Abstract: Engineering safety diagnosis of crashed subway electric multiple units (EMUs) was
conducted for safety assessment. Several advanced engineering analysis techniques including
nondestructive evaluation (NDE) techniques and stress and structural analyses programs, were
performed for better understandings and exploration of failure analysis and safety concerns. Moreover,
stress and structural analyses using commercial I-DEAS software provided important information on
stress distribution and load transfer mechanisms as well as the amount of damages during the crash.
One-dimensional crashworthiness was conducted to estimate the speed at the time of the accident by
investigating the permanent deformation of the train. The estimated speed was used as the input value
of a three-dimensional crashworthiness analysis. A good agreement has been found between
structural analysis results and the results of actual damages in EMUs during crash. In this
investigation, various advanced engineering analysis techniques for the safety analysis of subway
EMUs have been introduced and the analysis results have been used to provide the critical
information for the safety assessment of crashed EMUs.
Abstract: The new composite method combined by fiber laminates and steel plate composites was
applied for reinforced concrete members. The experimental investigation for the applicability of this
method was presented for flexural member. Two different fiber materials such as carbon and
fiberglass with steel plate were used. All specimen using fiber material and steel plate were divided by
two different groups such as control group without strengthening, innovated fiber-steel laminate
composites group. Failure modes and load-deflection curves were presented for flexural members by
fiber-steel laminate composites. Numerical analysis for tested beam was investigated.
Abstract: A micromechanics model based on the theoretical framework of plastic localization
into a band introduced by Rice  is developed. The model employed consists of a planar band with
a square array of equally sized cells, with a spherical void located in the centre of each cell. The
micromechanics model is applied to analyze the rupture mechanisms associated with mixed mode
ductile fracture. The stress state is characterized by the stress triaxiality T and the Lode parameter μ,
which adequately describe the stress state ahead of a crack tip under mixed mode loading of an
isotropic elasto-plastic material. The main focus is the influence of μ on void growth and
coalescence behavior. It is shown that the Lode parameter exerts a strong influence upon this
Abstract: Pressure casting dies are subjected to a large number of thermal as well as mechanical load
cycles, which are leading to a characteristic thermally induced crack network on the die surface. As a
typical representative for a die material the cyclic thermo-mechanical behavior of the hot work tool
steel grade 1.2343 (X38CrMoV5-1) is investigated both experimentally as well as numerically. On
the one hand the information from isothermal compression-tension tests is used in a subsequent
analysis to calibrate a constitutive model that takes into account the characteristic combined
isotropic-kinematic hardening/softening of the material. On the other hand the non-isothermal
mechanical response of the material to thermal cycles is characterized by means of a periodic laser
pulse applied to a small plate-like specimen which is cooled on the back. The residual stresses
developing at the surface of the irradiated region of the specimen are determined ex-situ by means of
X-ray diffraction. The obtained values agree well with the results of an accompanying finite-element
study. This information is used to verify the calibrated constitutive model. The material law is finally
used for the prediction of stresses and strains in a die.
Abstract: If Fiber Reinforced Metal Laminates (FRMLs) were delaminated, the decrease of
stiffness and fiber bridging effect would result in the sudden aggravation of fatigue characteristics.
It was reported that the delamination of FRMLs resulted from the crack of Al alloy layers and that it
depended on the crack growth. When FRMLs with circular holes was un-cracked but was
delaminated, it was impossible to analyze them by conventional fracture parameters expressed as
the function of cracks. Therefore, a new analytical model called Pseudo Crack Model (PCM) was
suggested to compare the delaminations whether cracks were made or not. The relationship
between the crack consumption rate (Ccrack) and the delamination consumption rate (Cdel) was
discussed and it was also known that the effect of the Ccrack was larger than that of the Cdel.
Abstract: The diverse studies on Al/GFRP laminates with the circular holes, therefore, have been
carried out recently. The recent studies just focused on the behavior of the fatigue crack
propagation and the delamination when the shape and the size of the notches were changed.
Therefore, this study evaluated the location effect of the defects in the vicinity of the circular notch
of the high strength monolithic aluminum and Al/GFRP laminates on the initiation life (Ni) of the
fatigue cracks, the relationship between the crack length (a) and the fatigue life (N). In addition,
the fatigue crack behavior of Al/GFRP laminates was studied when the fatigue loading and the
interlaminar delamination took place at the same time during crack propagation. In conclusions,
(1) for the monolithic aluminum, 10% of the failure life at θ2=30° was more increased than that at
θ3=60°. (2) The crack length and the fatigue life behavior of Al/GFRP laminates according to the
location of the artificial defect were different from those of the monolithic aluminum. Namely, the
fatigue life of θ1=0° and θ2=30° were remarkably shorter than those of θ3=60° and θ4=90°.
Abstract: The CRISFIS project (supported by ADEME agency) consists in jointly studying the
squealing and cracking aspects of the high power disc brakes for TGV very high speed trains. This
paper deals with the progress concerning the cracking part. An experimental and modelling strategy
is adopted in order to better understand and predict brake disc cracking. Braking tests conducted on
an industrial scale-one test bench are presented. In a first step, the influence of the pad-type on the
thermal loading applied to the disc is studied by means of an infrared camera and thermocouples
embedded in the pads and in the disc. In a second step, the thermal maps extracted from
thermographic monitoring are used as input data for thermal-mechanical calculations. Finally, the
results of modelling and tests are compared to the damage observed on the brake discs.
Abstract: It is well known that the main failure mechanisms in die-casting mould are heat checking
due to thermal fatigue and melt-out caused by chemical reaction between die and molten alloys.
Thermal fatigue tests were carried out using the thermal cycle simulator to establish the proper
method to estimate the thermal fatigue resistance of hot die steel. In this study, the thermal shock
tester consisted of induction heating and water spray cooling unit was constructed to evaluate
thermal crack propagation resistance and the sum of crack length per unit specimen length, Lm is
proposed as the index representing the susceptibility to crack initiation and propagation. Also, new
concept of measurement for the melt-out behavior was suggested. AISI H13 hot work tool steel was
solution treated and tempered at various temperatures, to control the hardness and toughness that
have effect on the behavior of thermal crack propagation. The result of thermal fatigue test showed
that there is optimum value of hardness and impact energy to maximize the thermal crack
propagation resistance. The influence of nitriding on melt-out resistance was also investigated. The
dissolution rate due to melt-out phenomenon tended to be smaller for thicker compound layer.
Furthermore, the resistance to melt-out was affected by the compound layer thickness rather than
that of diffusion layer. The results of the both tests properly reflect the effect of materials properties
on failure modes of die-casting mould and it means those test methods are suitable to evaluate the
durability of hot work tool steel for die-casting.
Abstract: The experimental investigation was performed to find the associated changes in
characteristics of fretting wear with various water temperatures. Fretting can be defined as the
oscillatory motion with very small amplitudes, which usually occur between two contacting surfaces.
The fretting wear, which occurs between cladding tubes of nuclear fuel rod and grids, causes in
damages the cladding tubes by flow induced vibration in a nuclear reactor. In this paper, the fretting
wear tests were carried out using the zirconium alloy tubes and the grids with increasing the water
temperature. The tube materials in water of 20, 50 and 80 were tested with the applied load of
20N and the relative amplitude of 200. The worn surfaces were observed by SEM, EDX and 2D
surface profiler. As the water temperature increased, the wear volume was decreased. However, oxide
layer was increased on the worn surface. The abrasive wear mechanism was observed at water
temperature of 20 and adhesive wear mechanism occurred at water temperature of 50 and 80.
As the water temperature increased, surface micro-hardness was decreased. Also, wear depth and
wear width were decreased due to increasing stick phenomenon. Stick regime occurred due to the
formation of oxide layer on the worn surface with increasing water temperatures.