Center for Composite Materials - University of Delaware

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.

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