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Volume 4, Number 1, March 2011

The inverse problem about the theoretical analysis of a drill string bending in a channel of an inclined bore-hole with localized geometrical imperfections is studied. The system of ordinary differential equations is first derived based on the theory of curvilinear flexible elastic rods. One can then use these equations to investigate the quasi-static effects of the drill string bending that may occur in the process of raising, lowering and rotation of the string inside the bore-hole. The method for numerical solution of the constructed equations is described. With the proposed method, the phenomenon of the drill column movement, its contact interaction with the bore-hole surface, and the frictional seizure can be simulated for different combinations of velocities, directions of rotation and axial motion of the string. Geometrical imperfections in the shape of localized smoothed breaks of the bore-hole axis line are considered. Some numerical examples are presented to illustrate the applicability of the method proposed.

Key Words
curvilinear drilling; geometrical imperfections; drill string raising; contact forces; resistance forces.

V.I. Gulyayev, S.N. Khudoliy and E.N. Andrusenko:
Dept. of Mathematics, National Transport University, Suvorov str., 1, 01010, Kiev, Ukraine

This paper deals with the modeling of the plane frame structure-foundation-soil system. The superstructure along with the foundation beam is idealized as beam bending elements. The soil medium near the foundation beam with stress concentrated is idealized by isoparametric finite elements, and infinite elements are used to represent the far field of the soil media. This paper presents the modeling of shear wall structure-foundation and soil system using the optimal membrane triangular, super and conventional finite elements. Particularly, an alternative formulation is presented for the optimal triangular elements aimed at reducing the programming effort and computational cost. The proposed model is applied to a plane frame-combined footing-soil system. It is shown that the total settlement obtained from the non-linear interactive analysis is about 1.3 to 1.4 times that of the non-interactive analysis. Furthermore, the proposed model was found to be efficient in simulating the shear wall-foundation-soil system, being able to yield results that are similar to those obtained by the conventional finite element method.

Key Words
triangular element; shear wall structure; super element; drilling degree of freedom.

M. Dalili: Civil Engineering Faculty, Universiti Putra Malaysia, Malaysia; Institute of Advanced Technology, Universiti Putra Malaysia, Malaysia
A. Alkarni: Civil Engineering Faculty, King Saud University, Riyadh, Saudi Arabia
J. Noorzaei and M. Paknahad: Civil Engineering Faculty, Universiti Putra Malaysia, Malaysia; Institute of Advanced Technology, Universiti Putra Malaysia, Malaysia
M.S. Jaafar and B.B.K. Huat: Civil Engineering Faculty, Universiti Putra Malaysia, Malaysia

A global-local finite element modeling technique is employed in this paper to predict the fatigue life of radial truck tires. This paper assumes that a flaw exists inside the tire, in the local model. The local model uses an FEM fracture analysis in conjunction with a global-local technique in ABAQUS. A 3D finite element local model calculates the energy release rate at the belt edge. Using the analysis of the local model, a study of the energy release rate is performed in the crack region and used to determine the crack growth rate analysis. The result considers how different driving conditions contribute to the detrimental effects of belt separation in truck tire failure. The calculation of the total mileage on four sizes of radial truck tires has performed on the belt edge separation. The effect of the change of belt width design on the fatigue lifetime of tire belt separation is discussed.

Key Words
fatigue life; tire; global-local finite element method; crack; energy release rate.

Kyoung Moon Jeong: R&D Center, Kumho Tires Co. Inc., Gwangju 506-711, Korea
Hyeon Gyu Beom: Dept. of Mechanical Engineering, Inha University, Incheon 402-751, Korea
Kee-Woon Kim: R&D Center, Kumho Tires Co. Inc., Gwangju 506-711, Korea
Jin-Rae Cho: School of Mechanical Engineering, Pusan National University, Busan 609-735, Korea; Research & Development Institute of Midas IT, Gyeonggi 463-400, Korea

A methodology for jointed rock mass characterization starts with a research based on geological data and tests in order to define the geotechnical models used to support the decision about location, orientation and shape of cavities. Afterwards a more detailed characterization of the rock mass is performed allowing the update of the geomechanical parameters defined in the previous stage. The observed results can be also used to re-evaluate the geotechnical model using inverse methodologies. Cases of large underground structures modeling are presented. The first case concerns the modeling of cavities in volcanic formations. Then, an application to a large station from the Metro do Porto project developed in heterogeneous granite formations is also presented. Finally, the last case concerns the modeling of large cavities for a hydroelectric powerhouse complex. The finite element method and finite difference method software used is acquired from Rocscience and ITASCA, respectively.

Key Words
underground structure; numerical modelling; rock formation.

Luis Ribeiro e Sousa: University of Porto, Faculty of Engineering, Dept. of Civil Engineering,
Rua Dr. Roberto Frias s/n 4200-465 Porto, Portugal
Tiago Miranda: University of Minho, Dept. of Civil Engineering, School of Engineering, DEC Campus de Azurem 4800-058 Guimaraes, Portugal

In this study, two extreme cases of compatibility of the horizontal displacements between the foundation and soil are considered, for which the pressure and settlements of the isolated footings and member end actions in structural elements are obtained using the three dimensional models and numerical experiments. The first case considered is complete slip between foundation and soil, termed as the uncoupled analysis. In the second case of analysis, termed as the coupled analysis, complete welding is assumed of joints between the foundation and soil elements. The model and the corresponding computer program developed simulate these two extreme states of compatibility giving insight into the variation of horizontal displacements and horizontal stresses and their intricacies, for evaluation of the influence of using the interface elements in soil-structure interaction analysis of three dimensional multiscale structures supported by isolated footings.

Key Words
isolated footing, interface element, link element, mat foundation, settlement, soil-structure interaction.

H.M. Rajashekhar Swamy: Rao Bahadhur Y.Mahabaleshwarappa Engineering College, Bellary-583104, India
A. Krishnamoorthy: Manipal Institute of Technology, Manipal, India
D.L. Prabakhara: Sahyadri College of Engineering and Management, Addyar, Mangalore, India
S.S. Bhavikatti: BVB College of Engineering, Hubli, India

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