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Review of Impact Damages Modelling in Laminated Composite Aircraft Structures
Laminated composites have an important application in modern aeronautical structures. They have extraordinary properties, like high strength, stiffness and lightweight. Nevertheless, a serious obstacle to more widespread use of those materials is their sensitivity to impact loads. As a consequence of that, impact damage initiation and growth are appearing in them. Failures that occur in laminated composite structures can be intralaminar and interlaminar. To date a lot of models for impact damages in laminates have been developed with higher or lower accuracy. Those models can replace real and expensive testing in laminated structures with some approximation. By using specialized software the damage parameters in laminate aircraft structures can be predicted (at certain conditions). In that way numerical simulation of impact on certain laminates can be done and the obtained results from the simulations presented in a form of graphic damage distributions.
Keywords: damages, impact, laminated composite structures.
Conclusion
Impact damages in aircraft structures from laminated
composites are very complex and the most common are:
matrix cracking, fibre failure and delamination. The
ability to predict the initiation and growth of damage is
crucial for predicting performance and developing reliable
and safe designs of composites. By using simulation in
modelling the impact damage the test costs of aircraft
structures from composite laminates will be reduced.
Due to the wide use of composite materials in
different aircraft structures, it is necessary to introduce
new approaches for impact damage modelling. Efficient
methodologies are modelling composite structures with
specialized finite element methods that take into account
macromechanical structural properties and by use of
numerical methods with complicated analysis codes. In
order to validate those methodologies, for further use in
the strength structures design, verification of the
numerical model is necessary. A comparison of the
obtained experimental and numerical results is further
made in order to establish if the proposed models are
accurate and valid.
Composite damages exist at the microscale level,
while impact loads are applied at the structural level.
Because of that it is needed to consider multiscale
approach for that kind of problem.
The development of suitable constitutive laws for
modelling composite laminate failures and material
models with finite element codes under impact provides
significant assistance in the design and exploitation
phases of specified structures. The most known failure
criteria (2D, 3D) for composite materials are: Tsai-Wu,
Chang-Chang and Hashin. They are used in order to
predict the level or degree of damage, fracture and failure
of composite structures.
The development of the computational models and
simulations are needed in studying the onset and growth
of impact damages. In numerical simulation of impact on
composite structures two- or three-dimensional models
exist. For impact damage analysis of composite laminates
commercial software ABAQUS and LS-DYNA is most
frequently used. Pro/ENGINEER, ANSYS and some noncommercial software is also suitable for the same
purpose. By using it at some circumstances (geometry,
boundary conditions, mesh, load etc.) distribution of
damage, stress, strain, deformations can be analysed and
presented.
Essentially in considering impact damages modelling
in laminated composites of aeronautical structures is to
investigate the dynamic response of composite laminates
under impact and predict the damage initiation/growth in
such structures. For that analysis numerical modelling and
simulations provide important and valuable results.
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