Blast-Resistant Window v1.4

Blast-Resistant
Window
Hans Julian Sunaryanto
SP/SU15 Co-op – University of Illinois at Urbana-Champaign ‘16

Purpose
• Provide a permanent window design able to
withstand high pressure waves
• Decrease injuries and damages suffered due to
window failures in cases of exposure to high
pressure waves
• To create a design that is highly adaptable and
applicable in its purpose (walls, doors, windows,
etc.) and materials (lexan, acrylic,
annealed/tempered glass, etc.)

Procedure & Software
Used
Create design based
on wanted
parameters
Product Analysis &
Specs Evaluation
Cost Evaluation
Satisfied?
Edit and optimize
existing design
lightly
Not even close
Meh
YES
PTC Creo Parametric 3.0
PTC Mathcad 3.0
RMTool
ISADS
aPriori 2015

Design Considerations
• Created with the purpose of providing a blast-
resistant window for Box Canyon’s permanent
control building
• Allows for visual confirmation of testing steps from
within the building
• Allows for higher-scale tests without compromising
personnel safety

Design Considerations
• Must also be easily applicable to systems other than
control building’s windows
• Low maintenance, long lifespan
• Space-efficient
• Cost-efficient

Design #1 - Strengths
• Robust design
• Increases maximum pressure capacity by 6.27 psi
(each damper for 1.57 psi)

Design #1 - Weaknesses
• Inefficient use of space
• Cost-per-capacity is high
o $628.77 for entire window, $55.63/psi of capacity
o Due to high machinery cost - complex custom-made parts

• More efficient use of space
• Increases maximum pressure
capacity by 10.02 psi (each damper
for 2.51 psi)
• Cost-per-capacity is lower
o $ 463.27 for entire window, $24.28/psi of capacity

Design #2 - Weaknesses
• Weak structural strength
o Much higher shear than stress
• Ineffective shock absorption
o Angle w/ vertical <45°

• Most efficient use of space
• Cost-per-capacity is lowest
o $501.24 for entire window,
$12.58/psi of capacity
• Increases maximum pressure capacity by 18.2 psi
(each damper for 4.55 psi)
• High structural strength

Design #3 - States
Relaxed Compressed

Pressure-Impulse Curves
• Reference values obtained from ISADS’ P-I curve for
designated polycarbonate thickness
• Using approx. 20 data points on prospective critical
pressures

Pressure-Impulse Curves
• Hand calculations on:
• Finding net force applied
• Finding total force absorbed by dampers
• Finding displacement-, velocity- and acceleration-time relationships
• Micro-harmonic equations of motion on normal windows
• Time taken for full compression (known final displacement)
• Creating pressure-time curve for a specific peak overpressure from
reference curve
• Adding time considerations (harmonic & damping motions) while
maintaining peak overpressure
• Drafting a new pressure-time curve for specified design
• Integrating curve to obtain critical impulse value for specified pressure

Micro-Harmonic Motion
Blast wave direction
Inertial
motion
Inertial
motion
n+1/4 n+3/4

• Effects overall window strength during reverse
motion phase
• Good commercial use, horrible protective use
• Direction of inertial motion opposes direction of blast wave; higher
stress every (n+¾th) in exposure time
• Grains in center affected the most
• Premature failure in the center; starts with micro-scale crack
• Crack propagates very quickly in brittle materials
• Premature failure most evident at lower exposure time
o Harmonic motion period is in the order of micro/nanoseconds
o Enough time for window to complete hundreds of cycle – both
lower and higher exposure time will experience this
o Longer exposure time allow grains to ‘adjust’ as force received
increases more gradually. This modifies grain shape to withstand
more force before first crack (to a certain extent)

• New design effectively ‘removes’ this effect
o Directly attached to both sides (Screws and inner frame)
o Decreases premature crack significantly
• Higher window strength especially at lower
exposure time (most evident in P-I curve to the right
of the vertical asymptote)
o Helps create a different slope in the P-I curve.

Design #3
Critical Pressures
• 29.8 psi: normal polycarbonate lexan (CR100) failure
• 51.9 psi: enforced window failure (with 1.75 cm lexan)
• 19.6 psi: normal acrylic failure
• 41.7 psi: enforced window failure (with 1.75 cm acrylic)
• 180.3 psi: first structural crack
• 243.7 psi: first structural failure

Design #3
Part Name Cost
Front Window Frame 43.67
Lexan Window 12.80
Inner Frame 18.70
Damper Body (x4) 13.86 (x4)
Damper Spring #1 (x4) 5.27 (x4)
Damper Actuator (x4) 6.02 (x4)
Damper Elbow #1 (x4) 18.11 (x4)
Damper Support (Ax2 & Bx2) 2.23 (x4)
Damper Elbow #2 (x4) 10.02 (x4)
Damper Head (x4) 3.55 (x4)
Fasteners (Screws) ~3.00
Assembly & Machine Use Cost 160.55
Predicted Mark-up Price 200.31
Total 691.99
• Radial tolerance set at 0.1 cm; pin-shaft at 0.1 mm; others at 0.25-1.00 cm
• Based on 60th percentile across the United States (aPriori): TX is at 63rd

Adaptability
• For window surfaces with <7.25 psi maximum
pressure capacity, must use anti-shatter film as
window will break before damper acts
• 7.25 psi is obtained from 2.5(FoS)*2.9psi(Total static resistive forces)
• 6.88 psi is the maximum pressure the window needs to withstand
before damper reaches full compression
• Will require replacement after every blast (cracks)
• Does not require replacement or anti-shatter film
when using any window surface with >7.25 psi max.
pressure capacity

Recommendations
• Use of anti-shatter film is advised regardless of
window surface
• Additional thin lexan sheet attached to the back
window frame (to create air-and-water-tightness)
• Use of Hydraulic fluid to fill Damper Elbows #1’s and
#2’s cavities (i.e. Thioplast G21)

Blast-Resistant Window v1.4

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Editor's Notes