Mechanics of Time-Dependent Materials

, Volume 22, Issue 3, pp 351–371 | Cite as

Time dependent voiding mechanisms in polyamide 6 submitted to high stress triaxiality: experimental characterisation and finite element modelling

  • Nathan SellesEmail author
  • Andrew King
  • Henry Proudhon
  • Nicolas Saintier
  • Lucien Laiarinandrasana


Double notched round bars made of semi-crystalline polymer polyamide 6 (PA6) were submitted to monotonic tensile and creep tests. The two notches had a root radius of 0.45 mm, which imposes a multiaxial stress state and a state of high triaxiality in the net (minimal) section of the specimens. Tests were carried out until the failure occurred from one of the notches. The other one, unbroken but deformed under steady strain rate or steady load, was inspected using the Synchrotron Radiation Computed Tomography (SRCT) technique. These 3D through thickness inspections allowed the study of microstructural evolution at the peak stress for the monotonic tensile test and at the beginning of the tertiary creep for the creep tests. Cavitation features were assessed with a micrometre resolution within the notched region. Spatial distributions of void volume fraction (\(\mathit{Vf}\)) and void morphology were studied. Voiding mechanisms were similar under steady strain rates and steady loads. The maximum values of \(\mathit{Vf}\) were located between the axis of revolution of the specimens and the notch surface and voids were considered as flat cylinders with a circular basis perpendicular to the loading direction. A model, based on porous plasticity, was used to simulate the mechanical response of this PA6 material under high stress triaxiality. Both macroscopic behaviour (loading curves) and voiding micro-mechanisms (radial distributions of void volume fraction) were accurately predicted using finite element simulations.


Semi-crystalline polymer Voiding Synchrotron radiation computed tomography Tensile test Creep test Finite elements 



The authors should thank Anthony Bunsell for scientific and technical discussions and Nicolas Lenoir (UMS 3626 Placamat, CNRS Université de Bordeaux) for tomographic observations of the undeformed notch.


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Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  • Nathan Selles
    • 1
    Email author
  • Andrew King
    • 2
  • Henry Proudhon
    • 1
  • Nicolas Saintier
    • 3
  • Lucien Laiarinandrasana
    • 1
  1. 1.MINES ParisTech, CNRS UMR7633PSL Research University MAT-Centre des MatériauxEvry CedexFrance
  2. 2.SOLEIL SynchrotronSaint-AubinFrance
  3. 3.Arts et Métiers ParisTech, I2M-DuMAS, CNRS UMR5295Esplanade des Arts et MétiersTalenceFrance

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