In many machining process, the workpiece must be fixed by a jig. In many case attached and clamping of these jigs are left to the discretion of the operator. So, clamping force of the jig is left to the sense of the operator. Now skilled workers are decreasing, so the development of tools which enable the clamping force uniform is required. In addition, changes the clamping force during process leads a reduction of tool life and machining accuracy. So, the development of tools that can manage the clamping force during processing is also required. Therefore, we developed a clamping monitoring system of the jig. In this system the load cell are interposed between workpiece and jig, to detect the clamping force, and operator can check the clamping force by monitor tool. This system also manages the clamping force the processing with the wireless communication. This paper Introduce the development of the load cell using a semiconductor strain sensor in the system.

抄録全体を表示

It has generally been assumed that metallic materials usually fail as a result of microvoid nucleation induced by particle fracture. In the present study, we examine this hypothesis by employing high-resolution 4D observations combined with the recently developed 4D image analysis method to correlate fracture surface to fracture origins embedded in materials before loading. All the dispersion particles embedded in the entire field of view (16,667 particles) were tracked during loading. The position coordinates of each fracture surface were tracked backward in time from the fracture surface image toward the initial unloading state on the basis of the scattered data interpolation with radial basis functions. It has been revealed that high density micro pores filled with supersaturated gas exhibit premature growth, thereby inducing ductile fracture, whereas the particle fracture mechanism operates only incidentally. This finding suggests that intense heat treatment, which is generally believed to enhance the mechanical properties of metallic materials, has entirely the opposite effect.

抄録全体を表示

Desiccation cracking is a phenomenon in which cracks are caused by shrinkage of drying paste material. However, mechanical properties of paste material have not measured because it is difficult to measure. In the present study, Young's modulus and fracture strength are evaluated by indentation test. As a result, Young's modulus is constant even if the paste thickness varies. On the other hand, fracture strength is proportional to the paste thickness. In order to analyze the mechanics of desiccation cracking, the dependence of the mechanical properties on the paste thickness is should be noted.

抄録全体を表示

The cracking in desiccating paste is frequently observed. Desiccation cracking is caused by stress due to displacement constraint by friction. In this study, digital image correlation is used to measure the displacement and strain field of the paste in order to clarify the behavior of the desiccation cracking. The tensile strain in one-dimensional paste is calculated from the measured strain and uniform shrinkage strain. The result shows that the tensile strain contributed to cracking depends on paste thickness. Also it is found that the desiccation cracking arises in order of the paste strength.

抄録全体を表示

Three-dimensional (3-d) stress field exists in the very vicinity of a crack tip within the singular stress field of plane stress. The paper examines the effect of the 3-d field to the measurement of stress intensity factors by the caustic method where the crack is under the mixed mode loading of mode I and II. The experimental studies show that the 3-d field extends as far as half the thickness of plate specimens under the mixed mode loading condition. This result is the same as that of mode I loading. The values of KI in the 3-d field are smaller than the true K_I value, and those of K_<II> in the 3-d field are larger than the true value of K_<II>.

抄録全体を表示

Crack opening displacement, COD, is measured along a crack in a plate specimen by Moire interferometry. The crack is the one of opening mode. The COD is measured not only in the singular stress field that satisfies the plane stress condition but also in the three dimensional stress field that exists in the very vicinity of the crack tip. The COD measured in the singular stress field of plane stress is proportional to square root of the distance r from the crack tip. This fact is in agreement with the two dimensional linear elastic fracture mechanics. In the three dimensional stress field, on the other hand, the measured COD is approximately proportional to 0.57th power ofr. This fact is in agreement with the theoretical prediction given by Benthem, and also by Bazant and Estenssoro.

抄録全体を表示

It is very important to grasp the strain in the micro scale area of devices. However, there are not useful methods to measure stress/strain components in a nano-micro scale area. In this study, Orientation Imaging Microscope (OIM) parameters of plastically deformed specimens were measured by Electron Backscattered Diffraction (EBSD) method, and the relationships between some OIM parameters and plastic strain induced by tensile test were discussed. Pure iron with body centered cubic structure was used as specimen materials. From IPF maps, change in crystallographic orientation within grains by plastical deformation were observed. Then, the relationships between average KAM and GROD values and plastic strain indicated good linearity. Therefore, the equivalent plastic strain in micro scale area is able to be approximately predicted by average KAM and GROD values.

抄録全体を表示

In the paper, the distributions of the elastic moduli in a flexible tree: Ohbagi ( Macaranga tanarius) were measured by tensile and compressive tests to clarify bending property of the tree. The specimens of the tree were removed from different radial positions on the cross sections in four heights. The compressive Young's moduli were roughly constant 2 GPa regardless of the positions. The tensile Young's moduli were ranged from 6 to 8 GPa at outlying positions independently of the height and were several times larger than the compressive ones. On the basis of the measured moduli, the tree model having different elastic moduli for tension and compression was analyzed to clarify the neutral plane in the bending deformation. Large bending deformation was found to occur by shifting the neutral plane to tensile stress side.

抄録全体を表示

A detection of a plastically deformed region in pure aluminum is investigated using a measurement of elastic modulus distribution. Firstly, a relationship between the plastic strain and the elastic modulus is investigated by using strain gage. The change of elastic modulus of 5.5% is obtained for 2% strained specimen. Secondly, elastic modulus distribution of a specimen having various plastic strains from 0% to 2% is measured by a strain measurement using speckle interferometry. As the result, a tendency of elastic modulus change with plastic strains can be measured by speckle interferometry.

抄録全体を表示

When a brittle material brakes impulsively, a crack will propagate at speed of several hundreds m/s then suddenly bifurcates into two cracks. Energy release rate on a uniform tensioned specimen can be measured by applying COD method experimentally. But discrepancies had been shown between a theoretical formula and former results from experiments especially near a notch tip. In this paper, COD method had applied to the results from FEM analysis to determine the exact position of a virtual crack tip that matches the results with a theoretical formula.

抄録全体を表示

Displacement distribution in a steel plate specimen during tensile test was measured with Digital Image Correlation (DIC) method. Video image of the specimen surface was continuously taken during tensile test and static images were selected from the movie file. Displacement distribution for plastic deformation after yield point was mainly considered. Analytical method to measure large local deformation at the necking area was considered and strain distribution was obtained from the displacement distribution from uniform deformation stage to near the final fracture. Stress-strain relation was investigated for the plastic deformation and it was found that similar relation holds from uniform deformation stage and the stage of necking near the fracture.

抄録全体を表示

In this study, the replica of the metal processing surface was produced using the transparent silicone. The new measuring method which examined the transmission image was proposed with a scattering of the spot light in the replica. The Characteristic various patterns were provided by passing light in a transparence replica. Those patterns were able to be classified in a point pattern, a circulation pattern, an oval pattern, four patterns of the diffraction pattern. It is possible that these patterns estimate the shape of the reflection plane, namely shape and processing method of the machined surface. This report makes a specimen of the end mill processing that is used a lot as a general processing method and shows the reliability as the measurement system of the assay by the transparence replica method.

抄録全体を表示

A new highly sensitive strain measurement method has been developed by applying the change of electronic conductivity of CNTs. In order to control the shape of MWCNTs, MWCNT is developed by applying a chemical vapor deposition (CVD) method. It is found that the shape of MWCNTs can be controlled by changing the thickness of catalyst particles and deposition temperature. The quality of the grown CNTs was measured by Raman spectroscopy. Electrical resistance of the vertically aligned CNTs was also measured by four-point proving method. The obtained gauge factor was 100. This result clearly indicated the possibility of a highly sensitive strain sensor using CNTs.

抄録全体を表示

A new pressure measurement method has been developed by applying the change of the electronic conductivity of CNTs. It is reported that the electric conductivity of MWCNTs changes drastically under uniaxial strain because of the drastic change of their band gap. In this study, the authors have developed a two-dimensional pressure sensor, which consists of area-arrayed fine bundles of MWCNTs by applying MEMS technology. The special resolution of the developed sensor was 500 μm, which was higher than that of human finger, 1000 μm. Under the application of compressive strain, the electric resistance was confirmed to increase almost linearly with the applied strain.

抄録全体を表示

Applicability of acoustic emission (AE) method to the diagnosis of leaks in an engine gasket was studied. Wide band type AE sensors were attached on the gasket around the cylinder, and nitrogen gas was gradually injected to the cylinder in order to occur leaks. It was demonstrated that continuous AE signals due to leaks are detected at the internal pressure exceeding a certain level. Since the average signal level (ASL) was increased according to the internal pressure, it was found that the amounts of leaks could be evaluated by the ASL. It was also found that the AE counts are preferable to detect the occurrence of leaks because of the feature that the leaks lead to significantly change of the counts. The result of wavelet transform of the leak AE signal indicates that both of the peak frequency and its intensity vary with time so that the time-frequency analysis is useful to evaluate the leak behavior.

抄録全体を表示

Mechanical interactions between cells and extracellular matrix (ECM) direct many important cellular processes such as proliferation, migration and differentiation. Cell-ECM interactions have been studied on 2D substrate so far, but it is obvious that cell function and behavior are different in 2D and 3D. So interest in 3D mechanical field of cellular microenvironment has been increased. However, little is known regarding to the relation between cell function and 3D mechanical field of cellular microenvironment. As a novel tool for quantitative 3D deformation measurement of microenvironment, digital volume correlation (DVC), which is able to quantify the 3D internal deformation across the entire volume of an object, has increasingly gained attention. In this paper DVC was developed by MATLAB in order to measure mechanical field of cellular microenvironment, and the accuracy of this DVC algorithm was evaluated by using computer-simulated 3D volume images with controlled displacements. Results reveal that this DVC program is enough to be applied in 3D cellular microenvironment displacement and strain calculation.

抄録全体を表示

The X-ray diffraction method is used to measure the residual stress in injection-molded SFRP plates made of crystalline thermoplastic matrix. The stress in the matrix was measured by sin^2 Ψ method using Cr-Kα radiation. According to micromechanics analysis, the matrix stresses in the fiber direction, σ^m_1 , perpendicular to the fiber direction, σ^m_2 , and shear stress τ^m_<12> can be expressed as the functions of the applied (macro) stresses, σ^A_1 , σ^A_2 ,τ^A_<12> as follows: σ^m_1 = α_<11> σA_1 + α_<12> σ^A_2 ,. σ^m_2 = α21 α^A_2 , τ^m_<12> = α_<66> τ^A_<12> . Using skin-layer strips cut parallel, 45° and perpendicular to the molding direction, the stress in the matrix was measured under the uniaxial applied stress. The proportional constants of the above equations were determined experimentally, and compared with the micromechanics prediction. Microscopic phase stresses due to the mismatch of the thermal expansion coefficients between matrix and fiber was negligible in X-ray measurements. A new method is proposed to determine the residual macrostress in SFRP from the X-ray measurements of measurement of matrix stresses.

抄録全体を表示

In order to clarify the collision phenomenon of the traffic machine in motion, such as automobile and aircraft, it is necessary to examine not only the deformation and the behavior of composed structural member but also the dynamic characteristic of friction coefficient and restitution coefficient in the collided contact surface. In this study, the restitution coefficient was estimated from the strain waveform measured by collision test using the Air Gun. The velocity and deformation dependence of the restitution coefficient was examined by carrying out the collision test at the different speed.

抄録全体を表示

Pulse holographic microscopy is applied to take photographs of a rapidly bifurcating crack in PMMA plate specimen. Two photographs are taken simultaneously on both surfaces of the specimen. Crack opening displacement, COD, is measured along the two branch cracks as well as the mother crack. The two branch cracks are through cracks and have the same CODs on the both surfaces of the specimen. One of the two branch cracks has COD that is proportional to square root of the distance r from the crack tip, consequently, the COD gives the energy release rate of the branch crack. The total energy release rate of the bifurcating crack can be given by COD of the mother crack. It is found that the two branch cracks have energy release rate of 56% and 44% of the total energy release rate, respectively.

抄録全体を表示

The indentation test is a method to extract material plastic and elastic properties by pressing sharp indenter to the specimen. In this test, load and displacement are continuously recorded. In recent our studies, we can transform load-displacement curves into stress-strain curves. However, it is indicated by past research that if strain exceeds more than predefined strain (critical strain), the load-displacement curves are unlikely be affected. In this report, we examined how load-displacement curves are varied while increasing strain rate and relation between strain rate and critical strain by FE analysis. Finite element analysis is used and the analysis data is confirmed valid by comparing experimental result of the Indentation test. As a result, it turned out that higher strain rate become, the more load-displacement curves are affected and high strain area, which is located in direct beneath of the indenter have only little impact on load-displacement curves of the Indentation test.

抄録全体を表示

This report deals with two-dimensional motion of vehicles after the collision. The motion of vehicle to the stop from the after collision is clarified by the numerical analysis using equation of motion and equation of equilibrium which deduced as rigid body vehicle. In this numerical analysis, the four-wheel vehicle model was used instead of equivalent two-wheel vehicle model generally used. Then, the motion analysis experiment by the vehicle models with different height of center gravity is earned out for the verification of the numerical analysis. Several analytical results on vehicle motion using the four-wheel model are examined and compared with experimental result.

抄録全体を表示

The strain rate dependency of a variety of plastics was studied through dynamic tensile tests. The values of parameters for the Tanimura-Mimura 2009 (T-M 2009) model of each group of plastics were reexamined. Experimental data obtained by precise tensile tests and the procedure to determine the material parameters for T-M 2009 were described.

抄録全体を表示

Historical development of the SHPB method is briefly reviewed, and the concept of mechanical impedance is emphasized as a key technology. Various incident waves are shown for the constant strain rate, the strain rate change, the reverse deformation, and so on. It is also discussed the effect of mechanical impedance of loading bars on stress distribution of a specimen and ramped incident wave is a useful method to realize uniform stress distribution at high strain rate deformation..

抄録全体を表示

To improve the mechanical properties of powder metallurgy parts, high velocity compaction (HVC) is a prospective production technique. In the experiments, a press-ready premix consisting of Distaloy AE, 0.5% graphite and 0.6% Kenolube were used and maximum stress of the cylindrical specimens were measured by a split Hopkinson pressure bar (SHPB).The failure behavior was also observed using high speed video camera. These experimental results were compared and examine by densities, size, and aspect ratio of the specimens.

抄録全体を表示

Polyamide 11 (PA11) is one of bioplastics (plant-derived plastics or recyclable-resource-based plastics). In this study, we added three different nano silica of the surface treatment to PA11, and we compared and examined of the effect of the each nano silica on the dynamic properties.

抄録全体を表示

High-speed and quasi-static compression tests were conducted using short cylinder of pure aluminum A1050-0. The objective is to examine the effect of strain-rate history on the deformation behavior. The order of strain-rate was around 10^3 /s in high-speed or 10^<-2> /s in low-speed. The yield stress increased when the strain-rate changed from low-speed to high. The stress increased after the strain-rate change was more rapid comparing the slope where the bar was compressed under the low-speed condition only. On the other, the yield stress decreased in the case where the strain-rate changed from high-speed to low. The slope in stress-strain curve after the strain-rate change was steeper, in comparison with the result by low-speed compressive operation only. Further, the 3-step compressive operation was performed, where the specimen was compressed under high - low - high or low - high - low speed condition. Similarly, the positive effect in strain-rate history appeared.

抄録全体を表示

In order to evaluate quantitatively the strain dependence of the activation volume of iron containing of 0.01 mass % C at very high strain rates, strain rate reduction tests are performed at strains of about 0.09,0.17,0.22,0.26,0.32,0.39 and 0.44, respectively at the strain rate of about 10000/sec. The reduction ratio caused by the collision between an impact bar and a decelerator is 0.586 of the strain rate before reduction. The activation volume is determined from the amount of the flow stress drop obtained from the reduction tests. The results indicate that the activation volume decreases slightly with strain.

抄録全体を表示

In order to clarify the location of projectile after penetrating into sand, an originally developed "Magnet-Coil" method using electromagnetic induction was applied. It allows us the multi-point measurement of the location of a moving magnet in opaque media like sands. We have already confirmed that it has sufficient measurement accuracy in the case of straight penetration. However, in our previous experiments, it was found that the penetrating projectile meandered. Therefore, in this study, we conducted free fall experiments and tried to formulation of output signal of coil using distance from coil center as parameter. As a first result, it was found that different signals are obtained at different off-center arrangement, and this information was useful for the formulation.

抄録全体を表示

Then system of shock impact test by using airsoft rifle is developed to evaluate the design technology of anti-bird strike structure of airplane. Simple ball bullet is shot to specimen in the test by the airsoft rifle and stress response in load cell of the test system is evaluated by the modified Hertz contact theory and the wave equation which are used to analyse the viscoelastic characteristics of the specimen. In the results of experiment, the obvious relationship between quasi-static and impact responses of specimen is observed subjectively, and the effect of hardening by the impact is obvious in the results of muscles of chicken. The evaluated viscoelastic relationship is applied to simulate the impact test by using LS-DYNA with fundamental viscoelastic constitutive equation and the material parameters derived from the impact test, and the well similar behaviour has been simulated by the constitutive equation.

抄録全体を表示

We investigated the effects of shape of the target on ejecta size when aluminum alloy 2017-T4 spheres with a diameter of 3.2 mm impacted aluminum alloy 6061-T6 targets with a plane surface and a curved surface at velocities of 2 to 7 km/s. We used a two-stage light-gas gun at the Institute of Space and Astronautical Science (ISAS)/Japan Aerospace Exploration Agency (JAXA). To examine the scattering angles of the ejecta, the following was placed 50 mm in front of the target: a witness plate (150 mm × 150 mm, 2 mm in thickness) made of copper with a hole of 30 mm. The ejection behaviors of fragments were observed using a high-speed video camera. The size distributions of the ejecta were examined in detail. We compared the size distribution of the ejecta when impacting on the plane surface target and when impacting on the curved surface target.

抄録全体を表示

The effects of impact velocity and specimen thickness on the size distributions of ejecta resulting from projectile perforation of CFRP (carbon fiber reinforced plastic) plates were investigated. Two types of quasi-isotropic CFRP plates [+45° /0° /-45° /90° ]_<2s> (16 ply) and [+45° /0° /-45° /90° ]_<3s> (24 ply) were used for targets. Spherical projectiles made of aluminum alloy with a diameter of 7 mm (A2017-T4) were used. Projectiles were accelerated using a two-stage, light-gas gun at Nagoya Institute of Technology. The ejecta that were collected from in front of and behind the targets were compared.

抄録全体を表示

The temperature of spacecraft and satellites in low Earth orbit varies from approximately -150°C to 200°C. In this study, we investigated the influence of temperature on ejecta composition and crater formation in thick aluminum alloy targets for an impact velocity of 2 km/s, using a two-stage light-gas gun. The size distribution of ejecta collected from the test chamber were examined in detail.

抄録全体を表示

In this paper, in order to obtain three kinds of fracture toughness K_c, K_d, K_<arr> of engineering plastics namely PC, PBT and PEEK, the brittle fracture toughness test is performed on load time from 5 × 10_<-5> s to 1000 s by the method of using instrument Charpy impact test machine and ordinary tensile test machine. The brittle fracture toughness test were performed in the wide range of stress intensity factor rate K/t from 0.1 to 10^6 MPa・mm^<1/2>/s. It is cleared by these tests that (a) fracture toughness K_c, K_d, K_<arr> of PC are 220, 200 〜 100 and 60 MPa-mm^<1/2> and (b)K_c K_d, of PBT are 200 and 170〜70 MPa・mm^<1/2> and (c) K_c, K_d of PEEK are 250 and 200 〜 120 MPa・mm^<1/2>. These rate tendencies of brittle fracture toughness of engineering plastics are similar to those of general metal materials.

抄録全体を表示

The dynamic behavior of projectiles upon impact with granular media was recorded using two high-speed video cameras for capturing different angles. We used eight types of spheres with diameters in the range of 6-20mm as the projectiles and three types of the granular media. Post-impact motion of the projectiles depended on the impact angles of the projectiles, the density ratio, and the diameter ratio and not on the impact velocity. On the basis of the area of the transient regions, an empirical equation was derived for determining the critical angle of projectiles as a function of the density ratio and the diameter ratio.

抄録全体を表示

The effects of oblique impact angle on ejecta fragment size were investigated by striking aluminum alloy 6061-T6 targets with 3.2-mm-diameter aluminum alloy 2017-T4 spheres at velocities 4 km/s. The two-stage lighet-gas gun at the Institute of Space and Aeronautical Science (ISAS)/ Japan Aerospace Exploration Agency (JAXA), was used for the experiments. The cumulative number of ejecta was proportional to the square of the vertical-direction component of the impact velocity. The experimental formula for the cumulative number distribution of ejecta size was created using bilinear exponential distribution.

抄録全体を表示

Glass is widely used in industrial fields, and is essential to modern life. The piece of broken glass would be dangerous if they hit a human body, e.g. the eyes. There is a reasonable way to make a glass safer-to install a layer of glass film onto it. In order to examine the performance of the film, a falling ball test was conducted. The method is to drop a steel ball from certain height onto a fixed glass and then to observe the broken glass with and without films. But the strength of the glass still has not been quantified. A falling ball test was done according to JIS R 3212, and the results of the strain measurements with the film were more strength than that without film.

抄録全体を表示

From a perspective of materials for the grinding machine, it is important to clarify not only the static mechanical properties but also the impact mechanical properties. In the present study, the impact compressive properties of the abrasive material for grinding were investigated. Quasi-static testing was carried out at strain rates of 8.3×10^<-5> to 8.3×10^<-3> s-1. The impact compressive testing was preformed by mean of split Hopkinson pressure bar method. The strain rate of the impact test was approximately 10^2 s^<-1>. In comparison with the quasi-static (QS) test, the increase in fracture stress with increasing strain rate did not occur in the impact test. This was caused by the strain rate dependency of strength for the vitrified bonds.

抄録全体を表示

The compressive properties of foamed polyethylene (PE) film with a closed cell for electronic devices have been investigated. A commercial closed cell foamed PE film was used. This foamed PE film has characteristics of thin (100μm) and closed-cell structure. In the present study, the effect of strain rate on compressive properties of the foamed PE film was experimentally investigated. Quasi-static testing was carried out at strain rates of 10^<-3> to 10^<-1> s^<-1>. The strain rate of the impact test was approximately 10^3 s^<-1> using split Hopkinson pressure bar method. Within the set of experiments, the compressive stress increased with the strain rate. In particular, the flow stress increased substantially with the increasing strain rate in the impact deformation. The plateau deformation was observed immediately after the compressive testing started, with no linear-elastic response phase. The densification strain was decreased with increasing the strain rate.

抄録全体を表示

7000 series aluminum alloy has been mainly used as aircraft materials because 7000 series aluminum alloy has the highest intensity ratio among the aluminum alloy. Recently, 7000 series aluminum alloy foam has been developed. 7000 series aluminum alloy foam can be expected high strength than pure aluminum foam, and has attracted attention as a new shock absorber and structural members in the transport machinery and aircraft. In this study, the compressive deformation behavior of a foam material with closed cells made of 7075 aluminum alloy was examined under static, medium and dynamic loading speed conditions. A dropping weight testing apparatus and a Split Hopkinson Pressure Bar (SHPB) were used for medium and dynamic tests, respectively. The variation of the specimen density caused the difference of strength. By comparing the plateau stress at medium speed and static tests, it was found that the compressive strength is decreased with increasing strain rate. It is possibly considered that the specimen deformation behavior changed due to the different strain rates.

抄録全体を表示

The effect of pre-fatigue under high humidity environment on the quasi-static and impact tensile properties of7075 aluminum alloys was investigated. An impact tensile test was performed by means of the Split Hopkinson pressure bar method. Within the set of experiments, the flow stress was unaffected by the pre-fatigue deformation in the quasi-static and the impact test. It was shown that the elongation of the pre-fatigue specimen was slightly lower than that of the non-fatigue specimen in the both tests. The pre-fatigue specimen under high humidity environment had a lower elongation than under low humidity environment. It is thought that the decrease in elongation occurred by arrangement of the dislocations locally due to the pre-fatigue deformation under high humidity environment. Additionally, the elongation of the pre-fatigue specimen under high humidity environment in the quasi-static test decreased than that in the impact test. We infer that it is because the dislocation movement was enhanced by hydrogen during deformation in the quasi-static test.

抄録全体を表示

This study discusses about the influence of the velocity of small projectile and the structure of lamination on the fracture of out-of-plane impact plate laminated with CFRP and ceramics layer. A small projectile was launched from the test device at 300 and 860 m/s of the velocity condition at low and high-speed tests, respectively. Impact release of compressed He gas and explosion of gunpowder were applied to the low and high-speed test machine, respectively. CFRP plates were fabricated with [0/90]43s or [0/90]32s prepreg with epoxy matrix, while some types of SiC plates were sandwiched between the CFRP plates. The difference of absorbed energies of the ceramic parts during the impact of high velocity condition was calculated by the proposed model in a reference, when the thickness of the ceramic layer was changed The test results, at first, showed that improved shooting machine was necessary to investigate the fracture behavior of the specimen under high-velocity conditions, because fracture behavior of CFRP plate depended on the condition of impact velocity of the small projectile. It was effective to sandwich the thick ceramic layer between CFRP layers in the laminate to increase the absorb energy of the ceramic part during impact.

抄録全体を表示

Stamp formed parts of continuous fiber reinforced thermoplastic composites (CFRTP) show local degradation in strength caused by wrinkling and fiber misalignment. In addition those causes, micro damage or residual stresses are supposed to reduce the strength of formed parts. In this study strength of hemispheres formed under various forming conditions was examined. Strength of the hemispheres varied on blank holder forces in spite that fiber alignment was all the same. In order to clarify the reason residual stresses in fibers of formed parts were evaluated by using micro-Raman spectroscopy.

抄録全体を表示

This study presents a numerical approach for compression molding of randomly-dispersed carbon-fiber-reinforced thermoplastics (CFRTPs) by using smoothed particle hydrodynamics (SPH), in which the flow behavior of the CFRTPs is assumed to be viscoelastic. The fiber orientation was analyzed by the orientation tensors with a large interaction coefficient corresponding to a fiber-network structure. The random orientation of fibers was preserved even after a great elongation because of the material nature of strong fiber-fiber interaction. Furthermore, stiffness distribution of a molded composite was predicted based on the obtained orientation tensors and the stiffness tensor of a unidirectional CFRTP. The calculated distributions of elastic moduli were almost homogeneous except for the flow tips, depending on the random orientation after molding. These predictions agreed with the experiment.

抄録全体を表示

Abstract Polypropylene (PP) -used discontinuous carbon fiber reinforced thermoplastic (CFRTP) often exhibits insufficient mechanical properties because PP is known to show poor adhesion to carbon fibers. Additionally, a Vf limitation of discontinuous CFRTP also decrease the composite strength. In this study, the relationship among adhesion, Vf and mechanical properties in newly developed PP-used CFRTP sheet were evaluated. Interfacial Shear Strength (IFSS) between CF and PP can be quantitatively controlled by changing the modified PP content in matrix resin. Higher IFSS saturated with bending strength that indicates IFSS was no longer dominant the failure mode. The bending strength was also saturated in higher Vf. It is probably due to increasing the points of intersection in the dense CF network that reduces the utilization of strength in carbon fiber.

抄録全体を表示

This study aims to establish new non-destructive inspection (NDI) technique using inverse calculation with digital image correlation (DIC) method for existing old structure especially made of composite materials. The DIC technique is applicable to multiscale measurement for full-field strain measurement so that it is feasible to implement NDI for large scale structure such as aircraft body and bridges. Comparing two digital images before and after external loading, displacement distribution is identified and then mechanical constant (in this case moduli) can be obtained applying virtual field method with virtual work principle. In this paper, we first introduce the technique of mechanical property identification method using inverse calculation in virtual work principle and then report the current work even it is still on way to study. We employ three-points flexural test and measure the mechanical property of unknown laminated composite material.

抄録全体を表示

We utilized a unit cell model that considers microscopic damage including matrix cracking and fiber breaking, and incorporates constitutive laws of thermosetting resin or thermoplastic resin for the matrix. The tensile damage and strength of the composite were investigated for various fiber lengths and/or matrix properties. We compared the simulated strengths with experiments for carbon fiber-reinforced polypropylene.

抄録全体を表示

In injection molding of carbon fiber reinforced thermoplastic matrix composites (CFRTP), to detect ununiformity in fiber dispersion and deviation in fiber orientation are necessary in actual use, because they affect seriously on the strength of molded parts. In this study, to develop prompt detection method thermal response on the surface when the injection molded parts were directly heated by induction heating was examined whether it reflected the inner fibers state. Temperature rise measured resulted that it varied depending on fiber length and presence of weld.

抄録全体を表示

The purpose of this study is to construct frame structure with high impregnation materials by high cycle molding. In this study, inner pressure molding by heating device of high frequency IH was adopted as high cycle molding. Braiding technique with two guide rings was proposed to fabricate the braided fabric of pipe joint shape. Fiber orientation of braided fabric with pipe joint shape is a non-uniform state because braiding process has rotation processes. Therefore, fiber orientation of braided fabric at the rotation process was evaluated. Molding temperature history was measured when pipe joint product is molded. And essential molding time was calculated. Molding time for pipe joint product was investigated.

抄録全体を表示

The purpose of this paper is to establish design guide for development of high cycle molding as a total process from reinforcement fiber to molding in terms of "intermediate material design", "structure design" and "molding design". In terms of intermediate material design, commingled yarn, which was fibrous intermediate material, made by commingling reinforcement fiber and resin fiber was developed. In terms of structure design, braided fabric was produced. In terms of molding design, by using this braided fabric, pultrusion system, which was one of continuous molding method, was proposed for thermoplastic composites.

抄録全体を表示

Although fuel-cell vehicles are almost put on the market, supply system for hydrogen gas has many problems to be solved, such as hydrogen embrittlement. Hence from cracks hydrogen gas is easy to be leaked, which means loss of water on earth, nondestructive test (NDT) of high-pressure hydrogen cylinders is important. Leaking hydrogen gas means loss of water on earth. In this study we discuss NDT on ferrous metals for conventional commercial use. Since magnetization is approach to anhysteresis curve under plasticity, additional plastic deformation in high-pressure hydrogen cylinders can be detected to evaluate its deterioration. We also discuss residual magnetic distribution caused by stress-induced martensite transformation can detect ununiform mechanical properties in the cylinders.

抄録全体を表示