Near Infrared Thermal Imaging for Process Monitoring in Additive Manufacturing

This work presents the design and development of a near infrared thermal imaging system specifically designed for process monitoring of additive manufacturing. The overall aims of the work were to use in situ thermal imaging to develop methods for monitoring process parameters of additive manufacturing processes. The main motivations are the recent growth in use of additive manufacturing and the underutilisation of near infrared camera technology in thermal imaging. The combination of these two technologies presents opportunities for unique process monitoring methods which are demonstrated here. A thermal imaging system was designed for monitoring the electron beam melting process of an Arcam S12. With this system a new method of dynamic emissivity correction based on tracking the melted material is shown. This allows for the automatic application of emissivity values to previously melted areas of a layer image. This reduces the potential temperature error in the thermal image caused by incorrect emissivity values or the assumption of a single value for a whole image. Methods for determining materials properties such as porosity and tensile strength from the in situ thermal imaging are also shown. This kind of analysis from in situ images is the groundwork for allowing part properties to be tuned at build time and could remove the need for post build testing that would determine if it is suitable for use. The system was also used to image electron beam welding and gas tungsten arc welding. With the electron beam welding of dissimilar metals, the thermal images were able to show the preheating effect that the melt pool had on the materials, the suspected reason for the process’s success. For the gas tungsten arc welding process analysis methods that would predict weld quality were developed, with the aim of later integrating these into the robotic welding process. Methods for detecting the freezing point of the weld bead and tracking slag spots were developed, both of which could be used as indicators of weld quality or defects. A machine learning algorithm was also applied to images of pipe welding on this process. The aim of this was to develop an image segmentation algorithm that could be used to measure parts of the weld in process and inform other analysis, like those above

D. H. Lawrence’s ‘Men Must Work and Women as Well’ in Aldous Huxley’s Brave New World.

The article presents an examination of an allusion to the work of the 20th-century English author D. H. Lawrence within the 1929 novel Brave New World, by Aldous Huxley. Introductory details are offered relating the friendship between Huxley and Lawrence. Specific instances of references to Lawrence\u27s essay Men Must Work and Women as Well, within Huxley\u27s dystopian novel are then identified and explained

Laser diode area melting for high speed additive manufacturing of metallic components

Additive manufacturing processes have been developed to a stage where they can now be routinely used to manufacture net-shape high-value components. Selective Laser Melting (SLM) comprises of either a single or multiple deflected high energy fibre laser source(s) to raster scan, melt and fuse layers of metallic powdered feedstock. However this deflected laser raster scanning methodology is high cost, energy inefficient and encounters significant limitations on output productivity due to the rate of feedstock melting. This work details the development of a new additive manufacturing process known as Diode Area Melting (DAM). This process utilises customised architectural arrays of low power laser diode emitters for high speed parallel processing of metallic feedstock. Individually addressable diode emitters are used to selectively melt feedstock from a pre-laid powder bed. The laser diodes operate at shorter laser wavelengths (808 nm) than conventional SLM fibre lasers (1064 nm) theoretically enabling more efficient energy absorption for specific materials. The melting capabilities of the DAM process were tested for low melting point eutectic BiZn2.7 elemental powders and higher temperature pre-alloyed 17-4 stainless steel powder. The process was shown to be capable of fabricating controllable geometric features with evidence of complete melting and fusion between multiple powder layers

CU Defense - Lightweight Cranial Protection and Low Altitude Parachute Systems

The Clemson family proudly embraces its school\u27s rich military heritage and students in every department regularly demonstrate patriotism and respect for our nation\u27s armed forces. Our multidisciplinary team of undergraduates has sought to study and improve currently used technology to give soldiers an advantage in the field. We currently have two active projects, as described below. Lightweight Cranial Protection Current standard-issue combat helmets weigh more and offer less protection than desired. Equipment weight reduction is a constant goal for the armed forces, and enhanced safety is always favored. With recent technological developments in the application of dilatants, or shear-thickening fluids (STF), it appears that a helmet\u27s design and construction can be improved. We intend to apply several STF compositions to selected ballistic fibers using multiple impregnation methods. The resulting fibers will be tested for variations in ballistic performance. Low Altitude Parachute System currently used parachutes are designed to inflate slowly to avoid injury on opening. As a result, there is a range of heights that are too low for current parachutes to behave effectively. Using past current research and simulation software, we intend to study the various shapes and sizes of parachutes used throughout history and design a parachute system that will be effective at these low altitudes. This research could lead to the development of products that vastly increase the quality of life and safety of military, law enforcement, and rescue operations