Magnesium substituted hydroxyapatite (Mg-HA) thin films were prepared using rf-magnetron sputtering method. The Mg-HA films were coated onto a titanium (Ti) substrate from a mixed HA/MgO powder target. The molar ratio of Mg to Ca in the mixture target was varied in the ratio of 0:10, 2:8, 4:6, 6:4 and 8:2. The Mg-HA films were heated or subjected to hydrothermal treatment. The chemical compositions of the Mg-HA films were determined by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The crystal lattice parameters from XRD patterns of Mg-HA films were calculated. The chemical analysis by XPS showed that the non-heated, heated, subjected to hydrothermal treatment Mg-HA films contained Mg. The XRD patterns showed that the heated Mg-HA films composed of HA, beta-tricalcium phosphate (β-TCP) and MgO. The subjected to hydrothermal treatment Mg-HA films composed of HA and MgO. The lattice parameters of the HA in the heated and subjected to hydrothermal treatment Mg-HA films (Mg:Ca=2:8, 4:6, 6:4, 8:2) were smaller than that in the heated and subjected to hydrothermal treatment HA films (Mg:Ca=0:10).

View full abstract

The adsorption of Sr on HA and the adsorption of Cs on silicate were investigated. Montmorillonite, Zeolite was used as a silicate. We heated the HA and the silicate from 100℃ to 1000℃ for 1 hour. The unheated HA and the heated HA were immersed into the solution containing Sr. The concentration of Sr ion in the solution before and after the adsorption experiment measured using inductively coupled plasma atomic emission spectrometry (ICP-AES). The unheated silicate and the heated silicate were immersed into the solution containing Cs. The concentration of Cs ion in the solution before and after the adsorption experiment measured using inductively coupled plasma mass spectrometry (ICP-MS). We set Montmorillonite and HA powder in a mortar and mixed them with a pestle. And then we heated them at 600℃ or 700℃ for 1 hour. Differential thermal analysis and thermogravimetry (TG-DTA) were used for thermal analysis of the mixture of montmorillonite and HA powder.The Sr adsorption rate of HA by ICP-AES showed that the adsorption ratio of Sr decreased with increasing heating temperature. From ICP-MS measurement, Montmorillonite and Zeolite heated up to 500℃ or 600℃ showed more than 90% of Cs adsorption, respectively. The TG-DTA curves showed that no chemical reaction was observed between montmorillonite and HA at 0℃-1200℃.

View full abstract

We have developed a coronary artery bypass graft connecting device. This device can achieve bypass formation easily with the integrated low energy adhesion technique which can adhere living tissues with minimal invasion by using low level heat and pressure energies. Branch vessels from the aorta (inner diameter < 4 mm) adhered to each other with 80-120 degrees Celsius for a minute to evaluate the adhesion performance of the developed device. The maximum shear tensile strength measured with a tensile test machine was 0.014 MPa with an adhesion temperature of 120 degrees Celsius and basic performance for the vessel adhesion was confirmed.

View full abstract

The aim of this study was to examine non-contact stent heating methods to adhere tissues to stents using an alternating magnetic field. We propose two kinds of coils (C-shaped and I-shaped), which apply the alternating magnetic field to the stent from the outside and inside, respectively. The speeds of the temperature rise in the stents were measured using J-type thermocouples for the C-shaped and I-shaped coils. The C-shaped coil took 90 s to reach 41℃, whereas the I-shaped coil took 19 s to reach 80℃.

View full abstract

We have developed a blood flow meter using a curved pipe. In this study, we investigated the influence of the bending angle of a curved pipe on flow measurement by means of computational fluid dynamics (CFD) analysis. We analyzed the pressure distribution and the secondly flow in the curved pipe. As a result, the measurement positions for the blood flow were determined. Corresponding to increase of the bending angle, although the measurement accuracy was improved, the influence of the secondary flow was increased.

View full abstract

We developed the mock experimental setup of catheter cardiac ablation which measures the catheter tip contact force. In this study, we introduce the improvement of experimental setup and study content of the relationship between the catheter tip force and the resulted ablated depth, and the catheter contact force-related tip deformation. The result of visualization experiment showed the more flexible deformation with Flex tip than Duo tip.

View full abstract

Up to now, there is no study which has visualize the fracture phenomenon of red blood cells under high shear stress condition such as the rotational blood pump. Conventionally many hemolysis data were derived through the indirect assessment by the photometric method. Direct observation of red blood cell's destruction phenomenon maybe supply us the useful information for the development of blood pump with the better blood compatibility. This study prototyped the experimental setup to continuously observe the red blood cells in shear flow. The prototyped setup enabled us to visualize red cells for the very short time period of eight seconds. However the shear flow field became instable to monitor individual cell after longer time period. The usage of thickness tape improved the device rotational stability.

View full abstract

In vitro antithrombogenic testing is a useful pre-evaluation for ex vivo test of a continuous flow pump as an artificial heart. In our previous study, we have quantitatively obtained the results that the increasing shear rate prevented the thrombus formation using a double-cylinder type rheometer. However, it is not yet cleared that the thrombosis procedures occurred at between the inner and the outer cylinders. This paper describes that the optical and direct observation of the in vitro thrombosis under shear flow fields. This results showed that the thrombus formation started from the surface of rotating outer cylinder made of glass. Thus, it is considered that in vitro thrombosis closely related to the not only blood coagulability and/or shear rate, but also chemical condition of blood-contacting surface.

View full abstract

It was reported that nano-scale voids increase the ductility of the ultra-fmed-grained metal in the specific situation that they can enhance the dislocation activity. However, their influence to the deformation mechanism of ultra-fined-grained metal has not been well-examined yet. In this research, their effects to the deformation mechanisms, such as dislocation activity, grain boundary sliding, and grain boundary migration, of the ultra-fined-grained metal are studied. Furthermore, the possibility of the mechanical characteristic improvement of ultra-fined-grained metal by nano-scale voids is discussed.

View full abstract

The calculation using anisotropic hyperelastic model of hip joint torque generated by competitive swimwear was investigated in this paper. An anisotropic hyperelastic model considering cyclic deformation of swimwear fabrics was introduced in order to reproduce the mechanical characteristics of swimwear fabrics on the analysis. The material parameters of the proposed model were approximated using the cyclic tensile loading test results. The stress calculation of swimwear was investigated using this model. Finally, hip joint torque generated by the swimwear was calculated from the calculation results. Therefore, the calculation of hip joint torque generated by swimwear enables the new design of swimwear considering the value of hip joint torque.

View full abstract

In this research, an evaluation method which considers the uncertainty of crack length is presented about the analysis of the crack structure which uses the extended finite element method (XFEM). In the presented method, Taylor's expansion of the stiffness matrix is carried out around the definitive crack tip position. As a result, suitable displacement is obtained by the linear approximation and/or the quadratic approximation.

View full abstract

A compression behavior of polymer foam was analyzed by using horaogemzation FEM code. A unit cell for the homogenization method was applied to a part of the microstructure. The polymer matrix of the unit cell was modeled hyperelasticity to consider non-linear characteristics. An original simulation model of the polymer foam was assumed to have two sizes of cells. (Cell is an air bubble in foam material.) Position of cells was assumed to be alternately and periodically. The diameter of cells was adjusted to make the density of the simulation model and the density of polymer foam coincident. The applicability of the analysis method to polymer foam was shown by comparison between the analysis results and the compression test results.

View full abstract

By the development of the field of calculation dynamics, the CAE software is complicated with many functions. In addition, it is difficult to predict various analytical techniques and methods that will be suggested from now on. Therefore the software development using a design pattern is flexible, and extensibility is provided. We put Visitor pattern ,Decorator pattern together, and this article applied the Option pattern that simulated an aspect point to FEM program and evaluated the effectiveness and utility.

View full abstract

We study a sphere-to-sheet transition of a surface model using the grand canonical Monte Carlo simulation technique on dynamically triangulated lattices. This transition is closely connected to a pore formation of liposome and also to the lamellar-to-onion transition. The model is defined on a triangulated sphere with a pore, which is topologically identical with a disk. The perimeter length of the pore is allowed to vary, and consequently we have two different phases at high bending region; one is a spherical phase and the other is a planar phase. We find that these two phases are separated by a first-order transition.

View full abstract

In this paper, we simulate the tethered membrane model using the Parallel Tempering Monte Carlo (PTMC) technique. We find that the speed of the PTMC technique is faster than that of the Metropolis MC technique, which is the standard non-parallel technique. Indeed, a parallelizable part included in the PTMC simulation program is much larger than the non-parallelizable part. This is the reason why the PTMC technique is very effective for the simulations of the membrane model.

View full abstract

Generally, a vortex ring can be generated by piston motion in a cylindrical tube. Some past studies had presented a condition to generate equivalent vortex rings from orifice outlet to those from straight nozzle outlet, whose diameter equal to piston diameter. In this paper, we numerically simulated the vortex rings generated by both the straight outlet and orifice outlet. However, it found that the condition cannot generate the equivalent vortex rings and we need to modify the condition.

View full abstract

Recently, environment problems, such as global warming, climate change, air pollution, acid rain and many others, become serious issues on earth. To solve the problem, alternative renewable energy is required. In this paper, we have been developing a new compact and flexible wave power generator. In order to optimize the device, we analyzed the behavior of the device numerically. However, we found that the commercial CFD codes cannot simulate the behaviors because of large displacement and rotation of the device on free surface. Therefore, the mesh-free methods such as SPH are the better alternatives. However, there is a problem that long calculation time with SPH method. So we aimed at speed-up of calculation time by GPGPU in this study.

View full abstract

Ocean energy recently attracts people's attention as one of the renewable energy resources and there is a great deal of ocean energy resource around Japan. But we cannot easily utilize them due to typhoon problems. For solving the problems, we have developed a compact, low-cost but flexible wave power generator which can work under the motions of multi-degree of freedom. In this study, we experimentally analyze the motion of the mock-up generator under the artificial wave in the small-scale tank. We focus on the influence of the movement of magnet weights on the motion of device.

View full abstract

In this study, a high efficiency ultra-wide gap active magnetic bearing is proposed. It has homopolar type rotors with a permanent magnet between them. The stators are composed of bias and control components. The bias components generate bias magnetic fluxes by the strong permanent magnets, while the control ones generate control fluxes by the electromagnets. The control fluxes don't act directly on the homopolar rotors, but can change the bias fluxes. The control forces are generated by the imbalance of the bias fluxes. Even though the wide air gap, it is feasible to reduce the energy consumption and maintain the high control performance.

View full abstract

We investigated the method of using the Singular Spectral Analysis(SSA) to estimate the attenuation haracteristic. If you make a harmonic input to the linear vibration system having damping, forced vibration damped oscillation occurs. It was suggested that by this method, and extracts the damped oscillation, it is possible to estimate the attenuation characteristic.

View full abstract

In this paper, we have proposed a one-legged hopping robot with hip, knee and ankle joints. Each joint of the leg is wire-driven by the motor mounted on the body, so that the weights of legs become lighter. We have shown by experiments that wire driven leg can be moved properly.

View full abstract

In this paper , a biped running robot with parallel linkage and leg springs are proposed. Springy leg is suitable for energy efficient running while stabilizing control becomes difficult. Experiment result for control of legs are presented in this paper.

View full abstract

In the design of railway bogies, the compatibility between curving performance and running stability is important. Especially, there are a lot of tight curved sections in LRTs. Bogie with independently rotating wheels (IRW) could be useful to realize both curving performance and running stability. For example, EEF bogie and IRW with inverse tread conicity have been proposed. In this paper, a new-type IRW with oblique axle is proposed and the equation of motion is derived. Characteristics of hunting motion are investigated with the eigenvalue analysis. Furthermore, full vehicle model simulation with the new-type IRWs is conducted to evaluate curving performance of the proposed IRW.

View full abstract

In this paper, it was validated whether it is possible to use the line-load generated by rubber O-ring as an indicator of life evaluation instead of compression set. An instrument to evaluate the sealing performance under the condition that gave any load to a rubber O-ring was created. The load when leakage occurs was measured in the state that a rubber O-ring was compressed by using the instrument. Mechanical tests were carried out under various conditions. The effect of strain rate, differential pressure and the degree of deterioration of the rubber O-ring, to the load when leakage occurs were investigated.

View full abstract

In this paper, the purpose of this study is lifetime evaluation of seal performance of the O ring made in NBR (Nitrile- Butadiene Rubber) used for sealing up of the GIS (Gas Insulated Switchgear). We developed thermo -mechanical viscoelastic model using finite element analysis to predict aging of EP (Ethylene-Propylene)-rubber O-rings. To expand this life prediction method to NBR O-rings, material property of NBR was investigated experimentally. Stress relaxation tests and biaxial tension tests were performed to identify material property. As a result, experimental and calculated elastic potential showed good coincident and some values related temperature dependency indicate necessity of reexamination.

View full abstract

The weld pass sequence generally affects residual stress profiles. In this study, the profiles of bead welded specimens were experimentally examined. The material used in this study was the low alloy steel SQV2A (JIS G 3120), which is equivalent to ASTM A533 Type B Class 1. Phase transformation usually occurs around the welding area in SQV2A and also affects the profiles. Two specimens were fabricated. One was single pass bead welded (single pass specimen), and the other was five pass bead welded (five pass specimen.) Residual stresses of these specimens were measured by using the strain relief method. The measurement results show that longitudinal residual stress on the welded surface of the single pass specimen was lower than that of the opposite side surface due to phase transformation. Longitudinal residual stress around the 5th pass area of the five pass specimen was similar to that of the single pass specimen. The residual stress in the previous welded area, where passes from the 1st to the 4th were welded, was higher than that of the 5th pass area. These findings show that residual stress occurred around the welding area of these specimens and that residual stress around the last pass area was lower than that of previous pass area due to phase transformation during the welding process.

View full abstract

In this paper, we discuss on an applicability of FEA to corrosion thinning of steel structures. We take a dam gate as an example of the steel structure and calculate the same gate FEA model by use of two different commercial FEA codes, Abaqus and ADINA. This FEA model has the thin elements on the arms. We simulate the corrosion thinning by step-by-step removing these elements. From the comparison of calculated stress on the gate arm, the element removing function is applicable to the simulation of the corrosion thinning.

View full abstract

The object of study is to evaluate creep-fatigue strength of perforated plate. In this study, fatigue test and creep-fatigue test with relatively long hold time (30 minutes, 60 minutes, and 150 minutes) were conducted under strain-controlled. The specimen is perforated plate that made of SUS304 stainless steel. It was found that strain hold time is longer in creep-fatigue test, the number of failure cycles is more decrease and crack growth rate per cycle is faster. In Campbell curve, fatigue damage and creep damage calculated by Stress Redistribution Locus (SRL) method to failure cycle is better than applying Neuber rule to failure cycle. However, the stress relaxation model that used in the SRL method is overestimated stress relaxation, so applying the method to crack initiation life of creep-fatigue test with holding time 150 minutes is predicted danger.

View full abstract

This paper describes the applicability of a computer code "SLOSH-3D" developed in-house on estimating of sloshing wave crest impact pressure acting on a fixed roof of cylindrical tank. A large shaking table test, conducted on the E-Defence shaking table, has been analyzed. In the shaking table test, partially water-filled cylindrical tank (diameter:3m, height:3m,water depth:2.3m or 1.9m) with a flat fixed roof was subjected to a sinusoidal excitation at the first sloshing resonant frequency. Based on the computed results, time histories of pressure acting on the tank roof and wall is presented. The computer code well simulated the observed waveform with a spiky rising large pressure at the time of liquid impact on the tank wall, including appearance of negative pressures in the post impact period, with sufficient accuracy. As for the liquid impact zone of the tank roof including the water splash phenomena, the numerical computations indicated good agreement with the observed results.

View full abstract

The evaluation of magnetic properties of fatigue-damaged and fatigue-cracked electromagnetic steel sheets were investigated. In fatigue tests, plastic deformation area around notch or crack tip was observed. In macro-magnetic measurement using B-H analyzer, magnetic properties of fatigue-damaged specimens were deteriorated, especially in fatigue-cracked specimens. By observing magnetic domain structure around fatigue crack using magneto-optical Kerr microscope, the structure shape changed and the width of magnetic domain decreased. It seems that the change of magnetic domain structure is one of the causes of deterioration of the magnetic properties. In addition, the effect of residual stress around fatigue crack was also discussed.

View full abstract

The purpose of study is to investigate insulation properties and flame resistance of electrical cables in fire. The electrical cables in nuclear power plant are responsible for the power supply and control. The property of the cable must be maintained during fire accidents. However, the heat of a fire affects insulation resistance of the cable. Further, the cable would become new fire source when the cable surface temperature reaches a certain temperature. Thus, the clarification of insulation properties and combustion characteristics of the electrical cable is necessary in order to maintain the safety in case of fire in the nuclear power plant. In this paper, we conducted two experiments to clarify the combustion characteristics and insulation of the electrical cable in fire using a combustion test device. First, the cables were applied heat for 120 minutes under some temperature conditions. Heater temperature was constant for 120 minutes or changed at the time of 60 minutes. Second, heat was applied to the cables in a state of superposition. In both experiments, the cable surface temperature and the insulation resistance while applying heat were measured. Therefore, the combustion characteristics and insulation properties of the electrical cable in fire were clarified.

View full abstract

A novel blood pump with a maglev motor has been developed for cardiac function recovery of acute heart failure patients. The blood pump assists patient's heart and the rotational speed is changed in synchronization with heart beat in order to increase coronary flow and reduce heart load. The impeller levitation stability in the radial direction which is restricted with passive stability was evaluated during the pumping by using a mock circuit filled with water. The levitated impeller contacted on the casing when the rotating speed is higher than 1,800 rpm. Partial electromagnet was invented to prevent impeller connecting and its performance was evaluated: The electromagnet could generate 1.1 N with a gap between electromagnet and impeller of 3.0 mm and a current of 2.5 A.

View full abstract

A novel cardiovascular system simulator with coronary circulation reproduction has been developed to evaluate the new cardiac disease treatment. In order to verify the effectiveness of the coronary circulation reproduction, the maglev blood pump developed in our laboratory was connected with the mock circulation loop, and coronary flow change was observed when bypass ratio was changed under continuous mode. The coronary flow rate was increased with increasing bypass ratio such as similar change in the animal experiment and basic ability to mimic the coronary flow of the system was evaluated.

View full abstract

Seated posture on the wheelchair is important, because it may cause swallowing and respiratory difficulty, develop a pressure sore and affect motor performance. Although systems that can measure angles of seated posture that are defined by the international standard ISO16840-1 have been introduced, there are many points to be improved. The developed system aims to measure the seated posture in three dimensions by recognizing numeric markers pasted on the subject using images captured by stereo video cameras. System that can recognize markers, measures 3D co-ordinate of markers and angles of nodal lines composed by markers has been developed using MATLAB (MathWorks). By defining the relation of up, down, left and right of numeric markers, and utilizing the information, recognition ratio was improved. Measured co-ordinates and angles were compared with that of measured by MAC3D (Motion Analysis). Average co-ordinate errors were within 11 [mm], however, toward depth X direction and when the trunk was bent forward, errors become larger. Average angle error was 1.7[deg], and errors of angles in sagittal and transverse planes where the X co-ordinates relate and when the trunk was bent forward, also become larger, because they are calculated from the marker co-ordinates.

View full abstract

A wearable leg support system based on manual control for people with lower limb paralysis has been proposed in this paper. We had developed a wearable leg support system, Manipuleg-2, that the wearer can control leg via a control lever attached at his or her shoulder. To show the effectiveness of Manipuleg-2 we have developed a mock prosthesis that an able-bodied man can put on with his knee bended.

View full abstract

The bellows exhaust pipe connecting the engine and the muffler is heated by high-temperature exhaust gas and moreover exposed to thumping vibration from the engine and the body bouncing. To ensure reliability of the pipe in these harsh conditions, we have to develop a technique to evaluate the bellows strength accurately on the design phase. In this study, on the basis of theoretical formula listed in the Japanese Industrial Standards (JIS), we developed a bellows calculation model by using single shell elements with equivalent stiffness. Also, we modify the model by the results of modal testing to achieve higher accuracy. Then we evaluated the calculated maximum stress on the bellows by comparing it with the measured value on the excavator operating.

View full abstract

Recently, capacity of wind turbine has become large and its drive train transmits huge torque. In order to prevent a slip in bolt connections which carry the main torque, we inserted friction disc, which are made of high friction coefficient material, to the bolt connected flange. In order to investigate the mechanical properties of the friction disc, we conducted a friction test by using small scale specimens. It was found that the similar behavior to work hardening occurred in friction tests. The maximum static friction coefficient doesn't decrease unless the connection surface slips. On the other hand, in the case the connection slips, maximum static friction coefficient becomes lower.

View full abstract

Stress distributions in an infinite plate (containing a press-fit rigid disk) under uniaxial tension have been analyzed in consideration of contact friction. The stress distributions around circular hole boundary have been calculated under no loading and increasing loadings. Obtaining numerical results for the cases of frictionless contact and friction contact, the effects of contact friction on the stresses around the circular hole boundary are made clear. These results may be useful to strength design of plates connected with bolts and rivets, or strength analysis of materials containing inclusions.

View full abstract

This report deals with the influence of the interference between an elastic sphere and a spherical cavity on the stress distribution and displacement around cavity, which has simply a smooth elastic sphere, in an elastic solid under tension at infinity. The contact stress between the sphere and the cavity is expressed with series of Legendre functions, and the stress and displacement are numerically analyzed by point matching method. Using the numerical results for the elastic sphere, the effects of interference and loads are shown on the stresses around the spherical cavity boundary.

View full abstract

In this study, dynamic compression properties of polymer foam were investigated by compression tests. Polyurethane foam test specimens, relative densities of which were 0.21g/cm^3, 0.27g/cm^3, 0.37g/cm^3, were applied to the cyclic compression tests. Cyclic compression tests conducted under different strain rate. The effect of relative density and strain rate on the mechanical properties were shown.

View full abstract

A purpose of the present study is to develop three dimensional FEM programs that users can modify without any restriction. The FEM program is based on both 8-node Hexahedral element and 4-node Tetrahedral element. This program can generate elements automatically using the algorithm of 3D Delaunay triangulation. User can scale-up,scale-down and drag analysis model freely. Analyzed results are shown by several contour maps and text data.

View full abstract

In this paper, experimental and theoretical investigations have been conducted to evaluate the axial force of a hook bolt which clamps a sleeper and a railway track. The experimental tests were carried out by fastening the hook bolt with a torque wrench and the axial force of the bolt is measured form three pairs of strain gauges, bonded on counterfacing sides of the bolt. The axial force is determined from the 3 points gauge data using the least square method. In analytical part, the curved beam theory is used to model the specimens and thereby we have calculated the moment distribution of the hook bolt. The experimental results agree well with the theoretical ones and it is shown that the present analytical solution is available for estimating the axial force of the hook bolt.

View full abstract

Piles are widely used to support laterally loaded structures, such as bridges, tanks, and buildings. Elastic solutions based on the Winkler foundation model are widely used to design piles at working load. However, most design formulas are derived assuming that the piles are subjected to the only horizontal shear force. This paper describes an analytical solution for the pile which is subjected to an uniformly distributed load as well as a shear force. After deriving the exact solution, the influences of the distributed load on the bending moment of the pile are clarified.

View full abstract

A tandem nut screw drive with a load equalization mechanism has been developed for the purpose of building a high thrust electric linear actuator. The mechanism is equipped with links and joints that connect two nuts so that they can relatively rotate small angle. When the loads acting on the nuts get some unbalance, it causes a difference between the reactive torques generated on the nuts, which rotates the nuts relatively to reduce the unbalance. Theoretical analysis taking frictions on the joints into account is carried out to estimate the residual load difference. Experiments using a 160 kN screw drive with the load equalization mechanism show that the load unbalance is less than 5%, which is small enough to avoid irregular wearing.

View full abstract

This paper presents an analysis of the effect of surface hardening treatment on the plastic collapse load of the hardened steel. The surface hardening steel has been studied in many papers. However, many of them are focused on the wear or fatigue strength. Surface hardening treatment not only improves the anti-wear performance but also raises the yield stress. It is crucially important to evaluate the plastic collapse load of surface hardened steel in plastic forming process. Therefore, the authors have theoretically analyzed the plastic collapse load of the surface hardened beam with rectangular cross-section when the beam is subjected to bending. To confirm the validity of the present solution, three dimensional elasto-plastic FEM analysis was employed and the numerical results agree well with the present solutions.

View full abstract

In this study, the effect of microscopic structure on mechanical characteristics of stretch fabric was evaluated to reasonable design of fabric. Stretch fabric shows anisotropic mechanical behavior because of its microstructural effect. In order to obtain the macroscopic mechanical characteristics of the fabric, uniaxial tensile tests were conducted. Also, the deformation of the yarn was recorded by the microscope to investigate the effect of microscopic structure on the macroscopic mechanical characteristics. The recorded videos were analyzed with motion image analysis software TEMA (Photron Ltd.). From the analysis result, microscopic strain and the angle between warp and weft yarn were obtained., The microscopic behavior of stretch fabric was clarified comparing microscopic strain with macroscopic stress.

View full abstract

We provide a modeling method of strain rate dependent material which derived from force-displacement relationships for strain rates measured by high speed tensile tests. This material model consists of a stress-strain rate relationship for hardening characteristics and a damage function for softening and fracture characteristics. This model is implemented in LS-DYNA by using user subroutines. To evaluate the modeling method, high speed tensile tests, the material modeling with test result and simulations on the high speed tensile tests with the material model were carried out. Then it found that the force-displacement relationships of analysis match to those of the tests.

View full abstract