{"project":{"acronym":"","projectId":94179,"title":"Development and Characterization of a Novel Additive Manufacturing Technology Capable of Printing Propellants with High Solids Loadings","primaryTaxonomyNodes":[{"taxonomyNodeId":10537,"taxonomyRootId":8816,"parentNodeId":10533,"level":3,"code":"TX01.1.4","title":"Solids","definition":"This area covers propulsion systems that operate with solid propellants, where the propellants are pre-mixed oxidizers and fuels.","exampleTechnologies":"Polybutadiene Acrylic Acid Acrylonitrile Prepolymer (PBAN), Hydroxyl Terminated Poly Butadiene (HTPB)","hasChildren":false,"hasInteriorContent":true}],"startTrl":2,"currentTrl":3,"endTrl":3,"benefits":"
The purpose of this proposal is to present a new AM technology that has been demonstrated to print heterogeneous materials with solids loadings comparable to current industry standards. This is revolutionary because propellants that were previously regarded as unprintable can now be printed, which opens the door to improve propellant burning rates with new geometries.
","description":"Ever since rockets have been around, there has been a demand to improve propulsion systems by increasing propellant performance in order to reduce production time and costs. It is known that propellant burning rates can be enhanced with geometric manipulation and that Additive Manufacturing (AM), particularly Fuse Deposition Modeling (FDM), has demonstrated its ability to create unique geometries with high resolution at lower costs. However, it is currently impossible to print heterogeneous materials with high solids loadings. This is an issue because many solid and hybrid propellants rely on high solids loadings for high performance. Solids loadings could be lowered, but this would significantly reduce performance. The purpose of this proposal is to present a new AM technology that has been demonstrated to print heterogeneous materials with solids loadings comparable to current industry standards. This is revolutionary because propellants that were previously regarded as unprintable can now be printed, which opens the door to improve propellant burning rates with new geometries. This technology is very new and needs to be developed and understood through parameter characterization. System properties such as nozzle dimensions and printing path and material properties such as viscosity and reaction characteristics will be studied to determine material printability. The mechanical integrity of the prints will be tested as well. Compatible propellants that are competitive with industry standards will be printed into unique geometries and with functionally graded regions where the burning rate varies locally by varying the distribution of reactive additives. The burning rate of those samples will be compared to cylindrical samples in order to determine those effects. Promising geometries will be scaled up to a small rocket motor and will be compared to standardly used grain geometries.
","startYear":2017,"startMonth":8,"endYear":2020,"endMonth":7,"statusDescription":"Completed","principalInvestigators":[{"contactId":449791,"canUserEdit":false,"firstName":"Steven","lastName":"Son","fullName":"Steven Son","fullNameInverted":"Son, Steven","primaryEmail":"sson@purdue.edu","publicEmail":false,"nacontact":false}],"programDirectors":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programExecutives":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programManagers":[{"contactId":183514,"canUserEdit":false,"firstName":"Hung","lastName":"Nguyen","fullName":"Hung D Nguyen","fullNameInverted":"Nguyen, Hung D","middleInitial":"D","primaryEmail":"hung.d.nguyen@nasa.gov","publicEmail":true,"nacontact":false}],"projectManagers":[{"contactId":239214,"canUserEdit":false,"firstName":"Jonathan","lastName":"Jones","fullName":"Jonathan E Jones","fullNameInverted":"Jones, Jonathan E","middleInitial":"E","primaryEmail":"jonathan.e.jones@nasa.gov","publicEmail":true,"nacontact":false}],"coInvestigators":[{"contactId":347284,"canUserEdit":false,"firstName":"Monique","lastName":"McClain","fullName":"Monique Mcclain","fullNameInverted":"McClain, Monique","primaryEmail":"mcclain5@purdue.edu","publicEmail":false,"nacontact":false}],"website":"https://www.nasa.gov/strg#.VQb6T0jJzyE","libraryItems":[],"transitions":[{"transitionId":75331,"projectId":94179,"transitionDate":"2021-07-01","path":"Closed Out","details":"The performance of solid rocket motors and missiles depend on the configuration of the solid propellant grain, which is burned to create thrust. Due to the limited casting processes that can allow one to change the shape of a solid propellant grain (and therefore the thrust) to a certain degree, there is a need to explore techniques such as additive manufacturing to expand the feasible design space of propellant grains. Using a technique called Vibration Assisted Printing (VAP), it recently became possible to use additive manufacturing to 3D print high performance propellant and other viscous materials at a fine resolution (0.6 mm) compared to other commercially available techniques. The VAP process uses vibration at the syringe tip to enable fast flow of the material without high reservoir pressures (which can lead to binder dewetting from particles and safety concerns for confined energetic materials) or significant formulation modifications (i.e. low volume loading or shear thinning agents).
The objectives of this Ph.D. dissertation work were to: 1) additively manufacture high viscosity ammonium perchlorate composite propellant formulations (72-76 vol.%) without significant defects, 2) experimentally analyze 3D printed propellant microstructure and high pressure combustion properties, 3) develop and characterize a photopolymer that is compatible with energetic materials (including mixtures with opaque fuels such as aluminum particles) that can enable rapid, complete curing, 4) investigate the high pressure combustion of 3D printed functionally graded propellants made of different formulations, 5) develop a fundamental understanding of VAP process parameters, and 6) develop a fundamental understanding of the combustion dynamics of functionally graded propellant. The completed research objectives provide a foundation for constructing defect free, complex, functionally graded structures out of viscous materials. Although the focus of this work was primarily on solid propellant, the processes and methods applied in this thesis can be used to 3D print other energetic materials (i.e. propellants, explosives, and pyrotechnics) as well as inert composite mixtures (i.e. particulate or whisker ceramics/ablatives) into new configurations that could potentially improve important performance metrics (i.e. increase burning surface area in propellants, lower erosion rate in nozzles, or lower shrinkage in post-processed ceramics.
\tThe Space Technology Research Grants Program will accelerate the development of "push" technologies to support the future space science and exploration needs of NASA, other government agencies and the commercial space sector. Innovative efforts with high risk and high payoff will be encouraged. The program is composed of two competitively awarded components.
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