MECHANICAL TESTING OF FUSED FILAMENT 3-D PRINTED COMPONENTS FOR DISTRIBUTED MANUFACTURING

Fused filament fabrication (FFF)-based open-source 3-D printers offer the potential of decentralized manufacturing both in developing and developed countries. Unfortunately, a severe lack of data and standards relating to material properties and printed components limit this potential. This thesis first investigates the mechanical properties of a wide-range of FFF materials and provides a database of mechanical strength of the materials tested. The results demonstrate that the tensile strength of a 3-D printed specimen depends largely on the mass of the specimen, which provides a means to estimate the strength of 3-D printed components. Then this information is used to evaluate a bicycled pedal, which was 3-D printed and tested following the CEN (European Committee for Standardization) standards for racing bicycles. The results show the pedals meet the CEN standards and can be used on bicycles at lower costs than standard pedals. This investigation indicates the viability of distributed manufacturing

RepRapable automated open source bag valve mask-based ventilator

This study describes the development of an automated bag valve mask (BVM) compression system, which, during acute shortages and supply chain disruptions can serve as a temporary emergency ventilator. The resuscitation system is based on the Arduino controller with a real-time operating system installed on a largely RepRap 3-D printable parametric component-based structure. The cost of the system is under $170, which makes it affordable for replication by makers around the world. The device provides a controlled breathing mode with tidal volumes from 100 to 800 milliliters, breathing rates from 5 to 40 breaths/minute, and inspiratory-to-expiratory ratio from 1:1 to 1:4. The system is designed for reliability and scalability of measurement circuits through the use of the serial peripheral interface and has the ability to connect additional hardware due to the object-oriented algorithmic approach. Experimental results demonstrate repeatability and accuracy exceeding human capabilities in BVM-based manual ventilation. Future work is necessary to further develop and test the system to make it acceptable for deployment outside of emergencies in clinical environments, however, the nature of the design is such that desired features are relatively easy to add with the test using protocols and parametric design files provided

Viability of distributed manufacturing of bicycle components with 3-D printing: CEN standardized polylactic acid pedal testing

Recent advancements in open-source self-replicating rapid prototypers (RepRap) have radically reduced costs of 3-D printing. The cost of additive manufacturing enables distributed manufacturing of open source appropriate technologies (OSAT) to assist in sustainable development. In order to investigate the potential this study makes a careful investigation of the use of RepRap 3-D printers to fabricate widely used Black Mamba bicycle components in the developing world. Specifically, this study tests pedals. A CAD model of the pedal was created using parametric open source software (FreeCAD) to enable future customization. Then poly-lactic acid, a biodegradable and recyclable bioplastic was selected among the various commercial 3-D printable materials based on strength and cost. The pedal was 3-D printed on a commercial RepRap and tested following the CEN (European Committee for Standardization) standards for racing bicycles for 1) static strength, 2) impact, and 3) dynamic durability. The results show the pedals meet the CEN standards and can be used on bicycles. The 3-D printed pedals are significantly lighter than the stock pedals used on the Black Mamba, which provides a performance enhancement while reducing the cost if raw PLA or recycled materials are used, which assists in reducing bicycle costs even for those living in extreme poverty. Other bicycle parts could also be manufactured using 3-D printers for a return on investment on the 3-D printer indicating that this model of distributed manufacturing of OSAT may be technically and economically appropriate through much of the Global South

Conceptual design and rationale for a new agrivoltaics concept: Pastured-raised rabbits and solar farming

Land-use conflicts created by the growth of solar photovoltaics (PV) can be mitigated by applying the concept of agrivoltaics, that is, the co-development of land for both PV and agricultural purposes, to commercial-scale solar installations. In this study, we present a conceptual design for a novel agrivoltaic system based on pasture-fed rabbit farming and provide the technical, environmental and economic analyses to demonstrate the viability of the concept. Included in our analysis are the economic advantages to the PV operator of grazing rabbits at a density sufficient to control vegetative growth, thus reducing the economic and environmental costs of mowing; the dual-revenue stream from the sale of both rabbits and electricity, contrasted with estimates of the capital-investment costs for rabbits co-located with, and also independent of, PV; and the economic value to the rabbit farmer of higher colony-growth rates (made possible by the shading and predator protection provided by the PV arrays and of reduced fencing costs, which are the largest capital cost, by being able to leverage the PV systems for rabbit fencing. We also provide an environmental analysis that suggests that rabbit-PV farming is a pathway to a measurable reduction in agriculturally-generated greenhouse-gas emissions. Our calculations indicate that the co-location of solar and rabbit farms is a viable form of agrivoltaics, increasing overall site revenue by 2.5%–24.0% above projected electricity revenue depending on location and rental/ownership of rabbits, while providing a high-value agricultural product that, on a per weight basis, has significantly less environmental impact than cattle