Effects of Immersion on Knowledge Gain and Cognitive Load in Additive Manufacturing Process Education.

Although the additive manufacturing (AM) market continues to grow, industries face barriers to AM adoption due to a shortage of skilled designers in the workforce that can apply AM effectively to meet this demand. This shortage is attributed to the high cost and infrastructural requirements of introducing high- barrier-to-entry AM processes such as powder bed fusion (PBF) into in-person learning environments. To meet the demands for a skilled AM workforce, it is important to explore other mediums of AM education, such as computer-aided instruction (CAI) and virtual reality (VR), which can increase access to hands-on learning experiences for inaccessible AM processes. However, limited work compares virtual and physical AM instruction or explores how the differences in immersion and presence between mediums can affect the knowledge gained and the mental effort exerted when learning about different AM processes. To address this gap in the literature, this research evaluates the use of CAI, VR, and in-person instruction in AM process education when learning about material extrusion (ME) and PBF. Our findings show that the differences in immersion and presence between CAI, VR, and in-person instruction do not have a statistically significant effect when learning about ME, but do have a significant effect when learning about PBF. Specifically, we found that VR generally yields equivalent effects in knowledge gain and cognitive load to in-person PBF education while offering advantages in both metrics over CAI learning. The findings from this work thus have significant implications for using VR as an alternative to in-person training to improve designer development in process-centric AM education of typically high-barrier-to-entry AM processes.

Dataset of process-structure-property feature relationships for AlSi10Mg material fabricated using laser powder bed fusion additive manufacturing.

This dataset reports microstructure and mechanical property features of AlSi10Mg manufactured using laser powder bed fusion over a wide range of processing conditions. Samples were fabricated with different combinations of laser power, scan speed, and hatch spacing to probe dense regimes as well as porous samples resulting from keyholing and lack of fusion. Pore and grain/sub-grain features for each processing set were quantified. Sample porosity was measured using Archimedes density measurements and X-ray computed tomography (XCT). XCT was also used to characterize the surface roughness of samples along with pore size and morphology. Electron backscatter diffraction (EBSD) was used to characterize the grain size and morphology while scanning electron microscope (SEM) imaging and was used to measure solidification cell size. Uniaxial tension tests were performed to ascertain yield and ultimate tensile strengths, elongation, and elastic modulus, and microhardness was measured using Vickers indentation.

Catalog of triply periodic minimal surfaces, equation-based lattice structures, and their homogenized property data.

The use of lattice structure in the Design for Additive Manufacturing (DfAM) engineering practice offers the ability to tailor the properties (and therefore the response) of an engineered component independent of the material and overall geometry. The selection of a lattice topology is critical in maximizing the value of the lattice structure and its unique properties for the intended application. To support this, we have compiled a catalog of lattice structures from the literature that includes all Triply Periodic Minimal Surfaces (TPMS) for which a low-order Fourier series fit is known (so that they can be modeled and manufactured). We also include equations that do not directly correspond to known TPMS but do produce a triply periodic structure without sharp corners that would give rise to stress concentrations. This catalog includes images, elastic mechanical property data, and CAD models useful for the visualization, selection, and implementation of these lattice structures for any engineered structure.

Teaching Designing for Additive Manufacturing: Formulating Educational Interventions That Encourage Design Creativity.

As additive manufacturing (AM) processes become more ubiquitous in engineering, design, and manufacturing, the need for a workforce skilled in designing for additive manufacturing (DfAM) has grown. Despite this need for an AM-skilled workforce, little research has systematically investigated the formulation of educational interventions for training engineers in DfAM. In this article, we synthesize findings from our experiments with 596 engineering design students to inform the development of educational interventions-comprising content presentations and design tasks-that encourage student learning and creativity. Specifically, we investigated the effects of four variations of DfAM educational interventions by manipulating the following: (1) the content of DfAM information presented, (2) the order of presenting the DfAM content, (3) the definition of the AM design task, and (4) the competitive structure of the AM design task. The effects of these variations were experimentally tested by comparing changes in students' DfAM self-efficacy and the creativity of students' design outcomes. Validated measures were also developed as part of our studies to help mature the nascent field of DfAM education. Based on the findings of our experiments, we discuss how task-based educational interventions can be formulated to (1) increase students' DfAM self-efficacy, (2) encourage students to generate ideas of high AM technical goodness, and (3) encourage students to generate more creative ideas when using AM. The novel synthesis of our findings in this article will help educators formulate effective DfAM educational interventions and tasks to foster a workforce skilled in DfAM.

Is Additive Manufacturing an Environmentally and Economically Preferred Alternative for Mass Production?

The manufacturing sector accounts for a large percentage of global energy use and greenhouse gas emissions, and there is growing interest in the potential of additive manufacturing (AM) to reduce the sector's environmental impacts. Across multiple industries, AM has been used to reduce material use in final parts by 35-80%, and recent publications have predicted that AM will enable the fabrication of customized products locally and on-demand, reducing shipping and material waste. In many contexts, however, AM is not a viable alternative to traditional manufacturing methods due to its high production costs. And in high-volume mass production, AM can lead to increased energy use and material waste, worsening environmental impacts compared to traditional production methods. Whether AM is an environmentally and economically preferred alternative to traditional manufacturing depends on several hidden aspects of AM that are not readily apparent when comparing final products, including energy-intensive and expensive material feedstocks, excessive material waste during production, high machine costs, and slow rates of production. We systematically review comparative studies of the environmental impacts and costs of AM in contrast with traditional manufacturing methods and identify the conditions under which AM is the environmentally and economically preferred alternative. We find that AM has lower production costs and environmental impacts when production volumes are relatively low (below ∼1,000 per year for environmental impacts and below 42-87,000 per year for costs, depending on the AM process and part geometry) or the parts are small and would have high material waste if traditionally manufactured. In cases when the geometric freedom of AM enables performance improvements that reduce environmental impacts and costs during a product's use phase, these can counteract the higher production impacts of AM, making it the preferred alternative at larger production volumes. AM's ability to be environmentally and economically beneficial for mass manufacturing in a wider variety of contexts is dependent on reducing the cost and energy intensity of material feedstock production, eliminating the need for support structures, raising production speeds, and reducing per unit machine costs. These challenges are not primarily caused by economies of scale, and therefore, they are not likely to be addressed by the increasing expansion of the AM sector. Instead, they will require fundamental advances in material science, AM production technologies, and computer-aided design software.

Dataset of process-structure-property feature relationship for laser powder bed fusion additive manufactured Ti-6Al-4V material.

The processing, structure, and property features for Ti-6Al-4V additively manufactured using laser powder bed fusion (L-PBF) over a range of processing parameter combinations are reported. In terms of processing, laser power and laser scanning speed were varied over a wide range, to investigate dense processing space as well as regimes likely to result in keyhole, lack of fusion, and beading up defects, which can occur during L-PBF. Archimedes measurements were used to measure porosity, while X-ray computed tomography (XCT) was used to quantify pore sizes, pore morphologies, and overall porosity, and finally, optical microscopy was used to quantify prior-ß grain characteristics. Average pore size and shape, porosity, prior- ß grain size and aspect ratio, and surface roughness for each processing parameter set are reported. Uniaxial tension tests and microhardness measurements were performed, with elastic modulus, yield strength, ultimate tensile strength, elongation to necking, elongation to fracture, and Vickers microhardness reported.

Design and manufacturability data on additively manufactured solutions for COVID-19.

Designers around the world have leveraged the rapid prototyping and manufacturing capabilities of additive manufacturing (AM), commonly known as 3D printing, to develop numerous engineering design solutions for the COVID-19 pandemic. This dataset consists of the design and manufacturability data for twenty-six such engineering design solutions spanning three categories: (1) face masks (N = 12), (2) face shields (N = 6), and (3) hands-free door openers (N = 8). The designs were collected from open-source websites such as Thingiverse, GrabCAD, and the NIH 3D Print Exchange. The manufacturability of these designs was simulated using Ultimaker Cura software and three measures were obtained: (1) build time, (2) build cost, and (3) build material. Furthermore, these simulations were performed for multiple materials and infill densities for comparison. Additionally, the manufacturing cost using injection molding was simulated using the Cost Estimation Tool in Solidworks. This dataset comprises (1) the STL files for the designs, (2) the simulated manufacturability data (for additive manufacturing and injection molding), and (3) images that depict the build orientation used in these manufacturability simulations. This dataset can facilitate the development of future innovations that leverage the capabilities of AM processes. Furthermore, this dataset can be used by designers and manufacturers to compare solutions and choose appropriate ones for manufacturing.

Glasses-type wearable computer displays: usability considerations examined with a 3D glasses case study.

This study presents usability considerations and solutions for the design of glasses-type wearable computer displays and examines their effectiveness in a case study. Design countermeasures were investigated by a four-step design process: (1) preliminary design analysis; (2) design idea generation; (3) final design selection; and (4) virtual fitting trial. Three design interventions were devised from the design process: (1) weight balance to reduce pressure concentrated on the nose, (2) compliant temples to accommodate diverse head sizes and (3) a hanger mechanism to help spectacle users hang their wearable display on their eye glasses. To investigate their effectiveness, in the case study, the novel 3D glasses adopting the three interventions were compared with two existing 3D glasses in terms of neck muscle fatigue and subjective discomfort rating. While neck muscle fatigue was not significantly different among the three glasses (p = 0.467), the novel glasses had significantly smaller discomfort ratings (p = 0.009). Relevance to Industry: A four-step design process identified usability considerations and solutions for the design of glasses-type wearable computer displays. A novel 3D glasses was proposed through the process and its effectiveness was validated. The results identify design considerations and opportunities relevant to the emerging wearable display industry.