Compliant, low profile, independently releasing, non-protruding and genderless docking system for robotic modules

An apparatus for coupling with a mating coupling module to facilitate the joining of two disjoined structures without requiring precise alignment between the disjoined structures during the coupling of them may include a rotating drive mechanism, a hollow cylindrical body operatively connected to the rotating drive mechanism, wherein the hollow cylindrical body has at least one internal spiral channel, and at least one connector claw positioned within the hollow cylindrical body and guided by the internal spiral channel, wherein the at least one connector claw is configured to extend outwardly from the coupling module to engage the mating coupling module when brought in close proximity but not necessarily in precise alignment with the mating coupling module

Selective Separation Sintering (SSS) A New Layer Based Additive Manufacturing Approach for Metals and Ceramics

Selective Separation Sintering (SSS) is a powder layer based Additive Manufacturing approach. SSS can fabricate high temperature ceramic and metallic parts at comparatively lower cost with high quality. In the printing process a dry powder of higher sintering temperature is deposited into the base material which makes up the part. The inserted powder defines the boundary of the part and separates the part from its surroundings. When printing of all layers is completed the deposited dry powder serves as a separation coating which defines the shape of the part. In the sintering process the base material is sintered into a solid part while the separation coating remains as loose powder. The part is then separated from the surrounding area at the separation coating surfaces, and is post processed if necessary. Preliminary results have proven the capability of SSS in successfully printing ceramic and metallic parts. Future experiments are planned for improving the process resolution.Mechanical Engineerin

Extraterrestrial Construction Using Contour Crafting

Most proposals for construction of settlements on Moon and Mars are based on transporting structural elements from Earth and assembling them at the destination. A far less expensive and potentially practical approach is using Contour Crafting, a large-scale AM process, in conjunction with in-situ materials. Our trials with sulfur based concrete and sintered lunar regolith simulant made by NASA show strong promise. Our project ultimately aims at demonstration of lunar outpost infrastructure construction involving landing pads, blast walls, roads, shade walls and protective hangars. This paper reports on our very early efforts in the first stage of the project.Mechanical Engineerin

An Evaluation of Cross-Sectional Image Generation Schemes in the Selective Inhibition Sintering (SIS) Process

Selective Inhibition Sintering of metal alloys (SIS-metal) has been proven effective in the additive manufacture (AM) of low resolution bronze parts. The use of high precision inkjet print heads represents a significant advancement in the SIS-metal process. The fabrication of complex three-dimensional metallic parts requires SIS-metal compatible, cross-sectional image processing based on the part boundary profile. Thus, three candidate layer-processing approaches were identified and validated for rudimentary geometries. These approaches were identified from previous research as well as preliminary investigations. The validation criteria is based upon maintaining part integrity, the amount of powder waste produced, processing time, the ability to handle various part geometries, and the ease of access to inhibited regions. Results are discussed for deploying the three candidate layer processing approaches for rudimentary shapes, and a preliminary evaluation is presented for their use on more complex geometries.Mechanical Engineerin

Calibration of a Piezo-Electric Printhead in the Selective Inhibition Sintering (SIS) Process for Fabrication of High Quality Metallic Parts

Selective Inhibition Sintering (SIS) is a disruptive Additive Manufacturing process capable of printing parts from polymers, metals and ceramics. In this paper the application of a commercial piezo-electric printhead in SIS-metal is studied. This replaces the single-nozzle solenoid valve previously used in the process and allows the fabrication of high quality metallic parts due to smaller droplet sizes as well as high resolution printing mechanisms. A Design of Experiments (DoE) approach has been utilized to study the effects of important factors in printing the inhibitor. These factors include: composition of the inhibitor, quality of the print, and amount of fluid deposited for each layer. Based on the results of these experiments, parameters have been identified for the creation of highly accurate three-dimensional parts.Mechanical Engineerin

Ceramics 3D Printing by Selective Inhibition Sintering

Selective Inhibition Sintering (SIS) has been proven effective in producing polymeric and metallic parts. Due to the low cost and high quality of SIS printing, the impact of SIS printing in the 3D printing industry could be disruptive. The potential of SIS is further extended to ceramics, an important but hard to print material, by the same mechanism of creating an easy-to-break sacrificial mold. Due to the high sintering temperature of ceramics, fluid based inhibitors delivered by inkjet printing tend to not be effective in SIS for ceramics. Accordingly, the new concept of inhibition by dry powder delivery is implemented. Preliminary experiments have shown the feasibility and ease of printing of simple ceramic parts. Additional experiments are underway to increase the possible part complexity and accuracy, and to optimize the sintering process.Mechanical Engineerin

On The Development of Additive Construction Technologies for Application to Development of Lunar/Martian Surface Structures Using In-Situ Materials

For long-duration missions on other planetary bodies, the use of in-situ materials will become increasingly critical. As man's presence on these bodies expands, so must the breadth of the structures required to accommodate them including habitats, laboratories, berms, radiation shielding for natural radiation and surface reactors, garages, solar storm shelters, greenhouses, etc. Planetary surface structure manufacturing and assembly technologies that incorporate in-situ resources provide options for autonomous, affordable, pre-positioned environments with radiation shielding features and protection from micrometeorites, exhaust plume debris, and other hazards. This is important because gamma and particle radiation constitute a serious but reducible threat to long-term survival of human beings, electronics, and other materials in space environments. Also, it is anticipated that surface structures will constitute the primary mass element of lunar or Martian launch requirements. The ability to use in-situ materials to construct these structures will provide a benefit in the reduction of up-mass that would otherwise make long-term Moon or Mars structures cost prohibitive. The ability to fabricate structures in situ brings with it the ability to repair these structures, which allows for self-sufficiency necessary for long-duration habitation. Previously, under the auspices of the MSFC In Situ Fabrication and Repair (ISFR) project and more recently, under the joint MSFC/KSC Additive Construction with Mobile Emplacement (ACME) project, the MSFC Surface Structures Group has been developing materials and construction technologies to support future planetary habitats with in situ resources. One such technology, known as Contour Crafting (additive construction), is shown in Figure 1, along with a typical structure fabricated using this technology. This paper will present the results to date of these efforts, including development of novel nozzle concepts for advanced layer deposition using the Contour Crafting process. This process, conceived initially for rapid development of cementitious structures on Earth, also lends itself exceptionally well to the automated fabrication of planetary surface structures using minimally processed regolith as aggregate, and imported binder material or binders developed from in situ materials. This process has been used successfully in the fabrication of construction elements using lunar regolith simulant and Mars regolith simulant, both with various binder materials. These binder materials have resulted from extensive evaluation and include both "imported" binder materials that might be launched from Earth as well as some binder materials that can theoretically also be derived from existing regolith materials. They were chosen to 1) reduce penetrating radiation as much as possible, primarily with hydrogen-bearing polymers, 2) attempt to provide an air-tight structure, 3) sufficiently mix and adsorb to regolith grains for strength, 4) maximize tolerance to day-night thermal cycling, 5) possibly increase electrical conductivity to dissipate any accumulated static charge, and 6) ease their application on planetary surfaces (specifically, the accommodation of reduced atmosphere and lack of heat sinks). Some of these materials have been tested with respect to radiation mitigation, micrometeorite resistance, and resistance to larger, slower-traveling pieces of regolith impinging on the surface, simulating nearby launch and landing activities. Conceptual designs for a Continuous Feedstock Delivery/Mixing System (CFDMS) will also be presented and future planned activities will be discussed as well

Advancements in the SIS Process

Selective Inhibition of Sintering (SIS) is a new layer-based rapid prototyping process. This paper reports the progress in research and development of the SIS process. Specific printer path generation method, experimentation with various powder and inhibitor materials, and systematic models leading to optimum performance given various factors affecting part strength, surface quality, and dimensional accuracy are presented.Mechanical Engineerin