Transcript
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 – Exploded View
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 – Exploded View
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
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
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)
Micro-Harmonic Motion
• 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.
Micro-Harmonic Motion
Pressure-Time Curves
Pressure-Time Curves
Pressure-Time Curves
Pressure-Impulse 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 Spring #2 (x4) 3.10 (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)
Damper Spring #3 (x4) 1.08 (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?
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