Jia-Lin Tsai

National Chiao Tung University, Hsin-chu-hsien, Taiwan, Taiwan

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Publications (11)5.85 Total impact

  • Ting-Chu Lu, Jia-Lin Tsai
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    ABSTRACT: Load transfer efficiency from matrix to carbon nanotubes (CNTs) plays an important role in the mechanical response of CNTs nanocomposites as it may affect the effectiveness of the nano-reinforcements. For double-walled carbon nanotubes (DWCNTs), the outer graphene layer as well as the inner layer may be responsible for the load bearing capacity. In this study, the load transfer efficiency within DWCNTs was investigated using a multiscale simulation scheme. The multiscale simulation consists of two steps. First, the atomistic behaviors between the adjacent graphite layers in DWCNTs were characterized using molecular dynamic (MD) simulation, from which a cylindrical equivalent continuum solid of DWCNTs with embedded spring elements was proposed to describe the interactions of neighboring graphene layers. Two kinds of interatomistic properties in DWCNTs, i.e., van der Walls (vdW) interactions and artificial build-up covalent bonds, were considered in the equivalent solid. Subsequently, the equivalent solid was implemented as reinforcement in the micromechanical model of CNTs nanocomposites for evaluating the load transfer efficiency. Results indicated that the DWCNTs with covalent bonds exhibit superior load transfer efficiency than those with only vdW interactions. In addition, when the DWCNTs get long, the load transfer efficiency of DWCNTs increases accordingly.
    Composites Part B Engineering 01/2013; 44(1):394–402. · 2.14 Impact Factor
  • Shi-Hua Tzeng, Jia-Lin Tsai
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    ABSTRACT: The stress distribution of CNTs embedded within polyimide matrix subjected to applied loading was investigated using molecular dynamics simulation. The purpose of evaluating the stress distribution of CNTs is to characterize the loading transfer efficiency between the nano-reinforcement and surrounding polyimide matrix, which basically is an essential factor controlling the mechanical properties of nanocomposites. Three different interfacial adhesions between the CNTs and polyimide molecular were considered, that is, vdW interaction, CNTs with surface modification, and covalent bond. The stress distribution of the CNTs was calculated by using the Lutsko atomistic stress formulation1,2 and by taking the derivative of the potential functions as well. Results revealed that when the CNTs surface was modified, the higher load transfer efficiency from the polyimide to the CNTs was observed resulting in the higher modulus of the nanocomposites. It is noted that, if no surface modification on CNTs, the load transfer efficiency which basically depends on the intensities of the vdW interaction is relatively low. As a result, the surface modification on CNTs is an effective manner to improve the load transfer efficiency as well as the modulus of nanocomposite, which should be suggested in the fabrication of CNTs nanocomposites.
    Journal of Reinforced Plastics and Composites 06/2011; 30(11):922-931. · 0.90 Impact Factor
  • Jia-Lin Tsai, Nai-Ren Chang
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    ABSTRACT: This research aims to investigate the damping responses of the epoxy-based nanocomposites as well as the composite sandwich structures with the nanocomposite as core materials. Both the silica nanoparticles and the rubber particles (CSR, CTBN) were introduced in the epoxy matrix through the sonication process to form the nanocomposites. Furthermore, the nanocomposites were sandwiched between the unidirectional composites laminates to fabricate the nanocomposite sandwich structures. The damping performances of the nanocomposites as well as their sandwich structures were determined from the forced vibration technique together with the half-power method. Meanwhile, the flexural stiffness of the material systems was evaluated by the resonance frequency obtained from the vibration tests. Results indicated that either silica nanoparticles or rubber particles can improve the damping responses of the epoxy-based nanocomposites. However, it was found that when the rubber particles were present alone, the stiffness of the nanocomposites was dramatically reduced. By introducing the hybrid material systems (10 wt% silica nanoparticles and 10 wt% rubber particles), the superior damping properties and flexural stiffness can be concurrently accomplished. Moreover, when the hybrid material system was employed as core materials in the sandwich structures, this enhanced damping property can also be observed in the vibration tests.
    Journal of Composite Materials 01/2011; 45(21):2157-2164. · 0.94 Impact Factor
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    Jia-Lin Tsai, Shi-Hua Tzeng, Yu-Jen Tzou
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    ABSTRACT: The fracture behavior of a graphene sheet, containing a center crack (length of 2a) was characterized based on the atomistic simulation and the concept of continuum mechanics. Two failure modes, i.e., opening mode (Mode I) and sliding mode (Mode II), were considered by applying remote tensile and shear loading, respectively, on the graphene sheet. In the atomistic simulation, the equilibrium configurations of the cracked graphene subjected to applied loadings, before and after the crack extension of 2Δa, were determined through molecular dynamics (MD) simulation, from which the variation of the potential energy and the strain energy release rate of the discrete graphene sheet because of crack extension was calculated accordingly. It is noted that because of the discrete attribute, there is no stress singularity near the crack tip, and thus, the concept of stress intensity factor that is generally employed in the continuum mechanics may not be suitable for modeling the crack behavior in the atomistic structures. For the sake of comparison, the continuum finite element model with the same geometric parameters and material properties as the atomistic graphene sheet was constructed, and the corresponding strain energy release rate was calculated from the crack closure method. Results indicated that the strain energy release rates obtained from the continuum model exhibit good agreement with those derived from discrete atomistic model. Therefore, it is suggested that the strain energy release rate is an appropriate parameter, which can be employed in the atomistic model and the continuum model for describing the fracture of covalently bonded graphene sheet.
    International Journal of Solids and Structures 01/2010; 47(3):503-509. · 1.87 Impact Factor
  • Jia-Lin Tsai, Jie-Feng Tu
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    ABSTRACT: The mechanical properties of graphite in the forms of single graphene layer and graphite flakes (containing several graphene layers) were investigated using molecular dynamics (MD) simulation. The in-plane properties, Young’s modulus, Poisson’s ratio, and shear modulus, were measured, respectively, by applying axial tensile stress and in-plane shear stress on the simulation box through the modified NPT ensemble. In order to validate the results, the conventional NVT ensemble with the applied uniform strain filed in the simulation box was adopted in the MD simulation. Results indicated that the modified NPT ensemble is capable of characterizing the material properties of atomistic structures with accuracy. In addition, it was found the graphene layers exhibit higher moduli than the graphite flakes; thus, it was suggested that the graphite flakes have to be expanded and exfoliated into numbers of single graphene layers in order to provide better reinforcement effect in nanocomposites.
    Materials & Design. 01/2010; 31(1):194–199.
  • Jia-Lin Tsai, Shi-Hua Tzeng, Yu-Tsung Chiu
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    ABSTRACT: This research is aimed at characterizing the elastic properties of carbon nanotubes (CNTs) reinforced polyimide nanocomposites using a multi-scale simulation approach. The hollow cylindrical molecular structures of CNTs were modeled as a transverse isotropic solid, the equivalent elastic properties of which were determined from the molecular mechanics calculations in conjunction with the energy equivalent concept. Subsequently, the molecular structures of the CNTs/polyimide nanocomposites were established through molecular dynamics (MD) simulation, from which the non-bonded gap as well as the non-bonded energy between the CNTs and the surrounding polyimide were evaluated. It was postulated that the normalized non-bonded energy (non-bonded energy divided by surface area of the CNTs) is correlated with the extent of the interfacial interaction. Afterwards, an effective interphase was introduced between the CNTs and polyimide polymer to characterize the degree of non-bonded interaction. The dimension of the interphase was assumed equal to the non-bonded gap, and the corresponding elastic stiffness was calculated from the normalized non-bonded energy. The elastic properties of the CNT nanocomposites were predicted by a three-phase micromechanical model in which the equivalent solid cylinder of CNTs, polyimide matrix, and the effective interphase were included. Results indicated that the longitudinal moduli of the nanocomposites obtained based on the three-phase model were in good agreement with those calculated from MD simulation. Moreover, they fit well with the conventional rule of mixture predictions. On the other hand, in the transverse direction, the three-phase model is superior to the conventional micromechanical model since it is capable of predicting the dependence of transverse modulus on the radii of nanotubes.
    Composites Part B: Engineering. 01/2010;
  • Jia-Lin Tsai, Ting-Chu Lu
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    ABSTRACT: The load transfer efficiency from surrounding matrix to the carbon nanotubes (CNTs) in the CNTs reinforced nanocomposites was studied. Both single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) were taken into account in the investigation. A cylindrical representative volume element (RVE) containing the CNTs and matrix phases were employed in the shear lag analysis from which the axial stress distribution as well as the load transfer efficiency in the CNTs was characterized. The effects of the layer number, atomistic interaction of graphite layers, and the aspect ratio of the CNTs on the load transfer efficiency were of concern. Results indicated that the SWCNTs exhibit a greater load transfer efficiency than MWCNTs associated with the same CNTs volume fraction in the nanocomposites. Moreover, the incompetent behaviors of the MWCNTs would become substantial as the number of graphite layers increases, and the deficient load transfer efficiency in the MWCNTs would not be modified effectively even though the chemical bonding between the graphite layers were constructed.
    Composite Structures - COMPOS STRUCT. 01/2009; 90(2):172-179.
  • Jia-Lin Tsai, Nai-Ren Chang
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    ABSTRACT: The flexural damping behaviors of composite laminates were characterized analytically in this study. A 2-D analytical model was developed based on the extension of Ni–Adams model [Ni RG, Adams RD. The damping and dynamic moduli of symmetric laminated composite beams—theoretical and experimental results. J Compos Mater 1984;18(2):104–21] accounting for the energy dissipation contributed by the laminar stresses of σxy and σyy. The specific damping capacity (SDC) of the composite was determined in accordance with the energy dissipation concept, which was defined as the ratio of the dissipated energy to the stored energy for per circle of vibration. The 2-D analytical model was validated by comparing the SDC of [0/−60/60]s and [0/90/45/−45]s laminates with the experimental data and the finite element (FEM) results. In addition, the effects of interlaminar stress on the flexural damping responses of laminated plates were also characterized in the 3-D FEM analysis. Results indicated that the interlaminar stress effect may not be so significant that the current 2-D model is adequate for the evaluation of the damping responses of the composite laminates. Furthermore, the present predictions, as compared to the Ni–Adams [Ni RG, Adams RD. The damping and dynamic moduli of symmetric laminated composite beams—theoretical and experimental results. J Compos Mater 1984;18(2):104–21] and Adams–Maheri [Adams RD, Maheri MR. Dynamic flexural properties of anisotropic fibrous composite beams. Compos Sci Technol 1994;50(4):497–514] models, generally demonstrate good agreements with the experimental data and the FEM results.
    Composite Structures - COMPOS STRUCT. 01/2009; 89(3):443-447.
  • Jia-Lin Tsai, Yang-Kai Chi
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    ABSTRACT: This study aims to investigate the thermal residual stress effect on the constitutive behaviors of fiber composites with three different fiber arrays, i.e., square edge packing, square diagonal packing, and hexagonal packing. The repeating unit cell (RUC) containing fiber and matrix phase was employed to describe the mechanical behaviors of fiber composites. For the fiber phase, it was assumed to be linear elastic, whereas the matrix was a nonlinear material. The generalized method of cell (GMC) micromechanical model originally proposed by Paley and Aboudi [Paley M, Aboudi J. Micromechanical analysis of composites by the generalized cells model. Mech Mater 1992; 14(2):127–39] was extended to include the thermal–mechanical behavior, from which the thermal residual stress within the fiber and matrix phases was calculated. Through numerical iteration, the constitutive relations of the composites in the presence of residual stress were established. Results show that for the composites with square edge packing, the mechanical behaviors are affected appreciably by the thermal residual stress. On the other hand, the composites with hexagonal packing and square diagonal packing are relatively less sensitive to the thermal residual stress.
    Composites Part B-engineering - COMPOS PART B-ENG. 01/2008; 39(4):714-721.
  • Jia-Lin Tsai, Shi-Hua Tzeng
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    ABSTRACT: This research aims to propose a continuous micromechanical model for characterizing the mechanical properties of the nanocomposites containing silica nanoparticles embedded in polyimide matrix. The molecular structures of the nanocomposites were established through molecular dynamic (MD) simulation, from which the non-bonded gap as well as the non-bonded energy between the nano-sized inclusion and the surrounding matrix were evaluated. It was postulated that the normalized non-bonded energy (non-bonded energy divided by surface area of the inclusion) is correlated with the degree of interfacial interaction. Subsequently, an effective interphase micromechanical model including inclusion, matrix and effective interphase was developed, in which the dimension of the effective interphase was assumed equal to the non-bonded gap and the corresponding elastic stiffness was calculated from the normalized non-bonded energy. Comparison of the results calculated from the micromechanical model and the MD simulation indicates that the effective interphase model is capable of describing Young's modulus of particulate nanocomposites with accuracy. In addition, it was revealed that when the particulate size decreases, the corresponding modulus of the nanocomposites increases.
    Journal of Composite Materials - J COMPOS MATER. 01/2008; 42(22):2345-2361.
  • Jia-Lin Tsai, Yang-Kai Chi
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    ABSTRACT: This study aims to investigate the fiber array effect on modal damping behaviors of fiber composites. Three different fiber arrays, i.e., square edge packing (SEP), square diagonal packing (SDP), and hexagonal packing (HP), were considered to represent the microstructures of the unidirectional composites. Repeating unit cells (RUCs) suitable for describing the characteristics of the microstructure were adopted in the generalized method of cell (GMC) micromechanical analysis. The energy dissipation concept was then employed to calculate the specific damping capacities of composites in the material principal directions. The specific damping capacities obtained from micromechanical analysis were regarded as the equivalent damping properties homogenizing in the composites. In conjunction with the modal shapes of the composite structures determined from the finite element analysis, the specific damping capacity was extended to characterize the corresponding modal damping of the composite rods and plates. Both free–free and clamped-free boundary conditions were taken into account in the composite structures. Results indicated that the structures constructed from the composites with SDP fibers exhibit better damping behaviors than the other two cases.
    Composites Part B-engineering - COMPOS PART B-ENG. 01/2008; 39(7):1196-1204.