Thermal history correlation with mechanical properties for polymer selective laser sintering (SLS)

Taylor, Samantha Sparr
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This thesis investigates the in-situ thermal history of parts manufactured with the Selective Laser Sintering (SLS) process. It compares the effectiveness of two different cameras, a stationary reference mid-wave infrared (IR) and a bore-sighted mid-wave IR camera, by evaluating correlations between strength, elongation, and fracture location to the observed thermal history of the selective laser sintered parts produced. ZYX tensile bars were built to leverage the high dependence of tensile strength on interlayer bonding, which is generally assumed to be related to thermal conditions from layer to layer. Various thermal history analysis methods, for example: cold subregion temperature, average layer temperature, and outline average temperature, were examined to discover the best method for predicting fracture location and correlating with build strength. In addition, several smoothing techniques that reduced the noise over time when using the different thermal analysis methods were assessed in their ability to improve the correlation of the given thermal method to the mechanical strength and fracture location.