Amphibious Seismic Survey Images Plate Interface at 1960 Chile Earthquake

The southern central Chilean margin at the site of the largest historically recorded earthquake in the Valdivia region, in 1960 (Mw = 9.5), is part of the 5000-km-long active subduction system whose geodynamic evolution is controversially debated and poorly understood. Covering the area between 36° and 40°S, the oceanic crust is segmented by prominent fracture zones. The offshore forearc and its onshore continuation show a complex image with segments of varying geophysical character, and several fault systems active during the past 24 m.y. In autumn 2001, the project SPOC was organized to study the Subduction Processes Off Chile, with a focus on the seismogenic coupling zone and the forearc. The acquired seismic data crossing the Chilean subduction system were gathered in a combined offshore-onshore survey and provide new insights into the lithospheric structure and evolution of active margins with insignificant frontal accretion

Measurement of forced surface convection in directed energy deposition additive manufacturing

The accurate modeling of thermal gradients and distortion generated by directed energy deposition additive manufacturing requires a thorough understanding of the underlying physical processes. One area that has the potential to significantly affect the accuracy of thermomechanical simulations is the complex forced convection created by the inert gas jets that are used to deliver metal powder to the melt pool and to shield the laser optics and the molten material. These jets act on part surfaces with higher temperatures than those in similar processes such as welding and consequently have a greater impact on the prevailing heat transfer mechanisms. A methodology is presented here which uses hot-film sensors and constant voltage anemometry to measure the forced convection generated during additive manufacturing processes. This methodology is then demonstrated by characterizing the convection generated by a Precitec® YC50 deposition head under conditions commonly encountered in additive manufacturing. Surface roughness, nozzle configuration, and surface orientation are shown to have the greatest impact on the convection measurements, while the impact from the flow rate is negligible. </jats:p

Infrared measurement of the temperature at the tool-chip interface while machining Ti-6Al-4V

Click on the DOI link to access the article (may not be free).The challenges associated with machining titanium alloys (e.g.,Ti-6Al-4V) are directly related to high cutting tool temperatures due to the low thermal conductivity of these alloys and the heat generated in the primary shear zone and at the tool-chip interface. Transparent yittrium aluminum garnet (YAG) tools are used in the current study to orthogonally machine a Ti-6Al-4V disk. Although YAG tools are not industrially relevant, they permit the temperature on the tool-chip interface to be measured. These measurements are relevant because they can be used to validate cutting models, which are in-turn used by industry to improve cutting processes. An infrared camera, using a high frame rate (700 Hz) and a large field of view (20 mm(2)), observes the tool-chip interface through these tools and measures the temperature distribution and records the chip curl and breakage while cutting with a feed rate of 50 mu m/rev and cutting speeds between 20 m/min and 100 m/min. In addition to the temperature measureirlents, cutting forces are recorded and the chip formation is documented using a high-speed (3 kHz) visible-light camera. Results show that radiant temperature increases with speed while the cutting and thrust fortes show no significant trend. Analysis of the temperature distribution from one edge of the chip to the other reveals differences from 6 % to 21 %, indicating that caution must be used when performing thermographic measurements of chip temperatures from the side of the cutting zone. Finally, post process measurements are performed using a scanning white-light interferometer to investigate any correlation between the tool condition and cutting temperature. Although the qualitative analysis of some cases appears to reveal a correlation between the condition of the YAG tool and the measured temperature distribution, further work work is required to understand this relationship.Department of Energy contract number DE-EE0006396