Research Projects

Additive manufacturing (3D Printing) opens up new capacity for tuning geometry and in some cases material properties that were not available to researchers previously. These capabilities change traditional considerations for design of products, systems, supply chains, and even business models. While there have been some notable successes, much of what has been done with additive manufacturing largely replicates parts made by traditional processes. New design methods and tools are needed to better utilize the capabilities of additive manufacturing.

Traditional methods of manufacturing utilize validated tooling and control of key process parameters to assure consistent product outcome. They often rely on statistical sampling to assure process control at minimal cost. However, additive manufacturing (AM) requires new approaches. On the one hand, the number of process variables increases because the properties and geometry are formed point by point. This increases the potential failure conditions by order of magnitudes. At the same time, production quantity is much too small to apply statistical process control at the part level. Thus, new methods are required.

One promising approach is in controlling the process parameters through the process in order to verify the quality at each point. However, this requires both new sensing modalities to track all the properties of interest efficiently and methods that can efficiently analyze the terabytes of data that can be generated.

One of the ways that we are addressing this challenge is through the study of new methods for active thermal probing to gather data about the printed parts during the printing process in order to assure that all elements are within spec or to even adjust process parameters in real time to improve process consistency.

Thermal image high intensity projection of a BYU logo shows how spatially controlled heating can be achieved.

One of the earliest methods of additive manufacturing (3d Printing) was laser sintering (LS). In LS, a laser is scanned over the surface of a semicrystalline polymer powder preheated close to its melting point. As the laser scans over the material, it heats the powder and fuses the particles together to form the geometry. The parts have excellent accuracy and strength comparable to injection molded components. However, there is a relatively limited range of materials that are used with the method, and material toughness remains well-below what is achieved with traditional manufacturing methods.

A possible culprit in these issues is the very fast heating time that is used. In order to economically produce parts while maintaining the ability to create fine features, the laser must be focused to a fine spot that is scanned very rapidly over the surface. This creates large temperature gradients that could locally degrade the material and limited time for complete densification. We are exploring the impact of these constraints by using a projected image to cure large areas (cm^2) simultaneously. We have demonstrated dramatic improvements in ductility (elongation at break) while maintaining comparable strength to traditional LS parts while using the same raw material.

Ongoing efforts are considering the mechanisms for these improvements and exploring how these benefits might be extended to other material systems.

Sponsor: National Science Foundation

LAPS processing increases both ductility and strength of Nylon 12 (PA 12) materials compared to commercial processes.

Several additive manufacturing (AM) processes rely on inkjet printing as a key component. In particular, two (binder jetting, high speed sintering/multijet fusion), require that the droplets be printed into a powder bed. The details of these interactions can make a significant difference in the quality of the resulting surfaces as seen in the images to the right.

These small droplets (Ø < 50 microns) impact even smaller powder particles at speeds of up to 10 m/s. The kinetic energy is often comparable to the wetting energy resulting in significant particle rearrangement on impact. The dynamics of this process play a key role in the accuracy of the geometric shape produced and can be a source of either beneficial particle realignment or void formation.

A high speed video provides some insight into the complex dynamics of these processes. In the video, a single nozzle is moving over the powderbed and printing droplets to form a line filmed at 2000 frames per second. Watch in slow motion as droplets splash, powder flies, and droplets merge into larger balls.

Existing work provides an incomplete picture of these interactions and is largely based on relatively low kinetic energy conditions in which droplets are substantially larger than the powder particles. A better understanding of these processes will enable better development of new materials and binders/inks for higher performance materials.

Binder Jetting is a promising AM method that spreads thing layers of powder and then deposits small droplets of binder using ink jet printing. After printing all the layers, the binder is cured, the part is removed and then post processed by infiltration or sintering to achieve its final properties.

This process can be relatively low-cost with a high build rate, but the physics of the process are complex involving powder handling, high speed droplet impacts rearranging powder structure, chemical reactions, and sintering processes. We are working to understand these physical processes to establish a firm foundation to help binder jetting transition into a main-stream manufacturing process.

High speed X-ray imaging of droplets hitting stainless steel powders in dry and pre-wetted conditions showing the impact of pre-wetting on reducing powder rearrangement. C. Inkley, J. Lawrence, and N. B. Crane, Additive Manufacturing, 103619, 2023. https://doi.org/10.1016/j.addma.2023.103619

Additive manufacturing (AM) is a process that builds objects layer by layer, offering a unique advantage over conventional manufacturing methods: real-time access to the internal conditions of the product during fabrication. By leveraging this advantage, it becomes possible to monitor the manufacturing process and significantly reduce internal defects, which are often unavoidable in traditional manufacturing.

Flash thermography (FT) emerges as a promising tool for achieving online monitoring in AM processes, particularly in binder jetting (BJ) or powder bed fusion (PBF). This technique involves applying a short thermal pulse to the surface of the sample, followed by the use of an infrared (IR) camera to capture the surface temperature evolution over the entire sample. By analyzing the temperature data within a region of interest (ROI), critical material properties such as thermal diffusivity, thermal conductivity, and density can be extracted.

When applied to the powder bed of the BJ printing process, FT offers transformative capabilities:

Real-time density monitoring of the powder bed. At this point, the time required for measuring the thermal properties and density of SS316L powder has been reduced to a maximum of 100 seconds, with an accuracy within 2.5% error. These results bring us significantly closer to achieving real-time density monitoring during the AM process.

Defect detection during the manufacturing process.

Parameter optimization, facilitating the development of more efficient and consistent processes.

Mechanistic studies, enabling exploration of phenomena such as the formation of defects in the green body and the heterogeneity of the green body, which are challenging or impossible to study using other methods.

Electrowetting is a phenomenon in which a droplet shape is altered in the presence of an electric field. When utilized with a thin dielectric layer, electrical current is eliminated and a highly efficient actuation system can be created by controlling the field across the droplet. Traditionally this is done with a series of electrodes of the same approximate size as the droplet allowing for programmable droplet motion required in lab-on-a-chip systems for DNA sequencing or medical diagnostics.

We have developed a variety of actuation methods that allow for higher speed and/or higher accuracy motion. These include continuous electrowetting across distances much larger than the droplet utilizing a single electrode pair and sub-electrode stepping motion that allows for high accuracy open-loop position control.

In one illustration of a possible applications, the technique was used to move a metallized plate to tune a resonator frequency. This could be extended to other electrical devices to allow for high efficiency and high power RF electronics in a compact package.

Sponsor: National Science Foundation

Most corrosion-preventing coatings such as paints serve as a barrier to the ion transport that drives metallic corrosion. However, there are some cases in which a controlled corrosion rate is desired and/or coatings may be undesirable. For example, magnesium is of interest for temporary implants such as anchors in orthopedic surgery. It is biodegradable, nontoxic and has favorable mechanical properties for bone interface. However, it typically degrades too quickly in an aqueous environment. Alloying elements and coatings can help, but many raise toxicity concerns. We are exploring an alternative method of impeding the corrosion reaction.

We are creating surface textures in the magnesium similar to super hydrophobic surfaces. When immersed in a saline solution, the corrosion process generates hydrogen gas. This gas is trapped by the surface texture and dramatically slows the corrosion rate. The surface texture parameters may be used to control the time profile of the degradation alone or in combination with other corrosion control methodologies in order to achieve clinically required degradation rates.

Sponsor: National Science Foundation

Wetting is key to a wide variety of industrial processes. Examples include soldering, painting, adhesive, food processing, cleaning, and corrosion. It is critical to understand how common processing conditions impact the wetting phenomena in order to improve performance of these products or add new functionality. It has previously been demonstrated the droplet wetting states can be changed by exciting droplet vibration modes. However, the excitation frequency must be tuned for each droplet volume making this an impractical method for most applications. We are studying the use of high frequency (>10 kHz) excitations as an alternative approach.

We have shown previously unreported spreading effects due to the high frequency vibration. Droplet diameters increase linearly in proportion to the vibration acceleration of the surface across a wide range of viscosities. This may provide the means for careful modulation of wetting of droplets on a surface.

Ongoing studies are considering how this could impact wetting on textured substrates.

Sponsor: National Science Foundation

Our lab focuses on advancing origami-inspired manufacturing, aiming to enable the high volume production of complex, dynamic mechanisms that leverage the unique capabilities of origami. By addressing the constraints that limit the adoption of origami in production, we seek to make its benefits accessible to industries and applications requiring compact, expandable solutions. Our research is distinguished by a strong emphasis on design for manufacturing, ensuring that origami-based designs are not only innovative but also manufacturable at scale. The outcomes of our work have the potential to revolutionize fields ranging from construction and aerospace to everyday consumer products.

While the energy savings of switchable insulation has been studies for years, implementation has been constrained by the availability of a low-cost switchable insulation. This sub-area focuses on designing and testing shape-changing insulation for buildings and spacecraft. These systems regulate heat flow by transitioning between "conducting" and "insulating" states. The insulating state matches the performance of traditional materials, while the conducting state resembles the effect of no insulation. This dynamic capability enables energy-efficient solutions for varying environmental conditions.

Caption: Conceptual design for a insulation system compatible with roll to roll manufacturing that can be switched between insulative and conducting states. https://www.mdpi.com/1996-1073/17/16/3959

Here, we explore sheet-based manufacturing methods, including Sheet Lamination and Roll-to-Roll processing, to construct mechanisms from raw sheet materials. These approaches streamline production by taking advantage of the intrinsic properties of sheets, paving the way for scalable, efficient fabrication of dynamic mechanisms.

This sub-area investigates techniques for producing origami-inspired mechanisms that extend across multiple planes. By integrating surrogate folds—hinges that mimic paper creases—into the manufacturing process, we reduce material usage, shrink the build footprint, and create space for larger or more complex systems. Multiplanar manufacturing also optimizes actuation strategies, contributing to more versatile and compact designs.
The manufacturing system can be much smaller than the final deployed state. This approach could allow direct digital fabrication of large complicated systems in a compact stowed position ready for transport. Once transported to the point of use, these systems could then be deployed. These systems may be valuable in overcoming transportation and manufacturing constraints in building construction, space vehicles, and on-orbit manufacturing.

Caption: Origami kayak design printed with different number of layers. The multiplanar design takes up much less space allowing for a large kayak to be printed on a small build plate. https://doi.org/10.1016/j.mechmachtheory.2024.105906

Origami has traditionally been practiced with paper and other thin sheet materials, but fiber-reinforced composites could provide improved performance if they can be manufactured with flexible hinges. We are developing methods of combining elements of traditional composite fabrication techniques with elements of additive manufacturing to enable scalable production of origami devices from continuous fiber composites.

Caption: Origami structures created by selective infiltration of carbon fiber.