VALIDATION OF LARGE SCALE FRACTURE AND FRAGMENTATION SIMULATIONS

1
VALIDATION OF LARGE SCALE FRACTURE AND
FRAGMENTATION SIMULATIONS V. B. Chalivendra, I.
Arias, J. Knap, A. J. Rosakis and M. Ortiz
Motivation Dynamic fragmentation
Numerical results comparisons
Elucidate the advantages and identify the limits
of the cohesive element approach compared to
other classical fracture approaches.
Objectives of the study
Multi-scale branching behavior for various impact
velocities
Design well instrumented benchmark experiments
that isolate dynamic crack branching, kinking,
microcracking, and overall fragmentation as the
primary phenomena under validation
scrutiny. Provide ultimate, albeit reasonable,
challenges to simulation.
Experimental design considerations
Use model brittle solids so that the
constitutive behavior is well approximated by
elasticity and does not obscure the fracture
phenomenon. Provide very well controlled boundary
conditions and high speed/full-field diagnostics
(high temporal and spatial resolution). Use
independently measured fracture parameters to
calibrate cohesive elements.
Experimental configuration
Crack deflection and subsequent penetration for
an interface angle of 45o
Crack deflection and subsequent penetration for
an interface angle of 60o
Directions of future work
Accurate Control of Initial Boundary
Conditions Use modified Hopkinson bar to
produce controlled loading high symmetry,
pulse shape and duration control
Determine local particle velocity profile by
strain measurement at crack faces and validate
its consistency with bar strain measurements
Use high-speed photography to observe loading in
real time Determination of correct cohesive law
parameters for accurate numerical modeling
Steel wedge