Description: The nondestructivecharacterization of advanced composites, such ascarbon-fiber reinforced polymers (cfrp), by electromagnetic means iswell established [6]-[24]. What isneeded to advance the state of the art are sophisticated inversionalgorithms that allow layup and impact damage to be determined inlocalized regions, which means that the more traditional methods ofmodel-based inverse methods must be replaced by voxel-based methods.Thus, one will be able to better distinguish such things asdelaminations from fiber-breakage due to impact damage, or otherparameters thatcharacterize the mechanical state of the cfrp structure, such aselastic modulus and Poisson's ratio on avoxel-by-voxel basis. This information can then be input to damageevolution models. We describetwo such methods, bilinear conjugate-gradients and set-theoreticestimation. The challenge is to extend these methods to anisotropicmaterials. We do that in this project, and will develop thealgorithms for inclusionin our proprietary eddy-current code, \vic, during Phase II.In addition, we continue our program of discovering and exploitingparallelism in VIC-3D(R) to speed up the modeling and processing ofproblems that involve massive data generation.

Benefits: NASA LaRC already owns a copy of VIC-3D(R) which it uses for modeling forward and inverse problems in eddy-current NDE. With the enhancements proposed in this project, NASA LaRC will be able to extend its modeling capability to more accurately characterize damage conditions in cfrps, as well as run large problems much more efficiently.

There are 35 commercial and university research institutions around the world that own copies of VIC-3D(R) which they use for the same purposes as NASA LaRC. They will have the same advantages with the enhanced version of VIC-3D(R). Furthermore, aerospace companies, such as Boeing, and SpaceX (Elon Musk), that are developing vehicles that use advanced composites, such as carbon-fiber reinforced polymers (cfrp) will be able to use the enhanced version of VIC-3D(R). A more prosaic industry that is using cfrp advanced composites in their vehicles is auto racing, especially IndyCar. With a successful Phase II, we will be in a better position to approach them and offer our services through VIC-3D(R) for inspecting their cars. Composites are also being used in the burgeoning wind-turbine industry, and, of course, in sporting equipment, such as golf clubs and tennis rackets.