Crash and Safety overviewweb.iitd.ac.in/~achawla/public_html/736/11-Crash_Safety_practices.pdf ·...
Transcript of Crash and Safety overviewweb.iitd.ac.in/~achawla/public_html/736/11-Crash_Safety_practices.pdf ·...
Crash and Safety overview
Contents1. Crash Rules and regulation in Europe and USA
2. Crashworthiness Restraint Technologies
3. Crash Legal Requirements
4. New Car Assessment Program (NCAP)
5. Front Impact Overview
6. Side Impact Overview
7. Roof Crash Overview7. Roof Crash Overview
FMVSS :‐ US Crash Regulations ECE :‐ Europe Crash Regulations
Ref:‐ Safety Companion 2011 (Carhs)
Crashworthiness Restraint Technologies
Lap / ShoulderSafety Belts
Seat Belt Use Reminder
Dual PretensionersBelt Comfort Guide
Energy Management System
Dual Pretensioners
Knee Air Bags
Driver and PassengerFront Air Bags ‐‐ Dual Level
Automatic Door Locks
Rollover‐capableHead Curtain Air Bag
PassengerSensing
Side Impact Air BagsSystem
Crash Legal Requirements and Consumer Rating
Legal requirementsFMVSS 208 ConsumerECE‐R94…
Consumer ratingsUS NCAPEURO NCAP
•Test setups (rigid barrier, ODB, … )
•Dummies (5%ile female, 50%ile male, …)… ( % , % , )
•Crash velocities (40km/h, 56km/h, … )
Basis of ratings: Dummy criteriaBasis of ratings: Dummy criteria
Design of Restraint SystemAdjustment of belt + airbag systems for best overall performance
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Front ImpactFront Impact
Types of Frontal Load cases
Frontal impact
yp
High Speed Low speed
FMVSS 208 CONSUMER METRIC TEST Danner
OFFSET DEFORMABLE
BARRIERIIHS EURONCAP
RIGID BARRIERNCAP
IIHS , EURONCAP
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Physics of a Crash
v• Kinetic Energy = ½ mv2
• Work = F*D; where• F ‐> Average Force on Vehicle by Wall• D ‐> Crush + Rebound of Vehicle
• Dissipate KE into Vehicle Deformation (or Work) but away from occupant
• Energy Dissipation Rate α Injury
F
• Energy Dissipation Rate α Injury
• Constant Force as “ideal”• Axial Crush as preferred mode• Maximize Crush Space• Minimize Intrusion
Structural Deformation in a Crash
rce
Crush
For
Bending
Deflection
Crush Space Measurement
Static Crush Space = Free Crush + Crushed ComponentsDynamic Crush = Static Crush Space + Dynamic Dash Intrusion
Load Distribution PhilosophyLoad Distribution PhilosophyTransition Zone bridges offset between loadpaths in crush zone & safety cage;
enables effective load transfer & provides stability control
Side Impact
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Primary Load Path in Side Impact
St t l it iStructural criteria:• Load transfer continuity to doors.• Small relative displacements• Small absolute displacements up to t=40ms for enabling air bag inflationt 40ms for enabling air bag inflation
Roof Crush
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)
Ref:‐ Safety Companion 2011 (Carhs)