EXTRACTING THE EFFECTIVE CONSTITUENT PROPERTIES OF DAMAGED UNI-DIRECTIONAL COMPOSITE LAMINA

摘要

Damage in laminated composite structures made up of uni-directional laminae is typically defined, measured, and analyzed as a reduction of thermo-mechanical properties of the composite laminae. However, damage in a composite lamina results from damage in the constituents. Therefore, composite damage can be expressed as constituent damage that is necessary for damage modeling using Multicontinuum Technology (MCT). A method to reverse engineer the effective damaged constituent properties that produce the damaged lamina properties utilizing a finite element micromechanics model and multi-continuum technology is discussed. The method used to estimate the constituent properties from lamina properties is an iterative process that requires damaged composite lamina properties and some of the constituent properties. Using this method, a degraded lamina with cracks is effectively described as a continuum with a combination of reduced and intact constituent properties. The method is implemented for two possible matrix failure/damage modes. The first is a matrix failure mode with the matrix crack-face perpendicular to the intact fibers, termed here as matrix normal cracking. The second mode is the classical matrix transverse cracking with transverse ply cracks running parallel to the fibers. Results of this reverse engineering method are presented for these two failure modes.