DATE:

Friday, March 24, 2006

TITLE:

OPTIMIZATION FOR PREDICTABLE ENERGY ABSORPTION IN COMPOSITE STRUCTURES (No. 111)

TIME:

3:30 PM

LOCATION:

GMCS-214

SPEAKER:

Satchi Venkataraman
Department of Aerospace Engineering
San Diego State University

ABSTRACT:

Predicting crash response of complex structures is challenging even for metal structures. This difficulty in predicting crash behavior arises from the multitude of competing failure paths in a complex structure. For composite materials this problem worsens because each composite laminate is a multi-load-path component with a number of failure modes that combine to produce myriad of progressive failure paths. This not only makes it difficult to design composite structures for maximum energy absorption. It also makes it difficult to design tests that characterize complex failure modes that occur after the laminate is weakened by partial failures (such as matrix cracking).

The presentation will first show that deterministic design of composite laminates for maximum energy absorption is likely to lead to designs that are extremely sensitive to small variations in loading and material properties. Consequently, the progressive failure of these laminates is very unpredictable, and the inevitable imperfections in manufacturing will greatly reduce energy absorption. Next we will show that with small sacrifice in deterministic performance, it is possible to find laminates that have predictable behavior, in that their energy absorption is robust with respect to imperfections. We will conclude that this robustness would be useful in both the design for crash and the design of tests intended to characterize the complex progressive failure modes of composite structures.


Satchi Venkataraman is a faculty member of the aerospace engineering and engineering mechanics department at San Diego State University. His current research is in failure predictability optimization in laminated composites and reliability based design optimization.

HOST:

Jose E. Castillo