixture design for

each assembly and sub-assembly of the bus skeleton.

The flexibility of selecting between different techniques in bus

welding fixtures designs, which suitable to the factory

planning and capabilities.

Identifying initial cost estimation for the bus projected. For

the implementation of such a design, which is determined by

the expected profit and speed of decision-making for the

implementation of the product or not and is determined by the

price of the integral relationship between the programs of

CATIA and MS-Access avoiding thus to deal with external

programs such as the Oracle, Sap or Paan.

Finally, stresses analysis of through advanced technologies

provided through the fifth edition of the CATIA program

compared with the previous versions. Stress analysis in the

bus project includes two important issues here. The first topic

is to dynamic analyze the stresses on the bus skeleton of the

bus to check the bus structure durability and its ability to

protect the passengers lives inside in case of collisions with

moving or fixed objects, as well as in cases of Bus Roll-Over

Test. The second theme is to analyze the thermal stresses on

the body skeleton structural bus resulting from the welding

operations. This analysis is important. To determine the most

important points on the bus skeleton structure that should be

clamped to avoid distortions. The analysis will provide us with

the necessary force required at which point to overcome the

tube distortion based on thermal stresses.

Fig. 2. The program main menu

Fig. 3. The proposed operations on the bus skeleton.

Figure 3 illustrates the most important operations to be

performed on the bus skeleton structure. In each of those

applications we need first to construct a computer 3D model,

and without this model we cannot move to any of the

following related steps. Whenever, the rapid construction of

the computer 3D model, the rapid speed related steps could be

done, the rapid speedily access to the optimum design, and

then the fastest decision making could be done.

The target of this project proposal in the first stage is to

construct the bus skeleton 3D model via CATIA or AutoCAD

programs. The first program stage focuses on achieving this

goal in a very short duration, without taking the optimum

design into consideration. The optimum design will be care in

the following program stages.

III. THE USED PROGRAMS

Program - at the first stage - is an interactive language

between CATIA and AutoCAD programming, and Excel

Programming. The coordinated stored in Excel file will

arranged in the suitable manner that can be read in the CATIA

or AutoCAD programs. The Excel coordinate sheet will be

controlled through another set of Excel sheets, which work as

a translator from Excel sheet to other to simplify the

arrangement problem. This technique for this reason becomes

easier for the programmer to read, follow and control the data.

All the cells in each sheet are connected together with a sum

of relations and equations to simplify the full excel file

control. In case of the CATIA programming, the CATscript

file is divided into a number of divisions.

The first part is responsible in connecting the CATIA program

with the MS-Excel file. The second part is responsible in

receiving data from the Excel coordinate sheet, and store them

into variables inside the CATIA macro, ―The stored

coordinate variables in the case of minibus is more than 3000

items‖. The third part, receiving the stored coordinates items

from the second part of the program, and then converted into

points. The fourth part of the program connecting between

points to construct lines and Splines, the fifth program part

prints the lines and splines on the CATIA screen. The dealing

with AutoCAD program is nearly the same steps with little bit

minor modifications. The whole programs items are controlled

using the visual basic program.

PROGRAM OPERATION PROCEDURE.

Once running the program, the dialogue box in Figure 17

appears to select the vehicle type that will be working on it, as

example for the first stage "MiniBus". The dialogue Figure 18

shows the selection of the operation type, as example "Bus

Skeleton Design".

Fig.17. Bus side curve control screen



Fig.18. The Bus Roof Curve ontrol Screen

To design the skeleton structure for a new minibus, the side

curve must be firstly select, and for this purpose the dialogue

box in figure 17 is designed to control the bus side curve. The

curve is controlled by adjusting its coordinates. Whenever the

curve contains more points, whenever the smooth curve can

we obtain.

Figure 17 shows, the curve coordinates of the mini-bus

Cruiser, which by changing these coordinates especially in

―Y‖ and ―Z‖ directions and kind, the side of the screen shows

the shape of the curve representative of the new curve and the

coordinates directly relate to the page program Excel cells for

control, which in turn relate to the program page of the Excel

program which integrated with CATIA, and contains the

software on 25 points for the curve representative side in order

to give you the maximum degree of flexibility in the

extraction by a new curve.

The next step for the mini-bus structure design is the roof

curve design, and for this purpose, a dialogue box is designed

as shown in Figure 18, as the same technique used in the side

curve. Through the powers of 26 control points, any roof

curve can be design easily, as possible to the roof to reach the

optimal design and is worth mentioning that must be adhered

to the limits of certain in this drawing curves whether abroad

or to the inside - and that these limits are subject to either

previous experience in the BB design or the limitations posed

by each country in its own designs, such as the maximum

width and height of the top of the vehicle so as not to conflict

with the heights of bridges or display methods provided for in

the design codes used in this state.

CATIA and AutoCAD aided Bus Industry

The next step is to run the CATIA or AutoCAD program to

start the macro directly from the Desktop or to run it through

the pull-down menus from within a program CATIA or

AutoCAD Tools. The program draws the proposed bus or

minibus components design through the graphical media even

in CATIA or AutoCAD. The components for the minibus are

about the 350 part, each representing a tube or section in the

bus structure. The software synthesis of Relations between

CATIA or AutoCAD as a graphical media and the MS-Excel

program automatically and then, extracts these values to put

them in a Parameters, and then re-called again for the printing

this data on the graphical media program screen. Figure 19

shows part of the CATIA product tree.

Fig. 19. The CATIA Product Tree

Figure 20 shows the full mini bus skeleton mini bus for the

crouser product. Using a tailor made AutoLISP code, all the

model tube converted into wire frame (lines and splines) in the

middle centre of the buss tubes as in figure 21. In the second

level, another AutoLISP code runs to search the entire

drawing data base and select all the lines and splines co-

ordinates and extract their first and end points co-ordinates

and store into excel file as a database. These two codes save a

lot of time of the data entry work.

Figure 22 shows the re-build of the buss wire frame into

CATIA graphical environment.

Fig. 20. The Bus Skeleton model on the AutoCAD Environment

Fig. 21. The Bus skeleton wire Frame on the AutoCAD Environment



Fig. 22. The Bus skeleton wire Frame on the CATIA Environment

CONCLUSIONS

Computer aided bus skeleton design, is a powerful tool to

support bus building companies, The work in this project must

be done in steps, The first step which in this paper focus in

how to rapid build the bus skeleton.

REFERENCES

1. H.M. Helmy, ―Design Automation of Parametric Bus Skeleton Using concurrent Engineering Approach.", 2nd ARAB AUTO Conference of

Cairo, Nov. 2000.

2. H. M. Helmy, ―Finite Element Analysis of NASCO City Bus, with extension to Dynamic Effects of Engine and Power Transmission

system.", Military Technical College Conference at Cairo, April 2001.

3. F. Lan, J chen, J. Lin, ―Comparative analysis for bus side structure and lightweight optimization.", Proceedings of the Institution of Mechanical

engineers; Vol. 218, No. 10, pp. 1067, Oct 2004. 4. Suthep Butdee, Federic Vignat, ―TRIZ Method for Light Weight Bus

Body Structure Design.‖, 9th Global Congress on Manufacturing and

Management (GCMM2008), 12-14 November 2008, Holiday Inn, Surfers Paradise, Australia.

5. S. Butdee , F. Vignat , TRIZ method for light weight bus body structure

design.‖, Journal of Achievements in Materials and Manufacturing Engineering, vol. 31,No.2, Dec. 2008, JAMME.

6. Manokruang S., Butdee S., Methodology of Bus-Body Structural

Redesign for Lightweight Productivity Improvement., AIJSTPME (2009) 2(2): 79-87.

7. Kumket B., Jongprasithphon S., Butdee S., Welding Joint Analysis

using FEM together with Physical Experiment for a Bus Body Structure based on the Standard No.1, AIJSTPME (2010) 3(2): 49-55.

8. M. Vural, H. F. Muzafferoglu, U.C. Tapici, " The effect of Welding

fixtures on welding Distortions.", JAMME, Journal of Achievements in Materials and Manufacturing Engineering, V 20, 1-2, 511-514, 2007.

9. U.C. Tapici, "Fixture Design for Robotic Welding application and

analysis of welding Distortion.", Master Degree Thesis, Istanbul Technical University, Institute of Science and Technology, 2006.

10. Yusuf özçatalbaş, tayfun findik, adem kurt, kubilay karacif, alpay Özer

ve halil ibrahim vural, ―An experimental approach for determining-The distortion tendency in welded structures.‖, J. Fac. Eng. Arch. Gazi

Univ., Vol 23, No 1, 139-145, 2008.

11. J. Bruce Emmons and Leonard J. Blessing, ―Ultralight Stainless Steel Urban Bus Concept, SAE Technical.‖, Paper Series 2001-01-2073.

12. J. Bruce Emmons, Sidney Diamond, and Phillip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES - A. Lightweight Stainless Steel Bus Frame: Phase III.‖, High Strength Weight Reduction Materials

FY 2003 Progress Report.

13. Mark T. Smith, Tony Petree, Sidney Diamond, and Philip S. Sklad, ―5. LIGHTWEIGHT VEHICLE STRUCTURES - B. Large Castings for

Advanced Cab Structures.‖,High Strength Weight Reduction Materials

FY 2003 Progress Report. 14. Curt A. Lavender, Kurt M. Knop, Sidney Diamond, and Philip S. Sklad,

―5. LIGHTWEIGHT VEHICLE STRUCTURES - C. New-Generation

Frame for Pickup/Sport Utility Vehicle Application High Strength Weight Reduction Materials FY 2003 Progress Report.

15. J. Bruce Emmons, Sidney Diamond, and Phillip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES - A. Lightweight Stainless Steel Bus Frame―Phase III‖, High Strength Weight Reduction

Materials FY 2004 Progress Report, 143.

16. Anthony E. Mascarin, Sidney Diamond, and Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES-B. Stainless Steel Bus Structure-Manufacturing Cost Analysis.‖, High Strength Weight

Reduction Materials FY 2004 Progress Report 149.

17. Srdjan Simunovic, Sidney Diamond, and Philip S. Sklad, ―5. LIGHTWEIGHT VEHICLE STRUCTURES - C. Side Impact Analysis

of a Lightweight Stainless Steel Bus Structure.‖, High Strength Weight

Reduction Materials FY 2004 Progress Report, 153. 18. Curt A. Lavender, Kurt M. Knop, Sidney Diamond, and Philip S. Sklad,

―5. LIGHTWEIGHT VEHICLE STRUCTURES - D. New-Generation

Frame for Pickup/Sport Utility Vehicle Application.‖, High Strength Weight Reduction Materials FY 2004 Progress Report 159.

19. Travis McCloud, Bill Harris, Sidney Diamond, and Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES - E. Lightweight Trailer—Liburndas Project.‖, High Strength Weight Reduction Materials FY

2004 Progress Report 163.

20. Ben Ubamadu, Bill Harris, James J. Eberhardt, Philip S. Sklad, and Michael Starbuck, ―5. LIGHTWEIGHT VEHICLE STRUCTURES - A.

Lightweight Trailer—Liburndas Project.‖, High Strength Weight

Reduction Materials FY 2005 Progress Report. 21. Nirmal M. Tolani, James J. Eberhardt, Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES - B. Application of

Superplastically Formed (SPF) Aluminum for Truck Body Panels.‖, FY 2005 Progress Report High Strength Weight Reduction Materials.

22. Brian Knouff, Jay Batten, James J. Eberhardt, and Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES - C. Advanced Composite Support Structures.‖, High Strength Weight Reduction Materials FY

2005 Progress Report. 23. Curt A. Lavender, Kurt M. Knop, James J. Eberhardt, Philip S. Sklad,

―5. LIGHTWEIGHT VEHICLE STRUCTURES -D. New-Generation

Frame for Pickup/Sport Utility Vehicle Application.‖, High Strength Weight Reduction Materials FY 2005 Progress Report.

24. Curt A. Lavender, Don Trettin, Nirmal Tolani, James J. Eberhardt, and

Philip S. Sklad, ―5. LIGHTWEIGHT VEHICLE STRUCTURES - E. Advanced Superplastic Forming Development for Heavy Vehicle

Structures.‖-High Strength Weight Reduction Materials FY 2005

Progress Report. 25. Darrell R. Herling, James J. Eberhardt, and Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES -F. Development of

Magnesium for Heavy Vehicle Powertrain Components.‖, FY 2005 Progress Report High Strength Weight Reduction Materials.

26. J. Bruce Emmons, James J. Eberhardt, and Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES -G. Lightweight Stainless Steel Bus Frame―Phase III.‖, FY 2005 Progress Report High Strength

Weight Reduction Materials.

27. S. Simunovic, G. A. A. James J. Eberhardt, and P. S. Sklad, ―5. LIGHTWEIGHT VEHICLE STRUCTURES -H. Side Impact Analysis

of a Lightweight Stainless Steel Bus Structure.‖, High Strength Weight

Reduction Materials FY 2005 Progress Report. 28. Anthony E. Mascarin, James J. Eberhardt, and Philip S. Sklad, ―5.

LIGHTWEIGHT VEHICLE STRUCTURES -I. Stainless Steel Bus

Structure—Manufacturing Cost Analysis.‖, FY 2005 Progress Report High Strength Weight Reduction Materials.

29. Maged Rasmy Abd El Malk, "Design and Optimization of Space Frames

with Vehicular Applications.', Master Degree Thesis, Faculty of Engineering Cairo University, Giza, Egypt, April 2003.

30. Sherif Mohamed Ali Reda Elseufy, ―Save Design study for bus rollover

using finite element analysis (FEA)‖, Master Degree Thesis, Faculty of Engineering, Cairo University, Giza, Egypt, 2011.

31. Vikas Yadav, "Finite Element Modeling And Side Impact Study Of A

Low-Floor Mass transit bus, master of science thesis, department of mechanical engineering and the faculty of the graduate school of

Wichita State University B. E. Shivaji university, Dec 2006.

32. Ganesh R. Panneer, ―School bus Crashworthiness.‖ Master Degree Thesis, West Virginia University, 1998.

33. PankajChandna, Cian Bhushan, V.P. Singh, Devender Kumar, Amit

Kumar, " Finite Element Analysis of A Bus Body structure Using CAE Tools.", pp. 1-6, HTC2008.

bus skeleton design

Documents