This is a copy of the slides presented at the meeting but not formally written up for the volume.

While material fracture is generally considered undesirable, recent experimental work has indicated that cracking can be utilized to create small scale nanowire structures with diameters of 100nm and smaller. Typical nanowire fabrication techniques include the use of a scanning tunneling microscope and electrochemical deposition. Compared to fracture fabricated nanowire structures current fabrication techniques are either extremely slow or require large amounts of post-processing. To become a viable nanowire fabrication technique the cracking of materials must be directed. We propose a computational model to predict propagation paths in large scale crack systems. We utilize the level set method to investigate the creation of nanoscale crack patterns. The level set method allows for large scale simulations of many crack tips while easily accommodating large scale deformations. Unlike traditional methods such as finite elements explicit modeling of the cracks is not needed. We show that the use of multiple materials and etched regions can effectively direct the cracking of a thin film. Using these patterns nanowire structures can be constructed which would be difficult to obtain otherwise.