Investigation of Stress Concentrations in Stereolithographic Modeled Parts
Faculty Mentor Name
David Lanning
Format Preference
Poster
Abstract
Additive manufacturing by stereolithography (SLA) is increasingly used in aerospace and mechanical applications due to its versatility, design flexibility, and rapid prototyping capabilities. However, the mechanical behavior of SLA-printed parts with stress concentrations remains insufficiently characterized. This research investigates how localized stresses in complex geometries and printing parameters influence the tensile strength and fracture behavior of SLA-printed resin specimens. Test specimens with double semicircular notches were designed using Peterson’s notch analysis to achieve a theoretical stress concentration factor (Kt) of 2.2. Unnotched SLA specimens were also tested as controls. All test specimens were printed with consistent geometry while varying key parameters such as print orientation, curing temperature, curing time, and post-processing methods.
Experimental results show that curing temperature significantly affects ultimate tensile strength, with specimens cured at 80 °C consistently outperforming those cured at manufacturer recommended conditions. Measured effective Kt values were substantially lower than theoretical predictions, indicating that SLA parts do not strictly follow classical elastic stress concentration theory. Data and observed behavior suggests the presence of local plasticity, notch strengthening, and strain-dependent stiffening. This can be potentially linked to rubber modified thermoset resins and polymer chain redistribution. These findings highlight the complex nature of SLA part performance and demonstrate the need for revised design considerations when using resin-printed components in structural applications.
Investigation of Stress Concentrations in Stereolithographic Modeled Parts
Additive manufacturing by stereolithography (SLA) is increasingly used in aerospace and mechanical applications due to its versatility, design flexibility, and rapid prototyping capabilities. However, the mechanical behavior of SLA-printed parts with stress concentrations remains insufficiently characterized. This research investigates how localized stresses in complex geometries and printing parameters influence the tensile strength and fracture behavior of SLA-printed resin specimens. Test specimens with double semicircular notches were designed using Peterson’s notch analysis to achieve a theoretical stress concentration factor (Kt) of 2.2. Unnotched SLA specimens were also tested as controls. All test specimens were printed with consistent geometry while varying key parameters such as print orientation, curing temperature, curing time, and post-processing methods.
Experimental results show that curing temperature significantly affects ultimate tensile strength, with specimens cured at 80 °C consistently outperforming those cured at manufacturer recommended conditions. Measured effective Kt values were substantially lower than theoretical predictions, indicating that SLA parts do not strictly follow classical elastic stress concentration theory. Data and observed behavior suggests the presence of local plasticity, notch strengthening, and strain-dependent stiffening. This can be potentially linked to rubber modified thermoset resins and polymer chain redistribution. These findings highlight the complex nature of SLA part performance and demonstrate the need for revised design considerations when using resin-printed components in structural applications.