Papers by Author: Chyan Bin Hwu

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Authors: Chyan Bin Hwu, Ying Chun Liang
Authors: Chyan Bin Hwu
Abstract: The crack problems are important not only in macromechanics but also in micromechanics. Because of its importance a lot of analytical, numerical and experimental studies have been published in journals and books. Among them, the study of Green’s function attracts many researchers’ attention because analytically it may provide solutions for arbitrary loading through superposition and numerically it can be employed as the fundamental solutions for boundary element method and as the kernel functions of integral equations to consider crack interaction problems. Although a lot of Green’s functions have been presented in the literature, due to mathematical infeasibility most of them are restricted to two-dimensional problems and very few of them consider possible coupled stretching-bending analysis which may occur for general unsymmetric composite laminates subjected inplane and/or out-of-plane forces and moments. In this paper we consider an infinite composite laminate containing a traction-free crack subjected to concentrated forces and moments at an arbitrary point of the laminate. By employing Stroh-like formalism for the coupled stretching-bending analysis, recently the Green’s functions for the infinite laminates (without holes) were obtained in closed-form. Based upon the non-hole Green’s functions, through the use of analytical continuation method the Green’s functions for cracks are now obtained in explicit closed-form and are valid for the full fields. By proper differentiation, the associated stress intensity factors are also solved explicitly.
Authors: Chyan Bin Hwu, Tai Liang Kuo, Chun Chih Huang
Abstract: By employing the Stroh formalism for two-dimensional anisotropic thermoelasticity, fracture analyses of interface corners between two dissimilar anisotropic elastic materials under thermal loadings are considered in this paper. It was proved that the consideration of thermal effects will not influence the stress singularity but will induce heat flux singularity if the singularity of the temperature field is not permissible. To calculate the stress intensity factors via path independent H-integral, it was found that the one proposed previously for the mechanical loading conditions should be modified by adding an additional surface integral accounting for the thermal effects. Two examples considering cracks and corners in isotropic plates are presented to show the correctness and validity of the modified H-integral.
Authors: Cheng Wen Fan, Jhih Hua Huang, Chyan Bin Hwu, Yu Yang Liu
Abstract: In this paper, the mechanical properties, such as the axial and radial Young’s moduli, shear moduli, buckling loads and natural frequencies, of single-walled carbon nanotubes, are estimated by a finite element approach. Each carbon nanotube is simulated as a frame-like structure and the primary bonds between two nearest-neighboring atoms are treated as isotropic beam members with a uniform circular cross-section. In the modeling work, the BEAM4 element in commercial code ANSYS is selected to simulate the carbon bonds and the atoms are nodes. As to the input parameters of the BEAM4 element, they are determined via the concept of energy equivalence between molecular dynamics and structural mechanics, and represented in terms of the force constants of the carbon bonds found in molecular mechanics. Based on this modeling concept, finite element models of both armchair and zigzag types of carbon nanotubes with different sizes are established and the mechanical properties of these tubes are then effectively predicted. Most of the computed results which can be compared with existing results show good agreement. Moreover, the effects of tube diameter, length etc., on the mechanical properties are also investigated.
Authors: Chyan Bin Hwu, Won Jun Lee
Abstract: By employing the Stroh formalism for plane anisotropic thermoelasticity, closed-form solutions for the orders of stress and heat flux singularities of multi-material wedges have been obtained. Several different boundary conditions are considered in this paper such as insulated or isothermal as well as free-free or fixed-fixed or free-fixed or fixed-free wedge boundaries. The solutions show that the singular orders are influenced by the wedge configurations (n wedge angles), boundary conditions, elastic constants and heat conduction coefficients, but are independent of the thermal moduli.
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