3D printing is one of the key technologies in space exploration. The disparity in gravitational forces between Earth and space presents both challenges and opportunities with regard to material handling. This article examines the potential of employing ultrasonic levitation as a handling tool for substrate-free additive manufacturing processes in microgravity environments. Through preliminary experiments, we demonstrate the feasibility of manipulating polymer powders using acoustic fields while concurrently melting the levitated material. Subsequent experiments conducted in our drop tower facility confirm our ability to manipulate particles with acoustic traps under microgravity conditions. Building upon these findings, we outline plans to further advance our research using an expanded acoustic levitation system capable of three-dimensional object manipulation. Our objectives include moving and orienting large components beyond the wavelength limit in microgravity, manipulating granular raw material while melting it in proximity to the print part, and achieving a semi-continuous fusion of print material with the print part. Therefore, we present an intelligent control strategy based on the results of a digital twin simulation. Furthermore, we utilize a stereo camera combined with computer vision as feedback for the control system to ensure precise handling of the manipulated objects and particles. This study represents a significant advance toward the realization of efficient substrate-free additive manufacturing processes in microgravity environments, with potential applications for in-space manufacturing. Ultimately, this could result in long-term space missions becoming less reliant on supply deliveries, thus reducing cost and additionally enabling faster response to unforeseen issues.

Multiple global trends and drivers have resulted in a steep escalation of tech-socio-economic inequities in basic human needs across industrialized as well as industrializing nations. This escalation is paralleled by the growing trend of novel and simple frugal innovations for meeting basic human needs, which are applied across various communities in the world towards bridging gaps of inequity. Frugality in this context is defined as minimizing the use of capital resources while delivering effective manufacturing product outcomes. It is noteworthy that frugal innovations are abundantly observed in the biological designs in nature. This paper is aimed at understanding the methodology of frugal engineering behind the resulting frugal manufacturing innovations through discovering the cross-section of frameworks of biological designs in nature and equitable social innovations. Authors have applied the framework of biological designs as these designs are observed to deliver multifunctionality, resilience, and sustainability, which are key to a frugal and equitable innovation platform and achieved by the frugal engineering process. As water is one of the most basic human needs, this paper uses water as an illustrative example to understand the frugal engineering process. The authors discuss designs in nature from cactus, tree roots, and human skin, and design parallels in related frugal innovations namely in fog-capturing nets, ice stupa, and Zeer (pot-in-a-pot), respectively, for equitable water access. The authors propose and discuss a resulting methodology for frugal engineering. This methodology can be utilized as a starting point for developing case-specific socially conscious manufacturing solutions.

The design and manufacturing of lightweight structures (also termed lightweighting) are essential for many industrial applications to reduce material and energy consumption, impacting industries from automobiles to aerospace. Through millions of years of evolution, biology has utilized intricate designs and materials that are both lightweight and strong as a part of evolution, enabling organisms to adapt efficiently to their environments and providing a library of lightweighting approaches. This paper provides a comprehensive overview of biological design strategies for lightweighting. The authors introduce a biological design toolbox for lightweighting, a modular list of design attributes biological species utilize to develop lightweight structures. Selected representative lightweight biological examples and the fundamental science governing their design strategies are analyzed and discussed using the design toolbox, which could be applied in manufacturing engineered parts and systems. Their corresponding simulated and/or manufactured designs were also studied to highlight the gaps and opportunity space in the current bio-inspired design practices. To address these gaps, a holistic bio-inspired design framework for lightweighting is proposed as a part of future research based on the critical analysis of the design toolbox for lightweighting.

This paper reports a study of the evolution of directional texture and its role in the manipulation of tribofilm layers under boundary lubrication (BL). The use of surface protective tribofilms/lubricant chemistries along with the use of textured surfaces has gained significant attention as an effective BL strategy to provide advanced lubrication. However, the evolution of surface texture in the direction of motion under continuous asperity-to-asperity contact remains unexplored, especially in correlation with the tribofilm properties on textured surfaces. Mechanical polishing using SiC abrasive paper was used to generate directional and concentric surface texture on 52100 steel discs. Tribological tests of varying time durations were performed using MoS₂-based lubricant to systematically study the evolution of texture and tribofilm using a pin-on-disc rotational setup. A laser microscope was used for areal texture characterization while tribofilm was characterized using SEM/EDS, Raman, and FIB/TEM. The results show that directional texture manipulates the early onset and tribo-chemical reactions and the delivery of lubricant tribofilm on the asperities during the evolution process.