R. Rongo^1,2, D. D’Ambrosio^1,2, G. Iovine^2,3, F. Lucà⁴, V. Lupiano⁵, V.P.Boñgolan⁶, W. Spataro^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.2, pp. 105-130, 2015, DOI:10.3970/cmes.2015.109.105

Abstract Determining sectors that could be affected by lava flows in volcanic areas is essential for risk mitigation purposes. Traditionally, when adopting methods based on probabilistic numerical simulations, the hazard is assessed by analysing a huge set of simulations of hypothetical events, each characterized by a distinct probability of occurrence based on statistics of historical events. If lateral or eccentric eruptions are also taken into account, simulated lava flows usually start from the nodes of regular grids of potential vents, uniformly covering the study area. In this study, an alternative approach to evaluate flow-type hazard, based on a nonuniform grid of… More >

Fei Yin¹, Deli Gao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.1, pp. 25-38, 2012, DOI:10.3970/cmes.2012.089.025

Abstract The methods to design the casings used in oilfields, are currently based on the assumptions that the remote crustal-stress-field is axially symmetric, in plane strain. However, most of the failures of the casings are caused by non-uniform and asymmetric far-field crustal stresses, so that it is necessary for a proper design of the casings, to investigate and understand the casing's behavior under non-uniform far-field crustal stresses. A mechanical model is first established for the system, consisting of the casing and formation, by using the plane strain theory of linear elasticity. The non-uniform crustal stress is resolved into a uniform stress… More >

A. N. Guz, V. A. Dekret¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.3, pp. 165-170, 2006, DOI:10.3970/cmes.2006.013.165

Abstract Stability problem of composite material reinforced by two parallel short fibers is solved. The problem is formulated with application of equations of linearized three-dimensional theory of stability. The composite is modeled as piecewise-homogeneous medium. The influence of geometrical and mechanical parameters of the material on critical strain is investigated. More >

Sen Yung Lee¹, Jyh Shyang Wu²

CMES-Computer Modeling in Engineering & Sciences, Vol.40, No.2, pp. 133-154, 2009, DOI:10.3970/cmes.2009.040.133

Abstract The three coupled governing differential equations for the in-plane vibrations of curved non-uniform Timoshenko beams are derived via the Hamilton's principle. Three physical parameters are introduced to simplify the analysis. By eliminating all the terms with the axial displacement parameter, then reducing the order of differential operator acting on the flexural displacement parameter, one uncouples the three governing characteristic differential equations with variable coefficients and reduces them into a sixth-order ordinary differential equation with variable coefficients in term of the angle of the rotation due to bending for the first time. The explicit relations between the axial and the flexural… More >

Hsin-Yi Lai¹, C. K. Chen^1,2, Jung-Chang Hsu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.1, pp. 87-116, 2008, DOI:10.3970/cmes.2008.034.087

Abstract An innovative solver for the free vibration of an elastically restrained non-uniform Euler-Bernoulli beam with tip mass of rotatory inertia and eccentricity resting on an elastic foundation and subjected to an axial load is proposed. The technique we have used is based on applying the Adomian modified decomposition method (AMDM) to our vibration problems. By using this method, any$i$th natural frequencies can be obtained one at a time and some numerical results are given to illustrate the influence of the physical parameters on the natural frequencies of the dynamic system. The computed results agree well with those analytical and numerical… More >

J. Perko¹, B. Šarler²

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.1, pp. 55-68, 2007, DOI:10.3970/cmes.2007.019.055

Abstract This work introduces a procedure for automated determination of weight function free parameters in moving least squares (MLS) based meshless methods for non-uniform grids. The meshless method used in present work is Diffuse Approximate Method (DAM). The DAM is structured in 2D with the one or two parameter Gaussian weigh function, 6 polynomial basis and 9 noded domain of influence. The procedure consists of three main elements. The first is definition of the reference quality function which measures the difference between the MLS approximation on non-uniform and hypothetic uniform node arrangements. The second is the construction of the object function… More >

Zhenyu Xue¹, Ashkan Vaziri¹, John W. Hutchinson¹

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.1, pp. 79-96, 2005, DOI:10.3970/cmes.2005.010.079

Abstract A constitutive model for the elastic-plastic behavior of plastically compressible orthotropic materials is proposed based on an ellipsoidal yield surface with evolving ellipticity to accommodate non-uniform hardening or softening associated with stressing in different directions. The model incorporates rate-dependence arising from material rate-dependence and micro-inertial effects. The basic inputs are the stress-strain responses under the six fundamental stress histories in the orthotropic axes. Special limits of the model include classical isotropic hardening theory, the Hill model for incompressible orthotropic solids, and the Deshpande-Fleck model for highly porous isotropic foam metals. A primary motivation is application to metal core structure in… More >

Imen Mejri^1,2, Ahmed Mahmoudi¹, Mohamed Ammar Abbassi¹, Ahmed Omri¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 83-114, 2014, DOI:10.3970/fdmp.2014.010.083

Abstract This study examines natural convection in a square enclosure filled with a water-Al₂O₃ nanofluid and subjected to a magnetic field. The side walls of the cavity have spatially varying sinusoidal temperature distributions. The horizontal walls are adiabatic. A Lattice Boltzmann method (LBM) is applied to solve the governing equations for fluid velocity and temperature. The following parameters and related ranges are considered: Rayleigh number of the base fluid, from Ra=10³ to 10⁶, Hartmann number from Ha=0 to 90, phase deviation (γ =0, π/4, π/2, 3π/4 and π) and solid volume fraction of the nanoparticles between ø = 0 and 6%.… More >

Sen-Yung Lee¹, Shueei-Muh Lin^2,3, Kai-Ping Chang¹

CMC-Computers, Materials & Continua, Vol.51, No.1, pp. 1-19, 2016, DOI:10.3970/cmc.2016.051.001

Abstract The two coupled governing differential equations for the out-of-plane vibrations of non-uniform beams with variable curvature are derived via the Hamilton's principle. These equations are expressed in terms of flexural and torsional displacements simultaneously. In this study, the analytical method is proposed. Firstly, two physical parameters are introduced to simplify the analysis. One derives the explicit relations between the flexural and the torsional displacements which can also be used to reduce the difficulty in experimental measurements. Based on the relation, the two governing characteristic differential equations with variable coefficients can be uncoupled into a sixth-order ordinary differential equation in terms… More >

M.F. Liu¹

CMC-Computers, Materials & Continua, Vol.22, No.2, pp. 97-128, 2011, DOI:10.3970/cmc.2011.022.097

Abstract A new invented Orthogonal Tapered Beam Functions (OTBFs) have been introduced in this paper and used in accordance with the Rayleigh-Ritz method to determine the natural frequencies and mode shapes of the non-uniform rectangular isotropic plates with varying thickness in one or two directions. The generation of the OTBFs is based on the static solution of a one-dimensional beam problem subjected to constant applied load, and then extends to an orthogonal or orthonomal infinite set of admissible functions by performing the three-term recurrence scheme. A wide range of non-uniform rectangular plate whose domain is referenced by a so-called truncation factor… More >