Member 2018

Professor

IMG_2824.JPGJun Koyanagi
2017- Associate Professor at Tokyo University of Science
2013-2016 Junior Associate Professor at Tokyo University of Science
2006-2012 Assistant Professor at Japan Aerospace Exploration Agency (JAXA)
2004-2005 Research Associate at Waseda University

Research Associate

1.jpgSaori Murata

1st year student doctor (D1)

MioSato.jpgMio Sato


RESERCH TOPIC: Evaluation of Interfacial Strength in Carbon-fiber TriA-X
In this study, the interfacial strength of carbon TriA-X composites was measured by a micro-drop test. In-situ observations were conducted on the microscope stage with handmade micro-mechanical testing apparatuses. The specimen consisted of the carbon fiber and the TriA-X resin micro-drop and the interfacial strength between the two was determined by comparing experimental data and computational simulations. An axisymmetric model was developed in which cohesive elements were introduced on the interface and used to study the damage mechanics of the resin.

2nd year graduate student(M2)


hiroki-kuramoti.JPGHiroki Kuramochi


RESERCH TOPIC:Fatigue Analysis of Metallic Materials with Voids
Jet engine parts contain some voids that can lead to crack initiation and evolution around them when subjected to cyclic fatigue loads. In this study, the analysis of fatigue crack growth occurring in metallic materials containing voids was carried out using the finite element method (FEM) or extended finite element method (XFEM). Two-dimensional finite element plate models containing two holes resembling voids were developed and used to simulate crack propagation under applied cyclic loading using the ABAQUS software package. The evaluation of was based on the value of the stress intensity factor or the plastic strain energy density per cycle.


takahiro-yamanaka.JPGTakahiro Yamanaka


RESERCH TOPIC:Dust-resistant Evaluation of Thermal Protection Material during Martian Atmospheric Entry
The quantity of eroded material that is generated when an air flow containing particles collides with heat protection materials is measured by the arc wind tunnel test. Furthermore, the velocity of these particles of the arc in the air flow (5.5 km/s) was calculated using the equations. From these results, the quantity of eroded heat protection material, the ablator, during reentry into the Martian atmosphere was approximated by equations.


yamamoto.JPGMichihiro Yamamoto


RESERCH TOPIC:Dispersion Behavior of Carbon-Polymer Composites
Using molecular dynamics (MD) and dissipative particle dynamics (DPD), the dispersion behavior of polyaniline and carbon materials such as graphene, carbon nanotubes, and fullerenes was investigated. To conduct structural health monitoring of off-shore wind turbines, polymer composites need to have robust mechanical and electronic properties. For fabrication of high performance composites, good dispersion behavior of carbon material in the polymer is necessary. MD methods were used to calculate energies for the dispersed and aggregated states. Using these energies, the dispersion behavior of composites was simulated using DPD.


yuta-yamazaki.JPGYuta Yamazaki


RESERCH TOPIC:Evaluation of Carbon Fiber Reinforced Plastic Interfacial Strength
The mechanical properties of CFRP are decided by the fiber, resin, and interfacial property. Therefore, it is important to evaluate the interfacial strength. In this study, finite element analysis modeling was performed to simulate and determine the fiber/resin interfacial shear strength by the microdroplet test. The purpose of this experiment was to determine the load when the resin is scraped off the carbon fiber by a knife edge. Numerical analysis was carried out using zero-thickness cohesive elements, which reproduce the interface between resin and fiber, to simulate the interfacial strength. Computational simulation was performed with the ABAQUS software package using an axisymmetric finite element model. To simulate curing of the prepared specimen, heat stress was considered in the model. By considering viscoelastic and continuum damage mechanisms for resin, resin failure could be simulated.Future work:
CFRP behavior under the impact situation will be evaluated. However, CFRP is heterogeneous and thus the macro/micro structure should be considered. To evaluate impact property, a multiscale analysis will be conducted.



yasuhisa-hukuda.JPGYasuhisa Fukuda


RESERCH TOPIC:Identification of Heat Flux at the Rear Heat Shield of MUSES-C (HAYABUSA) Capsule
The optimization of a heat shield design is essential to satisfy to the weight limit of a reentry capsule of an investigation satellite. One such weight saving approach involves making an exact estimate of the aerodynamic heating environment at the rear heat shield. The rear heat shield surface of the Hayabusa reentry capsule was covered with a single-sided aluminized polyimide tape and the overlapping part of tape on the rear heat shield did not burn out after the capsule returned to the earth. This observation shows that the actual heat flux at the rear heat shield during reentry was much lower than estimated. Therefore, we tried to identify the heat flux on the rear heat shield of the Hayabusa reentry capsule by carrying out heating tests using an inductively coupled plasma (ICP) heater.

1st year graduate student(M1)

Sawamura.jpg Yusuke Sawamura


RESERCH TOPIC:Numerical simulation of dynamic failure behavior for CFRP
In this study, dynamic and static failure tests for cylindrical CFRP are conducted, and their numerical simulations are performed using commercial finite element method software, ABAQUS. Multi-scale analysis is carried out for the numerical simulation to account for inhomogeneity of the CFRP. In the micro scale numerical simulation, a 2D periodic unit cell (PUC) analysis is conducted. The model simulates matrix failure and fiber/matrix interface debonding by continuum damage mechanics (CDM) considering rate dependence and cohesive zone modeling (CZM), respectively. Rate-dependent failure criteria under multi-axial loadings for macro scale simulation are determined based on the micro scale simulation.


Itano.pngNorie Itano


RESERCH TOPIC:Evaluation of interfacial strength by experiment and numerical simulation
This study simulates interfacial strength using molecular dynamics simulation (MD) to investigate the relationship between interfacial strength and molecular structure. Interfacial strength between carbon fiber and epoxy resin is evaluated by microdroplet experiment and the finite element method (FEM). In the microdroplet experiment, when a resin droplet is debonded from the fiber, the load on the fiber is measured. The interfacial strength is calculated using the FEM, and the interaction energy is calculated using molecular dynamics simulation. The results of the MD simulation agree with those of the experiment and the FEM.


IMG_1499.JPGSatoshi Tomita


RESERCH TOPIC: Time-dependent mechanical properties of carbon fiber-resin composite containing CNT layer
Finite element analysis modeling for the analysis of differences in time-dependent apparent modulus between carbon fiber-resin composite material models with and without a CNT layer was conducted. A computational simulation was performed with the ABAQUS software package using a beam finite element model. Stress relaxation test data was used to create a curve representing the relationship between elastic modulus and time, in order to define the viscoelasticity in the time domain. It was found that the apparent elastic modulus of the CNT layer must be smaller than the resin when the speed is high, in order to reproduce the time dependency of the apparent modulus of elasticity obtained from the experiment.


Shirai.jpg Sakie Shirai


RESERCH TOPIC: Numerical Simulation for strain rate and temperature dependence of Transverse Tensile Failure of UD-CFRP
In the present study, strain-rate dependence and temperature dependence of failure mode are numerically simulated by finite element analyses. In the analyses, interface failure and matrix failure are expressed by cohesive zone modeling and continuum damage mechanics, respectively. It is assumed that the damage initiates dependently of strain rate and temperature, and cohesive zone modeling is assumed to be temperature- and time-independent.
When temperature is high and/or strain rate is low, matrix crack occurs very often and the failure mode is matrix-failure-dominant mode. On the other hand, when temperature is low and/or strain rate is high, interface crack significant, i.e. failure mode becomes interface-crack-dominant mode.

Image.jpgMao Hososhima


RESERCH TOPIC:Fatigue life prediction based on thermodynamic entropy
In recent years, attempts have been made to treat irreversible thermodynamic entropy, a source of fatigue failure. Irreversible entropy in a system monotonically increases until the final fracture of a metallic material. The damage progresses, and the material ruptures when the entropy production reaches a certain value. In this study, fatigue tests on aluminum alloy Al2024-T4 and polyimide were carried out to calculate the entropy generation during the fatigue process. Entropy use for fatigue life prediction based on the calculated entropy generation value is also examined.

kazama.jpg Tomoya Kazama


RESERCH TOPIC:The Evalutaion of membarane material of inflatable aeroshell for atmospheric entry
The inflatable aeroshell is new key technology supporting atmospheric entry missions.
A Martin penetrator is promising application using an inflatable ring is critical because the inflatable aeroshell is deployed and supported by the gas pressure. The aerothermal environment during atmospheric entry differs depending on the atmosphere of the planet and the planetary entry conditions. The aerodynamic heating condition is estimated by a numerical simulation based on, the Martin penetrator mission. The durability of the membrane material for the inflatable ring is evaluated experimentally by CO2 laser heating and ICP heating according to the estimated results of the aerodynamic heating condition during Martin entry

Under graduate student(B4) New!

harasima.jpgAoi Harashima


takeda.jpgYuji Takeda


komori.jpgSyohei Komori


wakayama.jpgKodai Wakayama


hasegawa.jpg Kodai Hasegawa


segawa.jpgTakumi Segawa


kobasi.jpgTakumi Kohashi


kukita.jpgMako Kukita


kume.jpgSaori Kume


simizu.jpgSariko Shimizu


a.jpgSyohei Kasahara