Blast and Impact Resistant Composite Structures for Navy · PDF fileBlast and Impact Resistant...
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Composite Structures and Nano-Engineering Research
The University of Mississippi
Blast and Impact Resistant Composite Structures for Navy Ships
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
OBJECTIVE AND SCOPE OF RESEARCH
Light weight, fast, stealthy ships are required for the US Navy littoral operations. The
currently approved series of ships, the DD(X), has stringent requirements for reduced
topside weight as well as fire/smoke toxicity.
Need for reducing life cycle costs, and the ability to incorporate multi-functionality,
including blast, shock and impact resistant features lead towards the use of affordable
composite materials and sandwich structures.
Scope of our research includes: low-cost fire-resistant exfoliated graphite nano platelet
reinforced glass/carbon polymeric based composites with fly ash and 3-D fiber
reinforced foams; investigating their response to low-velocity impact, ballistic, shock
and blast loads; dynamic mechanical analysis for modulus, damping, creep and stress
relaxation; developing constitutive models and high-performance scalable computing
based modeling and simulations; accelerated testing for long-term durability; and their
radar-absorbing and EM-shielding characteristics for improved stealth and safety.
MATERIALS
FIBERS:
E-Glass,
T700 graphite,
HPG (Owens Corning)
CORES:
Tycor, Balsa, PVC,
Eco-Core
MATRICES:
Vinyl ester, Phenolic
NANO:
xGnP graphite platelet,
Cloisite 30B nanoclay,
MWCNT
TESTING
BLAST:
Blast load simulator
SHOCK:
Shock tube
IMPACT:
- Low velocity drop weight
- High strain Hopkinson Bar
- Ballistic projectile
DMA (Dynamic Mechanical
Analysis)
LONG TERM DURABILITY
MULTI-FUNCTIONAL
- EM Interference
- Radar Shielding
- Fire Resistance
ANALYSIS
- Modeling & Simulations
(AUTODYN, EPIC)
- Particle Dynamics
- Shock Models
SANDWICH STRUCTURES
- E-glass / Tycor 3-D foam core
- E-glass / Balsa wood core
- T700 Graphite / PVC foam core
NANO FILMS / COATINGS
- Graphite platelet films / coatings
- Elastomeric coatings
BLAST AND IMPACT RESISTANT COMPOSITE STRUCTURES FOR NAVY SHIPS
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
RESEARCH PARTNERS
The University of Mississippi (UM), Michigan State University (MSU), and University of
New Orleans (UNO), supported by the US Army Corps Engineer Research and
Development Center (ERDC) are utilizing their research strengths in modeling, analysis,
fabrication and testing of affordable blast, shock and impact resistant nanoparticle
reinforced composite structures for the new generation navy ships.
University of Alabama-Birmingham (UAB) is fabricating the large VARTM sandwich
composite panels and performing quasi-static, fire and ballistic tests.
North Carolina A&T State University (NC AT) is providing their patented low-cost fire
resistant fly ash based Eco-Core foams.
Northrop Grumman Ship Building (NGSB), Gulfport, MS is advising and facilitating UM on
these research efforts.
WebCore Technologies, Miamisburg, OH is providing their patented TYCOR® foam cores
for blast, shock and impact resistant sandwich panels.
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
SANDWICH COMPOSITES
Sandwich composites with balsa and foam cores are presently being featured in a
number of navy applications such as surface ship deck structures, radar masts and
boat hulls. In the present work, some new and emerging cores have been explored in
sandwich construction. Different core types that have been considered include:
Balsa wood, a traditional core material, used in present generation ship structures. Balsa is
a natural material, prone to local variation in properties due to cell size and cell thickness
variations;
Polyvinyl chloride (PVC) foam core is also used in present generation ship structures for
radar mast enclosures and boat hulls;
Eco-Core is an emerging fire resistant sandwich core. Fire damage in ship structures is of
significant concern. The burn-through resistance and heat insulation characteristics of Eco-
core makes it an attractive fire resistant core.
Tycor (TYCOR® from WebCore Technologies), an engineered three-dimensional fiber
reinforced damage tolerant core for sandwich structures, has the potential to provide
improved blast and ballistic resistance. In this core, glass fiber is reinforced through the
thickness of closed cell foam sheets to produce a web and truss structure.
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
TYCOR® 3-D STITCHED FOAM
WEBCORE TECHNOLOGIES
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
BLAST RESISTANCE OF SANDWICH COMPOSITES
Trial blast tests, simulating approximate threat levels of 2000 to 27,000 lbs TNT at about
150 feet, were conducted at the ERDC - Blast Load Simulator (BLS) facility.
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
One 4’ x 4’ E-glass/Tycor panel, with all-around
bolted b.c. was subjected to about 80 psi peak
pressure.
Panel was not breached and there are no visible
signs of damage.
Foam used for filling gaps between the frame and
target vessel blew out. Deflection gage disengaged
and laser over heated during the experiment
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
E-GLASS / TYCOR SANDWICH PANEL (fixed-free) - BLAST TEST
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
E-GLASS / TYCOR SANDWICH PANEL (fixed-free) - AFTER BLAST TEST
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
One 64” x 34” E-glass/Balsa core panel was subjected to about 60 psi peak pressure
with different holding fixture.
Panel slid through the supports and was completely damaged, with E-glass face skin on blast
side shearing into two halves at the middle.
Instrumentation, data acquisition and specimen clamping issues are being resolved for future
full-scale blast experiments.
Blast and Impact Resistant Composite Structures for Navy Ships
University of Mississippi
Sandwich composite panels, bolted at top/bottom
and two-sides free, undergoing blast tests of 16
to 18 psi peak pressure and 200 psi-ms impulse
(equivalent to ~ 2000 lbs of TNT at 140 feet).
Panels underwent 0.5 to 1.5 inches of mid-point
deflection, with no visible signs of damage.
BLAST TESTS ON SANDWICH COMPOSITE PANELS
P4 (initial pressure)
P5high-pressure
chamber
low-pressure
chamberpiston
P1(initial pressure)
intermediate-pressure
chamber with 1st diaphragm2nd diaphragm
P6 dump-tank
Blast tube
P4 (initial pressure)
P5high-pressure
chamber
low-pressure
chamberpiston
P1(initial pressure)
intermediate-pressure
chamber with 1st diaphragm2nd diaphragm
P6 dump-tank
Blast tube
SHOCK TESTS ON SANDWICH BEAM SPECIMENS
Shock tests were performed (at Michigan State University) on sandwich beam specimens
held under simply supported conditions and subjected to ~1350 psi peak pressure.
Innovative 20-pin finger sensor was used for measuring the deformations when fingers
contacted backside of specimen.
SHOCK RESPONSE OF SANDWICH BEAM SPECIMENS
CONSTITUTIVE MODELING AND SIMULATIONS
ANSYS AUTODYN (an explicit hydrocode that uses finite difference, finite volume, and
finite element techniques to solve wide variety of non-linear dynamic problems in solids,
fluids, gases, and their interactions) was used to model and analyze sandwich composite
beams under shock loading.
Experimental AUTODYN Simulation
PVC-Core
Balsa-Core
TYCOR-Core
Failure shapes, obtained experimentally and numerically, for
sandwich composite beams under shock loading.
TENSION AND COMPRESSION
HOPKINSON BARS
SHOCK TUBE
EXPERIMENTAL FACILITIES ESTABLISHED
AT UNIVERSITY OF MISSISSIPPI
Shock tube (with piston attachment) for
generating blast pressure wave forms up
to 15 Kpsi (100 MPa) and 50 milli sec
duration at 1000 ft/sec (300 m/sec)
velocity.
Split-Hopkinson Pressure Bars (SHPB)
for the high-strain rate evaluation of
nano-reinforced specimens, foams and
sandwich composites, in both tension
and compression.
Experimental blast response and quasi-static material property data were generated for
E-glass and carbon facesheet sandwich composite panels with balsa, PVC foam and
TYCOR® cores.
The Pressure vs Impulse (P-I) curve methodology that was developed to represent
estimated damage levels in civil infrastructure components subjected to blast loadings,
has been adapted for analyzing these sandwich composite panels.
P-I curve methodology enables the generation of a database of performance envelopes
for sandwich composite panels with a variety of skin and core material combinations
under various blast and shock loading scenarios.
Results show good correspondence between model predictions and experimental data
for the performance evaluation of sandwich composite panel configurations that were
analyzed.
COMPUTATIONAL SIMULATION AND ANALYSIS
The P-I (Pressure-Impulse) diagram mathematically relates a specific damage level to a
combination of blast pressure and impulse imposed on a particular structural element and
allows reduced order modeling of the sandwich composite panel systems.
P-I curves are also known as iso-damage curves with each curve representing a certain
response level such as mid-span deflection or rotation at supports, etc.
In a particular threat scenario, the pressure and impulse acting on a structure can be
determined by using scaling laws based on the distance of the structure from the blast
source.
Knowing the distribution of pressure and impulse due to a specific blast scenario, the
damage to individual components in terms of ductility demand can be determined from
the P-I chart, and can also be further mapped onto a structure consisting of many
such components.
P-I CURVE METHODOLOGY
Ro
yo Equivalent SDOF System
Force-Deflection Curve
P-I Curves
y/ yo
Composite Panel
PROCEDURE FOR GENERATING P-I CURVES NUMERICALLY