Abstract: The macroscopic hyperelastic behavior of fiber reinforced polymer composites is studied
using the micromechanical model and finite deformation theory. It is assumed that the fiber and
matrix are hyperelastic media and undergoing finite deformation. The local fields of a
representative volume element are calculated by the hyperelastic finite element method. Then an
averaging procedure is used to find the homogenized stress and strain and the macroscopic curves
of stress-strain are obtained. The several microstructural parametric effects on the macroscopic
hyperelastic behavior are considered. The numerical examples show the hyperelastic behavior and
deformation of the composites.
Abstract: Aeroelastic tailoring studies using effective computational method with genetic algorithm
have been conducted to find an optimized lamination set which give minimum structural weight. The
efficient and robust computational system for the flutter optimization has been developed using the
coupled computational method based on the micro genetic algorithm. It is shown that the wing
structural weight with both divergence and flutter constrains can be significantly reduced using
composite materials with proper optimum lamination compared to the case of isotropic wing model.
Abstract: In this study, advanced computational analysis system for nonlinear static aeroelastic
problems has been successfully developed by the composite structure (FEM)-fluid (CFD) combined
method with internal iteration steps. Major focus of the present study is to investigate the static
aeroelastic characteristics of laminated composite wings including the strong normal shock waves in
the transonic and low-supersonic flow regions. The results importantly indicate that the effect of
airfoil camber on the load distribution of laminated composite wing models can be nonlinear due to
the variation of ply orientations.
Abstract: This paper presents a real microstructure model which has the same fiber volume fraction and
tows’ spatial configuration with 3D rectangular composites to simulate the ballistic impact damage of
the composites struck by steel projectile. The commercial available FEM code of Ls-Dyna was
employed to calculate the interaction between the composite targets and steel projectile. From the
comparison of residual velocities between simulation and experiment, it is proven the microstructure
model can simulate the ballistic penetration with higher precision than the continuum model. The
acceleration vs. time curve reveals the complicated interaction between composite and projectile in
ballistic penetration. The prominent advantage of the microstructure model is that it can simulate the
local damage mode of the composites at real microstructure level and obtain vivid simulating results.
Abstract: A new type of composite used biodegradable resins and natural fibers is now being
developed and this new type of composites is designated as a green composite. This paper
presents a fabrication method and mechanical properties of the green composite used Kenaf fibers
as the reinforcement and PLA as the matrix. In order to obtain the higher tensile strength, various
kind of surface treatments were executed on the Kenaf fiber and some parameters were changed
during the process of fabrication. Then, these effects on the strength of green composite are also
Abstract: The aim of the current work was to investigate using fungi to treat hemp fibre to create
better bonding characteristics in natural fibre reinforced polypropylene composites. X-ray diffraction
(XRD), lignin testing and scanning electron microscopy (SEM), were used to characterise the effect
of treatment on hemp fibres. A combined alkali and fungal treated fibre composite produced the
highest tensile strength of 48.3 MPa, an increase of 32% compared to composites with untreated fibre.
Abstract: This study investigates the effect of recycling/reprocessing on the physical and
mechanical properties of composites based on radiata pine (Pinus Radiata) fibre and polypropylene
(PP) with a maleated polypropylene (MAPP) coupling agent, produced using a twin-screw extruder,
followed by injection moulding. Composites containing 40wt% fibre and 4wt% MAPP were
assessed mechanically and thermally, as well as for moisture absorption after being recycled up to
eight times. Both the tensile strength (TS) and Young’s modulus (YM) of composites were found to
decrease linearly from 41 MPa and 4556 MPa respectively to 31 MPa and 3800 MPa for composites
recycled eight times. However, the elongation at break was found to increase with increased
recycling due to fibre damage that occurred during reprocessing and the associated reduction of
average fibre length, found to decrease from 2.36mm to 0.37mm after recycling eight times.
Thermal stability and moisture resistance of composites improved with recycling due to the
improvement of interfacial bonding between fibre and matrix.
Abstract: An experimental testing program is being conducted to evaluate the effects of
environmental exposure on the mechanical properties of glass/vinyl ester filament wound pipes.
The effects of artificial exposure on the flexural and fracture properties are reported in this paper.
Three point bending specimens were employed to characterize the flexural properties. Fracture
resistance was assessed using pre-cracked notched ring specimens. Specimens were exposed for
300, 1000, and 3000 hours in the environment of interest before testing at room temperature. The
exposure conditions presented in this paper include: dry heat at 40 C, dry heat at 70 C, 65% and
100% relative humidity at room temperature; and salt spray and seawater environments at room
temperature. The results of this study indicate that the flexural strength and stiffness; and the
fracture resistance of the tested GFRP composite do not show significant degradation due to prior
exposure to the environments investigated for up to 3000 hours. The flexural ductility is shown to
degrade after exposure in high humidity environment.
Abstract: Fracture toughness and the possibility of recycling for Carbon Fiber Reinforced Plastics (CFRP)
under mode one and mode two loadings are examined. Epoxy matrix is modified by CNBR rubber
particle which diameter is smaller than 100 nano meter. Three kinds of rubber content (5,10,15%) are
used. Two types of test methods whose modes are different are conducted. After the specimen fracture,
recycled specimens are made by adhesion. Fracture toughness is measured at the tests. Fracture
surface is also observed by SEM. As a result, following conclusions are obtained. When the
interlaminar fracture test using recycled CFRP specimen is conducted under Mode one loading,
fracture toughness is improved using rubber modified matrix. For recycled CFRP specimen under
mode two loading, fracture toughness of CFRP using unmodified epoxy is improved. In this case,
fracture toughness for modified CFRP is improved but it is not as high as than CFRP with unmodified
recycle CFRP. From SEM ovservation on fracture sufface under mode two loading, there is a
difference on fracture surfaces. Specimen whose fracture toughness is high has a ductile properties.