Modeling dynamic behaviour including shockwave propagation and spall failure in orthotropic materials
In practice, most of the engineering materials manufactured using sheet metal forming processes, are orthotropic. The technological demands on such materials are coming from various manufacturing processes, aerospace structures, car crashworthiness and defence. Much research has been performed invol...
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| Format: | Thesis |
| Published: |
2017
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/9853/ http://eprints.uthm.edu.my/9853/1/Norzarina_Ma'at.pdf |
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| Summary: | In practice, most of the engineering materials manufactured using sheet metal forming
processes, are orthotropic. The technological demands on such materials are coming
from various manufacturing processes, aerospace structures, car crashworthiness and
defence. Much research has been performed involving analytical, experimental and
computational methods, it is generally accepted that there is still a need for improved
constitutive models. Moreover, there are numerous mechanics of materials issues that
have yet to be solved, related to finite strain deformation and failure of elastic and
plastic of material orthotropic. Based on this motivation, a constitutive model is
developed to predict a complex elastoplastic deformation behaviour involving
shockwaves and spall failure in orthotropic materials at high pressure. The important
feature of the proposed hyperelastic-plastic constitutive model formulated in this
research project is a Mandel stress tensor combined with the new generalised
orthotropic pressure. The formulation is developed in the isoclinic configuration and
allows for a unique treatment for elastic and plastic part. The stress tensor
decomposition of the new generalised pressure and Hill’s yield criterion aligned
uniquely within the principal stress space is adopted to characterize elastic and plastic
orthotropy. An isotropic hardening is adopted to define the evolution of plastic
orthotropy. The formulation is further combined with a shock equation of state (EOS)
and Grady spall failure model to predict shockwave propagation and spall failure in
the materials, respectively. The algorithm of the proposed constitutive model is
implemented as a new material model in the Lawrence Livermore National Laboratory
(LLNL)-DYNA3D code of UTHM’s version, named Material Type 92 (Mat92). The
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