Blast-Resistant Window v1.4

Blast-Resistant Window

Hans Julian SunaryantoSP/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 3.0RMToolISADS

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

Design #1 – Exploded View

Design #1 - Damper

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 higho $628.77 for entire window, $55.63/psi of capacityo Due to high machinery cost - complex custom-made parts

Design #2

Design #2 - Damper

Design #2 - Strengths• More efficient use of space

• Increases maximum pressurecapacity by 10.02 psi (each damperfor 2.51 psi)

• Cost-per-capacity is lowero $ 463.27 for entire window, $24.28/psi of capacity

Design #2 - Weaknesses

• Weak structural strengtho Much higher shear than stress

• Ineffective shock absorptiono Angle w/ vertical <45°

Design #3

Design #3 - Damper

Design #3 - Strengths• Most efficient use of space

• Cost-per-capacity is lowesto $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 - StatesRelaxed 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


• 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

Inertialmotion

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/nanosecondso Enough time for window to complete hundreds of cycle – both

lower and higher exposure time will experience thiso 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 effecto 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.


Pressure-Time Curves

Design #3Critical 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

Design #3

Part Name CostFront 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)

Questions?

Blast-Resistant Window v1.4

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