Zonglu Guo¹, Deli Gao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.1, pp. 65-76, 2013, DOI:10.3970/cmes.2013.090.065

Abstract The modeling of the bottomhole assembly (BHA) is an essential problem in directional drilling. Some basic equations for predicting the performance of the BHA are presented in this paper. These equations take into account the effects of the axial displacement. The method of weighted residuals and the Newton-Raphson iterations are used to compute the nonlinear effects of the deformation of the BHA. A computer program is developed for the analysis of the BHA in order to quantitatively predict the performance of the BHA in directional drilling. In addition, a case study is presented to evaluate the effect of the axial… More >

Mohammad Mashayekhi¹, Hossein M. Shodja^1,2, Reza Namakian¹

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.1, pp. 19-60, 2011, DOI:10.3970/cmes.2011.076.019

Abstract A meshless method called reproducing kernel particle method (RKPM) is exploited to cope with elastic-plastic fracture mechanics (EPFM) problems. The idea of arithmetic progression is assumed to place particles within the refinement zone in the vicinity of the crack tip. A comparison between two conventional treatments, visibility and diffraction, to crack discontinuity is conducted. Also, a tracking to find the appropriate diffraction parameter is performed. To assess the suggestions made, two mode I numerical simulations, pure tension and pure bending tests, are executed. Results including J integral, crack mouth opening displacement (CMOD), and plastic zone size and shape are compared… More >

Y.C. Shiah¹, C. L. Tan², R.F. Lee¹

CMES-Computer Modeling in Engineering & Sciences, Vol.69, No.2, pp. 167-198, 2010, DOI:10.3970/cmes.2010.069.167

Abstract In this paper, fully explicit, algebraic expressions are derived for the first and second derivatives of the Green's function for the displacements in a three dimensional anisotropic, linear elastic body. These quantities are required in the direct formulation of the boundary element method (BEM) for determining the stresses at internal points in the body. To the authors' knowledge, similar quantities have never previously been presented in the literature because of their mathematical complexity. Although the BEM is a boundary solution numerical technique, solutions for the displacements and stresses at internal points are sometimes required for some engineering applications. To this… More >

Anil Misra¹, Shiping Huang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.2, pp. 197-216, 2009, DOI:10.3970/cmes.2009.052.197

Abstract The behavior of contact between solid bodies with rough surfaces under combined normal and shear loading remains a problem of interest in many areas of engineering. In this paper, we have utilized a micromechanical methodology to derive an expression of stress-displacement relationship applicable to combined normal and shear loading conditions. The micromechanical methodology considers the mechanics of asperity contacts and the interface roughness in terms of asperity height and asperity contact orientation distribution. A numerical procedure is implemented to evaluate the derived expressions under complex and mixed loading conditions using an incremental approach. We find that the proposed numerical procedure… More >

K. Lee¹ and S.W. Lee ²

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.3, pp. 253-272, 2008, DOI:10.3970/cmes.2008.034.253

Abstract A geometrically nonlinear assumed strain formulation is used to develop a nine-node solid shell element with quadratic displacement through the thickness. The transversely quadratic element allows direct use of the constitutive equations developed for three-dimensional solids, which is convenient when material nonlinearity is involved. The nodal degrees of freedom associated with the quadratic terms in the assumed displacement through the thickness are statically condensed out at the element level. The results of numerical tests conducted on selected example problems demonstrate the validity and effectiveness of the present approach. For the cases involving linear elastic material, the differences between the present… More >

Y. C. Shiah¹, C. L. Tan², V.G. Lee³

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.3, pp. 205-226, 2008, DOI:10.3970/cmes.2008.034.205

Abstract The main impediment to the development of efficient algorithms for the stress analysis of 3D generally anisotropic elastic solids using the boundary element method (BEM) and the local boundary integral equation (LBIE) meshless method over the years is the complexity of the fundamental solutions and the computational burden to evaluate them. The ability to analytically simplify and reduce them into as explicit a form as possible so that they can be directly computed will offer significant cost savings. In addition, they facilitate easy implementation using existing numerical algorithms with the above-mentioned methods that have been developed for isotropy. In this… More >

C.E. Majorana¹, V.A. Salomoni

CMES-Computer Modeling in Engineering & Sciences, Vol.33, No.1, pp. 49-84, 2008, DOI:10.3970/cmes.2008.033.049

Abstract A dynamic analysis of a thin shell finite element undergoing large displacements and rotations is here presented. The constitutive model adopted derives from the coupling of an hyperelastic basic model fulfilling a De Saint Venant-Kirchhoff criterion with a scalar damage function depending on the maximum value of a suitable strain measure attained through the deformation history; then plastic effects are included using an isotropic/kinematic hardening law. A conservative time integration scheme for the non-linear dynamics of the hyperelastic damaged-plastic thin shell is applied. The main characteristic of the scheme is to be conservative, since it allows for the time-discrete system… More >

Shuangbiao Liu, Michael J. Rodgers, Qian Wang, Leon M. Keer, Herbert S. Cheng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.4, pp. 465-482, 2002, DOI:10.3970/cmes.2002.003.465

Abstract Computing the temperature rise and thermoelastic displacement of a material subjected to frictional heating is essential for the realistic modeling of the performance of mechanical components. This paper presents a novel set of frequency-domain expressions for the surface temperature rise and the surface normal thermoelastic displacement of a moving three-dimensional elastic halfspace subjected to arbitrary transient frictional heating, where the velocity of the body and its direction can be an arbitrary function of time. Frequency response functions are derived by using the Carslaw-Jaeger theory, the Seo-Mura result, and the Fourier transform. General formulas are expressed in the form of time… More >

D. Bergmair^1,2, S. J. Metz¹, H. C. de Lange², A. A. van Steenhoven²

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 1-15, 2013, DOI:10.3970/cmes.2013.091.001

Abstract A method to predict the permeation of water vapor, present in a laminar flowing humid carrier gas, through a hollow fiber membrane is presented. The method uses simulation particles that move like molecules, according to the kinetic gas theory, but carry the physical properties of an ensemble of molecules which they statistically represent. With this approach an ideal operational window for membrane modules can be found and parameters tested for, can be varied over orders of magnitude. The results show that the right dimensioning is essential for the efficient use of the membrane area. More >

Zaobao Liu^1,2, Weiya Xu¹, Jianfu Shao²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.2, pp. 99-122, 2012, DOI:10.3970/cmes.2012.084.099

Abstract In this paper, the Gauss process is proposed for application on landslide displacement analysis and prediction with dynamic crossing validation. The prediction problem using noisy observations is first introduced. Then the Gauss process method is proposed for modeling non-stationary series of landslide displacements based on its ability to model noisy data. The monitoring displacement series of the New Wolong Temple Landslide is comparatively studied with other methods as an instance to implement the strategy of the Gauss process for predicting landslide displacement. The dynamic crossing validation method is adopted to manage the displacement series so as to give more precise… More >