Abstract: At the previous study of new metal gasket, contact
width and contact stress were important design parameter for
optimizing metal gasket performance. However, the range of contact
stress had not been investigated thoroughly. In this study, we
conducted a gasket design optimization based on an elastic and plastic
contact stress analysis considering forming effect using FEM. The
gasket model was simulated by using two simulation stages which is
forming and tightening simulation. The optimum design based on an
elastic and plastic contact stress was founded. Final evaluation was
determined by helium leak quantity to check leakage performance of
both type of gaskets. The helium leak test shows that a gasket based
on the plastic contact stress design better than based on elastic stress
design.
Abstract: This article provides partial evaluation index and its
standard of sports aerobics, including the following 12 indexes: health
vitality, coordination, flexibility, accuracy, pace, endurance, elasticity,
self-confidence, form, control, uniformity and musicality. The
three-layer BP artificial neural network model including input layer,
hidden layer and output layer is established. The result shows that the
model can well reflect the non-linear relationship between the
performance of 12 indexes and the overall performance. The predicted
value of each sample is very close to the true value, with a relative
error fluctuating around of 5%, and the network training is successful.
It shows that BP network has high prediction accuracy and good
generalization capacity if being applied in sports aerobics performance
evaluation after effective training.
Abstract: A new method identifies coupled fluid-structure system with a reduced set of state variables is presented. Assuming that the structural model is known a priori either from an analysis or a test and using linear transformations between structural and aeroelastic states, it is possible to deduce aerodynamic information from sampled time histories of the aeroelastic system. More specifically given a finite set of structural modes the method extracts generalized aerodynamic force matrix corresponding to these mode shapes. Once the aerodynamic forces are known, an aeroelastic reduced-order model can be constructed in discrete-time, state-space format by coupling the structural model and the aerodynamic system. The resulting reduced-order model is suitable for constant Mach, varying density analysis.
Abstract: This study examines the inelastic behavior of adjacent planar reinforced concrete (R.C.) frames subjected to strong ground motions. The investigation focuses on the effects of vertical ground motion on the seismic pounding. The examined structures are modeled and analyzed by RUAUMOKO dynamic nonlinear analysis program using reliable hysteretic models for both structural members and contact elements. It is found that the vertical ground motion mildly affects the seismic response of adjacent buildings subjected to structural pounding and, for this reason, it can be ignored from the displacement and interstorey drifts assessment. However, the structural damage is moderately affected by the vertical component of earthquakes.
Abstract: In this study Homotopy Perturbation Method (HPM) is employed to investigate free vibration of an Euler beam with variable stiffness resting on an elastic foundation. HPM is an easy-to-use and very efficient technique for the solution of linear or nonlinear problems. HPM produces analytical approximate expression which is continuous in the solution domain. This work shows that HPM is a promising method for free vibration analysis of nonuniform Euler beams on elastic foundation. Several case problems have been solved by using the technique and solutions have been compared with those available in the literature.
Abstract: Modeling and vibration of a flexible link manipulator
with tow flexible links and rigid joints are investigated which can
include an arbitrary number of flexible links. Hamilton principle and
finite element approach is proposed to model the dynamics of
flexible manipulators. The links are assumed to be deflection due to
bending. The association between elastic displacements of links is
investigated, took into account the coupling effects of elastic motion
and rigid motion. Flexible links are treated as Euler-Bernoulli beams
and the shear deformation is thus abandoned. The dynamic behavior
due to flexibility of links is well demonstrated through numerical
simulation. The rigid-body motion and elastic deformations are
separated by linearizing the equations of motion around the rigid
body reference path. Simulation results are shown on for both
position and force trajectory tracking tasks in the presence of varying
parameters and unknown dynamics remarkably well. The proposed
method can be used in both dynamic simulation and controller
design.
Abstract: The effect of the discontinuity of the rail ends and the
presence of lower modulus insulation material at the gap to the
variations of stresses in the insulated rail joint (IRJ) is presented. A
three-dimensional wheel – rail contact model in the finite element
framework is used for the analysis. It is shown that the maximum stress
occurs in the subsurface of the railhead when the wheel contact occurs
far away from the rail end and migrates to the railhead surface as the
wheel approaches the rail end; under this condition, the interface
between the rail ends and the insulation material has suffered
significantly increased levels of stress concentration. The ratio of the
elastic modulus of the railhead and insulation material is found to alter
the levels of stress concentration. Numerical result indicates that a
higher elastic modulus insulating material can reduce the stress
concentration in the railhead but will generate higher stresses in the
insulation material, leading to earlier failure of the insulation material
Abstract: This paper study the behavior of the solution at the crack edges for an elliptical crack with developing cusps, Ω in the plane elasticity subjected to shear loading. The problem of finding the resulting shear stress can be formulated as a hypersingular integral equation over Ω and it is then transformed into a similar equation over a circular region, D, using conformal mapping. An appropriate collocation points are chosen on the region D to reduce the hypersingular integral equation into a system of linear equations with (2N+1)(N+1) unknown coefficients, which will later be used in the determination of shear stress intensity factors and maximum shear stress intensity. Numerical solution for the considered problem are compared with the existing asymptotic solution, and displayed graphically. Our results give a very good agreement to the existing asymptotic solutions.
Abstract: Interior brick-infill partitions are usually considered as
non-structural components and only their weight is accounted for in
practical structural design. In this study, their effect on the progressive
collapse resistance of an RC building subjected to sudden column loss
is investigated. Three notional column loss conditions with four
different brick-infill locations are considered. Column-loss response
analyses of the RC building with and without brick infills are carried
out. Analysis results indicate that the collapse resistance is only
slightly influenced by the brick infills due to their brittle failure
characteristic. Even so, they may help to reduce the inelastic
displacement response under column loss. For practical engineering, it
is reasonably conservative to only consider the weight of brick-infill
partitions in the structural analysis.
Abstract: The modeling of inelastic behavior of plastic materials requires measurements providing information on material response to different multiaxial loading conditions. Different triaxiality conditions and values of Lode parameters have to be
covered for complex description of the material plastic behavior.
Samples geometries providing material plastic behavoiur over the range of interest are proposed with the use of FEM analysis. Round samples with 3 different notches and smooth surface are used
together with butterfly type of samples tested at angle ranging for 0 to
90°. Identification of ductile damage parameters is carried out on
the basis of obtained experimental data for austenitic stainless steel.
The obtained material plastic damage parameters are subsequently applied to FEM simulation of notched CT normally samples used for
fracture mechanics testing and results from the simulation are
compared with real tests.
Abstract: Elastic boundary eigensolution problems are converted
into boundary integral equations by potential theory. The kernels of
the boundary integral equations have both the logarithmic and Hilbert
singularity simultaneously. We present the mechanical quadrature
methods for solving eigensolutions of the boundary integral equations
by dealing with two kinds of singularities at the same time. The methods
possess high accuracy O(h3) and low computing complexity. The
convergence and stability are proved based on Anselone-s collective
compact theory. Bases on the asymptotic error expansion with odd
powers, we can greatly improve the accuracy of the approximation,
and also derive a posteriori error estimate which can be used for
constructing self-adaptive algorithms. The efficiency of the algorithms
are illustrated by numerical examples.
Abstract: The present paper concerns with the influence of fiber
packing on the transverse plastic properties of metal matrix
composites. A micromechanical modeling procedure is used to
predict the effective mechanical properties of composite materials at
large tensile and compressive deformations. Microstructure is
represented by a repeating unit cell (RUC). Two fiber arrays are
considered including ideal square fiber packing and random fiber
packing defined by random sequential algorithm. The
micromechanical modeling procedure is implemented for
graphite/aluminum metal matrix composite in which the
reinforcement behaves as elastic, isotropic solids and the matrix is
modeled as an isotropic elastic-plastic solid following the von Mises
criterion with isotropic hardening and the Ramberg-Osgood
relationship between equivalent true stress and logarithmic strain.
The deformation is increased to a considerable value to evaluate both
elastic and plastic behaviors of metal matrix composites. The yields
strength and true elastic-plastic stress are determined for
graphite/aluminum composites.
Abstract: The effect of notch depth on the elastic new strainconcentration
factor (SNCF) of rectangular bars with single edge Unotch
under combined loading is studied here. The finite element
method (FEM) and super position technique are used in the current
study. This new SNCF under combined loading of static tension and
pure bending has been defined under triaxial stress state. The
employed specimens have constant gross thickness of 16.7 mm and
net section thickness varied to give net-to-gross thickness ratio ho/Ho
from 0.2 to 0.95. The results indicated that the elastic SNCF for
combined loading increases with increasing notch depth up to ho/Ho =
0.7 and sharply decreases with increasing notch depth. It is also
indicated that the elastic SNCF of combined loading is greater than
that of pure bending and less than that of the static tension for 0.2 ≤
ho/Ho ≤ 0.7. However, the elastic SNCF of combined loading is the
elastic SNCF for static tension and less than that of pure bending for
shallow notches (i.e. 0.8 ≤ ho/Ho ≤ 0.95).
Abstract: The characteristic bending strength (MOR) and mean
modulus of elasticity (MOE) of tropical hardwood red seraya (Shorea
spp.) plywood were determined using European Standard EN310 and
EN789. The thickness of the test specimen was 4.0mm, 7.0mm,
9.0mm, 12.0mm and 15.0mm. The experiment found that the MOR
of red seraya plywood in EN310 is about 12% to 20% and 7% to
24% higher than EN789 whereas MOE were about 28% to 41% and
30% to 36% lower than those obtained from EN 789 for test
specimens parallel and perpendicular to the grain direction. The
linear regression shows that MOR and MOE for EN789 is about 0.8
times less and 1.5 times more than EN310. The experiment also
found that the MOR and MOE of EN310 and EN789 also depend on
the wood species that used in the experiment.
Abstract: In the present study, a numerical analysis is carried
out to investigate unsteady MHD (magneto-hydrodynamic) flow and
heat transfer of a non-Newtonian second grade viscoelastic fluid
over an oscillatory stretching sheet. The flow is induced due to an
infinite elastic sheet which is stretched oscillatory (back and forth) in
its own plane. Effect of viscous dissipation and joule heating are
taken into account. The non-linear differential equations governing
the problem are transformed into system of non-dimensional
differential equations using similarity transformations. A newly
developed meshfree numerical technique Element free Galerkin
method (EFGM) is employed to solve the coupled non linear
differential equations. The results illustrating the effect of various
parameters like viscoelastic parameter, Hartman number, relative
frequency amplitude of the oscillatory sheet to the stretching rate and
Eckert number on velocity and temperature field are reported in
terms of graphs and tables. The present model finds its application in
polymer extrusion, drawing of plastic films and wires, glass, fiber
and paper production etc.
Abstract: Among the chemicals used for ammunition production, TNT (Trinitrotoluene) play a significant role since World War I and II. Various types of military weapon utilize TNT in casting process. However, the TNT casting process for warhead is difficult to control the cooling rate of the liquid TNT. This problem occurs because the casting process lacks the equipment to detect the temperature during the casting procedure This study presents the temperature detected by infrared camera to illustrate the cooling rate and cooling zone of curing, and demonstrates the optimization of TNT condition to reduce the risk of air gap occurred in the warhead which can result in the destruction afterward. Premature initiation of explosive-filled projectiles in response to set-back forces during gunfiring cause by casting defects. Finally the study can help improving the process of the TNT casting. The operators can control the curing of TNT inside the case by rising up the heating rod at the proper time. Consequently this can reduce tremendous time of rework if the air gaps occur and increase strength to lower elastic modulus. Therefore, it can be clearly concluded that the use of Infrared Cameras in this process is another method to improve the casting procedure.
Abstract: In this study, aeroelastic response and performance
analyses have been conducted for a 5MW-Class composite wind
turbine blade model. Advanced coupled numerical method based on
computational fluid dynamics (CFD) and computational flexible
multi-body dynamics (CFMBD) has been developed in order to
investigate aeroelastic responses and performance characteristics of
the rotating composite blade. Reynolds-Averaged Navier-Stokes
(RANS) equations with k-ω SST turbulence model were solved for
unsteady flow problems on the rotating turbine blade model. Also,
structural analyses considering rotating effect have been conducted
using the general nonlinear finite element method. A fully implicit
time marching scheme based on the Newmark direct integration
method is applied to solve the coupled aeroelastic governing equations
of the 3D turbine blade for fluid-structure interaction (FSI) problems.
Detailed dynamic responses and instantaneous velocity contour on the
blade surfaces which considering flow-separation effects were
presented to show the multi-physical phenomenon of the huge rotating
wind- turbine blade model.
Abstract: Self-compacting concrete (SCC), a new kind of high
performance concrete (HPC) have been first developed in Japan in
1986. The development of SCC has made casting of dense
reinforcement and mass concrete convenient, has minimized noise.
Fresh self-compacting concrete (SCC) flows into formwork and
around obstructions under its own weight to fill it completely and
self-compact (without any need for vibration), without any
segregation and blocking. The elimination of the need for
compaction leads to better quality concrete and substantial
improvement of working conditions. SCC mixes generally have a
much higher content of fine fillers, including cement, and produce
excessively high compressive strength concrete, which restricts its
field of application to special concrete only. To use SCC mixes in
general concrete construction practice, requires low cost materials to
make inexpensive concrete.
Rice husk ash (RHA) has been used as a highly reactive
pozzolanic material to improve the microstructure of the interfacial
transition zone (ITZ) between the cement paste and the aggregate in
self compacting concrete. Mechanical experiments of RHA blended
Portland cement concretes revealed that in addition to the pozzolanic
reactivity of RHA (chemical aspect), the particle grading (physical
aspect) of cement and RHA mixtures also exerted significant
influences on the blending efficiency.
The scope of this research was to determine the usefulness of Rice
husk ash (RHA) in the development of economical self compacting
concrete (SCC). The cost of materials will be decreased by reducing
the cement content by using waste material like rice husk ash instead
of.
This paper presents a study on the development of Mechanical
properties up to 180 days of self compacting and ordinary concretes
with rice-husk ash (RHA), from a rice paddy milling industry in
Rasht (Iran). Two different replacement percentages of cement by
RHA, 10%, and 20%, and two different water/cementicious material
ratios (0.40 and 0.35), were used for both of self compacting and
normal concrete specimens. The results are compared with those of
the self compacting concrete without RHA, with compressive,
flexural strength and modulus of elasticity. It is concluded that RHA
provides a positive effect on the Mechanical properties at age after
60 days.
Base of the result self compacting concrete specimens have higher
value than normal concrete specimens in all test except modulus of
elasticity. Also specimens with 20% replacement of cement by RHA
have the best performance.
Abstract: Hysitron TriboIndenterTM TI 950 system has been
used for studying the local viscoelastic properties of porcine
intervertebral disc end plate by means of nanoscale mechanical
dynamic analysis. The specimen of an endplate was cut from fresh
porcine vertebra dissected from 16 month animal. The lumbar spine
motion segments were dissected and 5 millimeter thick plates of
vertebral body, endplate and annulus fibrosus were prepared for
nanoindentation. The surface of the sample was kept in physiological
solution during nanoindentation experiment. We obtained mechanical
characteristics of different areas of native endplate (endplate middle
and vertebra and annulus fibrosus boundary).
Abstract: Transcription factor p53 has a powerful tumor
suppressing function that is associated with many cancers. However,
p53 of the molecular weight was higher make the limitation across to
skin or cell membrane. Thymidine dinucleotide (pTT), an
oligonucleotide, can activate the p53 transcription factor. pTT is a
hydrophilic and negative charge oligonucleotide, which delivery in to
cell membrane need an appropriate carrier. The aim of this study was
to improve the bioavailability of the nucleotide fragment, thymidine
dinucleotide (pTT), using elasic liposome carriers to deliver the drug
into the skin. The study demonstrate that dioleoylphosphocholine
(DOPC) incorporated with sodium cholate at molar ratio 1:1 can
archived the particle size about 220 nm. This elastic liposome could
penetration through skin from stratum corneum to whole epidermis by
confocal laser scanning microscopy (CLSM). Moreover, we observed
the the slight increase in generation of p53 by western blot.