Orientation preference and fractal character of short fatigue cracks in a weld metal

Short fatigue crack behaviour in a weld metal has been further investigated. The Schmid factor and the fractal dimension of short cracks on iso-stress specimens subjected to reversed bending have been determined and then applied to account for the distribution and orientation characteristics of short fatigue cracks. The result indicates that the orientation preference of short cracks is attributed to the large values of Schmid factor at relevant grains. The Schmid factors of most slip systems, which produced short cracks, are less than or equal to 0.4. Crack length measurements reveal that short crack path, compared to that of long crack, possesses a more stable and relatively larger value of fractal dimension. This is regarded as one of the typical features of short cracks.

Initiation and propagation of short fatigue cracks in a weld metal

Fatigue tests were performed using a purpose designed triangular shaped specimen to investigate the initiation and propagation of short fatigue cracks in a weld metal. It was observed that short fatigue cracks evolved from slip bands and were predominantly within ferrite grains. As the test progressed, the short crack density increased with minor changes in crack length. The growth of short cracks, in the early stage resulted mainly from coalescence with other existing cracks. The mechanism of short crack behaviour is discussed.

Wage differentials between permanent and temporary workers: Firm and occupational segregation

Published as an article in: Moneda y Crédito (2004), 219, pp.: 43-68.

¿Cómo influye la infraestructura de producción en el rendimiento de las empresas manufactureras?

[ES] Este artículo contribuye a adquirir un mayor conocimiento acerca del impacto estratégico de la infraestructura de producción en las empresas manufactureras españolas. La influencia de la infraestructura de producción en el rendimiento empresarial puede ser analizada desde dos perspectivas: la contingente y la proactiva. La perspectiva contingente sostiene que tal influencia depende de la postura estratégica de la empresa. Según el enfoque proactivo, el rendimiento empresarial viene determinado por la implantación de prácticas y políticas prometedoras por su contribución a crear capacidades de producción.