Jia-Lin Tsai

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

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Publications (20)38.21 Total impact

  • Sung-Chiun Shiu, Jia-Lin Tsai
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    ABSTRACT: This study aims to investigate the thermal and mechanical properties of graphene/epoxy nanocomposites using molecular dynamics (MD) simulation. Three different formats of graphene: graphene flakes, intercalated graphene and intercalated graphene oxide, were incorporated respectively in an epoxy matrix to form the graphene/epoxy nanocomposites. The mechanical properties of the graphene/epoxy nanocomposites, including Young's modulus (E), glass transition temperature (T-g) and coefficient of thermal expansion (CTE), in terms of three different formats of graphene, were characterized in this study. In addition to the mechanical properties, the influences of graphene on the density distribution of epoxy polymers in the nanocomposites were also examined. The results showed that the local density in the vicinity of the graphene is relatively high, and then progressively decreases to the bulk value in regions further away from the interface. On the other hand, for the mechanical and thermal properties, the nanocomposites with intercalated graphene exhibit a higher Young's modulus, a higher glass transition temperature and a lower thermal expansion coefficient than do those with graphene flakes. This is because the intercalated graphene can lead to a high amount of high density polymer in the nanocomposites, and thus enhance the overall properties of the nanocomposites. In addition, the interacted graphene oxide provides the best reinforcement of the three systems of nanocomposites. Based on the calculation of interaction energy, it appears that the oxide modification of the graphene surface can effectively lead to the high interaction energy, such that the graphene oxide can demonstrate a relatively high reinforcing efficiency.
    Composites Part B Engineering 01/2014; 56:691-697. DOI:10.1016/j.compositesb.2013.09.007 · 2.60 Impact Factor
  • 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. DOI:10.1016/j.compositesb.2012.04.059 · 2.60 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 09/2011; 45(21):2157-2164. DOI:10.1177/0021998311401065 · 1.26 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. DOI:10.1177/0731684411421637 · 1.19 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 02/2010; 47(3):503-509. DOI:10.1016/j.ijsolstr.2009.10.017 · 2.04 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 and Design 01/2010; 31(1):194–199. DOI:10.1016/j.matdes.2009.06.032 · 3.17 Impact Factor
  • Jia-Lin Tsai, Hung Hsiao, Yi-Lieh Cheng
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    ABSTRACT: The research is aimed to investigate the mechanical behaviors of epoxy-based nanocomposites reinforced with spherical nanoparticles. Five different contents of silica nanoparticles — 5, 10, 15, 20, and 40 wt% — were introduced in the samples. Through a sol—gel technique, the silica particles with a diameter of 25 nm were exfoliated uniformly in the epoxy matrix. Experimental results obtained from tensile tests indicate that the modulus of nanocomposites increases with the increment of particulate inclusions, and the enhancing behavior is coincided with the model predictions obtained from the Mori—Tanaka micromechanical model. In addition, the fracture tests conducted on single-edge-notch bending specimens reveal that the inclusion of nanoparticles can effectively increase the fracture toughness of the nanocomposites. Furthermore, the extent of the enhancement is more appreciable in the brittle matrix system rather than in the ductile matrix system. Subsequently, by inserting the silica epoxy mixture into the unidirectional glass fiber through a vacuum hand lay-up process, the glass fiber/silica/epoxy composite samples were fabricated. Results depicted that the in-plane shear strength increases until the increment of particle loadings are up to 10 wt%. In addition, results obtained from the compression tests revealed that the glass/epoxy specimens with 20 wt% silica loading exhibit superior compressive strengths than those that do not contain any silica particles.
    Journal of Composite Materials 01/2010; 44(4):505-524. DOI:10.1177/0021998309346138 · 1.26 Impact Factor
  • 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; DOI:10.1016/j.compositesb.2009.06.003 · 2.60 Impact Factor
  • Jia-Lin Tsai, Yi-Lieh Cheng
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    ABSTRACT: The research is aimed to investigate the compressive strengths of glass/epoxy nanocomposites, containing various loadings of spherical silica nanoparticles. Through a sol—gel technique, the silica particles with a diameter of 25 nm were exfoliated uniformly into the epoxy resin. Subsequently, by inserting the silica—epoxy mixture into the unidirectional glass fiber through a vacuum hand lay-up process, the glass fiber/epoxy composite laminates with 10, 20, and 30 wt% of silica nanoparticles were fabricated. Quasi-static and dynamic compression tests were conducted on the brick composite specimens with fiber orientations of 0°, 5°, 10°, 15°, and 90° using a hydraulic MTS machine and a split Hopkinson pressure bar, respectively. Observations on the failure specimens indicated that for fiber orientations less than 15°, the fiber microbuckling is the dominant failure mechanism. On the other hand, for the 90° samples, the out-of-plane shear failure is the main failure mechanism. In addition, it was denoted that as the silica contents increase, the compressive strengths of the glass/epoxy composites are improved accordingly. The enhancing mechanism in the compressive strengths can be properly explicated using the microbuckling model.
    Journal of Composite Materials 11/2009; 43(25):3143-3155. DOI:10.1177/0021998309345317 · 1.26 Impact Factor
  • Jia-Lin Tsai, Bao-Hung Huang, Yi-Lieh Cheng
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    ABSTRACT: The research aims to investigate the interlaminar fracture toughness of glass fiber/epoxy composites, which consist of the silica nanoparticles and the rubber particles. Two kinds of rubber particles, one is the reactive liquid rubber (CTBN) and the other is the core-shell rubber (CSR), were employed to modify the fracture toughness of epoxy resin. In general, the disadvantage of adding rubber particles into polymeric resin is the dramatic reduction of stiffness although the toughness could be modified accordingly. In order to enhance the fracture toughness of the fiber composites without sacrificing their stiffness, the silica nanoparticles in conjunction with the rubber particles were introduced into the epoxy matrix to form a hybrid nanocomposite. Experimental results obtained from tensile tests on bulk epoxy confirm the presumption that the reduction of the epoxy stiffness because of the presence of rubber particles can be effectively compensated by the silica nanoparticles. Furthermore, the fracture tests conducted on the double cantilever beam specimens revealed that the inclusion of silica nanoparticles together with the CSR particle can appreciably increase the fracture toughness of the glass/epoxy composites up to 82%. On the other hand, when the epoxy matrices were modified with CTBN rubber particles and silica nanoparticles, the improvement of the interlaminar fracture toughness was around 48%. It is noted that the role of the silica nanoparticles on the fracture toughness of fiber composites with rubber-modified epoxy matrix is different. For the CSR-modified epoxy matrix, the contribution of silica nanoparticle on the fracture toughness is destructive. In contrast, for the CTBN-modified epoxy matrix, the silica nanoparticles can synchronously improve the fracture toughness of composites.
    Journal of Composite Materials 11/2009; 43(25):3107-3123. DOI:10.1177/0021998309345299 · 1.26 Impact Factor
  • 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 09/2009; 90(2):172-179. DOI:10.1016/j.compstruct.2009.03.004 · 3.12 Impact Factor
  • 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 07/2009; 89(3):443-447. DOI:10.1016/j.compstruct.2008.09.003 · 3.12 Impact Factor
  • 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 10/2008; 39(7):1196-1204. DOI:10.1016/j.compositesb.2008.03.003 · 2.60 Impact Factor
  • 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 08/2008; 42(22):2345-2361. DOI:10.1177/0021998308095503 · 1.26 Impact Factor
  • 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 06/2008; 39(4):714-721. DOI:10.1016/j.compositesb.2007.05.005 · 2.60 Impact Factor
  • Jia-Lin Tsai, Ming-Daw Wu
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    ABSTRACT: This research aims to perform a symmetric investigation regarding the organoclay effect on the mechanical behaviors of glass/epoxy nanocomposites. Tensile, flexural, as well as interlaminar fracture toughness are of concern in this study. To demonstrate the organoclay effect, three different loadings, 2.5, 5 and 7.5wt% of organoclay were dispersed in the epoxy resin using a mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were prepared by inserting the organoclay epoxy mixture into the dry glass fiber through a vacuum hand lay-up process. Tensile tests revealed that longitudinal tensile strength decreases as organoclay loading increases; on the other hand, transverse tensile strength increases with the increase of the organoclay. Furthermore, SEM observation on the transverse failure specimens indicates that the enhanced mechanism is due to the improved interfacial bonding between the fibers and the surrounding matrix modified by organoclay. The increasing tendency was also found in the transverse flexural strength of the nanocomposites. However, mode I fracture tests indicated that with the increase of the organoclay, the corresponding fracture toughness of the nanocomposites decreases appreciably. For the quasi-isotropic glass/epoxy laminates, since the failure is dominated by fiber rupture, the strength is not influenced significantly by the organoclay.
    Journal of Composite Materials 03/2008; 42(6):553-568. DOI:10.1177/0021998307087514 · 1.26 Impact Factor
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    Jia-Lin Tsai, Shin-Ming Hsu
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    ABSTRACT: This study aims to investigate the organoclay effect on the mechanical proper-ties of epoxy nanocomposites. In order to characterize the organoclay effect, three different loadings of organoclay, 2.5, 5, and 7.5 wt%, were dispersed into the epoxy with a mechanical blender followed by sonication. Tensile tests and fracture tests were carried out on these specimens to determine their stiffness, strength and fracture behaviors. The experimental results obtained from tensile tests indicate that the stiff-ness of the epoxy increases with the increment of organoclay inclusion; however, the corresponding failure strain decreases. On the other hand, fracture tests on single-edge-notch bending specimens reveal that the inclusion of organoclay may dramati-cally reduce the fracture toughness of nanocomposites. The decrease could be due to changes in the morphologies of the epoxy nanocomposites as well as the interfacial debonding between the organoclay and the surrounding epoxy.
    Journal- Chinese Institute of Engineers 01/2008; 31(1). DOI:10.1080/02533839.2008.9671355 · 0.21 Impact Factor
  • Jia-Lin Tsai, Kuei-Han Chen
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    ABSTRACT: This research aims to characterize the nonlinear rate-dependent behaviors of graphite/epoxy composites using micromechanical analysis. In this analysis, graphite fibers are considered as elastic solids, while the surrounding epoxy matrix exhibiting rate sensitivities are described using the three-parameter viscoplasticity model. By using Aboudi's generalized method of cells (GMC), the incremental form of the constitutive relations of the composites are expressed in terms of the constituent properties as well as the geometry parameters of the representative volume element. After a numerical iteration, the corresponding stress and strain relations of composites at different strain rates are generated. In order to verify the model predictions, off-axis graphite/epoxy composite specimens are tested at strain rates from 10 —4 to 550/s. For strain rates less than 1/s, the experiments are conducted using a hydraulic MTS machine, while high-strain-rate tests were carried out using a split Hopkinson pressure bar. Experimental results indicate that the stress and strain curves are quite sensitive to the strain rate; moreover, when the strain rates increase, the material stiffens. A comparison of model predictions with experimental results indicates that the rate-dependent behaviors of composites can be characterized effectively with the GMC model in conjunction with the viscoplastic properties of epoxy.
    Journal of Composite Materials 05/2007; 41(10):1253-1273. DOI:10.1177/0021998306067307 · 1.26 Impact Factor
  • Jia-Lin Tsai, Jui-Ching Kuo, Shin-Ming Hsu
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    ABSTRACT: This research focuses on the fabrication of glass fiber/epoxy nanocomposites containing organoclay as well as understanding the organoclay effect on the transverse compressive strength of nanocomposites. To demonstrate the organoclay effect, three different loadings of organoclay were dispersed, respectively, in the epoxy resin using a mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were produced by impregnating dry glass fiber with organoclay epoxy compound through a vacuum hand lay-up procedure. Unidirectional block specimens were employed for transverse compression tests on a hydraulic MTS machine. Experimental observations indicate that glass/epoxy nanocomposites containing organoclay exhibit higher transverse compressive strength than conventional composites. Furthermore, the failure mechanisms for all tested specimens were found to be fiber and matrix debonding. Therefore, results indicate that the increasing characteristic in transverse failure stress may be ascribed to the enhanced fiber/matrix adhesion modified by the organoclay.
    Journal of Materials Science 11/2006; 41(22):7406-7412. DOI:10.1007/s10853-006-0800-6 · 2.31 Impact Factor
  • Jia-Lin Tsai, Jen-Chieh Huang
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    ABSTRACT: This study aims to investigate strain rate effect on the mechanical behaviors of nylon 6–clay nanocomposites. Both dry and wet nylon 6–clay nanocomposites are examined in this study. To determine the strain rate effect, the nylon 6 nanocomposites with 5 wt% loading of the organoclay are tested in compression at different strain rates. For strain rates less than 1/s, the experiments are conducted using a hydraulic MTS machine. However, the high strain rate tests are performed using a split Hopkinson pressure bar (SHPB). To establish reliable dynamic stress and strain curves for the nanocomposites, a pulse-shaper technology is employed in the SHPB tests. Experimental observations reveal that for dry nanocomposites, the linear portions of the stress and strain curves are not affected substantially by the strain rates, but the yielding stresses increase with the increment of the strain rates. On the other hand, for the wet nanocomposites, the stress and strain curves are almost nonlinear demonstrating significant stiffening behaviors as the strain rates increase. This stiffening behavior is continuous until the stress and strain curves are almost linear at the strain rate of 500/s. Comparison of nylon 6–clay nanocomposites and unfilled nylon 6 indicates that the supplement of 5 wt% organoclay in the dry nylon 6 can enhance the Young's modulus to 32% within the tested strain rate ranges. Moreover, for the wet nylon reinforced with organoclay, the increment of Young's modulus can be achieved up to 43%.
    Journal of Composite Materials 01/2006; 40(10):925-938. DOI:10.1177/0021998305056382 · 1.26 Impact Factor