[Faculty] Fwd: [CSRC-SDSU COLLOQUIUM]: Measuring Crack Density in Composite Laminates using Piezoelectric Sensors

[Jose Castillo]

*DATE: * Friday, October 18th, 2013

*TITLE: * Measuring Crack Density in Composite Laminates using
Piezoelectric Sensors

*TIME:*  3:30 PM

*LOCATION: * GMCS 214

*SPEAKER:*  Dr. Cecilia Larrosa. Exponent Inc.

The use of fiber reinforced composite materials has increased tremendously
in many applications from aerospace structures to sporting goods. These
materials have many advantages, but the major challenge in composites
design is their damage mechanics. Matrix cracking develops first,
decreasing structural performance and promoting other damage development.
The state-of-the-art inspection techniques cannot quantify crack density
and they require the component to be off-service. For better design,
safety, and maintenance of composite structures it is desirable to monitor
the increase of cracks in-service. The objective of this investigation is
to determine the quantity of matrix cracks in a composite laminate rapidly
and in-service using built-in piezoelectric actuators and sensors. A
diagnostic method was proposed which compared the sensed signal before and
after the presence of matrix cracks and related these signal changes to
crack density. It was found that change in the signal’s Power Spectral
Density can be used to quantify crack density, and its sensitivity was
dependent on the actuator to sensor orientation. This orientation
dependence was found to be the same as that of the laminate’s stiffness
degradation. A crack density monitoring method was developed that uses
signal changes and theoretical laminate stiffness degradation. The model
was tested on two layup configurations, and its crack density estimates
matched experimental crack density values within established error bounds.

*HOST:*  Dr. Satchi Venkataraman

For future events, please visit our website at:

http://www.csrc.sdsu.edu/colloquium.html



-- 

Jose E. Castillo  Ph.D.

Director / Professor

Computational Science Research Center

5500 Campanile Dr

San Diego State University

San Diego CA 92182-1245

619 5947205/3430, Fax 619-594-2459

 http://www.csrc.sdsu.edu/mimetic-book/

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