FATIGUE ANALYSIS OF ROTARY CEMENT ILN WELDED … filebeban haba, modulus Young, ketumpatan, dan...

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xx:x (201x) xxxxxx | www.jurnalteknologi.utm.my | eISSN 2180–3722 | Jurnal Teknologi Full Paper FATIGUE ANALYSIS OF ROTARY CEMENT KILN WELDED USING FINITE ELEMENT METHOD Hasan Basri a* , Irsyadi Yani a a Faculty of Engineering, University of Sriwijaya, Indonesia Article history Received 1 February 2016 Received in revised form 24 March 2016 Accepted 1 August 2016 *Corresponding author [email protected] Graphical abstract Abstract In this research, the implementation of Shell of Kiln problem has been discussed. The results obtained in this research are taken based on the simulation and experimental work. This research discusses only the simulation work. The simulation works are performed to evaluate the fatigue of the shell of a kiln. To validate the characteristic of fatigue problem simulation, the mechanical and thermal load are implemented on the shell of a kiln. The results are analyzed in detail in this research for fatigue life for the shell of a kiln. In this work, the shell of the kiln has been modeling by solid works and Fast2014. All the boundary conditions (mechanical load, thermal load, Young’s modulus, density, etc.) must be evaluated such as the actual condition. This simulation showed how the most relevant aspects of the developed work presented in this report can contribute to the state-of-the- art of the analysis fatigue life of Rotary Cement Kiln technique with innovative ideas and strategies. It also reviews if the obtained results achieve the proposed objectives. The main goal of the work presented in this research is to propose fatigue life analysis algorithm in the shell of a kiln using finite element analysis. Due to the dimensionality of the problem addressed, the research specification has to set limits to the applicability of the research by selecting only mechanical load problems in rotary cement kiln tasks; and goal-seeking, to predict the fatigue life simulation investigated. From the simulation, model and boundary conditions are defined. Crack growth behaviour in the rotary kiln was predicted. As the crack grows, the speed of crack depth increase. Keywords: FEA, fatigue analysis, rotary kiln, crack simulation Abstrak Dalam kajian ini, permasalahan Kiln shell telah dibincangkan. Keputusan yang diperolehi dalam kajian ini diambil berdasarkan simulasi dan kerja uji kaji. Kajian ini membincangkan simulasi sahaja. Simulasi dilaksanakan untuk menilai keletihan shell. Untuk mengesahkan ciri-ciri simulasi masalah keletihan, beban mekanikal dan haba dilaksanakan pada shell. Umur kelelahan dianalisis secara terperinci dalam kajian ini untuk shell. Dalam kajian ini, shell dibangun menggunakan software Solid works dan Fast2014. Semua beban mekanikal, beban haba, modulus Young, ketumpatan, dan lain-lain perlu dinilai seperti keadaan sebenar. Simulasi ini menunjukkan bagaimana aspek yang paling berkaitan yang dibangunkan dibentangkan dalam laporan ini boleh menyumbang kepada statei-of-the- art analisis keletihan teknik Cement Kiln Rotary dengan idea-idea dan strategi inovatif. Ia juga mengkaji jika keputusan yang diperolehi mencapai objektif yang dicadangkan. Matlamat utama kerja yang dibentangkan dalam kajian ini adalah untuk mencadangkan keletihan algoritma analisis kehidupan di shell tanur menggunakan analisis unsur terhingga. Dari simulasi, model dan keadaan, tingkah laku pertumbuhan retak dalam shell telah diramalkan. Sebagai retak tumbuh, kelajuan peningkatan kedalaman retak bertambah. Kata kunci: FEA, fatigue analysis, rotary kiln, crack simulation. © 2016 Penerbit UTM Press. All rights reserved

Transcript of FATIGUE ANALYSIS OF ROTARY CEMENT ILN WELDED … filebeban haba, modulus Young, ketumpatan, dan...

xx:x (201x) xxx–xxx | www.jurnalteknologi.utm.my | eISSN 2180–3722 |

Jurnal Teknologi

Full Paper

FATIGUE ANALYSIS OF ROTARY CEMENT KILN WELDED USING FINITE ELEMENT METHOD Hasan Basri a*, Irsyadi Yania

aFaculty of Engineering, University of Sriwijaya, Indonesia

Article history Received

1 February 2016 Received in revised form

24 March 2016 Accepted

1 August 2016

*Corresponding [email protected]

Graphical abstract Abstract

In this research, the implementation of Shell of Kiln problem has been discussed. The results obtained in this research are taken based on the simulation and experimental work. This research discusses only the simulation work. The simulation works are performed to evaluate the fatigue of the shell of a kiln. To validate the characteristic of fatigue problem simulation, the mechanical and thermal load are implemented on the shell of a kiln. The results are analyzed in detail in this research for fatigue life for the shell of a kiln. In this work, the shell of the kiln has been modeling by solid works and Fast2014. All the boundary conditions (mechanical load, thermal load, Young’s modulus, density, etc.) must be evaluated such as the actual condition. This simulation showed how the most relevant aspects of the developed work presented in this report can contribute to the state-of-the-art of the analysis fatigue life of Rotary Cement Kiln technique with innovative ideas and strategies. It also reviews if the obtained results achieve the proposed objectives. The main goal of the work presented in this research is to propose fatigue life analysis algorithm in the shell of a kiln using finite element analysis. Due to the dimensionality of the problem addressed, the research specification has to set limits to the applicability of the research by selecting only mechanical load problems in rotary cement kiln tasks; and goal-seeking, to predict the fatigue life simulation investigated. From the simulation, model and boundary conditions are defined. Crack growth behaviour in the rotary kiln was predicted. As the crack grows, the speed of crack depth increase.

Keywords: FEA, fatigue analysis, rotary kiln, crack simulation

Abstrak

Dalam kajian ini, permasalahan Kiln shell telah dibincangkan. Keputusan yang diperolehi dalam kajian ini diambil berdasarkan simulasi dan kerja uji kaji. Kajian ini membincangkan simulasi sahaja. Simulasi dilaksanakan untuk menilai keletihan shell. Untuk mengesahkan ciri-ciri simulasi masalah keletihan, beban mekanikal dan haba dilaksanakan pada shell. Umur kelelahan dianalisis secara terperinci dalam kajian ini untuk shell. Dalam kajian ini, shell dibangun menggunakan software Solid works dan Fast2014. Semua beban mekanikal, beban haba, modulus Young, ketumpatan, dan lain-lain perlu dinilai seperti keadaan sebenar. Simulasi ini menunjukkan bagaimana aspek yang paling berkaitan yang dibangunkan dibentangkan dalam laporan ini boleh menyumbang kepada statei-of-the-art analisis keletihan teknik Cement Kiln Rotary dengan idea-idea dan strategi inovatif. Ia juga mengkaji jika keputusan yang diperolehi mencapai objektif yang dicadangkan. Matlamat utama kerja yang dibentangkan dalam kajian ini adalah untuk mencadangkan keletihan algoritma analisis kehidupan di shell tanur menggunakan analisis unsur terhingga. Dari simulasi, model dan keadaan, tingkah laku pertumbuhan retak dalam shell telah diramalkan. Sebagai retak tumbuh, kelajuan peningkatan kedalaman retak bertambah.

Kata kunci: FEA, fatigue analysis, rotary kiln, crack simulation.

© 2016 Penerbit UTM Press. All rights reserved

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1.0 INTRODUCTION

A kiln is basically an industrial oven, and although the term is generic, several quite distinctive designs have been used over the years, such a kiln in PT. Semen Baturaja made about 1,200.000 tonnes of clinker per year. The Company was first established under the name of PT. Semen Baturaja (Persero) on November 14, 1974. The Company specifically engages in clinker production business with its production center located in Baturaja, South Sumatera, while the cement grinding and packing process are operated in Baturaja Plant, Palembang Plant and Panjang Plant to be distributed to the Company’s marketing areas. The Company, in its effort for business development, endeavors to improve the existing equipment in order to achieve the target of installed capacity amounting to 50,000 tons cement per year and to improve its installed capacity.

Rotary kiln shell is a large-scale welded structure with 4.5 m in diameter and 75 m in length and produced by welding thin cylindrical steel plate one by one. The shell of the kiln is made of mild steel plate. Mild steel is the only viable material for the purpose, but presents the problem that the maximum temperature of the feed inside the kiln is over 1400°C, while the gas temperatures reach 1900°C. The melting point of mild steel is around 1300°C, and it starts to weaken at 480°C, so considerable effort is required to protect the shell from overheating (FLSmidth).

Padded plates are directly soldered to the shell in the supporting rollers places to reduce their concentrated stress. Crack are often initiated at these welded joints, and the over long circumferential crack are prevailing at welded joints near the supporting rollers. However, Kikuchi et.al. (2010) has predicted of two interacting surface cracks of dissimilar sizes by finite element analysis. The simulations were performed for fatigue crack growth experiments and the method validity was shown on this research. It was shown that the offset distance and the relative size were both important parameters to determine the interaction between two surfaces of crack; the smaller crack stopped growing when the difference in size was large. It was possible to judge whether the effect of interaction should be considered based on the correlation between the relative spacing and relative size. In 2014, Fatigue crack growth simulation in a heterogeneous material using finite element method has generated by Kikuchi et.al. Kikuchi has developed a fully automatic fatigue crack growth simulation system using FEM and applied it to three-dimensional surface crack problems, in order to evaluate the interaction of multiple surface cracks, and the crack closure effects of surface cracks. The system is modified to manage residual stress field problems, and the stress corrosion cracking process is simulated.

To prediction of crack propagation under thermal, residual stress fields using S-Version FEM (S-FEM), Kikuchi was employed to solve a crack growth problem by combining with the auto-meshing technique, this re-meshing process of the local mesh becomes very simple, and modeling of three-dimensional crack shape becomes computationally easy. On the other hand, in 2004, Irsyadi has developed visualization of finite element analysis in 3D (C, C++, under Linux/Fedora), with this system, analysis for extra large problems such as fatigue life predictions becomes easy and fast. Irsyadi, Kikuchi, and Kanto employed numerical analysis of 3-D Surface Crack in 2006, and then, Irsyadi and Kikuchi was developed a numerical analysis in the low carbon steel by finite element method and experimental method under fatigue loading. In this research, they were predicted fatigue live of material under stresses.

Fatigue, or metal fatigue, is the failure of a component as a result of cyclic stress. The failure occurs in three phases: crack initiation, crack propagation, and catastrophic overload failure. The duration of each of these three phases depends on many factors including fundamental raw material characteristics, magnitude and orientation of applied stresses, processing history, etc. Fatigue failures often result from applied stress levels significantly below those necessary to cause static failure.

The prediction of fatigue life of rotary cement kiln welded shell is not completely understood and fascinating, therefore it should be investigated. For rotary kiln shell, cracks can grow with a complex overloading conditions for over thousands of tons, and then results in premature shell failure. The affecting conditions crack growth include material characteristics, initial crack size, service stresses, and stress concentration due to overheated in hot spot area, all these conditions are random. The fatigue life of the welded shell during crack growth need to be predicted numerically by using finite element analysis and experimentally. The fatigue life analysis attempts to provide the answers to general questions, which remain unclear on the evolution of the crack growth and its impacts on failure in rotary cement kiln system. In addition, the research is intended to bring our knowledge of the simulation and experimental of the fatigue life analysis in the welded joints of a rotary cement kiln in PT. Semen Baturaja. The primary objective of this study is to investigate the fatigue life of the crack growth analysis in the welded joints of a rotary cement kiln in PT. Semen Baturaja. We approach the goal through a combined analysis of fatigue growth observational data and numerical model simulation.

2.0 METHODOLOGY

Some materials, such as steel, show an endurance limit stress below which the fatigue life is essentially infinite. Other materials may not show such behavior

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but an effective endurance limit may be specified at some large number of cycles. the important parameters to characterize a given cyclic loading history are :

Stress range : σ = σmax - σmin

Stress amplitude: σa = 0.5 (σmax - σmin) Mean stress : σm = 0.5 (σmax + σmin) Load ratio : R = σmax/ σmin

The total fatigue life of a component can be considered to have two parts, the initiation life and the propagation life. The stress-life approach just described is applicable for situations involving primarily elastic deformation. Under these conditions the component is expected to have a long lifetime. For situations involving high stresses, high temperatures, or stress concentrations such as notches, where significant plasticity can be involved, the approach is not appropriate.

The main geometrical characteristics of the rotary kiln shell are shown in Table 1.

Table 1: The main geometrical characteristics of the rotary kiln

Magnitude Value UnitsCold real length Inner diameter Number of tires Slope (in direction to outlet) Maximum speed

75 4.5 3

3.5 3.5

meters meters

-- %

rpm

The thicknesses of the shells along the different sections of the rotary kiln are given in Table 2 and Figure 1. In Table 2 zero is placed in the upper end of the rotary kiln, called ‘inlet-I’. The distances between supports, in millimeters, are given in Table 3 where ‘III-outlet’ denotes the lower end of the rotary kiln.

Table 2: Thicknesses of the shells along the different sections of the rotary kiln

Section (mm)

Thickness (mm)

Section (mm)

Thickness (mm)

0 – 1,800 1,800 – 2,500 2,500 – 5,500 5,500 – 8,100 8,100 – 9,700 9,700 – 9,900

9,900 – 11,855 11,855 – 14,190 14,190 – 16,525 16,525 – 18,860 18,860 – 21,195 21,195 – 23,530 23,530 – 25,865 25,865 – 28,200 28,200 – 30,000 30,000 – 32,200 32,200 – 34,000 34,000 – 35,260

60 60 90 70 40 28 28 28 28 28 28 28 28 28 40 60 40 28

35,260 – 37,595 37,595 – 39,930 39,930 – 42,265 42,265 – 44,100 44,100 – 46,435 46,435 – 48,770 48,770 – 51,105 51,105 – 53,440 53,440 – 55,400 55,400 – 56,900 56,900 – 59,400 59,400 – 61,000 61,000 – 63,200 63,200 – 64,800 64,800 – 68,100 68,100 – 71,400 71,400 – 73,650 73,650 – 75,000

28 28 28 28 28 28 28 28 28 40 40 40 60 40 25 25 25 25

Figure 1. Diameter, length, and thickness variation of rotary kiln

Table 3: Distances between supports

Supports Distance (mm)Inlet – I

I – Girth Gear I – II II – III

III – Outlet

13,000 4,200 31,000 27,000 4,000

Tables 2, 3, Figure 1 and 2 is the rotary kiln (1) along with the structural elements to rotate the kilns (3), (10), (7), and (11) around its longitudinal axis. The kiln (1) includes an elongated, cylindrical, rotating shell (2) which has a feed end (8), an opposite discharge end (5). The kiln (1) is erected so that the discharge end (5) is at a lower level then the feed end (8) in order to cause the material being processed. It travels through the open processing zone to the discharge end (5). The kiln shell (2) is supported by riding rings or tires (3) that engage steel rollers (10) which are supported on concrete piers (4) and steel frames (6).

Figure 2. Rotary kiln configuration

Materials used for the kiln are shown in Table 4. These materials are used to build the kiln components. The shell, tire, roller and pinion are the main components in the kiln. However, the material has been modeled as isotropic and linear, elastic temperature dependent, according to the elastic properties of the steel used in Table 4. The kiln shell is welded circumferentially and longitudinally.

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Table 4: Materials are used for the kiln

Component MaterialShells Tires Rollers Pinion

ASTM A.36 Low alloy steel casting Low alloy steel casting 30 Cr Ni Mo 8 (ISO R 638 = II-68 Type 3)

As mentioned earlier there are mainly four methods to predict fatigue of welded components:

Nominal Stress Structural Stress Effective Notch Stress Linear Elastic Fracture Mechanics (LEFM)

The effects of welding residual stresses, R-ratio, wall thickness and improvement techniques are included in this research. In case of variable amplitude loading, Palmgren- Miner´s linear damage rule is used when the design methods nominal, structural and effective notch stress are applied.

3.0 RESULTS AND DISCUSSION

The results obtained in this research are taken based on the simulation and experimental work. This chapter discusses only the simulation work. The simulation works are performed to evaluate the fatigue of the kiln shell. To validate the characteristic of fatigue problem simulation, the mechanical and thermal load are implemented on the shell of kiln. The results are analyzed in detail in this chapter for fatigue life for the kiln shell.

In this work, the kiln shell has been modeling by Autodesk Inventor 2014. All the boundary conditions (mechanical load, thermal load, Young’s modulus, density, etc.) must be evaluated such as the actual condition. The simulation of the kiln shell is only conducted to determine the fatigue life of the kiln shell.

The development of modeling is the initial work that marks the natural condition of the designed software into the simulation platform. In this phase all algorithms of simulation condition are implemented using a standard Finite Element Analysis. Within this development model, the architecture is validated and the main functions and algorithms are tested. During the design, by using static analysis which has been implemented in the kiln shell. The model of the kiln shell, boundary conditions and initial crack as shown in Figure 3 and 4 are used in order to achieve robust performance, high reliability and minimal computational cost.

Figure 3. Model of the kiln shell

(a) (b)

(c) (d)

(e) (f)

Figure 4. Boundary Conditions (BC) and Initial Crack

Considering the cracked elastic plate shown on the following page, with Young’s modulus E and Poisson’s ratio ν. The height is small compared to the dimensions a and c, and the thickness is small enough that plane stress conditions. If the crack grows all the way across the plate and the plate separates into two pieces, the system will have zero strain energy. So the strain energy decreases as the crack grows. Calculating the change in strain energy of the plate if the crack grows by some amount dr. Using the same assumptions used previously to calculate the total strain energy.

Considering of a finite element analysis, characteristics of a kiln shell are a pretension and a mating part contact (Figure 4.a). The pretension can

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generally be modeled with static loading, thermal deformation, a constraint equation, or an initial strain. For a thermal deformation method, the pretension is generated by assigning virtual different temperatures and thermal expansion coefficients to the shell, clinker and temperature of gases. In this work, in order to generate a finite element model for the kiln shell with clinker and temperature of gases (Figure 4.b and 4.c), two kinds of models are introduced. All the proposed models are taken into account above primary characteristics such as a pretension effect and a contact behavior between shell, clinker and temperature of gases (see Figure 4.d). The prediction of the crack propagation are considered on crack emanating from contact surface between kiln shell and clinker and welded joint on the kiln shell surface (Figure 4.e). On this Finite Element model, the final mesh consisted of 40.856 elements and 45.245 nodes. The elements along the direction of crack advance had a length of 28 mm. Following the stress and deformation simulation, fatigue crack growth was modeled by repeated loading (mass of clinker and thermal gases), unloading, advancing the crack and then the loading again.

Under static analysis, stress and deformation in the kiln is obtained as shown i n F i g u r e 5 . From the simulation results, it is found that t h e critical area is occurred in the kiln. B y u s i n g the static value, subsequent fatigue analysis can be performed.

The calculated loads and stresses were used to perform a low cycle fatigue evaluation by using the actual operating data. The operating temperatures were lower than the temperatures anticipated in the design specifications. There were unknown cycles corresponding to the anticipated 450°C gas inlet temperature upset condition, and only three cycles to the normal operating temperature. Hence, the actual operating cycles were used to evaluate the fatigue damage.

Figure 5. Stress, displacement and strain of the static analysis

Since local stresses were far in excess of the yield strength of the materials at the stitch welds, elastic-plastic analyses were used to obtain the strain ranges needed to perform a low cycle fatigue evaluation. The evaluation was made using fatigue design curves obtained by applying a factor of cycles to the theoretical failure curves. Based on the design curves, a cumulative fatigue usage had been reached when failure occurred. This is consistent with the knowledge that cracks had initiated and grown to a critical size and propagated as fast fractures at this usage as shown in Figure 6. Actual failure occurred between the design fatigue curve and the theoretical mean failure data for small polished laboratory test specimens. Failure below the mean laboratory failure curve is expected due to size effects, surface finish effects, environmental effects and scatter in the data.

(a)

(b) Figure 6. Crack growth and Transition of stress

intensity factor

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The results of the structural analyses of the original design showed that the flexibility of the weight stresses and reduced thermal bending stresses in the duct. Hence, bending of the duct imposed high cyclic loads and stresses on the support truss, buckling several truss members. With properly designed duct supports. Bending of the duct does not bend the supporting truss. Moreover, the flexibility of the truss would have no effect on dead weight stresses in the duct. This is important since the typical design sequence involves first designing the duct, and then using the resulting weight to design the truss.

4.0 CONCLUSION

This research shows how the most relevant aspects of the developed work presented in this report can contribute to the state-of-the-art of the analysis fatigue life of rotary cement kiln technique with innovative ideas and strategies. It also reviews if the obtained results achieve the proposed objectives.

The main goal of the work presented in this research is to propose fatigue life analysis algorithm in the shell of a kiln using finite element analysis. Due to the dimensionality of the problem addressed, the research specification has to set limits to the applicability of the research by selecting only mechanical load problems in rotary cement kiln tasks and goal-seeking, to predict the fatigue life simulation investigated.

From the simulation, model and boundary conditions are defined. Crack growth behaviour in rotary kiln was predicted. As the crack grows, the speed of the crack depth increase.

References

[1] Energy Efficiency Component EU-China. A reference book for the industry. Beijing, 2009.

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FJ., Design and finite element analysis of a wet cycle cement rotary kiln. Finite Elements in Analysis and Design; 39(1):17–42, 2002.

[4] ABP, ASME boiler and pressure vessel code VIII division 2 - alternative rules. The American Society of Mechanical Engineers, 1995.

[5] ABP, ASME boiler and pressure vessel code II - material properties. The American Society of Mechanical Engineers, 1995.

[6] ABP, ASME boiler and pressure vessel code VIII division 2 -alternative rules, Appendix 5. Design based on fatigue analysis, 1995.

[7] Merk Blatter A., Technical rules for pressure vessels. Verlag KG, Carls Heymanns, 1997.

[8] Frederic O., The kiln book; materials, specifications and construction. Chilton Book Company, 1997.

[9] Liu XY., Specht E., Temperature distribution within the moving bed of rotary kilns: measurement and analysis. Chemical Engineering and Processing. Process Intensification 2010;49(2):147–50.

[10] Kikuchi M., Fatigue crack growth simulation in heterogeneous material using S-version FEM, International Journal of Fatigue 58, 2014.

[11] Kikuchi M., Growth prediction of two interacting surface cracks of dissimilar sizes, Engineering Fracture Mechanics 77, 3120–3131, 2010.

[12] Kikuchi M., Crack growth analysis in a weld-heat-affected zone using S-version FEM, International Journal of Pressure Vessels and Piping 90-91, 2012.

[13] Irsyadi Yani, Visualization of Finite Element Analysis in 3D (C, C++, Under Linux/Fedora), Seminar PPI Jepang Tengah, Toyohashi University of Technology, Japan.

[14] Irsyadi Yani, Masanori Kikuchi, “Numerical Analysis in the Low Carbon Steel by Finite Element and Experimental Method under Fatigue Loading”, Proceeding of The 5th International Conference on Numerical Analysis in Engineering (NAE), 2007.

[15] Irsyadi Yani, Masanori Kikuchi, Yasuhiro Kanto, ”Numerical Analysis of 3-D Surface Crack”, International Conference of Computational Mechanics and Numerical Analysis, 2006.

[16] Irsyadi Yani “Analysis K-Value on the crack pipe under Torsion” Jurnal Rekayasa Mesin, FT. Unsri Jurusan Teknik Mesin.

[17] Thamrin, I., Basri, H., “Exact and Numerical Solution of Pure Torsion Shaft”, Proceeding of 5th International Conference on Numerical Analysis in Engineering (NAE 2007). University of Sumatera Utara (IC-STAR USU), ISSN: 979-96139-6-7, pp.3.24-3.29, 2007.

[18] Basri, H., “Numerical Solution of Fatigue Stress in Journal Bearing”, Proceeding of 5th International Conference on Numerical Analysis in Engineering (NAE 2007), University of Sumatera Utara (IC-STAR USU), ISSN: 979-96139-6-7, pp. 8.1-8.7, 2007.

[19] Chandra, H., Basri, H., “Analisis Fatigue Poros Pompa Vakum“, (in Indonesian), Prosiding Seminar Nasional Sains dan Teknologi 2007, Lembaga Penelitian, Universitas Lampung, Bandar Lampung, 27-28 Agustus 2007.