CONTENTS 16.3 Experimental determination of FLDs 250 16.4 Calculation of forming limit diagrams 252 16.5 Factors affecting forming limits 255 16.6 Changing strain paths 258 16.7 Stress-based forming limits 260 NOTE OF INTEREST ............ 260 REFERENCES.·········· .261 PROBLEMS ....261 17 Stamping········· ····.263 17.1 Stamping 263 17.2 Draw beads 263 17.3 Strain distribution 265 17.4 Loose metal and wrinkling 266 17.5 Springback 268 17.6 Strain signatures 269 17.7 Die design 270 17.8 Toughness and sheet tearing 272 17.9 General observations 274 N0TES0 F INTEREST.............275 REFERENCES.........................275 PROBLEMS.···· ....275 i8 Hydroforming,·············· ....277 18.1 General 277 18.2 Free expansion of tubes 277 18.3 Hydroforming into square cross sections 279 18.4 Bent sections 281 NOTE OF INTEREST ....................... 283 REFERENCES.··· .283 PROBLEMS.....................................................283 l9 Other Sheet Forming Operations.....··············· ......285 19.1 Roll forming 285 19.2 Spinning 286 19.3 Foldable shapes 288 19.4 Incremental sheet forming 288 19.5 Shearing 290 19.6 Flanging,hole expansion,and beading 291 19.7 Hemming 292 NOTE OF INTEREST .................... 293 REFERENCES………………·· .293 PROBLEMS.....................................................293x CONTENTS 16.3 Experimental determination of FLDs 250 16.4 Calculation of forming limit diagrams 252 16.5 Factors affecting forming limits 255 16.6 Changing strain paths 258 16.7 Stress-based forming limits 260 NOTE OF INTEREST .............................................. 260 REFERENCES ....................................................261 PROBLEMS ..................................................... 261 17 Stamping ............................................ 263 17.1 Stamping 263 17.2 Draw beads 263 17.3 Strain distribution 265 17.4 Loose metal and wrinkling 266 17.5 Springback 268 17.6 Strain signatures 269 17.7 Die design 270 17.8 Toughness and sheet tearing 272 17.9 General observations 274 NOTES OF INTEREST ..............................................275 REFERENCES ....................................................275 PROBLEMS ..................................................... 275 18 Hydroforming ......................................... 277 18.1 General 277 18.2 Free expansion of tubes 277 18.3 Hydroforming into square cross sections 279 18.4 Bent sections 281 NOTE OF INTEREST .............................................. 283 REFERENCES ....................................................283 PROBLEMS ..................................................... 283 19 Other Sheet Forming Operations ............................ 285 19.1 Roll forming 285 19.2 Spinning 286 19.3 Foldable shapes 288 19.4 Incremental sheet forming 288 19.5 Shearing 290 19.6 Flanging, hole expansion, and beading 291 19.7 Hemming 292 NOTE OF INTEREST .............................................. 293 REFERENCES ................................................... .293 PROBLEMS ..................................................... 293