Accession Number : ADA332139

Title :   Nonlinear Aeroelastic Effects in Damaged Composite Aerospace Structures.

Descriptive Note : Final rept. 1 Apr 95-31 Mar 97,

Corporate Author : GEORGIA INST OF TECH ATLANTA SCHOOL OFAEROSPACE ENGINEERING

Personal Author(s) : BAuchau, O. A. ; Loewy, R. G.

PDF Url : ADA332139

Report Date : 27 OCT 1997

Pagination or Media Count : 40

Abstract : Matrix micro-cracking affects the stiffness properties of composite laminates and the corresponding sectional stiffnesses, most prominantly laminates exhibiting elastic coupling. Matrix micro-cracking gives rise to nonlinear materials behavior in the presence of nonuniformly distributed crack densities. Such matrix damage appears to have little effect on basic bending-torsion flutter speed. However, this damage can induce a limit cycle behavior at airspeeds somewhat below the flutter speed. The effect of damage on the aeroelastic behavior of wing-aileron systems is found to be more pronounced. Here again flutter speeds were found to be slightly lower in the presence of damage. However, in this case, a limit cycle behavior was observed for a significant range of airspeeds below the flutter speed. Reduced fatigue life could result from this limit cycle behavior, since much higher cyclic stresses are generated thereby in the wing-aileron structure.

Descriptors :   *COMPOSITE STRUCTURES, *AEROELASTICITY, *AEROSPACE CRAFT, FATIGUE LIFE, COMPOSITE MATERIALS, LAMINATES, STIFFNESS, CRACKS, ELASTIC PROPERTIES, BENDING, FLUTTER, TORSION.

Subject Categories : Research and Experimental Aircraft
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE