Disputas: Hamid Daiyan

M.Sc. Hamid Daiyan ved Matematisk institutt vil forsvare sin avhandling for graden PhD:  Experimental and Numerical Investigation of the Mechanical Response of Injection Moulded Polypropylene Materials

Hamid Daiyan

Tid og sted for prøveforelesning

10:15 Aud. 1, Geologibygningen: Mechanical behaviour and modeling of fibre-reinforced thermoplastics.


  • Associate Professor Júlio C. Viana, Department of Polymer Engineering, University of Minho
  • Professor Arild Clausen, Department of Structural Engineering, Norges teknisk-naturvitenskapelige universitet
  • Professor Jostein Hellesland, Matematisk institutt, Universitetet i Oslo

Leder av disputas

Professor John Grue


  • Erik Andreassen, SINTEF
  • Harald Osnes, Matematisk institutt, UiO
  • Frode Grytten, SINTEF


The performance of polymeric materials subjected to mechanical impact is of increasing interest, as these materials are frequently used in critical applications. The response to impact loads is of particular interest for automotive components with a role in passenger and pedestrian safety.

The present thesis considers the most common polymer material family used in cars, namely polypropylene-based materials. The thesis reports advances in experimental testing and numerical simulation, improving the understanding and prediction of the mechanical behavior of this class of materials. The PhD work was performed at SINTEF in Oslo, in collaboration with Plastal AS (Raufoss) and the University of Oslo.

The thesis addresses some of the challenges with these materials, both in terms of testing and simulation: The materials are highly ductile and special optical methods were used to obtain the true stress-strain up to large strains. Also, the mechanical properties are sensitive to the strain rate and the stress state (tension, compression, shear), and they are also affected by the processing (injection moulding in our case). Due to the complex mechanical response of these polypropylene-based materials, it is challenging to find an adequate material model which can be used by e.g. the automotive industry. The model should not require too much mechanical testing and data analysis, and it should not be too computation-intensive. Some of the challenges are related to uncertainties in the mechanical response and the testing, while some are related to limitations of the models.

The contribution of this thesis has been to improve the understanding of material performance and to address the challenges of material modelling for numerical simulations. As part of this, test methods and test specimen geometries have been analyzed. Finally, a material model specially developed for ductile polymers was calibrated with data from the thesis, and results from simulations were compared to experimental data for various loading cases.


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Publisert 9. juni 2011 09:09 - Sist endret 28. nov. 2011 13:39