Research Summary
Modeling Four Quadrant Low Velocity Impact on Thick-Section Composites with and without Interlayers
Authors: M. S. Walter, S. E. Boyd (ARL), T. A. Bogetti (ARL) and B. Z. (Gama) Haque
EXPERIMENTAL PROCESS
Panels approximately 400mm x 400m x 14mm (16” x 16” x 0.5”)
96cm (~38”) drop with 227.4 kg (~500lb) crosshead
Impact energy of 2141 J and 4.34 m/s
50.8 mm (2”) hemispherical tup
5 layers of 100oz 3WEAVE® S-2 Glass/SC-15 with UAF-472 interlayers from Adhesive Films, Inc.
Panel 1 – Baseline, no interlayers
Panel 2 – 4 x 5 mil TPU interlayers
Panel 3 – 4 x 10 mil TPU interlayers
4 impacts: halfway between panel center and quadrant centers
Force vs. Time and delamination area collected for each impact event
LS-DYNA MODEL
Utilized MAT162 composite damage model
Fabric layers modeled as individual parts (nearly 24K elements each)
TPU interlayers contained nearly 8K elements
Four impacts were modeled sequentially within a single simulation; necessary to carry damage through the impact process
25-ms per impact with 5-ms settle time (120-ms total time)
Steel support and cover plates modeled to more accurately replicate experimentation
FINITE ELEMENT PROCESS
Developed LS-DYNA model for nominally ½”, 5-layer 100oz 3WEAVE panel with clamped boundary condition
Optimized parameters to match force vs. time response of baseline panel
Estimated properties for bi-linear cohesive zone model (MAT186) of TPU interlayer
Simulated interlayer panels using optimized parameters and cohesive zone model
Compared experimental and simulation outputs for:
Damage area
Force vs. time response
FORCE VS. TIME REPONSE OF A PANEL WITHOUT INTERLAYER
MAT162 parameters were adjusted to match the simulation results to the experimental force vs. time responses for the baseline panel
EXPERIMENTAL DAMAGE AREA
No Interlayer
5 mil Interlayer
10 mil Interlayer
FINITE ELEMENT DAMAGE AREA
No Interlayer
5 mil Interlayer
10 mil Interlayer
FUTURE WORK
Re-examine MAT162 damage/delamination criteria for 100oz material
Characterize TPU interlayer
Uniaxial tension, planar tension, etc.
Single and double lap shear
Determine properties critical for durability
ACKNOWLEDGEMENTS
This research was supported in part by an appointment to the Postgraduate Research Participation Program at the U.S. Army Research Laboratory administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and USARL.
