Damage Resistance Characterization of Sandwich Composites Using Response Surfaces
Abstract
The influence of material configuration and impact parameters on the damage-resistance characteristics of sandwich composites comprised of carbon-epoxy woven fabric facesheets and Nomex honeycomb cores were investigated using empirically based response surfaces. A series of carefully selected tests were used to isolate the coupled influence of number of facesheet plies, core density, core thickness, impact energy, impactor diameter, and impact velocity on the damage formation due to impact normal to the surface. The ranges of selected material parameters were typical of those found in common aircraft applications. The diameter of the planar damage area, which was determined using through transmission ultrasonic (TTU) C-scan measurements and the maximum residual facesheet indentation depth, was used to describe the extent of internal and detectable surface damage, respectively. Estimates of the size of the planar damage region as a function of material system and impact parameters made using quadratic response surface correlated reasonably well with experimentally determined values. For a fixed set of impact parameters, estimates of the planar damage size and residual facesheet indentation suggest that impact damage is highly dependent on skin thickness and core density and thickness. Increasing the thickness of core and decreasing the number of facesheet plies generally resulted in the greatest reduction in the estimated planar damage dimension while increasing the amount of facesheet indentation. An increase in the impactor diameter results in a significant increase in the estimated planar damage size and a decrease in the residual facesheet indentation, particularly for those sandwich panels with thicker facesheets. Thus, blunt object impacts result in appreciable damage that is not detectable using visual inspection. The effects of impact energy and velocity on damage formation were also addressed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2002
- Accession Number
- ADA401607
Entities
People
- I. K. Samarah
- J. S. Tomblin
- T. E. Lacy
Organizations
- Wichita State University