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Post Doctoral Researcher
01 March 2019 - 01 September 2021
Graduate Student or Post Graduate
01 August 2014 - 01 December 2018
Undergraduate Student
01 September 2010 - 01 June 2014
Mechanical engineering PhD graduate and post-doctoral researcher at the National Renewable Energy Laboratory, specializing in composite materials research for renewable energy applications, with a strong concentration on manufacturing, mechanical characterization and validation, structural analysis, structural health monitoring methods (particularly acoustic emission and guided ultrasonic waves) and statistical analysis.
Many marine energy systems designers and developers are beginning to implement composite materials into the load-bearing structures of their devices, but traditional mold-making costs for composite prototyping are disproportionately high and lead times can be long. Furthermore, established molding techniques for marine energy structures generally require many manufacturing steps, such as secondary bonding and tooling. This research explores the possibilities of additively manufactured internal composite molds and how they can be used to reduce costs and lead times through novel design features and processes for marine energy composite structures. In this approach, not only can the composite mold be additively manufactured but it can also serve as part of the final load-bearing structure. We developed a conceptual design and implemented it to produce a reduced-scale additive/composite tidal turbine blade section to fully demonstrate the manufacturing possibilities. The manufacturing was successful and identified several critical features that could expedite the tidal turbine blade manufacturing process, such as single-piece construction, an integrated shear web, and embedded root fasteners. The hands-on manufacturing also helped identify key areas for continued research to allow for efficient, durable, and low-cost additive/composite-manufactured structures for future marine energy systems.
Paul Murdy; Jack Dolson; David Miller; Scott Hughes; Ryan Beach. Leveraging the Advantages of Additive Manufacturing to Produce Advanced Hybrid Composite Structures for Marine Energy Systems. Applied Sciences 2021, 11, 1336 .
AMA StylePaul Murdy, Jack Dolson, David Miller, Scott Hughes, Ryan Beach. Leveraging the Advantages of Additive Manufacturing to Produce Advanced Hybrid Composite Structures for Marine Energy Systems. Applied Sciences. 2021; 11 (3):1336.
Chicago/Turabian StylePaul Murdy; Jack Dolson; David Miller; Scott Hughes; Ryan Beach. 2021. "Leveraging the Advantages of Additive Manufacturing to Produce Advanced Hybrid Composite Structures for Marine Energy Systems." Applied Sciences 11, no. 3: 1336.
Core gaps are a common manufacturing defect observed in wind blade composite sandwich constructions, which occur when sheets of core material are not properly butted up against each other in the mold. The aim of this study was to characterize core gaps in composite sandwich constructions at the coupon scale to gain an initial understanding of the defect before developing appropriate methodologies for more complex subcomponents as part of a much broader wind blade structural validation and damage tolerance program. Long beam flexure in 4-point-bending was chosen as the most appropriate loading scenario. Beam specimens were characterized with and without 10 mm core gaps in fiberglass/balsa sandwich beams. The core gaps were characterized with two different resin systems: a Hexion epoxy and Arkema’s Elium resin system (a novel, infusible thermoplastic). Results showed that the Elium beams without the core gaps had a 15% lower static strength than their epoxy counterparts. The introduction of the core gap to the epoxy beams reduced their static strength by 35%. The Elium beams, however, exhibited negligible strength reductions with the inclusion of the core gap. Overall, this characterization study provided pertinent information with regards to core gaps as a manufacturing defect to allow for continued development of damage tolerance and subcomponent validation methodologies with the inclusion of manufacturing defects.
Paul Murdy; Scott Hughes. Investigating Core Gaps and the Development of Subcomponent Validation Methods for Wind Turbine Blades. AIAA Scitech 2020 Forum 2020, 1 .
AMA StylePaul Murdy, Scott Hughes. Investigating Core Gaps and the Development of Subcomponent Validation Methods for Wind Turbine Blades. AIAA Scitech 2020 Forum. 2020; ():1.
Chicago/Turabian StylePaul Murdy; Scott Hughes. 2020. "Investigating Core Gaps and the Development of Subcomponent Validation Methods for Wind Turbine Blades." AIAA Scitech 2020 Forum , no. : 1.
Fiber-reinforced-polymer composites (FRPs) possess superior mechanical properties and formability, making them a desirable material for construction of large optimized mechanical structures, such as aircraft, wind turbines, and marine hydrokinetic (MHK) devices. However, exposure to harsh marine environments can result in moisture absorption into the microstructure of the FRPs comprising these structures and often degrading mechanical properties. Specifically, laminate static and fatigue strengths are often significantly reduced, which must be considered in design of FRP structures in marine environments. A study of fiberglass epoxy unidirectional and cross-ply laminates was conducted to investigate hygrothermal effects on the mechanical behavior of a common material system used in wind applications. Several laminates were aged in 50 ∘C distilled water until maximum saturation was reached. Unconditioned control and the saturated samples were tested in quasi-static tension with the accompaniment of acoustic emission (AE) monitoring. Cross-ply laminates experienced a 54 % reduction in strength due to moisture absorption, while unidirectional laminate strengths were reduced by 40 %. Stress–strain curves and AE activity of the samples were analyzed to identify changes in damage progression due to aging.
Jake D. Nunemaker; Michael M. Voth; David A. Miller; Daniel D. Samborsky; Paul Murdy; Douglas S. Cairns. Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass–epoxy composites. Wind Energy Science 2018, 3, 427 -438.
AMA StyleJake D. Nunemaker, Michael M. Voth, David A. Miller, Daniel D. Samborsky, Paul Murdy, Douglas S. Cairns. Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass–epoxy composites. Wind Energy Science. 2018; 3 (1):427-438.
Chicago/Turabian StyleJake D. Nunemaker; Michael M. Voth; David A. Miller; Daniel D. Samborsky; Paul Murdy; Douglas S. Cairns. 2018. "Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass–epoxy composites." Wind Energy Science 3, no. 1: 427-438.
Fiber-Reinforced-Polymer composites (FRP's) possess superior mechanical properties and formability, making them a desirable material for construction of large optimized mechanical structures, such as aircraft, wind turbines, and marine hydro kinetic (MHK) devices. However, exposure to harsh marine environments can result in moisture absorption into the microstructure of the FRP's comprising these structures and often degrading mechanical properties. Specifically, laminate static and fatigue strengths are often significantly reduced, which must be considered in design of FRP structures in marine environments. A study of fiber-glass epoxy unidirectional and cross-ply laminates was conducted to investigate hygrothermal effects on the mechanical behavior of a common material system used in wind applications. Several laminates were aged in 50 °C distilled water until maximum saturation was reached. Unconditioned control and the saturated samples were tested in quasi-static tension with the accompaniment of Acoustic Emission (AE) monitoring. Cross-ply laminates experienced 54 % reduction in strengths from due to moisture absorption, while unidirectional laminates strengths were reduced by 40 %. Stress-strain curves and AE activity of the samples were analyzed to identify changes in damage progression due to aging.
Jake D. Nunemaker; Michael M. Voth; David A. Miller; Daniel D. Samborsky; Paul Murdy; Douglas S. Cairns. Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass-epoxy composites. 2018, 2018, 1 -18.
AMA StyleJake D. Nunemaker, Michael M. Voth, David A. Miller, Daniel D. Samborsky, Paul Murdy, Douglas S. Cairns. Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass-epoxy composites. . 2018; 2018 ():1-18.
Chicago/Turabian StyleJake D. Nunemaker; Michael M. Voth; David A. Miller; Daniel D. Samborsky; Paul Murdy; Douglas S. Cairns. 2018. "Effects of moisture absorption on damage progression and strength of unidirectional and cross-ply fiberglass-epoxy composites." 2018, no. : 1-18.