Nowadays, Malaysia facing with an explosive growth in vehicle ownership and utilization, which led to traffic congestion and pollution. In this situation, government policy encourages people to use public transportation. However, Malaysia are prefer to use private vehicle become many reasons including bad quality of services. In this regard, public transport operators are forced to place emphasis on the monitoring and improvements of the services provided. This study focuses on traveler’s satisfaction and preference towards public transport with service quality attributes. Self rate questionnaire was used to investigate overall customer satisfaction and factor that influence public transport users’ satisfaction. A survey was conducted on an actual public transportation network in Kuala Lumpur, Malaysia. The aim was to evaluate the parameters in passenger preference and satisfaction on public transportation network using statistical model included variable such as facilities, comfortness and quality of services. Data were analyzed using descriptive, correlation, factor and multiple regression analysis. Result show that influences of satisfaction parameters are more than preference parameters. The application of this study suggest that the public transport operation especially buses must improve their quality of services to the prospect passengers

Ambak, Kamarudin

Hafezi, Mohammad Hesam

Ismail, Rozmi

Mohd Nor, Rahim

English

UTHM Institutional Repository

International Review of Mechanical Engineering (I.RE.ME.), Vol. 7, N 3 lSSN 1970-8734 March 2013 Stress Intensity Factors under Mode 111 Loadings Abstract - This study presents a numerical investigation on the stress intensity factors (SIF) obtained under pure torsion loadings or mode 111. ANSYS finite element analysis (FEA) was used to determine the SIFs along the crack fiont of surface cracks embedded in the solid circular bars. 20-node isoparametric singular elements were used around the crack tip by shifting the mid-side node %-position close to a crack tip. Different crack aspect ratio, d b  were used ranging between 0.0 to 1.2 and relative crack depth, d D  were ranged between 0.1 to 0.6. Mode I SIF, KI obtained under bending moment was used to validate the proposed model and it was assumed that this proposed model was validated for analyzing mode 111 problems. It was found that, the FII and FIII were dependent on the crack geometries and the behavior of crack growth were also dependent on d b  and dD.  Copyright O 2009 Praise Worthy Prize S.r.Z. -All rights reserved. Keywords: Stress Intensity Factors, Mode III, Surface Crack, Finite Element Analysis I. Introduction Cylindrical solid bars or shafts have enormous number of applications in engineering practices especially to transmit power from one point to another. It is subjected to the torsion loadings for such purposes. Under a certain circumstance, the shaft failure could occur mainly due to the mechanical [l, 21 and material or environmental defects [3, 41. Therefore, the crack initiation takes the opportunity to start at these sites and any shape of the initiated cracks will take the semi-elliptical shape [5]. These crack shapes and geometries are used in this work to extract the stress intensity factors (SIFs). According to the literature surveys, it is hard to find the SIF under torsion loading, KIU [6, 71. This type of SIF is important to be studied in order to analyze the crack behavior under torsion. Therefore in this present work, the SIFs under torsion loadings will be studied and analyzed. Several important crack geometries are taken into the consideration such as the crack aspect ratio, d b  and the relative crack depth, d D .  The distributions of SlFs along the crack front are then numerically calculated using ANSYS finite element analysis software. 11. Finite Element Modeling The circular cross-section of the component with a surface crack is shown in Fig. 1. The geometry of the crack can be described by the relative crack depth, d D  and the crack aspect ratio, d b  where a is a maximum crack depth or minor axis of the ellipse, b is a major axis of the ellipse and h is a crack width. Any arbitrary points on the crack fiont can also be normalized as follow, x/h. The outer diameter of the cylinder, D  is 50 mm and the total length, l is 200 mm. The linear elastic material properties, Young's modulus, E = 222 GPa and Poisson ratio,v = 0.3 are used. Due to the non-symmetrical analysis involved, a full finite element model is constructed where the surface crack is situated in the middle location of the cylinder. The finite element (FE) model is developed using ANSYS software and special attention is given at the crack tip by employing 20-node iso-parametric brick elements8. The square-root singularity of stresses and strains is modeled by shifting the mid-point nodes to the quarter-point locations in the region around the crack fiont as shown in Fig. 2. The detail of fmite element model is shown in Fig. 3.  In order to remotely applied loadings to the component, an independent node is created and rigid element or multi- point constraint (MPC) is used to connect the nodes at the circumferential line at the end of the component to the independent node. Fig. 4 shows the technique of constructing the independent node connected to the model using rigid beam element. Torsion moment, T, and bending moment, Mz are separately applied to this independent node. Fig. 1 Nomenclature of semi-elliptical crack Manuscript received Janualy 2013, revised March 2013 Copyright O 2013 Praise Wbrthy Prize S.r.1. -All rights reserved A.E. Ismail, A.K. Arzfin, S. Abdullah, M.J Ghazali 0.0 0.1 0.2 0.3 0.4 0.5 0.6 a/lD Fig. 7 Effect of FuI on the d D  for different a/b Fig. 8 Full finite element model under pure torsion Fig. 9 Aerial view of the crack under pure torsion Therefore under pure torsion loading, several patterns of crack propagations are numerically expected to evolve. For the cracks which have d b  < 0.3 the maximum KID occurred at the d h  = 0.0, indicating that the crack initiated at this site producing deeper crack depth. While for the case d b  > 0.3, the maximum crack has occurred at the outer edge of the bar indicating that the crack initiated at the site. It will produce flaten-shaped crack. This is due to the maximum FIII will generate faster crack growth relative to the mini~~~um Fm The behavior of FIII obtained at x/h = 0.0 for different crack aspect ratio, d b  are plotted in Fig. 7. For this particular position, the maximum FIU attained for the d D  = 0.1 and the minimum FIII occurred at the d D  = 0.6 relatively. This is to conform the crack evolution that can be obtained during the crack growth under the torsion loadings. Fig. 8(a) shows the full finite element model subjected to the pure torsion loading and Fig. 8(b) shows the enlarged area A revealed the stress distribution around the crack with an insignificant plastic deformation. While Fig. 9(a) shows the aerial view of the crack revealing that the crack faces are completely closed with element distortion. The enlarged view of Fig. 8(b) and Fig. 9(b) also revealed the mymmetrical stress distributions to emphasis the important to develop a 111 finite element model in order to analyze the response of torsion loadings. IV. Conclusion In this paper, the stress intensity factors (SIF) were obtained using ANSYS finite element method (FEM) for surface cracks in round bars which was subjected to torsion loadings. For the surface crack under considerations, the crack aspect ratio, d b  was varied between 0.0 and 1.2, while the relative crack depth, a/b was also varied between 0.1 and 0.6. The SIFs were determined for several points along the crack front which was characterized by a normalized coordinate, x/h. The proposed model was validated through the comparison with the results for mode I SIF, KI, since lack of mode I11 SF ,  Km results available in the literature. It was observed that under mode III loading instead of producing Km, it also induced mode TI SIF, Kn. Results showed that at the deepest point on the crack £i-ont (x/h = 0.0), the KII was almost zero but it increased gradually when the points reached the outer surface of the bar. The behavior of KIII was strongly depend on the a/b, d D  and x/h and therefore producing different crack evolution during the crack growth under torsion loadings. Acknowledgements This work was supported in by Universiti Tun Hussein Onn Malaysia under Grant Vot. 100 1. References [l] A. Carpinten, R. Brighenti, S. Vantadori, Surface cracks in notched round bars under cyclic tension and bending, International Journal of Fatigue, Vol. 28, pp. 251-260,2007. [2] A.E. Ismail, kK. Ariffm, S. Abdullah, M.J. Ghazali, Elastic- plastic analysis of surface cracks in round bars under bending moments, International Review of Mechanical Engineering, Vol. 6, No. 3, pp. 602-606,2012. [3] M.D. Fonte, , M.D. Freitas, Stress intensity factor for semi- elliptical surface cracks in round bars under bending and torsion, International Journal ofFatigue, Vol. 21, pp. 457-463, 1997. [4] A.E. Ismail, A.K. Ariffm, S. Abdullah, M.J. Ghazali, M. AbdulRazzaq, Finite Element Analysis on the Stress Intensity Factor under Combined Bending and Torsion Loading, Key EngineeringMaterials, Vol. 462-463, pp. 1325-1330,2011. [5] X.B. Lin, R.A Smith, Shape growth simulation of surface cracks in tension fatigue round bars, International Journal of Fatigue, Vol. 19, pp. 461-469, 1997. [6] A.R. Shahani, S.E. Habibi, Stress intensity factors in a hollow cylinder containing a circumferential semi-elliptical crack subjected to combined loading, International Journal of Fatigue, VOL 29, pp. 128-140,2007, Copyright 0 2013 Praise Worthy Prize S.r.1. -All rights reserved International Review of Mechanical Engineering, Vol. 7, N.3 A.E. Ismail, A.K. Arzfln, S. Abdullah, M J  Ghazali [7] C.S. Shin, C.Q. Cai, Experimental and finite element analyses on stress intensity factors of an elliptical surface crack in a circular sh& under tension and bending, International Journal of Fracture, Vol. 129, pp. 239-264.2004. [8] A.E. Ismail, A.K. Ariffm, S. Abdullah, M.J. Ghazali, Effect of crack faces opening mechanisms on the combined stress intensity factors under bending and torsion moment, International Review of Modeling and Simulations, Vol. 4, No. 6, pp. 3232-3238,2011. Authors' information ' ~ e ~ a r t m e n t  of Engineering Mechanics, Faculty of Mechanical and ~Gufactur ing Engineering, Universiti Tun Hussein Om Malaysia, Batu Pahat, 86400, Johor, Malaysia 2,3,4~epartment of Mechanical and Materials Engineering, Faculty of Engineering and Built-Environment, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia. Tel: +603-8929 6517 Fax: +603-8925 9569 E-mail: emran(iiluthm.edu.mv', kamal@eng.ukm.m9, shahrum@eng.ukm.m?, marivam@eng.ukm.mv4. A1 Emran Ismail is a PhD graduate from Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. He received his MSc. fiom Universiti Teknologi MARA in 2003 and conferred B.Eng (Mechanical) fiom Universiti Putra Malaysia in 2000. He is a member of Institution of Engineers, Malaysia and member of Institution of Materials, Malaysia. Ahmad Kamal Ariffm graduated with a Mechanical Engineering degree fiom Universiti Kebangsaan Malaysia in 1990. He pursued his Ph.D at the University of Wales, Swansea in 2005 in the area of computational mechanics. He is a Fellow of the Institute of Materials Malaysia, founder of Malaysian Association of Computational Mechanics and also member of International Association of Computational Mechanics. Shahrum Abdullah graduated with a degree of Mechanical Engineering from Universiti Kebangsaan Malaysia in 1995. He then received Master Degree in Engineering Design fiom Loughborough University in 1997. His Ph.D degree was fiom the University of Sheffield in 2005 in the area of variable amplitude fatigue. He is a member of Institution of Engineers, Malaysia. Mariyem Jamcelah Ghazali graduated from llniversiti Sains Malaysia (USM) for p both degree and mastcr in area of Material Engineering in 1999 and 2000, respectively. In 2005, she reccivcd a PhD degree from the University of Shefrield in the area of Wear of Materials. She is a memher of Institution of Materials, Malaysia. Copyright 0 2013 Praise Worthy Prize S.r. l. - A11 rights reserved International Review of Mechanical Engineering, Vol. 7, N.3 

A1 Emran Ismail is a PhD graduate from Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. He received his MSc. fiom Universiti Teknologi MARA in

Ariffm graduated with a Mechanical Engineering degree fiom Universiti Kebangsaan Malaysia in

Effect of crack faces opening mechanisms on the combined stress intensity factors under bending and torsion moment,

Finite Element Analysis on the Stress Intensity Factor under Combined Bending and Torsion Loading,

Ghazali graduated from llniversiti Sains Malaysia (USM) for p both degree and mastcr in area of Material Engineering in 1999 and 2000, respectively. In

He pursued his Ph.D at the University of Wales, Swansea in 2005 in the area of computational mechanics.

received Master Degree in Engineering Design fiom Loughborough University in 1997. His Ph.D degree was fiom the University of Sheffield in 2005 in the area of variable amplitude fatigue. He is a member of Institution of Engineers,

Shahrum Abdullah graduated with a degree of Mechanical Engineering from Universiti Kebangsaan Malaysia in

Shape growth simulation of surface cracks in tension fatigue round bars,

Stress intensity factor for semielliptical surface cracks in round bars under bending and torsion,

Stress intensity factors in a hollow cylinder containing a circumferential semi-elliptical crack subjected to combined loading,

Surface cracks in notched round bars under cyclic tension and bending,

Passengers preference and satisfaction of public transport in Malaysia

Passengers preference and satisfaction of public transport in Malaysia

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