hydrostatic uniaxial triaxial compression tests de lee moo montgomery stephen hofer (2 résultats)

Wraps. Etat : Good. Presumed First Edition, First printing. x, 74 pages plus back cover. Illustrations (most with color). References. Velobound. Format is approximately 8.5 inches by 11 inches. Unlimited Release. Ink note on front cover. Mailing label on back. Sandia is currently developing a lead-zirconate-titanate ceramic 95/5-2Nb (or PNZT) from chemically prepared ('chem-prep') precursor powders. Previous PNZT ceramic was fabricated from the powders prepared using a 'mixed-oxide' process. The specimens of unpoled PNZT ceramic from batch HF803 were tested under hydrostatic, uniaxial, and constant stress difference loading conditions within the temperature range of -55 to 75 C and pressures to 500 MPa. The objective of this experimental study was to obtain mechanical properties and phase relationships so that the grain-scale modeling effort can develop and test its models and codes using realistic parameters. The stress-strain behavior of 'chem-prep' PNZT under different loading paths was found to be similar to that of 'mixed-oxide' PNZT. The phase transformation from ferroelectric to antiferroelectric occurs in unpoled ceramic with abrupt increase in volumetric strain of about 0.7 % when the maximum compressive stress, regardless of loading paths, equals the hydrostatic pressure at which the transformation otherwise takes place. The stress-volumetric strain relationship of the ceramic undergoing a phase transformation was analyzed quantitatively using a linear regression analysis. The pressure (P{sub T1}{sup H}) required for the onset of phase transformation with respect to temperature is represented by the best-fit line, P{sub T1}{sup H} (MPa) = 227 + 0.76 T (C). We also confirmed that increasing shear stress lowers the mean stress and the volumetric strain required to trigger phase transformation. At the lower bound of the tested temperature range, the phase transformation is irreversible. At the upper bound (75 C), the phase transformation is completely reversible as the stress causing phase transformation is removed.

Velobound. Etat : Very good. Presumed First Edition, First printing. x, 74 pages, plus covers. Tables. Figures (some with color). References Appendices A. - D. Rear cover has mailing label and ink notation. Sandia is currently developing a lead-zirconate-titanate ceramic 95/5-2Nb (or PNZT) from chemically prepared ("chem-prep") precursor powders. Previous PNZT ceramic was fabricated from the powders prepared using a "mixed-oxide" process. The specimens of unpoled PNZT ceramic from batch HF803 were tested under hydrostatic, uniaxial, and constant stress difference loading conditions within the temperature range of -55 to 75°C and pressures to 500 MPa. The objective of this experimental study was to obtain mechanical properties and phase relationships so that the grain-scale modeling effort can develop and test its models and codes using realistic parameters. The stress-strain behavior of "chem-prep" PNZT under different loading paths was found to be similar to that of "mixed-oxide" PNZT. The phase transformation from ferroelectric to antiferroelectric occurs in unpoled ceramic with abrupt increase in volumetric strain of about 0.7 % when the maximum compressive stress, regardless of loading paths, equals the hydrostatic pressure at which the transformation otherwise takes place. The stress-volumetric strain relationship of the ceramic undergoing a phase transformation was analyzed quantitatively using a linear regression analysis. The pressure (PT1 H) required for the onset of phase transformation with respect to temperature is represented by the best-fit line, PT1 H (MPa) = 227 + 0.76 T (°C). We also confirmed that increasing shear stress lowers the mean stress and the volumetric strain required to trigger phase transformation. At the lower bound (-55°C) of the tested temperature range, the phase transformation is permanent and irreversible. However, at the upper bound (75°C), the phase transformation is completely reversible as the stress causing phase transformation is removed.