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This document contains three technical papers: (1) 'Surface Flaw Effects on Crack Propagation from Subsonic Water Drop Impact' The effects of surface flaws on ceramic target damage from subsonic water drop impacts are investigated using numerical code simulations based on fundamental wave propagation and fracture mechanics concepts. (2) 'Effects of Surface Pores in Silicon Nitride Impacted by a Water Drop' A water drop impacting directly on a surface pore may significantly increase the probability of crack formation and growth near the pore boundary. (3) 'Strain Energy Release Associated with Circumferential Cracks Around Embedded Particles' Numerical code simulations are used to determine the strain energy release associated with circumferential cracks around spherical particles embedded in tension within homogeneous matrix materials.

This document contains three technical papers: (1) 'Surface Flaw Effects on Crack Propagation from Subsonic Water Drop Impact' The effects of surface flaws on ceramic target damage from subsonic water drop impacts are investigated using numerical code simulations based on fundamental wave propagation and fracture mechanics concepts. (2) 'Effects of Surface Pores in Silicon Nitride Impacted by a Water Drop' A water drop impacting directly on a surface pore may significantly increase the probability of crack formation and growth near the pore boundary. (3) 'Strain Energy Release Associated with Circumferential Cracks Around Embedded Particles' Numerical code simulations are used to determine the strain energy release associated with circumferential cracks around spherical particles embedded in tension within homogeneous matrix materials.

Recent developments in four numerical techniques in structural mechanics, which are used to extract fracture parameters for linear elastic, nonlinear and dynamic fracture mechanics, are reviewed. Primary emphasis is placed on the finite element methods for determining two- and three-dimensional (2-D and 3-D) stress intensity factors in linear elastic fracture mechanics. Crack opening displacements (COD) and J-integrals for 2-D, stable growth, ductile fracture, and use of elastic finite element method in its generation mode for obtaining dynamic elastic fracture parameters are discussed. The second topic is the finite difference method for analyzing the elasto-dynamic and elastic-plastic dynamic states in fracturing 2- and 3-D problems. The use of a super finite difference code to study dynamic ductile fracture using the void growth and coalescence model is discussed. The third topic is the boundary element method which has evolved into a practical tool for numerical analysis in 3-D linear elastic fracture mechanics. The final topic is the updated alternating technique, which was merged with a 3-D finite element code and together with a break-through in its analytical formulation, has become a cost-effective numerical technique in solving part and complete elliptical crack problems in 3-D linear elastic fracture mechanics. Comparisons between the J-integral of a 3-point bend specimen, the stress intensity factor for a surface flaw specimen and the dynamic stress intensity factor of a fracturing dynamic tear test specimen obtained by various investigators are made.