1. Risk & Reliability

•Risk Assessment for Train

•Optimization of maintenance

•Network-based R6 system

4. Micro-Nano Mechanics

•Molecular Dynamics for Semiconductor Processes

•Dislocation Dynamics for Semiconductor Devices

3. Fracture Mechanics

•Fractography

•High-Temperature Hardness

2. Life Cycle Assessment

•Application to sensitivity analysis in LCA

Research Field of Sakai-Izumi Lab.

1. Risk & Reliability

Interior Module Design of Rolling Stocks where Introduces Risk Assessment

We attach importance to the decision-making performance in risk assessment. It is investigated to apply the risk assessment in the design stage of railroad train. Specifically, the design of ceiling-shelf module is considered. By introducing the risk evaluation, not only the evaluation of function of single part but also the total performance for safety can easily be treated. After the formulation of risk assessment was stated, the application for several decision-makings in ceiling-shelf module was shown.

⑨⑧⑦⑥⑤④

③

①②

3200mm

Improved model with optimized fastening positions

Initial model with regular interval fastening positions

⑨⑧⑦⑥⑤

④

③

①②

3200mmRisk

Assessment

T.Yokoyama, S. Izumi, S. Sakai (2001)

J. Virulsri, S. Izumi, S. Sakai (2002)

• In nuclear power plant, in order to optimize conflicting objectives such as low levels of system unavailability and low costs in maintenance activities of nuclear power plant, the multi-objective optimization is applied. Nevertheless, some areas of the Pareto-solutions may lead to inappropriate optimal solutions because of their high sensitivities. Therefore, the new method of sensitivity analysis for selecting the Pareto optimal solutions is proposed in order to obtain the most suitable set of solutions for the maintenance activities.

Multi-objective 　 optimization 　 approach to maintenance of nuclear power plant

0

500

1000

1500

2000

2500

3000

0.0E+00 2.0E-05 4.0E-05 6.0E-05 8.0E-05 1.0E-04 1.2E-04 1.4E-04

B

C

Most appropriate point

Unavailability

Mai

nten

ance

Cos

t ($)

0

0.5

1

1.5

2

2.5

0.0E+00 2.0E-05 4.0E-05 6.0E-05 8.0E-05 1.0E-04

Most appropriate point

Unavailability

Sen

siti

vity

Ind

ex

B

C

A

The development network-based R6 system

• The necessity of flaw evaluation system is increasing with a lot of demands in applicable program that is convenient for users to operate. So it is important to share the technique of flaw evaluation all over the world and Java is expected to be a very strong tool to achieve this purpose.We developed R6 system and distributed it by using JavaRMI and XML.

R6 system

client

server

connect

)}0.65L0.7exp(){0.30.14L(1K 6r

2rr

R6 method

(Java)

2. Life Cycle Assessment

Formulation of sensitivity analysis in life cycle assessment using a perturbation method

S. Sakai, Lu Weizhe, S. Izumi (2001)• A new method for the efficient sensitivity

analysis in LCA is proposed. Introduction of a perturbation method to matrix-based life cycle assessment will enable one to evaluate the degree of influence of each element on the total sum of environmental loads. Special emphasis is placed on the advantage that the sensitivity matrix, in which each entity denotes the sensitivity of the corresponding element, is derived as a result of matrix operation. The proposed method is compared with another sensitivity analysis and the validity of current method has been confirmed. Using this formulation, the important elements can be distinguished easily and so the method is expected to be applied to the decision-making process.

1P 2P

3P

11

1

a

b

c

1b 2b

3bijij

ij aas

/

/

T a r g e t s e n s i t iv i t y

3. Fracture Mechanics

Stereoscopic Fracture Analysis It is necessary to clarify the cause of fracture or accident.This research can improve 3-D measuring accuracy and visualize fracture surface in reality.

2 ¼ C r-1Mo Creep-Fatigue fracture surface

J. Jiang, S. Sakai (2001)

Characterization of fatigue fracture surface using wavelet transformation

In the fatigue fracture surface, the ratio of the area which the striation covers, namely the striated surface ratio, has been said to be deeply related to K. Therefore, the striated surface ratio is the important factor for the stress estimation.

The wavelet transformation (WT) is well known to be suitable to the local feature characterization. The applicability of WT to the characterization of striated surface ratio is examined.

To examine the validity of the method, it was applied to the Cr-Mo fatigue fracture surface. It is evaluated by the method that the non-striated area is 10%, the striated area is 26% and the transition area is 64%.

The result is compared with that evaluated from visual observation. The results of the evaluation of the striated and non-striated area show good agreement with the result of the human observation.

K.Yamagiwa(2002)

Wavelet transformation

The evaluation of the damage of the thermal

power plant by using hot hardness test

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200Temperature(℃)

Vic

kers

har

dnes

s(HV)

Coupling part

Center pore at high- temperature

Periphery at high- temperature

Hardness-temperature curve

• The thermal power plants play an important role as an electric power supply source in our country. In such a situation, the plants which exceeded the design life increase year after year. So, the establishment of an accurate life prediction method of degradation damage in a state of high temperature components such as boiler and turbine is important.

• We evaluate damage of disposal turbine rotor material of the Cr-Mo-V steel by using hot hardness test. More accurate evaluations are realized as compared with room-temperature hardness one.

T.Murakami, S. Izumi, S. Sakai (2002)

Hot Hardness RT Hardness

4. Micro-Nano Mechanics

Dislocation Dynamics Simulation

In semiconductor devices, it is known that the dislocation causes electrical failures. But observation of dislocation motion in the micro-scale devices is very difficult. Therefore, it is useful for searching the source of dislocation if we can simulate the

dislocation movement.

T. Miyake, S. Izumi, S. Sakai (2002)

Simulation of dislocation annihilation.

The development of molecular dynamics potential for an Si-H system and its application to the translation

ally activated CVD process

• In order to investigate the reaction probability of silane dissociative adsorption, we developed a new Si-H potential. By using molecular dynamics with our potential, the dependence of the molecular and substrate temperatures on the reaction probability was investigated and was compared the results with the translationally activated process.

S. Izumi, S. Sakai (2002)

The Molecular Dynamics Study for the Damage and Etching Properties of Low Energy Ar Ion Implantati

on

• Molecular dynamics simulations have been performed for the Ar bombardment to Si surface in order to investigate the damage and etching properties. The dependence of the ion energy, the polar angle of the ion and substrate strain was investigated.

S. Izumi, S. Sakai (2001)

The interface energy and interface stress of amorphous silicon

• Surface energy and surface stress is a key parameter for predicting of the intrinsic stress of thin film. We have evaluated the statistical properties of the surface energy and the surface stress of amorphous silicon by using molecular dynamics. For applications in the continuum mechanics, the surface stress can be treated as the initial stress generated in a surface region with a thickness of about 0.4 nm.

Surface energy

Surface stress

1.44±0.03 )( 2mJ

-0.48±0.06 )( mN

S=64 [nm2]Amorphous siliconAmorphous silicon

S. Izumi, S. Hara, S. Sakai (2001)

Brief Presentation

Application of Reliability Application of Reliability Engineering to the Field of Engineering to the Field of

Life Cycle AssessmentLife Cycle Assessment The University of Tokyo

School of Engineering

Shinsuke Sakai

Brief Presentation

BackgroundBackground

• Lot of Uncertainty in LCA• Importance of identifying the prioritized elements

→ sensitivity• all sensitivities for each element must be

calculated • conventional evaluation method of sensitivity

→consumes much time for the procedure• the mathematical perturbation method combined

with matrix-based LCA enables us to perform an efficient sensitivity evaluation

Principle of MLCAPrinciple of MLCA

0

1

0

1

1

c

b

a321 ppp

1P 2P

3P

11

1

a

b

c

1b 2b

3b

00

1 1 b

a

m

m

p

Process amountProcess amount

Material balance for aMaterial balance for a0321 ppp

A

XAP

Treatment for B.C.Treatment for B.C.

XAP 1

Process Material : jiaij 、

Application to sensitivity analysisApplication to sensitivity analysis in LCA in LCA

ijijij aas

/

/

Target sensitivity

eIPPPPP 00

Small variation on ija

01 PA

APij

I

a

1

ija

A

Perturbation method

01 PAAP Iij

I

e

eIij

T

ITT

01 PAAB

PBPB

01

/

/

PAAB Iij

Tij

ijijij

a

aas

• is is calculated calculated onceonce

1A

Example of steel-making Example of steel-making processprocess