Keywords: interfacial shear strength, pull-out test, nano mechanics, molecular dynamics, effect of manufacturing defects, material modeling, as-built/as-is part process modeling, part qualification and certification
Summary:Emerging nano composite materials in the form of polymer-based nano composite or metallic based ultrafine-grained (UFG) alloys have shown tremendous increases in strength, ductility and have gained popularity in academia with improved mechanical, thermal, and electrical properties. In the last few years vast amount of nano materials have been manufactured and entered into commercial and military applications as improved advanced products with superior properties. The applications are: 1) thermoset composite with improved nano inserted matrix or improved interphase; 2) thermoplastic composite with long and short chopped fiber insertion; 3) novel propellant formulations with nano-particulates insertion; 4) adhesive coating of individual graphite microfibers with a continuous, highly-conductive metal layer; and 5) ultrafine-grained (UFG) alloys for potential armor and structural applications. Complex parts and superior joint structural performance can be obtained by improvements in interlaminar strength properties and matrix dominated properties such as delamination, transverse tensile (TT), and in-plane shear. Problems that adversely reduce the properties of nano composite are non-uniform distributions of particles inside the matrix, void shapes/sizes, bonding of nano particles with matrix and conventional fiber and nano fibers distribution and architectures. The presentation will address: 1) Evaluation of mechanical properties of different classes of nano composite by physical laboratory test. Ability to perform post test evaluation to determine the test outliers; 2) Validation of predictive methods for strength, stiffness, and conductivity such as Molecular dynamics (MD), and Nano mechanics (NM); and 3) Trade studies to determine the parameters of nano composite to achieve an optimum performance under service loading (i.e., Static, Fatigue, Impact).