Browsing by Author "Yaman, Mecit"

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    Investigation of Krypton bubbles in copper using x-ray techniques
    (2002) Yaman, Mecit; Härting, Margit
    Investigation of the micro-mechanical properties of bulk copper, containing a high concentration (3 atomic %) of krypton is performed by X-ray diffraction techniques. Stress determination and phase analysis are carried out to determine the residual stress of the host copper metal and the internal pressure of the krypton bubbles. Lattice parameter determination of krypton bubbles confirms solidification of krypton with a fee structure epitaxial to the host metal with a bubble pressure of 2.6 GPa. The sin2 φ technique of stress determination indicates no macro residual stress inside the copper matrix as predicted by the continuum ansatz of the elasticity theory. The pressure of the krypton bubbles manifests itself as a shear strain in the copper matrix and the shear strain is found to be below the yield strength of the copper matrix, thus explaining the long-term stability.
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    Scientific visualization of stress tensor information with applications to stress determination by X-ray and neutron diffraction
    (2007) Yaman, Mecit; Härting, Margit
    The visual analysis of mechanical stress facilitates physical understanding of the tensor quantity which is concealed in scalar and vector methods. In this study, the principles and techniques of scientific visualization are used to develop a visual analysis of mechanical stresses. Scientific visualization is not only applied to the final tensorial quantity obtained from the diffraction measurements, but the visual methods are developed from, and integrated into current residual stress analysis practices by relating the newly developed visual techniques to the conventional techniques, highlighting its advantages. This study consists of the mathematical analysis of the tensor character of mechanical stresses, discussion of the principles and techniques of scientific visualization (visual data analysis) in physical research, and tensor determination, visual analysis and presentation of residual stresses obtained from diffraction measurements.