Fundamentals of Automobile Body Structure Design

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Fundamentals of

Automobile Body Structure Design Table of Contents

Contents:

Chapter 1 - The Automobile Body .......................................................... 1 1.1 1.2 1.3 1.4 1.5

Description of the Automobile Body Types ................................................ 3 Body Nomenclature ....................................................................................... 5 Body Mass Benchmarking ........................................................................... 10 The Body Structure as a System ................................................................. 11 Note on Design Philosophy ........................................................................ 12

Chapter 2 - Body Structural Requirements ............................................13 2.1 2.2 2.3 2.4

Categories of Structural Requirements...................................................... 14 The Locate and Retain Function ................................................................. 17 Locate and Retain for Front Suspension Attachment Structure ............ 20 Flow Down of Requirements from Vehicle-Level Functions ................. 30

Chapter 3 - Automotive Body Structural Elements .................................35 3.1 3.2 3.3 3.4 3.5 3.6 3.7

Overview of Classical Beam Behavior ....................................................... 36 Design of Automotive Beam Sections........................................................ 41 Torsion of Thin-Wall Members ................................................................... 50 Thin-Wall Beam Section Design in Automobiles ..................................... 70 Buckling of Thin-Walled Members ............................................................ 77 Automobile Body Panels: Plates and Membranes ................................. 100 Summary: Automotive Structural Elements........................................... 116

Chapter 4 - Design for Body Bending ..................................................119 4.1 4.2 4.3 4.4 4.5

Body Bending Strength Requirement ...................................................... 120 Body Bending Stiffness Requirement ...................................................... 123 Internal Loads During Global Bending: Load Path Analysis............... 128 Analysis of Body Bending Stiffness ......................................................... 135 Principles of Good Joint Design ............................................................... 147

Chapter 5 - Design for Body Torsion ....................................................161 5.1 5.2 5.3 5.4 5.5

Body Torsion Strength Requirement ........................................................ 162 Body Torsion Stiffness Requirement ........................................................ 163 Internal Loads During Global Torsion: Load Path Analysis ................ 167 Analysis of Body Torsional Stiffness ........................................................ 178 Torsional Stiffness of Convertibles and Framed Vehicles ..................... 192

Chapter 6 - Design for Crashworthiness ..............................................209 6.1

Standardized Safety Test Conditions and Requirements...................... 210

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Fundamentals of Automobile Body Structure Design

Table of Contents cont. Front Barrier ................................................................................................ 211 Side Impact .................................................................................................. 236 Note on Rear Impact .................................................................................. 245 Note on Roof Crush .................................................................................... 247

Chapter 7 - Design for Vibration .........................................................251 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10

First-Order Vibration Modeling ............................................................... 252 Source-Path-Receiver Models of Vibration Systems.............................. 256 Frequency Response of a Single-Degree-of-Freedom System .............. 260 SDOF Models of Vehicle Vibration Systems .......................................... 266 Strategies for Design for Vibration ........................................................... 281 Body Structure Vibration Testing ............................................................. 283 Modeling the Body Structure Resonant Behavior.................................. 285 Vibration at Frequencies Above the Primary Structure Modes ........... 290 Note on Use of Rotating Phasors to Solve Damped Vibration Problems ..................................................................................... 306 Note on Mechanical Impedance Technique ............................................ 308

Chapter 8 - Design for Vehicle and Styling Integration .........................313 8.1 8.2 8.3 8.4 8.5 8.6 8.7

Designing the Best Body Structure........................................................... 314 Vehicle Layout ............................................................................................. 314 Exterior Body Surface ................................................................................ 326 Constraints on Body Structure from Vehicle Layout and Exterior Surface ........................................................................................... 331 Body Structure Topology ........................................................................... 334 Load Path Design at Suspension Attachments....................................... 339 Summary ...................................................................................................... 348

Chapter 9 - Material Selection and Mass Estimation in Preliminary Design ...........................................................................351 9.1 9.2

Materials for the Body-in-White ............................................................... 352 Preliminary Mass Analysis ........................................................................ 368

Appendices.......................................................................................381 A. B. C.

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Exercises ....................................................................................................... 381 Nomenclature .............................................................................................. 431 English & Metric Units & Typical Values for Key Parameters ............. 435

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6.2 6.3 6.4 6.5