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Design and Optimisation of Pressure Vessel Using Metaheuristic Approach 1 1
Sulaiman Hassan, 2Kavi Kumar, 3Ch Deva Raj, 4Kota Sridhar
Mechanical & Manufacturing Department, University Tun Hussein Onn Malaysia,Malaysia 2
Faculty of Science Technology and Human Development, University Tun Hussein Onn Malaysia,Malaysia 3
4
Mechanical Engineering Department, RVR &JC,Guntur,India
Mechanical & Manufacturing Department, University Tun Hussein Onn Malaysia,Malaysia 1
[email protected],
[email protected],
[email protected], 4
[email protected]
Keywords: - Design optimization, Ant colony optimization Algorithm, Pressure Vessels
Abstract: The objective of design optimization of pressure vessels is cost reduction by reducing weight with adequate strength and stiffness. Optimization is the act of obtaining the best result under given circumstances. Conventional design aims at finding acceptability design which merely satisfies the functional and other requirements of the problem. In general, there will be more than one acceptable designs and the purpose of design optimization is to choose the best. In the present work parameters such as thickness of the shell, and dish end, length and radius of the pressure vessel are optimized by making use of ACO has been shown for a Pressure vessel problem with four variables and four design constraints. It is found that the results obtained from ACO are better as its search is for global optimum as against the local optimum in traditional search methods. The results of the ACO have been checked using ANSYS, and it is found to perform satisfactorily. Introduction The pressure vessels are to store fluids under pressure. The fluid being stored may undergo a change of state inside the pressure vessel as in case of steam boilers or it may combine with other reagents as in a chemical plant. The pressure vessels are designed with great care because rupture of a pressure vessel means an explosion which may cause loss of life and property. The material of pressure vessels may be brittle such as cast iron, or ductile such as mild steel. Literature survey This paper[1] presents a hybrid swarm intelligence approach (HSIA) for solving nonlinear optimization problems which contain integer, discrete, zero-one and continuous variables. This paper[2] presents the design process of the pressure vessels and experimental results acquired by high-pressure tests. This paper[3] presents a practical review of the use of PC-based Finite Element software in the analysis of typical pressure vessel components. This paper[4] presents a modified particle swarm optimization (PSO) algorithm for engineering optimization problem with constraints. This paper[5] a generic algorithm based on Ant Colony Optimization to solve ulti- objective optimization problems. The proposed algorithm is parameterized by the number of ant colonies and the number of pheromone trails. This paper [6] proposes the Omicron ACO (OA), a novel population-based ACO alternative originally designed as an analytical tool. This paper[7] makes a comparison of the effectiveness of the three methods on a particular optimization problem, namely the tuning of the parameters for a PID controller. Ant Colony Algorithm Ant behavior was the inspiration for the metaheuristic optimization technique the ant colony optimization algorithm (ACO), is a probabilistic technique for solving computational problems which can be reduced to finding good paths through graphs.
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This algorithm is a member of ant colony algorithms family, in swarm intelligence methods, and it constitutes some metaheuristic optimizations. Initially proposed by Marco Dorigo in 1992 in his PhD thesis, the first algorithm was aiming to search for an optimal path in a graph;; based on the behavior of ants seeking a path between their colony and a source of food. The original idea has since diversified to solve a wider class of Numerical problems, and as a result, several problems have emerged, drawing on various aspects of the behavior of ants.
Problem Formulation The Problem is to design a compressed air storage tank with a working pressure of 1000 psi and a minimum volume of 750 ft3. The schematic of a pressure vessel is shown in Fig.6.1. The cylindrical pressure vessel is capped at both ends by hemispherical heads. Using rolled steel plate (SAEJ 2340 TYPE 830 R), the shell is to be made in two halves that are joined by two longitudinal welds to form a cylinder. Each head is forged and then welded to the shell. Let the design variables be denoted by the vector X=[x1, x2, x3, x4]T, x1 is the spherical head thickness, x2 is the shell thickness, x3 and x4 are the radius and length of the shell, respectively. The objective in this Project is to minimize the manufacturing cost of the pressure vessel. The manufacturing cost of the pressure vessel is a combination of material cost, welding cost and forming cost. That can be refer in Sandgren (1990) for more details on how cost is determined. The constraints are set in accordance with respective ASME codes. The mathematical model of the problem is:
Objective function Here our main objective is to reduce the cost by reducing weight of Pressure Vessel. So the objective function 2
2
0.6224 x1 x 2 x3 1.7781x1 x3 3.1661x 2 x 4 19.84 x 4 x1
f ( x)
x1 x2
x3 x4
Radius of the shell L Length of the shell Ts Thickness of the shell Tb Thickness of the dish end R
Design variables x x x x
Radius ( R) Length (L) Thickness of the shell Thickness of the dish end
Design parameters 1. Circumferential or Hoop Stress 2. Longitudinal Stress 3. Volume
x3 Ts
x4 Th
x1
x2
2
L
R
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Design constraints The four important constraints under consideration are 1. Hoop stress Allowable stress g1 x 0.0193x1 x4 d 0 2. Longitudinal stress Allowable stress g2 x 0.00954 x1 x3 d 0
3. Volume î inch3 4 3 2 g 3 x 750 u 1728 Sx1 Sx1 x2 d 0 4. Length 3 g 4 x x2 240 d 0
Variable bounds The upper and lower bounds on two design variables are 1. 25 d x1 d 150
25 d x2 d 240 3. 0.0625 d x3 d 1.25 2.
4. 0.0625 d x4 d 1.25 Note: All are in inch Problem Description A typical input data required to develop a mathematical model for pressure vessel design is Pressure vessel material = SAE J2340 ± 830R Where R=High Strength Recovery Annealed 1. Modulus of elasticity (E) = 200x109 4. Allowable Yield Strength = 540 MPA 2 N/mm 5. Applied Pressure = 6.80272 N/mm2 2. Yield Strength = 960 MPA (1000 PSi) 3. Factor of safety = 1.78 Input ACO parameters: ĮLVD7ULDOSDUDPHWHU ȕLVD7ULDOSDUDPHWHU 7KHUDWHRISKHURPRQHHYDSRUDWLRQȡ
=0.2 Number of iterations = 5000 Number of ants = 150 Number of Divisions for x1 = 150 Number of Divisions for x2 = 250
Number of Divisions for x3 = 10 Number of Divisions for x4 = 10
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Fixing up the above parameters is a very crucial in an optimization problem because there are no guide lines for these. One has to fix the ACO parameters for a particular depending on the convergence of the problem as well as on solution time. After executing various run with different ACO parameters depending on convergence of the value. Results and Discussions The values of best design variables and the constraints for the 5000 iteration obtained after running the program for Ant colony algorithm written in the C-language is given below. Graphical Results
The optimum values are obtained at 2829 th iteration and it remain as constant from the point on word that indicates that the optimal value is global minima. x1 = Radius of the shell = 40 inch x2 = Length of the shell = 232.26 inch x3 = Thickness of the shell = 0.537 inch x4 =Thickness of the shell =0.775 inch g1 =Constraints of Hoop Stress = -0.003 g2 = Constraints of Longitudinal Stress= -0.156 g3 = Constraints of volumes = -138821 g4 = Constraints of Length = -7.74 Finally function value f(x) = 4856.205 $ These results are compared with the results of the pervious works using various other optimization methods and are in a table given below
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ANSYS Analysis: Design of pressure vessel 1
ELEMENTS /EXPANDED TYPE NUM
Y Z
X
Structure of pressure Vessel 1 NODAL SOLUTION STEP=1 SUB =1 TIME=1 /EXPANDED SEQV (AVG) DMX =.313E-05 SMN =127.635 SMX =456.355
Z
Y X
MN
MX
127.635 200.684 273.733 346.782 419.83 164.16 237.208 310.257 383.306 456.355
von misses Stress of pressure vessel
Conclusion In the present work parameters such as thickness of the shell, and dish end, length and radius of the pressure vessel are optimized by making use of Ant colony metaphor;; powerful non- traditional optimization method and these results are compared with other Optimization Methods. It is found that the results obtained from ACO are better as its search is for global optimum as against the local optimum in traditional search methods. The results of the ACO have been checked using ANSYS, and it is found to perform satisfactorily. It can be concluded that by applying Ant colony algorithm, the optimal design parameters for the pressure vessel are obtained and the objective minimization of cost by reducing weight of Pressure vessel is achieved. In the present study the application of ACO has been shown for a Pressure vessel problem with four variables and four design constraints.
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References [1] GUO Chuang-xin, HU Jia-sheng , YE Bin , CAO Yi-MLD ³Swarm Intelligence For Mixed- 9DULDEOH'HVLJQ2SWLPL]DWLRQ´ Journal of Zhejiang University SCIENCE ISSN 1009-3095 [2] Tae-Hwan Joung, In-Sik Nho, Chong-Moo Lee, Pan-Mook Lee, Seung-Il Yang, Seok-Won Hong ³A Study on the Pressure Vessel Design, Structural Analysis and Pressure Test of a 6,000 m Depth-UDWHG8QPDQQHG8QGHUZDWHU9HKLFOH´WKH,QWHUQDWLRQDOVRFLHW\RI2IIVKRUHDQG3RODU Engineers ISBN 1-880653-64-8 [3] 0LFKDHO $3RUWHU'HQQLV +0DUWHQV3HGUR0DUFDO ³2Q8VLQJ )LQLWH (OHPHQW $QDO\VLVIRU Pressure Vessel 'HVLJQ´ PVP Vol. 368, ASME, New York, NY, pp. 139-146. [4] ;LDRKXL +X 5XVVHOO &(EUWKDUW