RD-E: 2603 Forming

Failure criteria defined with failure model /FAIL/FLD.

In Radioss it is possible to simulate failure with a failure model. FLD failure models are most commonly used for forming, which describe material failure in strain space. Here, one shell element and circular plate model are used to demonstrate the failure behavior with FLD failure model.

Options and Keywords Used

Input Files

Refer to Access the Model Files to download the required model file(s).

The model files used in this example are available in:

/radioss/example/26_Ruptured_plate

Model Description

FLD Failure Model (Forming Limit Diagram)

This failure model uses the generic forming limit diagram (FLD), defined for the given material. The curve is expressed in the area of principal strains (major and minor strains).


Figure 1.
The above FLD diagram shows:
  • In uniaxial test (by dεminordεmajor=v=0.33 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWcaaqaaiaadsgacqaH1oqzdaWgaaWcbaGaamyBaiaadMgacaWGUbGaam4BaiaadkhaaeqaaaGcbaGaamizaiabew7aLnaaBaaaleaacaWGTbGaamyyaiaadQgacaWGVbGaamOCaaqabaaaaOGaeyypa0JaeyOeI0IaamODaiabg2da9iabgkHiTiaaicdacaGGUaGaaG4maiaaiodaaaa@4E3B@) once point P1 (-0.0374,0.1133) is reached, the element fails
  • In eqibiaxial test (by dεminordεmajor=1 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaWcaaqaaiaadsgacqaH1oqzdaWgaaWcbaGaamyBaiaadMgacaWGUbGaam4BaiaadkhaaeqaaaGcbaGaamizaiabew7aLnaaBaaaleaacaWGTbGaamyyaiaadQgacaWGVbGaamOCaaqabaaaaOGaeyypa0JaaGymaaaa@4835@) once point P2(0.26,0.26) is reached, the element fails


Figure 2.
The damage will print either with /ANIM/SHELL/DAMA or /ANIM/SHELL/FLDF in the Engine file. Both define damage as:(1) D=εmajorεlim MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGebGaeyypa0ZaaSaaaeaacqaH1oqzdaWgaaWcbaGaamyBaiaadggacaWGQbGaam4BaiaadkhaaeqaaaGcbaGaeqyTdu2aaSbaaSqaaiGacYgacaGGPbGaaiyBaaqabaaaaaaa@4479@
It compares the current εmajor MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH1oqzdaWgaaWcbaGaamyBaiaadggacaWGQbGaam4Baiaadkhaaeqaaaaa@3DED@ with εlim MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH1oqzdaWgaaWcbaGaciiBaiaacMgacaGGTbaabeaaaaa@3C0B@ , which is from the FLD curve by the same εminor MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqGqFfpeea0xe9vq=Jb9vqpeea0xd9q8qiYRWxGi6xij=hbba9q8aq0=yq=He9q8qiLsFr0=vr0=vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaH1oqzdaWgaaWcbaGaamyBaiaadggacaWGQbGaam4Baiaadkhaaeqaaaaa@3DED@.


Figure 3.

Only with /ANIM/SHELL/FLDF and Ifail_sh=4 is it possible to compute just the damage and not delete the element. It used to have a better vision of dangerous zones.

Results

Use the above FLD curve in the plate example and failure printed in animation with /ANIM/SHELL/FLDF and /ANIM/SHELL/DAMA like:


Figure 4.
/ANIM/SHELL/FLDZ can also be used to print the failure zone.


Figure 5. Failure zone
FLDZ=6
Failure
εmajor>εlim MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaSbaaSqaaiaad2gacaWGHbGaamOAaiaad+gacaWGYbaabeaakiabg6da+iabew7aLnaaBaaaleaaciGGSbGaaiyAaiaac2gaaeqaaaaa@4231@
FLDZ=5
Marginal
εlim>εmajor>εmarginal MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaSbaaSqaaiGacYgacaGGPbGaaiyBaaqabaGccqGH+aGpcqaH1oqzdaWgaaWcbaGaamyBaiaadggacaWGQbGaam4BaiaadkhaaeqaaOGaeyOpa4JaeqyTdu2aaSbaaSqaaiaad2gaciGGHbGaaiOCaiaacEgacaWGPbGaamOBaiaadggacaWGSbaabeaaaaa@4C88@
FLDZ=4
Safe
εmarginal>εmajor>|εminor| MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaSbaaSqaaiaad2gaciGGHbGaaiOCaiaacEgacaWGPbGaamOBaiaadggacaWGSbaabeaakiabg6da+iabew7aLnaaBaaaleaacaWGTbGaamyyaiaadQgacaWGVbGaamOCaaqabaGccqGH+aGpdaabdaqaaiabew7aLnaaBaaaleaacaWGTbGaamyAaiaad6gacaWGVbGaamOCaaqabaaakiaawEa7caGLiWoaaaa@51A2@
FLDZ=3
Compression
εminor>εmajor>εminorRani1+Rani MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyOeI0IaeqyTdu2aaSbaaSqaaiaad2gacaWGPbGaamOBaiaad+gacaWGYbaabeaakiabg6da+iabew7aLnaaBaaaleaacaWGTbGaamyyaiaadQgacaWGVbGaamOCaaqabaGccqGH+aGpcqGHsislcqaH1oqzdaWgaaWcbaGaamyBaiaadMgacaWGUbGaam4BaiaadkhaaeqaaOGaeyyXIC9aaSaaaeaacaWGsbWaaSbaaSqaaiaadggacaWGUbGaamyAaaqabaaakeaacaaIXaGaey4kaSIaamOuamaaBaaaleaacaWGHbGaamOBaiaadMgaaeqaaaaaaaa@593B@
FLDZ=2
High wrinkle
εminorRani1+Rani>εmajor MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyOeI0IaeqyTdu2aaSbaaSqaaiaad2gacaWGPbGaamOBaiaad+gacaWGYbaabeaakiabgwSixpaalaaabaGaamOuamaaBaaaleaacaWGHbGaamOBaiaadMgaaeqaaaGcbaGaaGymaiabgUcaRiaadkfadaWgaaWcbaGaamyyaiaad6gacaWGPbaabeaaaaGccqGH+aGpcqaH1oqzdaWgaaWcbaGaamyBaiaadggacaWGQbGaam4Baiaadkhaaeqaaaaa@50AB@
FLDZ=1
Loose metal
εmajor2+εminor2>Factor_Loosemetal2 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaSbaaSqaaiaad2gacaWGHbGaamOAaiaad+gacaWGYbaabeaakmaaCaaaleqabaGaaGOmaaaakiabgUcaRiabew7aLnaaBaaaleaacaWGTbGaamyAaiaad6gacaWGVbGaamOCaaqabaGcdaahaaWcbeqaaiaaikdaaaGccqGH+aGpcaWGgbGaamyyaiaadogacaWG0bGaam4BaiaadkhacaGGFbGaamitaiaad+gacaWGVbGaam4CaiaadwgacaWGTbGaamyzaiaadshacaWGHbGaamiBamaaCaaaleqabaGaaGOmaaaaaaa@5781@


Figure 6. Failure zone in plate test

Conclusion

Failure model /FAIL/FLD used principal strain ratio to describe the material failure behavior which is suitable to describe material failure in forming.