BOOK Bois - Vehicle Crash Worthiness

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Transcript of BOOK Bois - Vehicle Crash Worthiness

VEHICLECRASHWORTHINESSANDOCCUPANT PROTECTIONPaul Du BoisClifford C. ChouBahig B. FiletaTawfik B. KhalilAlbert I. KingHikmat F. MahmoodHarold J. MertzJac WismansEditors:Priya PrasadJamel E. BelwafaSponsored by:Automotive Applications CommitteeAmerican Iron and Steel InstituteSouthfield, MichiganDisclaimerThe opinions included in this publication are those of the indi-vidual authors and in no way represent endorsement of the Edi-tors or American Iron and Steel Institute (AISI) Safety Panelmembers.copyright c 2004American Iron and Steel Institute2000 Town CenterSouthfield, Michigan 48075 Page iiiContentsIntroduction........................................................ 11.1 Motor Vehicle Safety..................................................................... 11.2 The Automobile Structure .............................................................. 31.3 Materials ...................................................................................... 41.4 Crashworthiness ........................................................................... 41.5 Crashworthiness Goals ................................................................. 51.6 Crashworthiness Requirements .................................................... 61.7 Achieving Crashworthiness ........................................................... 71.8 CrashworthinessTests................................................................... 81.9 Crashworthiness Models Requirements ...................................... 102.1 Introduction ................................................................................. 112.2 Current Design Practice.............................................................. 122.2.1 Comparison Between LMS and FE-Based CrashworthinessProcesses ....................................................................... 132.2.2 Lumped Mass-Spring Models ............................................... 162.2.3 Limitations of LMS Models................................................... 202.3 Crash/Crush Design Techniques for Front Structures .................. 262.3.1 Some Basic Principles of Designing for Crash Energy Manage-ment ................................................................................ 282.3.1.1 Desired Dummy Performance........................................ 292.3.1.2 Stiff cage Structural Concept ......................................... 292.3.1.3 Controlled Progressive Crush or Deformation With LimitedIntrusion ......................................................................... 302.3.1.4 Weight Efficient Energy Absorbing Structures and Support-ing Frame ....................................................................... 312.3.2 Review of Analytical Design Tools for Crash Energy Manage-ment ................................................................................ 322.3.2.1 Hybrid Models ............................................................... 322.3.2.2 Collapsible Beam Finite Element .................................. 352.3.2.3 Dynamic Effects............................................................ 362.3.3 New Design Methodology .................................................... 382.4 Analytical Design Tools ............................................................... 402.4.1 Component Design .............................................................. 402.4.1.1 Collapse Modes ............................................................ 412.4.1.2 Axial Collapse ............................................................... 422.4.1.3 Bending Collapse Mathematical Models ........................ 612.4.1.4 Combined Loading ........................................................ 70 Page iv2.4.1.5 Structural Joints ............................................................ 742.4.2 Design of Substructures....................................................... 752.4.2.1 General Analysis Methods ............................................ 762.4.2.2 Super-Collapsible Beam................................................ 782.4.2.3 Thin-Walled Finite Beam Element ................................. 802.4.2.4 Structural Programming................................................. 812.5 Vehicle Front Structure Design for Different Impact Modes .......... 842.5.1 Vehicle Front Structure Design for Current Standards ........... 852.5.1.1 FMVSS 208 .................................................................. 852.5.1.2 NCAP Test .................................................................... 852.5.1.3 IIHS Test ....................................................................... 872.5.2 Vehicle-to-Vehicle Frontal Collisions .................................... 882.5.2.1 Preliminary Relationships in Head-on Frontal Collision .. 892.5.2.2 Strategies for Designing Front Structures for Head-onImpact ............................................................................ 932.5.3 Assessment of Analytical Tools............................................ 982.5.4 Conclusion ......................................................................... 1002.6 References ............................................................................... 1023.1 Historical Background................................................................ 1113.2 Overview of Explicit FE Technology ........................................... 1173.2.1 Formulation........................................................................ 1183.2.2 Explicit Integration ............................................................ 1203.2.3 Shell Element .................................................................... 1213.2.4 Plasticity ........................................................................... 1233.2.5 Contact Treatment ............................................................. 1243.3 Models Development Between 1987 and 1997 ...................... 1253.4 Software Development Between 1987 and 1997 ........................ 1303.5 Limitations of Current Technology ............................................. 1323.6 Applications .............................................................................. 1363.6.1 Component Models ............................................................ 1373.6.2 Substructure Models .......................................................... 139................................................................................................... 1393.6.3 Full-scale vehicle structure models .................................... 1393.6.3.1 Model Statistics: ......................................................... 1423.6.3.2 Contact Definitions ...................................................... 143............................................................................................... 1433.6.3.3 Initial Condition ........................................................... 1433.6.3.4 Results ........................................................................ 1433.6.4 Integrated Vehicle-Occupant-Restraints Model ................... 143................................................................................................... 143Fig. 3.6.4.1 Integrated model ................................................... 146............................................................................................... 146 Page vFig. 3.6.4.2 Integrated model deformations .............................. 146............................................................................................... 147Fig. 3.6.4.3 Energy balance of integrated model simulation ..... 147............................................................................................... 147Fig. 3.6.4.4 Rear rocker velocity .............................................. 1473.7 Summary .................................................................................. 1483.8 References ............................................................................... 1514.1 Introduction ............................................................................... 1594.2 Barrier Collision ........................................................................ 1624.3 Basic Laws and Concepts of Motion ......................................... 1644.3.1 Basic Principles of Postulates ........................................... 1674.3.2 Particle Under Given Forces .............................................. 1674.3.3 Interactions ........................................................................ 1684.3.4 Two Additional Postulates .................................................. 1694.3.5 Idealizations....................................................................... 1694.3.6 Energy and Work ............................................................... 1694.3.7 Conservation of Energy ...................................................... 1704.4 Application of Concepts to Vehicle/Occupant Analysis.............. 1704.4.1 Background ....................................................................... 1704.4.2 Vehicle Response .............................................................. 1724.4.3 Pulse Waveform Efficiency (h) ............................................ 1744.4.4 Equivalent Square Wave (ESW): ........................................ 1774.4.5 Effect of Pulse Shape ........................................................ 1774.4.6 Occupant Response .......................................................... 1784.5 Axioms for Good Occupant Restraint Performance and Design . 1864.6 Vehicle/Occupant Velocity Profiles ........................................... 1884.6.1 Frontal Impact Analysis ..................................................... 1884.6.2 Side Impact Analysis ......................................................... 1894.6.2.1 Baseline Analysis ....................................................... 1894.6.2.2 Effects of Structural Ugrading ...................................... 1924.6.2.3 Effects of Cushioning