Jorgen
2007-08-28, 19:55
http://polymerfem.com/polymer_files/topics/fracture.png
If you are interested in predicting failure of polymers, plastics, or rubbers, and want to find out how different failure conditions (e.g. Mises stress, max principal strain, chain stretch) can predict failure under monotonic loading, then you should read this paper (http://polymerfem.com/polymer_files/UHMWPE_failure_paper.pdf) that is now available for download.
Abstract:
The development of accurate theoretical failure, fatigue, and wear models for ultra-high molecular weight polyethylene (UHMWPE) is an important step towards better understanding the micromechanisms of the surface damage that occur in load bearing orthopaedic components and improving the lifetime of joint arthoplasties. Previous attempts to analytically predict the clinically observed damage, wear and fatigue failure modes have met limited success due to the complicated interaction between microstructure deformations and continuum level stresses. In this work, we examined monotonic uniaxial and multiaxial loading to failure of UHMWPE using eight failure criteria (maximum principal stress, Mises stress, Tresca stress, hydrostatic stress, Coulomb stress, maximum principal strain, Mises strain, and chain stretch). The quality of the predictions of the different models was assessed by comparing uniaxial tension and small punch test data at different rates with the failure model predictions. The experimental data was obtained for two conventional (unirradiated and gamma radiation sterilized in nitrogen) and two highly crosslinked (150 kGy, remelted and annealed) UHMWPE materials. Of the different failures models examined, the chain stretch failure model was found to most accurately capture uniaxial and multiaxial failure data for both the conventional and the highly crosslinked UHMWPE materials. In addition, the chain stretch failure criterion can readily be calculated for contemporary UHMWPE materials based on available uniaxial tension data. These results lay the foundation for future developments of damage and wear models capable of predicting multiaxial failure under cyclic loading conditions.
If you are interested in predicting failure of polymers, plastics, or rubbers, and want to find out how different failure conditions (e.g. Mises stress, max principal strain, chain stretch) can predict failure under monotonic loading, then you should read this paper (http://polymerfem.com/polymer_files/UHMWPE_failure_paper.pdf) that is now available for download.
Abstract:
The development of accurate theoretical failure, fatigue, and wear models for ultra-high molecular weight polyethylene (UHMWPE) is an important step towards better understanding the micromechanisms of the surface damage that occur in load bearing orthopaedic components and improving the lifetime of joint arthoplasties. Previous attempts to analytically predict the clinically observed damage, wear and fatigue failure modes have met limited success due to the complicated interaction between microstructure deformations and continuum level stresses. In this work, we examined monotonic uniaxial and multiaxial loading to failure of UHMWPE using eight failure criteria (maximum principal stress, Mises stress, Tresca stress, hydrostatic stress, Coulomb stress, maximum principal strain, Mises strain, and chain stretch). The quality of the predictions of the different models was assessed by comparing uniaxial tension and small punch test data at different rates with the failure model predictions. The experimental data was obtained for two conventional (unirradiated and gamma radiation sterilized in nitrogen) and two highly crosslinked (150 kGy, remelted and annealed) UHMWPE materials. Of the different failures models examined, the chain stretch failure model was found to most accurately capture uniaxial and multiaxial failure data for both the conventional and the highly crosslinked UHMWPE materials. In addition, the chain stretch failure criterion can readily be calculated for contemporary UHMWPE materials based on available uniaxial tension data. These results lay the foundation for future developments of damage and wear models capable of predicting multiaxial failure under cyclic loading conditions.