Abstract: This paper describes the crashworthiness assessment and improvement of tlting train made of sandwich composites. The crashworhiness assessment of tilting train was conducted according to four collision scenarios of the Korean railway safety law. Collision analysis was carried out using explicit finite element analysis code LS-DYNA 3D. The finite element model consists of 3-D finite element model and 1-D equivalent model to save the finite element modeling and calculation time. It found that the crashworthiness analysis results were satisfied with the performance requirements except the crash scenario-2. In order to meet the crashworthiness requirements for crash scenario-2, the stiffness reinforcement for the laminate composite cover and metal frames of cabmask structure were proposed. Consequentially, it has satisfied the requirement for crash scenario-2.
Abstract: Bionanotechnology deals with nanoscopic interactions between nanostructured materials and biological systems. Polymer nanocomposites with optimized biological activity have attracted great attention. Nanoclay is considered as reinforcing nanofiller in manufacturing of high performance nanocomposites. In current study, organomodified-nanoclay with negatively charged silicate layers was incorporated into biomedical grade silicone rubber. Nanoparticle loading has been tailored to enhance cell behavior. Addition of nanoparticles led to improved mechanical properties of substrate with enhanced strength and stiffness while no toxic effects was observed. Results indicated improved viability and proliferation of cells by addition of nanofillers. The improved mechanical properties of the matrix result in proper cell response through adjustment and arrangement of cytoskeletal fibers. Results can be applied in tissue engineering when enhanced substrates are required for improvement of cell behavior for in vivo applications.
Abstract: The machining of Carbon Fiber Reinforced Plastics
has come to constitute a significant challenge for many fields of
industry. The resulting surface finish of machined parts is of primary
concern for several reasons, including contact quality and impact on
the assembly. Therefore, the characterization and prediction of
roughness based on machining parameters are crucial for costeffective
operations. In this study, a PCD tool comprised of two
straight flutes was used to trim 32-ply carbon fiber laminates in a bid
to analyze the effects of the feed rate and the cutting speed on the
surface roughness. The results show that while the speed has but a
slight impact on the surface finish, the feed rate for its part affects it
strongly. A detailed study was also conducted on the effect of fiber
orientation on surface roughness, for quasi-isotropic laminates used
in aerospace. The resulting roughness profiles for the four-ply
orientation lay-up were compared, and it was found that fiber angle is
a critical parameter relating to surface roughness. One of the four
orientations studied led to very poor surface finishes, and
characteristic roughness profiles were identified and found to only
relate to the ply orientations of multilayer carbon fiber laminates.
Abstract: Tribological behavior and wear regimes of ascast
and heattreted Al-Cu-Mg matrix composites containing SiC
particles were studied using a pin-on-disc wear testing apparatus
against an EN32 steel counterface giving emphasis on wear rate as
a function of applied pressures (0.2, 0.6, 1.0 and 1.4 MPa) at
different sliding distances (1000, 2000, 3000, 4000 and 5000
meters) and at a fixed sliding speed of 3.35m/s. The results showed
that the composite exhibited lower wear rate than that of the matrix
alloy and the wear rate of the composites is noted to be invariant to
the sliding distance and is reducing by heat treatment. Wear
regimes such as low, mild and severe wear were observed as per the
Archard-s wear calculations. It is very interesting to note that the
mild wear is almost constant in all the wear regimes.
Abstract: Lipases are enzymes particularly amenable for
immobilization by entrapment methods, as they can work equally
well in aqueous or non-conventional media and long-time stability of
enzyme activity and enantioselectivity is needed to elaborate more
efficient bioprocesses. The improvement of Pseudomonas
fluorescens (Amano AK) lipase characteristics was investigated by
optimizing the immobilization procedure in hybrid organic-inorganic
matrices using ionic liquids as additives. Ionic liquids containing a
more hydrophobic alkyl group in the cationic moiety are beneficial
for the activity of immobilized lipase. Silanes with alkyl- or aryl
nonhydrolizable groups used as precursors in combination with
tetramethoxysilane could generate composites with higher
enantioselectivity compared to the native enzyme in acylation
reactions of secondary alcohols. The optimal effect on both activity
and enantioselectivity was achieved for the composite made from
octyltrimethoxysilane and tetramethoxysilane at 1:1 molar ratio (60%
increase of total activity following immobilization and enantiomeric
ratio of 30). Ionic liquids also demonstrated valuable properties as
reaction media for the studied reactions, comparable with the usual
organic solvent, hexane.
Abstract: Novel acrylated epoxidized hemp oil (AEHO) based
bioresins were successfully synthesised, characterized and applied to
biocomposites reinforced with woven jute fibre. Characterisation of
the synthesised AEHO consisted of acid number titrations and FTIR
spectroscopy to assess the success of the acrylation reaction. Three
different matrices were produced (vinylester (VE), 50/50 blend of
AEHO/VE and 100% AEHO) and reinforced with jute fibre to form
three different types of biocomposite samples. Mechanical properties
in the form of flexural and interlaminar shear strength (ILSS) were
investigated and compared for the different samples. Results from the
mechanical tests showed that AEHO and 50/50 based neat bioresins
displayed lower flexural properties compared with the VE samples.
However when applied to biocomposites and compared with VE
based samples, AEHO biocomposites demonstrated comparable
flexural performance and improved ILSS. These results are attributed
to improved fibre-matrix interfacial adhesion due to surface-chemical
compatibility between the natural fibres and bioresin.
Abstract: The aim of our work is to study phase composition,
particle size and magnetic response of Fe2O3/TiO2 nanocomposites
with respect to the final annealing temperature. Those nanomaterials
are considered as smart catalysts, separable from a liquid/gaseous
phase by applied magnetic field. The starting product was obtained
by an ecologically acceptable route, based on heterogeneous
precipitation of the TiO2 on modified g-Fe2O3 nanocrystals dispersed
in water. The precursor was subsequently annealed on air at
temperatures ranging from 200 oC to 900 oC. The samples were
investigated by synchrotron X-ray powder diffraction (S-PXRD),
magnetic measurements and Mössbauer spectroscopy. As evidenced
by S-PXRD and Mössbauer spectroscopy, increasing the annealing
temperature causes evolution of the phase composition from
anatase/maghemite to rutile/hematite, finally above 700 oC the
pseudobrookite (Fe2TiO5) also forms. The apparent particle size of
the various Fe2O3/TiO2 phases has been determined from the highquality
S-PXRD data by using two different approaches: the Rietveld
refinement and the Debye method. Magnetic response of the samples
is discussed in considering the phase composition and the particle
size.
Abstract: Structural behavior of ring stiffened thick walled
cylinders made of functionally graded materials (FGMs) is
investigated in this paper. Functionally graded materials are inhomogeneous composites which are usually made from a mixture
of metal and ceramic. The gradient compositional variation of the
constituents from one surface to the other provides an elegant solution to the problem of high transverse shear stresses that are
induced when two dissimilar materials with large differences in material properties are bonded. FGM formation of the cylinder is
modeled by power-law exponent and the variation of characteristics is supposed to be in radial direction.
A finite element formulation is derived for the analysis. According to the property variation of the constituent materials in the radial
direction of the wall, it is not convenient to use conventional elements to model and analyze the structure of the stiffened FGM
cylinders. In this paper a new cylindrical super-element is used to model the finite element formulation and analyze the static and
modal behavior of stiffened FGM thick walled cylinders. By using
this super-element the number of elements, which are needed for
modeling, will reduce significantly and the process time is less in comparison with conventional finite element formulations. Results for static and modal analysis are evaluated and verified by
comparison to finite element formulation with conventional
elements. Comparison indicates a good conformity between results.
Abstract: The term hybrid composite refers to the composite
containing more than one type of fiber material as reinforcing fillers.
It has become attractive structural material due to the ability of
providing better combination of properties with respect to single fiber
containing composite. The eco-friendly nature as well as processing
advantage, light weight and low cost have enhanced the attraction
and interest of natural fiber reinforced composite. The objective of
present research is to study the mechanical properties of jute-coir
fiber reinforced hybrid polypropylene (PP) composite according to
filler loading variation. In the present work composites were
manufactured by using hot press machine at four levels of fiber
loading (5, 10, 15 and 20 wt %). Jute and coir fibers were utilized at a
ratio of (1:1) during composite manufacturing. Tensile, flexural,
impact and hardness tests were conducted for mechanical
characterization. Tensile test of composite showed a decreasing trend
of tensile strength and increasing trend of the Young-s modulus with
increasing fiber content. During flexural, impact and hardness tests,
the flexural strength, flexural modulus, impact strength and hardness
were found to be increased with increasing fiber loading. Based on
the fiber loading used in this study, 20% fiber reinforced composite
resulted the best set of mechanical properties.