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A confocal micro-X-ray fluorescence (XRF) method with a vacuum chamber was used for investigation of underfilm corrosion that occurs on a painted steel sheet used for automotive applications. A painted steel sheet was prepared by applying electrodeposition coating onto an electro-galvanized steel sheet with a zinc phosphate conversion coating. The spatial resolution of the confocal micro-XRF was about 10.9 ?m at an energy of 17.4 keV. The phosphorus signal from the zinc phosphate layer was able to be observed nondestructively by measuring under the vacuum condition. Each layer of the painted steel sheet was observed from the depth profile analysis of the characteristic elements of each layer. The painted steel sheet was scratched to expose the substrate surface, and then the sheet was then immersed in a NaCl solution for 10 days. The in-depth elemental map of Ti of the corroded steel sheet revealed blister-type corrosion around the scratch. The in-depth elemental maps of Zn and P suggested that the zinc phosphate layer dissolved from the scratched part into the NaCl solution.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2019-06-27, 資料番号: PA2020011000

A 67-year-old male living in Tsu city, Mie prefecture, Japan was referred to our hospital for further examination of acute liver injury and was diagnosed as having clinical hepatitis E virus (HEV) infection in January 2010. The HEV strain (HE-JA11-1701) isolated from the patient belonged to genotype 3 and European-type subgenotype 3e. It was presumed that the patient had been infected from a wild boar (Sus scrofa leucomystax) because he consumed meat/viscera from a wild boar that he had captured himself as a hunter approximately 2 months before disease onset. A specimen of the boar meat/viscera that the patient had ingested was not available. However, the HE-JA11-1701 strain was 99.8% identical within the 412-nucleotide sequence of the open reading frame 2 region to a HEV strain (JBOAR012-Mie08) that had been recovered from a wild boar captured near the patient's hunting area in 2008. A phylogenetic analysis confirmed that the two HEV strains had a close genetic relationship and were segregated into subgenotype 3e, supported by a high bootstrap value of 99%. Of note, the HE-JA11-1701 and JBOAR012-Mie08 strains were remotely related to the 3e strains reported in Japan and European countries, with a nucleotide difference of 7.9-13.9%, reinforcing the uniqueness of the 3e strains obtained in the present study. These results strongly support our speculation that the patient developed acute hepatitis E via consumption of HEV-infected boar meat/viscera. Genetic analyses of HEV strains are useful for tracing infectious sources in sporadic cases of acute hepatitis E.

Acute hepatitis due to hepatitis E virus (HEV) is endemic in Bangladesh, but its epidemiological characteristics and virological features remain obscure. An outbreak of acute icteric hepatitis E occurred in Rajshahi, Bangladesh during 2010 when 200 patients with visible jaundice visited physicians within a period of 1 month (January-February). Clinical and epidemiological data were collected from these patients using questionnaires. Nucleic acids were isolated from 15 patients who were selected at random to ascertain their HEV genotypes. Near-complete nucleotide sequences of the HEV genome were detected in two patients and partial ORF2 regions in the other 13 patients. All patients tested positive for IgM antibodies to HEV but negative for other hepatitis viruses. Most patients were icteric and complained of vomiting, fever, itching, and abdominal pain. All 15 HEV sequences formed a single cluster within genotype 1a. Two of the 7,186-nt HEV sequences were 99.8% identical. This is the first study to report the clinical, epidemiological, and molecular characterization of an outbreak of acute hepatitis E in Bangladesh.

Thermal imprinting of glass-optical devices and its numerical simulation using the finite element method were investigated. The constitutive equation of the glass material was estimated using compression creep tests based on conventional thermoviscoelastic theory. The relaxation modulus of D263 glass was approximated by the generalized Maxwell model. For glass thermal imprinting, a glassy carbon die was used on which line and space or microlens array patterns were machined with a focused ion beam (FIB). The optimum molding-temperature condition that gives precise transcription profile was investigated in detail. Finite element analyses were performed to simulate the experimental glass thermal imprinting. In comparing experimental and numerical results, the transcription heights of groove or microlens obtained by experimental tests approximately agreed with numerical values. Finite element analyses using thermoviscoelastic property of glass are reliable in estimating suitable conditions for glass thermal imprinting.

Although the electrical-resistance-change method is useful for monitoring delamination cracking of carbon-fiber-reinforced plastic (CFRP) laminates, the method requires many experiments or FEM analyses to obtain the relationship between the electrical resistance changes and parameters describing delamination cracking. In our previous studies, one of the authors proposed using an anisotropic electric potential function to analyze electric current density in CFRP laminates. The function was applied only to thick CFRP laminates. In the present study, the method is expanded to thin CFRP laminates using an image method. The number of images is determined using the electric current analysis of thick CFRP laminates. The electric potential changes caused by delamination cracking can be calculated using an anisotropic doublet line. The associated method is applied to calculate the electric voltage change at the surface of a thin CFRP laminate. The results are compared with an FEM analysis, and, overall, the method...

Summary Background In sub-Saharan Africa, it is unknown whether hepatitis E virus (HEV) infection is a common precipitating event of acute-on-chronic liver failure (ACLF). Aims To estimate the prevalence of HEV infection in general population and assess whether HEV is a common trigger of ACLF in cirrhotic patients in The Gambia, West Africa. Methods We first conducted an HEV sero-survey in healthy volunteers. We then tested cirrhotic patients with ACLF (cases) and compensated cirrhosis (controls) for anti-HEV IgG as a marker of exposure to HEV, and anti-HEV IgA and HEV RNA as a marker of recent infection. We also described the characteristics and survival of the ACLF cases and controls. Results In the healthy volunteers (n = 204), 13.7% (95% CI: 9.6–19.2) were positive for anti-HEV IgG, and none had positive HEV viraemia. After adjusting for age and sex, the following were associated with positive anti-HEV IgG: being a Christian, a farmer, drinking water from wells, handling pigs and eating pork. In 40 cases (median age: 45 years, 72.5% male) and 71 controls (39 years, 74.6% male), ≥70% were infected with hepatitis B virus. Although hepatitis B flare and sepsis were important precipitating events of ACLF, none had marker of acute HEV. ACLF cases had high (70.0%) 28-day mortality. Conclusions Hepatitis E virus infection is endemic in The Gambia, where both faecal-oral route (contaminated water) and zoonotic transmission (pigs/pork meat) may be important. However, acute HEV was not a common cause of acute-on-chronic liver failure in The Gambia.

The axial coefficients of thermal expansion (CTE) of various carbon nanotubes (CNTs), i.e., single-wall carbon nanotubes (SWCNTs), and some multi-wall carbon nanotubes (MWCNTs), were predicted using molecular dynamics (MDs) simulations. The effects of two parameters, i.e., temperature and the CNT diameter, on CTE were investigated extensively. For all SWCNTs and MWCNTs, the obtained results clearly revealed that within a wide low temperature range, their axial CTEs are negative. As the diameter of CNTs decreases, this temperature range for negative axial CTEs becomes narrow, and positive axial CTEs appear in high temperature range. It was found that the axial CTEs vary nonlinearly with the temperature, however, they decrease linearly as the CNT diameter increases. Moreover, within a wide temperature range, a set of empirical formulations was proposed for evaluating the axial CTEs of armchair and zigzag SWCNTs using the above two parameters. Finally, it was found that the absolute value of the negative axial CTE of any MWCNT is much smaller than those of its constituent SWCNTs, and the average value of the CTEs of its constituent SWCNTs. The present fundamental study is very important for understanding the thermal behaviors of CNTs in such as nanocomposite temperature sensors, or nanoelectronics devices using CNTs.

The reinforcement effects of two nanofillers, i.e., multi-walled carbon nanotube (MWCNT) and vapor grown carbon fiber (VGCF), which are used at the interface of conventional CFRP laminates, and in epoxy bulk composites, have been investigated. When using the two nanofillers at the interface between two conventional CFRP sublaminates, the Mode-I interlaminar tensile strength and fracture toughness of CFRP laminates are improved significantly. The performance of VGCF is better than that of MWCNT in this case. For epoxy bulk composites, the two nanofillers play a similar role of good reinforcement in Young’s modulus and tensile strength. However, the Mode-I fracture toughness of epoxy/MWCNT is much better than that of epoxy/VGCF.

We have attempted to reveal the deformation mechanism of amorphous metals by local lattice instability analysis, based on the positive definiteness of the atomic elastic stiffness coefficients, B i . In our previous study, changes in inhomogeneous structure are explained by the observation of the stability-switching or transition between detB i > 0 and detB i < 0. In this study, we have performed the indentation simulation on a binary amorphous metal, and discussed the inelastic deformation in the amorphous metal by Voronoi polyhedra analysis and the stability-switching of local lattice instability. The indentation simulation predicts that rearrangements of atoms occur not only on structures below the indentation point but also inside the amorphous metal structure. These structural changes produce a significant volume change in the Voronoi polyhedra, the stability-switching based on local lattice instability analysis, and a local volume reduction evaluated within scales of a few hundred atoms. [doi:10.2320/matertrans.M2012191]

Background Since previous studies have investigated the population dynamics of Japan-indigenous genotype 3 hepatitis E virus (HEV) using virus sequences, more nucleotide sequences have been determined, and new techniques have been developed for such analysis. Aims To prevent future hepatitis E epidemic in Japan, this study aimed to elucidate the cause of past HEV expansion. Methods The epidemic history of Japan-indigenous genotype 3 HEV was determined using the coalescent analysis framework. Bayesian skyline plot (BSP) and Bayesian estimate of phylogeny with relaxed molecular clock models were calculated using Markov chain Monte Carlo sampling. Results Japan-indigenous strains consist of New World strains (subtype 3a), Japanese strains (3b) and European strains (3e). The oldest lineage, 3b, appeared around 1929. Lineages 3a and 3e appeared around 1960. BSPs indicated similar radical population growth of the 3a and 3b lineages from 1960 to 1980. Conclusions Population dynamics of the three lineages shared some common characteristics, but had distinguishing features. The appearance of 3a and 3e lineages coincides with the increase of large-race pig importation from Europe and the USA after 1960. The epidemic phase of 3a and 3b strains from 1960 to 1980 could be related to increased opportunity for HEV infection arising from large-scale pig breeding since 1960. Our observations revealed new findings concerning the close relationship between the epidemic history of Japan-indigenous genotype 3 HEV and the improvement of the Japanese pig industry. Infection control in pig farms should be an effective method of preventing HEV infection in humans.

The criterion for the interlaminar strength of unidirectional carbon-fiber-reinforced plastic (CFRP) laminates is discussed. To evaluate the limit curve given by the relation between normal stress and shear stress on the fracture interface, two types of interlaminar strength tests were carried out using short beams of CFRP laminates. The criterion for the interlaminar fracture of the CFRP laminates was investigated in two-dimensional finite element analysis of the CFRP specimens. Interlayers made by carbon nanofiber were inserted between the prepregs of the CFRP laminates. A modified 'Tsai-Wu' criterion was employed to evaluate the critical curve of the interlaminar fracture of the CFRP laminates. The effect of the CNF interlayer on the criterion of the interlaminar strength of CFRP laminate is discussed in detail., Article, COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING. 42(7):703-711 (2011)

GPU-based computing has become one of the popular high performance computing fields. The field is called GPGPU. This paper is focused on design and implementation of a uniform GPGPU application that is optimized for both the legacy and the recent GPU architectures. As a typical example of such the GPGPU application, this paper will discuss the uniform implementation of the Caravela platform. Especially the flow-model execution mechanism will be considered referring the recent GPU architectures. To verify the design and the implementation on CUDA and OpenCL platform, this paper will evaluate the compatibility among the architectures, and also test measurements of performance.

In the present paper, fracture toughness of interface crack between thin film and substrate is evaluated by inverse analysis using laser ultrasonic waves. The laser beam is irradiated on the substrate which have a thin film on the lower side. The elastic-ultrasonic wave is excited by the laser beam, and it propagates in the transverse direction for the plate. The supersonic wave reflects on the back of monotony, becomes an expansion wave, and reaches the interface. Finally, the interface crack progresses caused by the expansion wave. In the present study, the interfacial stress is estimated by inverse analysis using Laplace-transformed boundary element method. The displacement history on the back-surface of the specimen can be related to interfacial stress by the transfer function. The transfer function can be obtained numerically by 3-dimensional analysis employing boundary element method. The specimens made from SiC substrate and Diamond thin layer are used in the present study. The fracture toughness of the interfacial crack can be extrapolated from the stress distribution in the vicinity of the crack tip. It is confirmed that the interfacial fracture toughness of SiC/Diamond is 0.16J/m2 from the present investigation.

Two 71-year-old males (Case 1 and 2) with liver dysfunction were admitted to our hospital and diagnosed with acute hepatitis E due to detection of hepatitis E virus (HEV) RNA or IgM class anti-HEV in their sera. Since they ate the same rare wild boar meat at the same ritual, the boar meat was considered to be the infection source. Phylogenetic analysis showed that HEV strain identified in Case 1 segregated to a cluster of "Aichi/Shizuoka Strains". It seems that the "Aichi/Shizuoka Strain", an atypical genotype 4 strain compared to those found in other part of Japan, is prevailing within this small geographic area.

ペグインターフェロン（PEG-IFN）α2aまたはグリチルリチン製剤（強力ネオミノファーゲンC：SNMC）を投与開始し，24週以上継続可能であったC型慢性肝炎64例を対象とし，有効性・安全性をretrospectiveに比較検討した．平均観察期間（中央値，週）はPEG群154，SNMC群145，ALT値（中央値，IU/L）は投与前，24週，48週時点において，PEG群64，34，30，SNMC群80，47，52，AFP値（中央値，ng/mL）は投与前，24週，48週時点において，PEG群12，9.2，7.2，SNMC群12，12.5，18であった．投与中の血小板，Hb，好中球数はSNMC群と比較しPEG群で有意に低値を示したが，減量により全例継続可能であった．PEG群で3例（8％），SNMC群で3例（11％）にHCCが発現した．肝発癌抑制を目的としたPEG-IFNα2a少量及びSNMC療法は，共に肝機能改善効果を認めたが，PEG群で有意にALT値，AFP値が改善した．

Glass-like carbon (GC) is expected as a die material for press molding of glass micro optical devices. However, the mechanical and thermal properties are not enough to use as precision mold die. So, GC composites reinforced by vapor grown carbon fiber (GC/VGCF composites) were developed to improve the properties. The GC/VGCF composites achieved high thermal conductivity and bending strength, and the decreased linear expansion coefficient and good mold releasability. However, surface roughness of the GC/VGCF composites after focused ion beam (FIB) etching increased up to 50nm, when VGCF of 28vol% was added.

The clarification of the sliding behavior between nested walls in a multi-walled carbon nanotube (MWCNT) is crucial for its applications in nano-electro-mechanical systems. The pull-out processes of some outer walls against other inner walls in MWCNTs are studied by molecular mechanics simulations to investigate this sliding behavior between nested walls. The pull-out force for both double-walled carbon nanotube (DWCNT) and MWCNT with more than two walls is found to be proportional to the diameter of the critical wall (i.e., the immediate outer wall at the sliding surface), and independent of nanotube length and chirality. The underlined mechanism for this phenomenon is systematically explored by investigating the interfacial shear stress during the pull-out and the corresponding surface energy density. The importance and necessity of considering MWCNTs with more than two walls are indicated from their higher surface energy densities than that of DWCNT. Furthermore, the obtained result demonstrates that the conventional definition of the interfacial shear strength is inappropriate for the sliding behavior between nested walls in MWCNTs. Finally, a simple universal theory is proposed for the first time to predict the pull-out force for an arbitrary sliding in a given MWCNT, directly from the diameter of the critical wall.

The thermo-viscoelastic constitutive equation of unidirectional carbon fiber reinforced plastic (CFRP) is evaluated using a numerical approach based on the finite element method (FEM) and homogenization theory. The constitutive equation of the CFRP is considered in the Laplace-transformed domain, and it is discussed on the basis of the correspondence principle, which is satisfied by each of the Laplace-transformed elastic moduli. Homogenization theory is employed to estimate the ‘homogenized elastic moduli’ of the composite composed of matrix resin and carbon fibers. Using the approximation of a generalized Maxwell model, the relaxation moduli of CFRP are obtained by numerical computation using the FEM. From the relaxation modulus of epoxy resin and elastic moduli of carbon fiber, thermo-viscoelastic properties of CFRP laminates at several temperatures can be estimated using the FEM with homogenization theory. The effectiveness of the present study is verified by comparing the experimental results and numerical calculations for the relaxation moduli of the CFRP laminates.

Extensive numerical simulation and experimental measurements have been conducted to understand the effects of processing parameters and material properties on sensor sensitivity in polymer/carbon nanotube (CNT) composite sensors. The numerical simulation was based on an improved three-dimensional statistical resistor network model incorporating the tunneling effect between the neighbouring nanotubes, and a fiber reorientation model. The behaviors of a sensor subjected to both tensile and compressive strains were investigated. Both numerical and experimental results indicate that a higher tunneling resistance or higher ratio of the tunneling resistance to the total resistance of the sensor leads to a higher sensor sensitivity. Processing conditions and material properties, such as weight fraction, diameter and conductivity of CNTs, curing temperature, mixing rate and barrier height of polymer matrix all play a role in determining the sensor sensitivity.

We have so far shown that amorphous metals have many “unstable” atoms even at the equilibrium state, by local lattice instability analysis (LLIA) which discusses the positive definiteness of atomic elastic stiffness coefficients, Bαij. In the present study, we put our focus on the stability switching by the “probabilistic” fluctuation and the “deterministic” mechanical load. We have performed molecular dynamics simulations on Ni amorphous and evaluated the stability switching under no-load equilibrium as well as uniaxial tension. It is definitely true that the ratio of unstable atoms decreases/increases according to the system energy ; however, it is revealed that one-way change of stabilization or destabilization never occur but both positive and negative stability-switching are activated from their ratio under the equilibrium state. That is, a straightforward image of “stabilization/destabilization of local configuration” is not correct for structural change in amorphous metal but “shuffle of atomic arrangement” which involves atomic stabilization and destabilization simultaneously. In fact, we have proved that (1) both switching drastically increase at the slow-down point just before the stress-strain peak, (2) many stabilization/destabilization atoms can be found in the locally deformed area, and (3) such switching atoms actually feel hydrostatic tension in the dilated local configuration on the way of “shuffle”.

The Mems-ONE is well known software which simulates thermo-viscoelastic properties in the conduct of nanoimprinting. Assuming the glass materials to be viscoelastic body, the relaxation shear modulus was measured by the creep test, Williams-Landel-Ferry (WLF) equation is applied for expressing the temperature dependence of liquid viscosity. We compared experimental with analytic results used by Mems-ONE with the condition of fixed pressure and time. Thermo-viscoelastic properties of the glass materials were estimated using unidirectional compression creep test based on traditional thermo viscoelastic theory. Glass was Borosilicate Glass (D263, Schott). Glass imprinting was carried out on Glassy Carbon (GC) mold with line & space10 μm patterns fabricated by dicing saw. The machining accuracy is most important thing as the evaluation mold. The glass imprinting temperature consulted thermo-viscoelastic properties of the glass materials. The numerical simulation was carried out on the small portion of mold and glass. The constant value of WLF equation fitting in high temperature translates the master curve of D263 with a high degree of accuracy. It caused the accuracy improvement of analysis result. In addition, we confirm that WLF equation intended to resin can use to the glass imprinting.

Uniaxial tensile tests of glass specimens were carried out at a range of strain rate and temperatures. The strain rate and temperature dependencies on the tensile strength (breaking stress) of the glass were investigated in detail. The relationship between tensile strength, strain rate and temperature can be expressed using exponential functions given by Norton's law and an Arrhenius type equation. An empirical equation expressing the temperature and strain rate dependencies of tensile strength was obtained from the experimental results. The strength of the glass was discussed from the standpoint of the thermo-viscoelastic properties of the material.

Many kinds of optical glass devices are needed in various fields such as optics, biotechnology, medical care and so on. If an optical device such as an aspheric lens does not have a simple shape, and/or its size is micro-/nanometer scale, press molding should be carried out at a higher temperature than the glass transition temperature (Tg) to reduce cost and increase productivity. However, the most suitable conditions for glass molding are generally determined by performing many experiments. Consequently, it is useful to be able to predict the most suitable molding condition by numerical simulation. Press molding experiments and numerical simulation using finite element analysis, in relation to micro press molding of the borosilicate glasses Pyrex and D263, were carried out. Thermo-viscoelastic properties of the glasses were estimated using unidirectional compression creep testing according to traditional thermo-viscoelastic theory. Glass micro press molding was carried out with a glassy carbon die with a line and space pattern machined by a dicing saw. The optimum molding temperatures for accurate transcription of the die profile to the glass were investigated. Numerical simulation of micro press molding of the glass was carried out by the finite element method using universal FEM code (ANSYS ver.11.0). Experimental and numerical simulation results for the cross-section shape and the height of the groove profile were in approximate agreement.

It is revealed that amorphous metals have many “unstable” atoms even at the equilibrium state, by local lattice instability analysis (LLIA) which discusses the positive definiteness of atomic elastic stiffness coefficients, Bαij. We have explored for relationships between the deformation and these unstable atoms in inhomogeneous or disordered structure. In the present study, we have discussed the changes in unstable atoms of det Bαij 0 atoms showdifferent stress. We have concluded that the stress relaxation is not caused by a straightforward image of “stabilization” or “destabilization”, but by “shuffle of atomic arrangement” which involves positive and negative switching simultaneously. In fact, we have observed many incidences of positive and negative stability-switching at the locally deformed area.

シカ及びイノシシの生食により感染したと思われるE型急性肝炎3例を経験したので報告する．症例1，2は71歳と48歳の男性で発症の約2カ月前に，偶然同一飲食店で別々にイノシシの肝を生食していた．症例3は69歳の男性で，発症の2カ月前から息子が狩猟で捕獲した複数頭のシカ生肉を頻回に自宅で調理し摂取していた．3症例とも入院時，肝逸脱酵素は著明に上昇していたが補液や安静で改善した．3症例の病初期血清におけるIgM-HEV抗体，IgG-HEV抗体，HEV-RNAが陽性でHEV genotypeは4型，塩基配列は相互に99.8％以上一致した．愛知県のヒト及びイノシシから分離されている「4型HEV愛知株」との間にも98.5％-99.8％の一致率を示し，北海道に蔓延するgenotype 4とは明らかに別系統であることが注目された．

In order to improve the interlaminar mechanical properties of CFRP laminates, hybrid CFRP/VGCF laminates have been fabricated by using a newly-developed method, i.e., powder method , where the powder of vapor grown carbon fiber (VGCF) is added at the mid-plane of [0°/0°] 14 CFRP laminates. Experimental results of double cantilever beam (DCB) tests indicate the improvement on the interlaminar mechanical properties of Mode-I fracture behavior with much higher critical load P C and fracture toughness G IC with VGCF interlayer. Crack propagation and fracture surface have also been observed to interpret this improvement mechanism. Moreover, based on experimental G IC , numerical simulations using finite element method (FEM) with cohesive elements have been carried out to analyze the delamination propagation. The interlaminar tensile strength of hybrid CFRP/VGCF laminates, which is obtained by matching the numerical load–COD (crack opening displacement) curves to experimental ones, is higher than that of base CFRP laminates.

A measurement technique for obtaining the thermo-viscoelastic properties of glass with high accuracy is discussed. An unidirectional compression creep test was employed to measure the relaxation modulus of the glass specimens. The creep function derived from the experimental creep test is approximated by a generalized Voigt model, and then converted into a relaxation modulus expressed by a generalized Maxwell model using the Laplace transform and its inversion. Relaxation moduli and shift factors of the glass specimens BK-7 and TaF-3 were estimated according to the presented procedure, and the accuracy of the relaxation modulus was verified by a numerical demonstration using finite element analysis. A fundamental numerical simulation of the press molding of glass lenses was carried out to illustrate the validity of the thermo-viscoelastic properties obtained by the presented approach. Residual stresses under processing conditions were estimated, and the optimal conditions for residual stress minimization ...

Several techniques are introduced to enhance the interlaminar fracture toughness of CFRP laminates using cup-stacked carbon nanotubes (CSCNTs). Prepared CSCNT-dispersed CFRP laminates are subject to Double Cantilever Beam (DCB) and End Notched Flexure (ENF) tests in order to obtain mode-I and mode-II interlaminar fracture toughness. The measured fracture toughnesses are compared to that of CFRP laminates without CSCNT to evaluate the effectiveness of CSCNT dispersion for the improvement of fracture toughness. All CSCNT-dispersed CFRP laminates exhibit higher fracture toughness, and specifically, CSCNT-dispersed CFRP laminates with thin epoxy interlayers containing short CSCNTs have three times higher fracture toughness than CFRP laminates without CSCNT. SEM observation of fracture surfaces is also conducted to investigate the mechanisms of fracture toughness improvement. Crack deflection mechanism is recognized in the CSCNT-dispersed CFRP laminates, which is considered to contribute the enhancement of interlaminar fracture toughness.

In order to improve the interlaminar mechanical properties of CFRP laminate, hybrid CFRP/VGCF laminates have been fabricated by newly-developed powder method. The critical load at crack growth Pc and fracture toughness GIC have been found to be increased with VGCF interlayer through double cantilever beam (DCB) tests. Fracture surfaces of DCB specimens have also been observed to interpret this improvement mechanism. Moreover, numerical simulations using finite element method (FEM) with cohesive elements have been carried out to analyze the delamination propagation. The numerically obtained interlaminar tensile strength of hybrid CFRP/VGCF laminates has also been verified to be higher than that of base CFRP laminates.

A lattice Boltzmann method (LBM) for two-phase viscoelastic fluid flows is proposed. The method is mainly an extension of the LBM for two-phase flows with large density differences proposed by Inamuro et al. [Journal of Computational Physics Vol.198, No.2 (2004), pp.628–644]. The viscoelastic effects are introduced by the constitutive equation based on the Maxwell model, which has a spring and a dashpot connected with each other in series. The method is applied to simulations of a drop under shear flow in viscoelastic fluids and of a bubble rising in viscoelastic fluids. In the simulation of drop deformation under shear flows, the effects of viscoelasticity on the deformation and orientation angle are evaluated. In the simulation of bubble rising in viscoelastic fluids, a cusp configuration at the trailing edge is investigated and compared with the theoretical prediction and other numerical results., Article, Journal of Computational Science and Technology 2(2):330-340

Interlaminar fracture toughness for mode I and II deformation were investigated for carbon fiber (CF)/epoxy laminates toughened by a carbon nanofiber/epoxy interlayer. Vapor grown carbon fiber (VGCF) and vapor grown carbon nanofiber (VGNF) were chosen as the reinforcement for the interlayer. To illustrate the effect of the interlayer on the fracture toughness of the laminates, several types of carbon fiber reinforced plastics/carbon nanofiber (CFRP/CNF) hybrid laminates were fabricated. Each laminate was composed of unidirectional carbon/epoxy prepregs with carbon nanofiber varying the interlayer thickness. Mode I interlaminar fracture toughness was evaluated by a standard double cantilever beam (DCB) test. Mode II interlaminar fracture toughness was evaluated by an end notched flexure (ENF) test using a three point bending test. The experimental results of the DCB test confirms that the mode I interlaminar fracture toughness for hybrid laminates is about 50% greater than the base CFRP laminates. Furthermore, the results of the mode II fracture toughness test confirms that the interlaminar fracture toughness for hybrid laminates is 2–3 times greater than base CFRP laminates. In addition, the results revealed the recommended range of CNF interlayer thickness is between 100 and 150 μm (approximately 20 g/m2 carbon nanofiber area density). The difference in the effect of the interlayer fracture properties under mode I and II deformation was discussed on the basis of fractographic observations derived from scanning electric microscope.

In the present paper, press molding for thermo-plastic resin toughened by carbon nanofiber were discussed. Polycarbonate (PC) and vapor grown carbon nanofiber (VGCF) are used for the resin matrix and the reinforcement. In order to investigate and simulate the molding process of the PC/VGCF composite by finite element method, the constitutive equation, namely thermo-viscoelastic property of the composites are required. The relaxation modulus (Master curve) and shift factor to characterize it's thermo-viscoelastic behavior were estimated by unidirectional compression creep test in this paper. The relaxation modulus for the composite were approximated by the discretized series form using generalized Maxwell model. The displacement history of the creep test were calculated by finite element method. The numerical and experimental results are compared and discussed in detail to confirm the validity of the estimated relaxation modulus obtained the present procedure.

In the present paper, press molding for thermo-plastic resin toughened by carbon nanofiber were discussed. Polycarbonate (PC) and vapor grown carbon nanofiber (VGCF) are used for the resin matrix and the reinforcement. In order to investigate and simulate the process molding process of the PC/VGCF composite by finite element method, the thermo-viscoelastic property of the composites are estimated using unidirectional compression creep test. The creep functions were converted into relaxation function based on the convolution integral form of the basic equation using Laplace transform. Experimental testing for press molding of the PC/VGCF composites using V-shape die has been carried out. The results of the V-shape profiles and those obtained by FEM analysis were compared to confirm the validity of the present analysis method based on thermo-viscoelastic theory. The effect of the carbon nanofiber for the formability improvement of the PC/VGCF composites was discussed in detail.