NASA Technical Memorandum 88976 ICOMP-87- 1 The Effects of Crack Surface Friction and Roughness on Crack Tip Stress Fields (hASA-!iB-88976) TEE EEEEClS CF CEACK NE7- 1 €I€ 1 SUbEACE ERICTlCN AkD LCUGHLESZ LP CEiACK IXF S'lEiESS FIELDS (IiASA) 14 I: CSCL 20s Unclas G3/39 U3642 Roberto Ball& Case Western Reserve University Cleveland, Ohio and Michael E. Plesha Institute for Computational Mechanics in Propulsion Lewis Research Center Cleveland, Ohio February 1987 * 1 LEWlSRIYARCH CENTER