Investigation of the Damage Behavior of Polyurethane in Stress Relaxation Experiments and Estimation of the Stress-at-Break σb with a Failure Envelope

  • Selina NeuhausEmail author
  • Henning Seibert
  • Stefan Diebels
Part of the Advanced Structured Materials book series (STRUCTMAT, volume 113)


In stress relaxation experiments the investigated polyurethane exhibits an unexpected, but repeatable failure during the relaxation period. Images, taken by a camera and a high speed camera, displayed crack initiation several minutes before rupture occurred. The crack growth rate then accelerates and leads to failure rapidly. The present investigation indicates different methods for analyzing the damage evolution with focus on the appearance of damage at low strains, accumulation of damage processes at higher strains, the influence of time on damage evolution and the identification of recovery phenomena during unloading and in the unloaded state. The results show that not only long times at high strains but also the loading history, especially loading and unloading processes, accelerate damage evolution. In a preliminary study the characterization of the ultimate tensile properties by a failure envelope appears to provide an adequate method for estimating the stress-at-break σb and the time-to-break tb in stress relaxation experiments.


Digital image correlation Crack initiation Crack growth Damage evolution Predeformation Failure envelope 



We gratefully acknowledge the support of Prof. Dr. rer. nat. habil. Wulff Possart, Chair for Adhesion and Interphases in Polymers, Saarland University, for providing access to materials and equipment for sample preparation and to the dry box.


  1. 1.
    Tobolsky AV (1956) Stress relaxation studies of the viscoelastic properties of polymers. J App Phys 27:673–685Google Scholar
  2. 2.
    Bergström JS, Boyce MC (1998) Constitutive modeling of the large strain time-dependent behavior of elastomers. J Mech Phys Solids 46:931–954Google Scholar
  3. 3.
    Kahn AS, Lopez-Pamies O (2002) Time and temperature dependent response and relaxation of a soft polymer. Int J Plasticity 18:1359–1372Google Scholar
  4. 4.
    Tobolsky AV, Prettyman IB, Dillon JH (1944) Stress relaxation of natural and synthetic rubber stocks. Rubber Chem Technol 17:551–575Google Scholar
  5. 5.
    Kausch HH (2012) Polymer fracture. Springer Science & Business Media, BerlinGoogle Scholar
  6. 6.
    Friedrich L (2017) Untersuchungen zum Materialverhalten poröser Elastomere während der Relaxation. Bachelor thesis, Chair of Applied Mechanics, Saarland UniversityGoogle Scholar
  7. 7.
    Smith TL, Stedry PJ (1960) Time and temperature dependence of the ultimate properties of an SBR rubber at constant elongations. J Appl Phys 31:1892–1898CrossRefGoogle Scholar
  8. 8.
    Smith TL (1963) Ultimate tensile properties of elastomers. I. Characterization by a time and temperature independent failure envelope. J Polym Sci Part A General Papers 1:3597–3615CrossRefGoogle Scholar
  9. 9.
    Smith TL (1964) Ultimate tensile properties of elastomers. II. Comparison of failure envelopes for unfilled vulcanizates. Rubber Chem Technol 4:792–807CrossRefGoogle Scholar
  10. 10.
    Lai JS, Findley WN (1968) Stress relaxation of nonlinear viscoelastic material under uniaxial strain. Trans Soc Rheol 12:259–280CrossRefGoogle Scholar
  11. 11.
    Wang TT, Klosner JM (1969) Relaxation properties of polyester-based polyurethane under small deformations superposed on large deformations. Trans Soc Rheol 13:193–208CrossRefGoogle Scholar
  12. 12.
    Smith TL (1958) Dependence of the ultimate properties of a GR-S rubber on strain rate and temperature. J Polym Sci 32:99–113CrossRefGoogle Scholar

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© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Selina Neuhaus
    • 1
    Email author
  • Henning Seibert
    • 1
  • Stefan Diebels
    • 1
  1. 1.Applied Mechanics, Saarland UniversitySaarbrückenGermany

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