Scholarly article on topic 'Integration of Engineering Design and CAE Tools in Generating the Preliminary Design of a Vacuum Chamber for Internal Combustion Use'

Integration of Engineering Design and CAE Tools in Generating the Preliminary Design of a Vacuum Chamber for Internal Combustion Use Academic research paper on "Materials engineering"

CC BY-NC-ND
0
0
Share paper
Academic journal
Procedia Engineering
OECD Field of science
Keywords
{"Computer Aided Engineering (CAE)" / "Computer Aided Design (CAD)" / "Vacuum Chamber" / "Engineering Design Process" / "Finite Element Analysis (FEA)"}

Abstract of research paper on Materials engineering, author of scientific article — Mohammad Azzeim Mat Jusoh, Mohd Syahar Mohd Shawal, Mohd Nor Fadhli Mohammad, Helmi Rashid, Razali Hassan, et al.

Abstract In general, variety of apparatus and tools had been developed in order to test and monitor the performance of flame propagation during combustion. As for this paper, the main objective is to present on the preliminary design outcome of a vacuum chamber, which shall be used in monitoring and investigating the performance of internal combustion experimentation during vacuum state. By adapting the Engineering Design Process, structured design phase had been conducted in order to generate a basic yet functional chamber which fits the objective. As a result, cylindrical shaped chamber with hemispherical head had been chosen as the final shape of the device. The simulation result shows that the device is able to sustain 10MPa of internal pressure; fulfilling the objective and design specifications. In future, the output shall be further studied in order to improve and enhance the design of the vacuum chamber.

Academic research paper on topic "Integration of Engineering Design and CAE Tools in Generating the Preliminary Design of a Vacuum Chamber for Internal Combustion Use"

Available online at www.sciencedirect.com

SciVerse ScienceDirect

Procedia Engineering 41 (2012) 1769 - 1774

Engineering

Procedia

www.elsevier.com/locate/procedia

International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012)

Integration of Engineering Design and CAE Tools in Generating the Preliminary Design of a Vacuum Chamber for Internal Combustion Use

Mohammad Azzeim Mat Jusoha*, Mohd Syahar Mohd Shawala, Mohd Nor Fadhli Mohammadb, Helmi Rashida, Razali Hassana, Muhamad Fauzi Othmana, Hazran Husaina

aFakulti Kejuruteraan Mekanikal (FKM), Universiti Teknologi MARA (UiTM) Shah Alam, Selangor, MALAYSIA bSamsung Electronics Malaysia Sdn Bhd, Perlabuhan Klang, Selangor, MALAYSIA

Abstract

In general, variety of apparatus and tools had been developed in order to test and monitor the performance of flame propagation during combustion. As for this paper, the main objective is to present on the preliminary design outcome of a vacuum chamber, which shall be used in monitoring and investigating the performance of internal combustion experimentation during vacuum state. By adapting the Engineering Design Process, structured design phase had been conducted in order to generate a basic yet functional chamber which fits the objective. As a result, cylindrical shaped chamber with hemispherical head had been chosen as the final shape of the device. The simulation result shows that the device is able to sustain 10MPa of internal pressure; fulfilling the objective and design specifications. In future, the output shall be further studied in order to improve and enhance the design of the vacuum chamber.

© 2012 Mohammad Azzeim Mat Jusoh. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Centre of Humanoid Robots and Bio-Sensor (HuRoBs), Faculty of Mechanical Engineering, Universiti Teknologi MARA.

Keywords: Computer Aided Engineering (CAE), Computer Aided Design (CAD), Vacuum Chamber, Engineering Design Process, Finite Element Analysis (FEA)

1. Introduction

Internal combustion engine is an important tool which operates under high pressure in order to power up specific device. In terms of experimentation activities, among the common problem is to monitor the performances and the flame propagation of internal combustion during low atmospheric pressure or vacuum state. As a solution, vacuum chamber is one of the most suitable devices which could operate under critical condition; in order to monitor the specified performance. The low pressure or vacuum state produced by the chamber provides a chance for scientist to monitor the actual phenomenon during combustion process.

In designing a basic vacuum chamber, various types of manuals and reference [1-4] are available for the basic guideline. For minimum requirement, the design must comply with the ANSI Standards B36 and B16; and also ASME Boiler and Pressure Vessel Code 1992. However, due to the difference in needs and level of complication of each design, a more straight forward method is required in order to suit the actual needs of different customer or consumer. As for research activities, various methods and techniques has been studied and applied in order to strengthen up the design contents of the pressure vessels. For example, Petrovic [5] have investigated on the influence of forces which act on a nozzle of a pressure vessel by utilizing finite element method. In terms of experimental and numerical study, Ahn et al. [6] have discussed on the

* Mohammad Azzeim Mat Jusoh Tel.: +603-5541 1823; fax: +603-5543 5160. E-mail address: m_azzeim@salam.uitm.edu.my.

1877-7058 © 2012 Published by Elsevier Ltd. doi:10.1016/j.proeng.2012.07.381

for the combustion characteristics of oxy fuel burner. In future, the application of such references shall used as guidelines to further improve on the design of the vacuum chamber.

The main purpose of this paper is to present on the preliminary design outcome of a basic yet functional vacuum chamber; which able to withstand 10MPa of internal pressure. Next is to identify on the most suitable and optimised parameter for the vacuum chamber, especially for weight improvement purposes. Finally, the aim is to adapt the Engineering Design process towards generating the preliminary design of this vacuum chamber.

Obviously, in designing the vacuum chamber, all parameters need to be considered in order to create a good design. It could be possible that during the end, the final design of this vacuum chamber might be similar with any available pressure vessels in market. However, considering the potential towards design research activities, we foresee this as a positive challenge towards increasing the versatility and options in product design. In future, the output of this study shall be used towards creating a more detailed and reliable design of the vacuum chamber, especially for activities which is related to internal combustion experimentation.

2. Methodology

The fundamental of design process can be divided into three main stages which is the Conceptual Design Stage, Preliminary Design Stage and the Detail Design Stage.

2.1 Conceptual Stage

The most important element in product design is defining the needs of the consumer. As informed previously, the main objective is to generate a design of vacuum chamber, which able to withstand 10MPa of internal pressure. Based on this requirement, the next action is to gather related information regarding the design contents of a vacuum chamber such as the basic shape of the design, size, material type, stresses, chamber displacement and others. Available options for the criteria stated shall be analyzed and finally, the best design shall be selected.

In terms of theoretical aspect, The Failure Theories concept shall be used in order to identify the safety factor of the product. One of the most common theories which can be used is the Von Mises criterion (Refer Equation 1); which states that failure occurs when the energy of distortion reaches the same energy for yield in uniaxial tension [7]. In order to ensure that the product will not yield during operation, the Von Mises stress value must be smaller than the yield stress of the material. The safety factor of the product is targeted within N = 1.5 ~ 4. Other than that, the basic equation related to Thin-Pressure Vessel design shall be referred as basis for the pressure vessel calculation (Refer Equation 2 ~ 3).

Longitudal Stress Hoop Stress Pressure Radial Thickness

(2) (3)

2.2 Preliminary Design Stage

The Preliminary Design Stage can be divided into three major phase which is Product Architecture, Configuration Design, and Parametric Design phase. In terms of product architecture, the design of a vacuum chamber can be found in almost any shape and size imaginable for example, sphere ellipsoid, cylinder with domed ends, cone, geodesic ball (triacontrahedron), diamond (octahedron), cylinder with flat ends, pyramid (tetrahedron) and box [3]. However, in order to design a low cost yet reliable vacuum chamber, specific conditions such as deflection control, best materials selection, proper surface preparations, design of the structural components, engineering the heating, cooling, shielding system, mechanism and several other criteria, should be controlled on in order to designing a good vacuum chamber.

The shape of the chamber can affect its volume and surface area. The smaller the total surface area, the smaller the quantity of gas loads from desorbing water molecule. Indirectly, this can reduce the pumping time of the chamber [11]. By choosing the right shape, the surface area can be reduced. Rectangular chamber are generally more expensive than other configuration. However, rectangular chamber is one of the preferred choice because on the ease of accessibility or when large chamber mass is required vibration dampening. Other than that sphere shape chamber is known to be less expensive and has less internal volume.

Another important aspect during the configuration design phase is the material selection process. During this stage, the property of materials must be analysed in order to meet the design requirement. For the head, shell and flange, the materials must have good forming and welding properties which is important properties because forming and welding are the important process in fabricating a chamber. Next, the material must have good corrosion and oxidation resistant and ease of cleaning, fabrication and beauty of appearance which will ease the maintaining process of the chamber. Finally, the material for the optical window must have excellent optical quality, very low thermal expansion, and exceptional transmittance over a wide spectral range, especially in the ultraviolet. It must also have good resistant to scratching and thermal shock.

3. Result

3.1 Product Architecture

Based on the output from Conceptual Stage activities, various options for the structural shape and architecture of the device have been evaluated. As a result, the cylindrical shaped vessel has been chosen as the main body and hemispherical shaped head has been chosen as the cover (Refer Fig 1). By progressing the concept and idea towards the Preliminary Design Stage, the final shape of the product has been generated. As a result, the vacuum chamber design has been divided into four main module which is the Main Body (cylindrical shell), Hemispherical head (cover), the Window Flange and the Optical window (Refer Fig 2).

Fig. 1: Functional Decomposition Chart Fig. 2: Overall View of the product (V acuum Chamber)

In order to achieve the objective, which is to come out with the optimum size of the product; the independent variable which is related to the weight of the chamber must be verified. The optimization factor plays a role towards achieving the minimum weight of the vacuum chamber. In this case, the outer radius, the length and thickness of the main body has been

identified as the main contributor. Any changes in these variables shall result in major changes towards the final weight of the chamber.

For the next step, several constraints need to be introduced in order to control the parameter of the product. Firstly, the Maximum Stress of the chamber must not exceed the yield strength of the chamber's material. This is to avoid plasticity from occuring during operation. Secondly, the total elongation of the vessel should not exceed 1.0 mm. Theoretically, any failure related to strain activities could contribute to other type of failure. The third constraint is the chamber must have minimum internal volume of 0.05m2 or 50 litre. This is to ensure that the chamber will have sufficient internal space for experimentation activities. Next, the outer diameter must be less 0.5 m and the overall length of vessel must be less than 1.0 m. Smaller chamber size contributes to easier access on transport and will consumed lesser space compared to normal conditions. Finally, the overall thickness must be less than 10% of the radius. This constraint has been introduced so that the chamber could satisfy thin-walled pressure vessels characteristics.

Considering all of the variables and constraints, CAE tools has been utilized in order to identify and compute the optimum size for this vacuum chamber. Using Matlab, the programming has been generated and executed. As a result, we managed to come out with the optimum size for this product (Refer Table 1).

Table 1. Comparison between Matlab Programming Result and Final Parameter

3.2 Configuration Design

Parameter Calculative Result Final Dimension

Outer radius (main body), ro 147.1 mm 150mm

Length (Main body), l 705.8mm 700mm

General Thickness, t 13mm 15mm

3.2.1 Material Selection

Based on literature studies, SUS304 Stainless Steel is had been chosen as the primary material for metal component, because of the common use in tanks and vessels design (Refer Table 2). It also has good forming and welding properties, which is an important process in fabricating the chamber. In terms of material properties, this material has good corrosion and oxidation resistance, ease of cleaning and fabrication, and finally good appearances, which will ease the maintenance process of the chamber. Also, considering the factor of design for human, the selection of a user friendly material is necessary especially in maintaining the cleanliness of the chamber.

Table 2. Overall Summary for Material Selection

Part name Material Type Yield Density Modulus of

Strength Elasticity Hemisphere Head 304 Stainless Steel 290 MPa 8030 kg/m3 193 GPa Main Body 304 Stainless Steel 290 MPa 8030 kg/m3 193 GPa Window Flange 304 Stainless Steel 290 MPa 8030 kg/m3 193 GPa Optical Window_Fused Silica_60 MPa_2203 kg/m3_73 GPa

Next, fused silica has been chosen for the optically flat window material because of the excellent optical quality, very low thermal expansion, and exceptional transmittance over a wide spectral range, especially in the ultraviolet. It also has good resistant to scratching and thermal shock.

In assembling the hemispherical head to both ends of the cylindrical shell, N = 24 pieces of M20 bolt shall be used for the fixture at each side. As for the flange and optical window area, it shall be assembled using minimum of N = 3 pieces of M20 bolt. Standard sizes of bolt were used to ease the operation and maintenance process of the chamber. Other than that, standard Parker O-ring O-ring shall be used in order to prevent leakage from occurring especially in between the fused silica-window surface and flange area.

3.2.2 Modelling and Computational Analysis

Using the final parameter as base, the 3D shape has been generated using CATIA software (Refer Fig. 2). Other criteria such as Window Flange section has also been added for physical view purpose. Next, the Finite Element Analysis (FEA) has been applied using the embedded function available in CATIA (Refer Fig. 3). The result shall be discussed in the next segment.

4. Conclusion and Discussion

The first analysis was executed in order to identify the maximum distortion energy value (Von-Mises criteria) of the chamber and the elongation of the chamber due to the design pressure. Considering the yield stress of SUS304 Stainless Steel material which is around 290 MPa; based on calculation, the safety factor for the most critical area on the main body is approximated around n=1.13 (Refer Fig 2(a) for Maximum Von Mises Criteria). Surprisingly, the analysis result is 3.5 times lower compared to the manual calculation of the main body which is around n=3.92. One of the reasons behind this gap is because, the theoretical calculation of the Von-Mises stress for the cylindrical shell has been done by considering the basic cylindrical shape only; without any opening or flange area. By adding in flange structure, the stress concentrates more on the connecting point or joints between the body and flange area.

Further studies need to be done to reinforce the openings section, to reduce the stress concentration on the critical areas. Eventhough the result is safe (n > 1.0) and majority of the main body is within good range (n ~ 2), it is best if we could push the safety factor of the critical region within the optimum range, which is within n=1.5 ~ 4. As a simple solution, by increasing the thickness from 15 mm to 20 mm, this result can easily be achieved. Another type of improvement that can be done is by increasing the welding height of the joints area. As for the Hemisphere Head (Refer Fig 2(b)), we managed to achieve a good result which is around n = 4.2. Eventhough the safety factor is smaller compare to the theoretical calculation which is n = 7, the result is good and within optimum range.

For the next analysis, based on theoretical calculation, the elongation of the chamber is around 0.155 mm. In theory, the chamber's design is able to satisfy the requirement which is the elongation constraint must be less than 1.0 mm. Compared to the simulation output, the actual result is slightly higher which is around 0.243 mm. However, this is still below the specified requirement, so this design can be considered as safe.

As a conclusion, the main objective which is to come out with a preliminary design of a functional and optimum weight vacuum chamber; has been achieved. Listed below are the overall summary of the research output :

• The objective has been achieved; which is to come out with a preliminary design of the vacuum chamber. Moreover, the final design is capable to fulfil specified objectives and criteria's of the vacuum chamber.

• Based on theoretical analysis and simulation result, the chamber is able to withstand the design pressure of 10 MPa.

• The optimum weight of the chamber been achieved which is around 1039.8 N or 106 kg.

Acknowledgements

The author would like to thank the Faculty of Mechanical Engineering (FKM) of UiTM Shah Alam for the facilities and support. Not forgetting all of the staff's effort either direct or indirectly. Also, unlimited gratitude for my fellow students, Mohd Nor Fadhli, Mohd Nizar and Mohd Ridhuan for their strong effort towards achieving this result. My best wishes to your life and future career.

Reference

[1] Dennis RM, Pressure Vessel Design Manual, 3rd Ed, 2004

[2] Somnath C., Pressure Vessel Design and Practice, CRC Press, Inc. 2005

[3] Ken H., Engineering a Better Vacuum Chamber, GNB Corporation.

[4] David R., Pressure Vessels, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, August 23, 2001

[5] A.Petrovic, Stress Analysis in Cylindrical Pressure Vessels with Loads Applied to the Free End of a Nozzle, International Journal of Pressure Vessels and Piping #78, 2001

[6] J.Ahn, H.J.Kim, K.S.Choi, Oxy-Fuel Combustion Boiler for CO2 capturing: 50 kW Class Model Test and Numerical Simulation, Journal of Mechanical Science and Technology #24, 2010

[7] Budynas-Nisbett, Shigley's Mechanical Engineering Design, 8th Edition, 2006

[8] Daniel K., Kerr AR, Ediss GA, Boyd D., Design and Fabrication of Quartz Vacuum Windows with Matching Layers for Millimeter-Wave Receivers, National Radio Astronomy Observatory Charlottesville, VA 22903, June 14, 2001

[9] Oli D., Practical Knowledge of Vacuum Windows, Steward Observatory, University of Arizona

[ 10] Dan W., An Introduction to Optical Window Design, University of Arizona, December 14, 2006

[11] Parker H, O-Ring Handbook, Parker Hannifin Corporation, Cleveland, OH, 2007

[12] Clemens K, Stress Analysis & Pressure Vessels, University of Cambridge, 2005

[13] Phil D, The Vacuum Chamber: Volume or Surface Area, Journal of Practical and Useful Vacuum Technology.

[14] Chan V and Salustri FA, Design for Assembly, 2005