Abstract: At the nanoscale, surface effect could cause atomistic structures a pre-stressed or
pre-deformed state, which would consequently have a great dependence on their bulk mechanical
properties. Besides, according to molecular mechanics [1,2], the effect of the non-bonding
interactions among the atoms that are separated by equal or more than two bonds, say, van der
Waals (vdW) forces, should be taken into account. Thus, the underlying objective of the study
attempts to explore the extent of the surface effect and the in-layer vdW interactions on the
mechanical properties of single/multi-walled carbon nanotubes(S/MWCNTs) with two different
types of chiralities, including zigzag and armchair.
To deal with the problem, an atomistic-continuum modeling (ACM) approach is introduced. The
ACM is established by molecular dynamics (MD) simulation and equivalent continuum modeling
(ECM). MD simulation is adopted to derive the initial equilibrium state of CNTs due to the surface
effect, and the ECM is applied to calculate the mechanical properties of CNTs. The ECM is
formulated based on the finite element (FE) approximations, which are composed of
three-dimensional beam elements and one-dimensional non-linear spring elements. They basically
represent the bonding and non-bonding interactions, respectively. The equivalent material constants
of these two types of elements are derived from classical molecular mechanics and beam theory.
The present results are also compared with those obtained from other simulations and experiments.
Abstract: Molecular Dynamics (MD) simulations of indentation and scratch over crystal nickel
(100) were carried out to investigate the microstructure evolution at nanoscale. The dislocation
nucleation and propagation during process were observed preferably between close-packed planes.
Dislocation loops are formed under both indentation and scratch process, and indentation and
friction energy were transferred to the substrate in the form of phonon of disordered atoms, then
part of the energy dissipated and rest is remain in the form of permanent plastic deformation.
Abstract: The elastic field around a nanosized spheroidal cavity is derived on the basis of surface
elasticity theory. The effects of surface energy, shape and size of the cavity are discussed. It is seen
that the stress field near the nanosized cavity depends on the shape and the size of the cavity as well as
the properties of the surface. These new characteristics are different from those predicted by the
classical elasticity and may illuminate some new mechanisms at nanoscale.
Abstract: In this paper, the iBone (Imitation Bone) model which is coupled with Turing
reaction-diffusion system and FEM, is used. The numerical simulation of bone forming process by
considering the osteoclasts and osteoblasts process are conducted. The results shown, that the bone
mass is increased with increase of the initial load value, then fibula and femur bones are obtained
respectively by keeping the required bone forming value. The different bone shapes are obtained by
changing the both bone keeping value and the compressing force value. When set larger bone keeping
value by keeping larger constant compressing force value, bone shape as a pipe with hole just like
femur, when set smaller bone keeping value by keeping the smaller constant compressing force value,
it is close to solid pillar as like fibula.
Abstract: Purpose: Experiment research and theory analysis to the heat transmission and mechanics
property about organism tissue. Method: Heat transmission and the dynamic change of temperature
should be survey in the course of sand-therapy, then compare it with simulative result; workpieces
were made, buried in different temperature and buried in the sand for 30 minutes, to test its
biomechanics property and compare to group without buried in sand. Result: (1) The initial
temperature field of the sand was not well mixed. (2) The test spot of the electric thermocouple was
inaccuracies when test the temperature. (3) Every parameter of the mathematical model is taken from
the bibliography, it may not fix actually to the parameter of the patient. (4) In the model, we did not
consider several factors such as sweat transit in the sand. (5) There was some differentiation between
parameter of the experiment such as temperature, humidity, wind speed in the natural environment.
The very common disease such as rheumarthritis, lumbag and cervical vertebra degeneration
brings huge pain to the patients. Medical treatments which are often used by the medical institutions
can not obtain efficient results. But sand-therapy, a great part of Uyghur medicine, has obviously
effects to these diseases [1, 2].
The sand-therapy provides positive effects in such diseases taking place in the hot sand in Turfan in
Xingjiang where special climate, special environment and strong sunshine have. But this treatment is
greatly effected by environment and climate and only can take place between July to September.
Nowadays, there is little research about the sand-therapy both domestically and internationally,
among them concentrated on influence of medical parameter of the human body and exploration to
cure the disease mechanism. The sand-therapy is effected by calorific, magnetic and mechanics, etc.,
involving a lot of disciplines. Some scholars have carried on qualitative analysis to sand-therapy and
other heat-therapy in terms of biomechanics [3,4], others have carried on thermal effects by experiment
manner and analysis [5,6], still others analysis sand-therapy deeply by animal experiment[7,8,9].
This paper has carried on experiment and theoretical analysis to part of hot-strength effect of
Uyghur medicine[10,11] and mechanics of bone tissue by temperature of sand-therapy[12,13], based on
thermal-physical model of thermal transmitting among human body and sand and numerical
simulation of temperature change in human body and sand in the course of sand-therapy.
Abstract: Recently, the intravascular therapy using microcoils and stents to treat aneurysms has
attracted researcher’s interest. In this study, in order to evaluate the effects of the stents, a numerical
simulation of two-dimensional flows has been carried out for a pipe with a model of an aneurismal
sac. Using aneurismal models with different inclined angles to the pipe, inflow conditions with
steady states or pulsations have been applied in the range of Reynolds number in human blood
flows. First, the computational results are compared with experiments under the steady inflow
condition, which has shown the reliability of the numerical simulation. Furthermore, the mechanism
of flows with an aneurismal model is discussed in the case with or without a stent, and consequently
the effect of the stent is clarified.
Abstract: Recently for the treatment of aneurysms, endovascular therapy with microcoils and stents
has started. This study explores the design of better stents by means of numerical computations from
the viewpoint of the fluid mechanics. Two-dimensional flows are numerically solved for a stented
duct with a model of an aneurysmal sac by changing the distribution of stent filaments under the
constraint of a constant porosity for the neck. Stents are assessed by whether the wall shear stress
(WSS) on the aneurismal wall and the shear rate (SR) within the aneurysm are made lower.
Barometers for the allocation of filaments are sought, and resultant optimized stents are those where
filament(s) should be attached to both the distal and proximal wall of the neck, with more filaments to
the distal wall, to make the WSS low, and filaments should be appropriately distributed in the off-wall
portion of the neck to make the SR low.
Abstract: The purpose of this study is to accumulate data to predict the ruptures of aneurysms on the
bifurcation of the middle cerebral arteries at the base of the brain. Particular stress is laid on
understanding the elemental nature of branch flows with/without an aneurysm. Therefore, “flow
patterns” and “wall shear stress”, which are important factors for the causes of ruptures, are
investigated by the three-dimensional experiments in vitro and the two-dimensional numerical
simulations with simplified models. In the branch arteries without an aneurysm, there is a possibility
of growing aneurysms at the location slightly away from a stagnation point. If an aneurysm forms into
a centrosymmetric shape for the inlet axis, it is considered that they tend to grow further in a
symmetrical plane. From the viewpoint of the risk of ruptures, recirculation flows become
problematic with the lower Reynolds number, while the influence of wall shear stress becomes larger
with the higher Reynolds number.
Abstract: The fracture is an important failure behavior of cancellous bone. Three-point-bending
experiment was used to study fracture behavior of cancellous bone. Three group specimens were
taken from two human femoral head and there was a non-angled crack and an angled crack in every
group respectively. By using Digital Speckle Correlation Method (DSCM), the displacement and
strain field were obtained at the crack-tip and the full specimen. The initial crack path was always at
the maximal strain location and could be predicted by the DSCM. In the macro-scope, the crack
propagation paths towards the load tip, and are independent of the initial crack angle.
Abstract: In this study, the directionally fixed air tunnel testing equipment are used for obtain nearly
close natural uniform wind and provide more stable wind speed for tunnel test. The changes of sand
ripple moving speed in different location are observed under given wind speed condition. The sand
ripple lines formation and moving process are tested on flat surface of sand, in Taklimakan desert.
The results shown that the sand ripple forming rapidly from non ripple surface to ripple surface and
moving along the wind direction. Though the sand ripples in the testing region have some difference
about its moving speed, the sand ripple moving speed appear linearity relationship between sand
moving displacement and the moving time. This phenomenon indicate that the sand ripple almost
occurs and moving at the same time in the uniform wind stream field.