Abstract: The hit rate is affected by the shooting impact of the human-rifle system. The impact
response of the human-rifle system is determined mainly by the geometrical parameters and contact
boundary conditions. In this study, the height and weight of the considered human model are 170
cm and 60 kg, as these parameters mirror 50 per cent of Korean males in their twenties. The rifle
model is applied on the K-2. The impact path analysis of three typical shooting postures: the
standing, kneeling and prone shooting postures is performed with experimental impulse-time
history during a shooting test. The biomechanical response such as impact transfer path, force
history and displacement history are investigated.
Abstract: The biomechanical changes brought on by spine fusion and the artificial disc designs to
restore physiologic motion were studied by using a cervical spine computer model. Fusion
increased the motion compensation at the adjacent segment during flexion and extension. The
global rotational stiffness and segmental disc forces were also increased after fusion. Among the
three prosthetic disc designs, the PDD-III (5-DOF spherical joint in plane parallel with the C5-C6
disc level) maintained the normal motion and minimized load build up of adjacent segment.
Abstract: As one kind of the most important cells in human body, myocardial cell becomes the focus of
attention, not only the biologist but also the researchers of mechanics. A new viscoelastic
constitutive model of the living myocardial cell is developed based on the micropipette suction
experiment in which the surface of the cell is aspirated into a small glass tube while tracking the
leading edge of its surface. Some numerical simulations are presented by finite element to model
the whole process of micropipette suction of the myocardial cell. Meanwhile, a model cell with both
mechanical behavior and physiological function is being developed, to prove the viscoelastic
constitutive model and to predict more results of myocardial cell under different physiology
Abstract: Dynamic crack propagation in PMMA was studied using the method of caustics in combination
with a Cranz-Schardin type high-speed camera. Three different types of specimen geometries were employed
to achieve the crack acceleration, deceleration and re-acceleration process in one fracture event. Dynamic
stress intensity factor KID and the crack velocity were evaluated in the course of crack propagation to obtain
the relationship between KID and the velocity The effect of crack acceleration and deceleration on the KID
-velocity relations was examined.
Abstract: The purpose of the present study is to evaluate thermal shock properties of the ATJ
graphite using laser irradiation techniques. Cracks of thermal shock specimens are initiated by
maximum tensile stress field. Thermal shock resistance of the ATJ graphite is correlated with
thermal parameter and mechanical property. To simulate the thermal stress conditions of rocket
nozzle throat for the evaluation of the thermal shock resistance of ATJ graphite, the laser irradiation
was applied at the central area of disk specimen. Thermal shock resistance was related to the
geometry, the maximum stress, and the thermal and mechanical property. Also the analyses of
transient temperature and thermal stress were performed by the finite element method with
nonlinear code ABAQUS. Analyses were specially performed for several kinds of shape to
determine the minimum power density which could be cracked the specimen. The shape of the
thermal shock specimen which was cracked under the lower power density was obtained and the
result will be proved to the test.
Abstract: Threshold stress intensity factor or KIH required to initiate a delayed hydride crack in the
axial direction of a Zr-2.5Nb tube was determined at temperatures of 160 oC to 280 oC. KIH
remained constant at temperatures from 160 to 250 oC, increased with an increasing temperature in
excess of 280 oC using a load decreasing method. To correlate KIH and dislocation twins, tensile
tests were conducted on the Zr-2.5Nb tube and textural changes during tensile tests were
investigated using an X-ray diffractometer. The extent of the twins increased from 150 to 300 oC
and then decreased at temperatures in excess of 300 oC with no twins occurring at 350 oC.
Temperature dependencies of KIH and a temperature limit for delayed hydride cracking were
discussed with cracking of hydrides by the twins. This study provides supportive evidence to the
feasibility of Kim’s DHC model.
Abstract: Experimental methods that can be used in three-dimensional mixed mode fracture
researches are investigated. The methods are capable of determining the initiation load, maximal
load, crack tip opening displacement, crack tip slipping displacement and initiation angle of the
mixed mode crack simply and conveniently. As an example, the effect of thickness on mixed-mode
I/II fracture of a kind of aluminum alloy is revealed by the methods.
Abstract: The objective of this study is to evaluate the mechanical properties of static, quasidynamic
and dynamic fracture toughness of glass-filled ceramic as promising structural material for
a dome port cover of a ramjet engine system. Static and quasi-dynamic tests were carried out using
SEPB (Single Edge Pre-cracked Beam) specimens. Static and dynamic fracture toughness tests
were also performed using ASTM and strain gage methods with SENB (Single Edge Notched
Beam) specimens machined with various notch radii. The critical notch radius was evaluated.
Below the critical notch radius, the static fracture toughness of the SENB specimen well agreed
with that of the SEPB specimen.
Abstract: The objective of this paper is to investigate failure characteristics of SA508 carbon steel
in ductile-brittle transition temperature region. To achieve this goal, a series of finite element
analyses as well as fracture toughness tests are performed for pre-cracked V-notch specimens. An
assessment of failure probabilities is, then, carried out employing Weibull stress models with
different rank probability options. Finally, a prototype of toughness scale diagram is derived
through comparison of estimated fracture toughness data with those for compact tension specimens.
The present results can be utilized to found a basis of realistic integrity evaluation on major nuclear
components containing defect.
Abstract: In this paper, the applicability of local approach is examined for SA515 Gr.60 nuclear
steel through a series of finite element analyses incorporating modified GTN and Rousselier models
as well as fracture toughness tests. To achieve the goal, fracture toughness test data of standard
compact tension (CT) specimens are used for calibration of micro-mechanical parameters. Then,
from finite element analyses employing the calibrated parameters, fracture resistance (J-R) curves
of CT specimens with different crack length to width ratio, with different thickness and
with/without 20% side-grooves are predicted. Finally, suitability of the numerically estimated J-R
curves was verified by comparison with the corresponding experimental J-R curves.