Mechanics of Nano, Micro and Macro Composite Structures
Politecnico di Torino, 18
20 June 2012
A. J. M. Ferreira, E. Carrera (Editors)
DAMPING BEHAVIOR OF
DING MATHEMATICAL RE
Matthias Klaerner, Lothar Kroll
Institute of Lightweight Structures
Chemnitz University of Technology
, web page: http://www.
Optimisation, GEP, genetic
DAMPING OF THERMOPLA
Thermoplastic fibre reinforced composites are characterised by
parameters in stiffness, strength and damping
as well as simultaneous advantages in mass
production and recycling applicability.
Moreover, thermoplastic frp have a significant higher
material damping than thermoset materials
and thus a
huge design space of the material
parameters influenced by
the matrix material, the fibres, the textile processing, the fibre
volume content as well as the lay up.
targeted modifications of the structural
dynamic behaviour and sound emission
of composite structures.
Especially modern very stiff and lightweight constructions tend to higher sound radiation
and thus NVH efforts in an early concept phase. This vibro
acoustic engineering of
lightweight structures using dynamic FEM or BEM simulation
s necessitates viscous damping
parameters as w
ell as the perception of the nonlin
The damping ratio has been
determined using free vibrations of cantilever beams with various fibre orientations. The
experimental results have been used to exa
mine the parameters of the ADAMS/BACON
damping model. This model is based on the three basic deformation modes: longitudinal and
transversal tension/compression as well as longitudinal shear and thus considers the
anisotropic characteristics of fibre reinf
. The model had been
developed and tested for unidirectional reinforced materials originally and was applied for
woven thermoplastic frps with reasonable results.
TWO STAGE OPTIMISATI
ry optimisation strategy
is used to determine functions
describing the dependencies of the damping ratio, e.g. related to the fibre orientation. Both
functions, of the ADAMS/BACON model and of the evolutionary optimisation, are compared
with the experiment
ation approach is inspired by
Gene Expression Programming Algorithm (GEP)
genetic representation [
this algorithm leads to long and unhandy
terms. Therefore a further development
outer loop the right mathematical structure
the inner loop
Winter, Matthias Klaerner, Lothar Kroll
AN EXAMPLE: DEPENDEN
CY OF THE FIBRE ANGL
The new evolutionary optimisation strategy determines functions to describe the
dependencies of the damping ratio.
Therefore, common thermoplastic frps with plain woven
glass fibres, a wrap
ration of 2:2 and Polyamid
Matrix are investigated. The
measurement results show a significant dependency of the fibre angle (see figure 1).
This dependency can be described by the ADAMS/BACON model (compare section 1)
necessitating all elastic parameters
of a single layer
and depending on three damping
coefficients: longitudinal, transversal and shear damping.
In contrast, the evolutionary
strategy achieves quite reasonable results in finding a function type only with these
: Damping ratio
of thermoplastic frp with woven reinforcements: measurement results
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