Preface - kmutt

KMUTT Annual Research Abstracts 2005
linearity arising from axial force. The non-linear
eigenvalue problem is solved by the direct
iteration method to obtain the beam’s non-linear
frequencies and corresponding mode shapes for
specified vibration amplitudes. We also present
changes in the frequency of vibration as a
function of amplitude, demonstrating the beam
non-linearity. A more accurate solution analyzed
in the frequency domain of the direct
numerical integration method is adopted as an
alternative solution. Large amplitude vibration
experimental modal analysis was also conducted
to complement the analytical results. The
measured results were found to be in good
agreement with those obtained from two
analytical solutions.
IJ-024 LARGE DEFLECTIONS OF VARIABLE-
ARC-LENGTH BEAMS UNDER UNIFORM
SELF WEIGHT: ANALYTICAL AND
EXPERIMENTAL
Tawich Pulngern, Marvin W. Halling,
Somchai Chucheepsakul
Structural Engineering and Mechanics, Vol. 19,
No. 4, 2005, pp. 413-423
This paper presents the solution of large
static deflection due to uniformly distributed self
weight and the critical or maximum applied
uniform loading that a simply supported
beam with variable-arc-length can resist. Two
analytical approaches are presented and
validated experimentally. The first approach is a
finite-element discretization of the span length
based on the variational formulation, which
gives the solution of large static sag deflections
for the stable equilibrium case. The second
approach is the shooting method based on an
elastica theory formulation. This method gives
the results of the stable and unstable equilibrium
configurations, and the critical uniform loading.
Experimental studies were conducted to
complement the analytical results for the stable
equilibrium case. The measured large static
configurations are found to be in good
agreement with the two analytical approaches,
and the critical uniform self weight obtained
experimentally also shows good correlation with
the shooting method.
IJ-025 NONLINEAR FREE VIBRATIONS OF
MARINE RISERS/PIPES TRANSPORTING
FLUID
Sakdirat Kaewunruen, Julapot Chiravatchradej,
Somchai Chucheepsakul
Ocean Engineering, Vol. 32, No. 3-4, 2005,
pp. 417-440
An investigation emphasizing on
nonlinear free vibrations of marine risers/pipes
to determine the nonlinear natural frequencies
and their corresponding mode shapes is
presented in this paper. Based on the virtual
work-energy functional of marine risers/pipes,
the structural model developed consists of the
strain energy due to axial deformation, strain
energy due to bending, virtual works due to
effective tension and external forces, and also
the kinetic energy due to both the riser and the
internal fluid motions. Nonlinear equations of
motion coupled in axial and transverse
displacements are derived through the Hamilton's
principle. To analyze the nonlinear free
vibrational behaviors, the system formulation
has been reformed to the eigenvalue problem.
The nonlinear fundamental frequencies and the
corresponding numerically exact mode shapes
are determined by the modified direct iteration
technique incorporating with the inverse
iteration. The significant influences of the
marine riser's parameters studied on its nonlinear
phenomena are then illustrated here first. Those
parameters demonstrate the nonlinear effects due
to the flexural rigidity, top tensions, internal
flow velocities, and static offsets.
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IJ-026 VEHICULAR BASIC NOISE MODEL
WITH 20 SECONDS OF EQUIVALENT SOUND
LEVEL
Pichai Pamanikabud, Marupong Tansatcha
IASME Transactions, Vol. 2, No. 5, July 2005,
pp. 769-773
Basic noise model of vehicle is the
primary parameter in the analysis and modeling
of the main highway noise forecasting model.
The model represents noise level with respect to
its speed that created by each type of vehicle as
the traffic noise source running on the highway
section. The objective of this study is to
analyzed and develop the basic noise model that
can be effectively used for each vehicle type in
Thailand. The novel technique of equivalent
sound level measurement in the time period of
20 second-L eq (20s) is employed in this study.
Nine vehicle types on highways in Thailand are
under the investigation. The L eq (20s) can cover
the range of noise levels of all vehicle types
International Journal