B.K. Raghu Prasad¹, T.V.R.L. Rao¹, A.R. Gopalakrishnan¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.3, pp. 179-196, 2009, DOI:10.3970/icces.2009.009.179

Abstract A simple numerical method namely Initial Stiffness Method using finite element method has been employed to study the size effect which is prominent in concrete structures. Numerous experimental investigations performed on notched plain concrete beams subjected to three point or four-point bending have revealed the fracture process to be dependent on size of the structural member. It was found that, the nominal stress at maximum load decreases as the size of the structure increases. The nominal stress at failure on the characteristic dimension of structure is termed as size effect. This has also been explained in energy concepts as, the… More >

C. K. Chen¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.3, pp. 163-178, 2009, DOI:10.3970/icces.2009.009.163

Abstract A classical alternating iteration method is applied to evaluate the stress intensity factors for a mixed oriented crack approaching semi-infinite plane or a straight crack. Conventional Gaussian-Legedre quadrature scheme is employed for the numerical integration in the crack vs. free boundary interacting problems; however, averaged image stresses along crack surfaces are invoked to simplify the alternating procedures in crack vs. crack interaction. Good correlation was achieved between the iterated solutions and the available solutions in the literature. As crack approach the free semi-infinite plane, mode I affect increases, however, maximum mode II stress intensity factors may shift to the lower… More >

Kuo-Ning Chiang¹, Chan-Yen Chou², Chung-Jung Wu², Chao-Jen Huang², Ming-Chih Yew²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.3, pp. 130-142, 2009, DOI:10.3970/icces.2009.009.130

Abstract An atomic-level analytical solution, together with a modified Morse potential, has been developed to estimate temperature-dependent thermal expansion coefficients (CTE) and elastic characteristics of bulk metals. In this study, inter-atomic forces are considered as a set of anharmonic oscillator networks which can be described by Morse potential, while the material properties can be defined by these inter-atomic forces; when temperature increases, the vibration of the anharmonic oscillator causes the phenomenon of temperature-dependent material properties. The results of analysis showed that the original Morse potential can give a reasonable prediction of the thermal expansion coefficients and elastic constants of metals at… More >

Harald Berger¹, Ulrich Gabbert², Reinaldo Rodriguez-Ramos³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 127-129, 2009, DOI:10.3970/icces.2009.009.127

Abstract Piezoelectric materials have the property of converting electrical energy into mechanical energy and vice versa. This reciprocity in the energy conversion makes piezoelectric ceramics very attractive for use as sensors and actuators. By combining piezoelectric fibers with passive non-piezoelectric polymer composites with superior properties can be created. But for design of such smart micro-macro structures homogenization techniques are necessary to describe the overall behavior of piezocomposites expressed by effective material coefficients.
A number o fnumerical and analytical methods have been developed to estimate the effective coefficients. Although analytical homogenization methods provide excellent results it is difficult to extend them to… More >

Xia Yuan¹, Wu Jichun², Zhou Luying³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 117-126, 2009, DOI:10.3970/icces.2009.009.117

Abstract This paper establishes a difference approximation on time-space fractional advection-dispersion equations. Based on the difference approximation an ideal numerical example has been solved, and the result is compared with the one of the rigorous time fractional advection-dispersion equation and the rigorous space fractional advection-dispersion equation respectively. The results show: when time fractional order parameter γ=1 or space fractional order parameter α=2, the numerical calculation result of the time-space fractional advection-dispersion equations is in accordance with that of the rigorous time fractional advection-dispersion equation or the rigorous space fractional advection-dispersion equation. The variation law of the result with parameter is also… More >

S. Ozaki¹, D.H. Chen²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 109-116, 2009, DOI:10.3970/icces.2009.009.109

Abstract In the present study, the collapse behavior of a thin-plate subjected to axial compression is investigated parametrically using the finite element method. It is revealed that the axial collapse of the plate, which has various hardening characteristics, is induced by two dominant factors: the stress limitation of the material and the limitation of in-plane deformation at the side edges of the plate. Then, a simplified collapse condition, which corresponds to two modes, is derived based on the plastic buckling theory and the effective width concept, and the validity of the simplified collapse condition is then verified by the comparison of… More >

Cheng-Hung Huang^1,2, Hsin-Hsien Wu¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 107-108, 2009, DOI:10.3970/icces.2009.009.107

Abstract The conjugate gradient method (CGM) is applied in an inverse fin design problem in estimating the optimum shapes for the non-Fourier spine and longitudinal fins based on the desired fin efficiency and fin volume at the specified time. One of the advantages in using CGM in the inverse design problem lies in that it can handle problems having a huge number of design parameters easily and converges very fast.
The validity of using CGM in solving the present inverse design problem is justified by performing the numerical experiments. Several test cases involving different design fin efficiency, design fin volume, specified… More >

G. Gambolati¹, M. Ferronato¹, C. Janna¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 99-106, 2009, DOI:10.3970/icces.2009.009.099

Abstract The Finite Element (FE) solution to consolidation equations in large geological settings raises a few numerical issues depending on the actual process addressed by the analysis. There are two basic problems where the solver efficiency plays a crucial role: 1- fully coupled consolidation, and 2- non-linear faulted (uncoupled) consolidation. Using a proper nodal numbering the FE matrices exhibit a block (or multilevel) structure. Krylov subspace solvers are attracting a growing attention, provided that a relatively inexpensive and effective preconditioner is available. For both problems possible preconditioners include the Diagonal Scaling (DS), the Incomplete Triangular Factorization (ILU), the Mixed Constraint Preconditioning… More >

Nabeel Z. Al-Rawahi¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 97-98, 2009, DOI:10.3970/icces.2009.009.097

Abstract Due to the complexity of multi-phase flow (MPF) phenomena research in this area is largely based on experimentation using laboratory scale test loops. The design of multi-phase flow test facilities is quite involved and requires careful attention. First, the test rigs have to produce results that are valid or can be scaled to actual full scale systems. This demands that the system geometry and dimensions, the flow drivers (pumps and compressors), flow controls (flow meters, pressure regulators, etc.) and the flow measurement sensors (pressure, temperature, velocity, ..etc) have to be selected so that a wide range of flow conditions can… More >

H. T. Wang¹, Z. H. Yao²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.2, pp. 95-96, 2009, DOI:10.3970/icces.2009.009.095

Abstract Carbon nanotubes (CNTs) may provide ultimate enhancement in stiffness and str\discretionary {-}{}{}ength for composite materials. This paper presents a rigid-fiber-based boundary integral equation formulation for the numerical simulation of debonding process and the corresponding strength of CNT reinforced composites. The CNT/matrix interfaces are assumed to fail when the interfacial shear force reaches a prescribed threshold, and the CNTs and matrix are considered to be detached in the failed areas. The matrix with one or several tens of originally well-bonded CNTs is subjected to an incremental tensile load and the effective stress-strain relations are readily obtained by the introduction of CNT/matrix… More >