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Scientific Research: Projects

SBIR and STTR Projects

WMI has received a number of Phase I and Phase II SBIR and STTR projects, several of which are currently active. This projects are briefly described here. Research highlights from several of these projects can be found under the Highlights link.

SBIR-Phase I and Phase II: Penetration Survivable Advanced Energetics (DOD)
It is well established that the heterogeneity of energetic materials at the mesoscale localizes deformation energy, generating “hot spots”. It is imperative to understand the nature of hot spot spatial distributions, as their coalescence leads to sustainable reaction. Given the difficulties in determining hot spot distributions experimentally, this is an ideal scenario for contributions via numerical simulation. However, important mesoscale details are only partially known, including detailed material morphology, inelastic material properties, and appropriate interfacial physics models. Here we propose simplifying the problem by examining two-dimensional surrogate materials with simplified morphologies and interfacial physics, permitting extensive validation data to be obtained. Molecular dynamics simulations will calibrate models for frictional sliding between grains and in cracks, including melting. A particle simulation technology that has been demonstrated to handle interfacial physics exceptionally robustly and efficiently will be validated and then used to resolve hot spot spatial distributions. By examining pristine and damaged systems, the importance of certain mesoscale characteristics will be isolated, and conclusions drawn regarding sensitivity to penetration events. A validated simulation capability will demonstrate the application of existing technology to a tailored, complex system, and provide a firm foundation for examining more realistic systems, and developing improved engineering material models.

SBIR-Phase I and Phase II: Molecular Simulation Tools for Predicting Hypergolicity in Ionic Liquids (DOD)
Hypergolic liquid propellants play a key role in advanced space and missile applications. In these systems when oxidizer and fuel come in contact with each other the exothermic energy of mixing and the heat from spontaneous chemical reactions result in self-sustaining combustion leading to mixture ignition.  There is a number of different oxidizer-fuel combinations used in hypergolic bipropellant formulations, while the fuel typically is hydrazine or one of its derivatives.  While hydrazine-based propellants exhibit desirable chemical kinetics and energetics they have several disadvantages, motivating the search for alternative hypergolic propellants. One of the main disadvantages of hydrazine-based propellants is that they are highly toxic and carcinogenic which, combined with high volatility of reaction products, makes these propellants very hazardous and problematic for handling and application. Recently a novel class of ionic liquids (ILs) with high nitrogen content has received significant attention as novel energetic materials due to very high heats of formation. Energetic ILs possess a number of advantages over conventional hypergolic propellants  such as high density, good oxygen balance, improved stability, low vapor pressure that results in reduced loss of material, and decreased hazards through formation of explosive fumes. Moreover, for application in hypergolic bipropellants it is not necessary to use an oxygen-balanced IL therefore allowing to tune combinations of cations and anions to achieve desired chemistry kinetics, thermodynamic and transport properties, as well as safety characteristics.   In order to efficiently design novel IL hypergolic systems a fundamental understanding of preignition and ignition stages is needed. Particularly important is the interplay of physical phenomena (mixing and interfacial transport) and chemical kinetics (key initiation reactions, preignition intermediates, and ignition events) whose unraveling would greatly facilitate development of new ILs with desired chemical, physical and processing characteristics for application in hypergolic propellants. Capitalizing on our extensive experience in molecular dynamics (MD) simulation of ILs and energetic materials using fully atomistic reactive (ReaxFF) and polarizable non-reactive (APPLE&P) force fields we propose to adopt these methods for investigation and prediction of hypergolicity in IL-based fuels. In Phase I we propose to demonstrate that information obtained from MD simulations can be correlated with hypergolicity of a given combination of IL and oxidizer for a subset of ILs which has been already characterized experimentally. Utilization of both reactive and non-reactive force fields will allow efficient and accurate modeling of chemical reactions and thermophysical properties.

STTR-PhaseI and Phase II: Force Fields for Modeling of Ionic Liquid (DOD)
The primary objective of this work was to develop and validate a transferable force field that will allow for reliable, accurate and efficient prediction of thermodynamic (heat of vaporization, surface tension, density, melting temperature), transport (viscosity, ionic and thermal conductivity, self-diffusion coefficients) and structural properties for a wide variety of ionic liquids (ILs) with potential applications as hypergolic propellants, high energy explosives, insensitive munitions, and in non-energetic applications such as energy storage, gas storage, separations, lubrication and actuators. Due to the demonstrated transferability of polarizable potentials, the core of our approach will be development of an atomistic polarizable force field applicable to a very broad set of ILs. Because of the expense of many-body polarizable simulations compared to those using non-polarizable models (a factor of 2-4), a force field hierarchy for ILs will be developed via systematic parameterization of computationally less expensive two-body non-polarizable force fields and united atom non-polarizable force fields. These force fields will be parameterized to reproduce as accurately as possible the structure, thermodynamics and transport properties of ILs obtained from simulations performed with highly accurate but more computationally expensive transferable potential. Molecular Dynamics (MD) simulations utilizing the developed force fields will enable expedient and accurate prediction of IL properties resulting in acceleration of the development cycle for novel materials with potential applications in a variety of industries ranging from defense to energy production and storage to mitigation of climate change. The transferable polarizable potential will be incorporated into a force field database called Atomistic Polarizable Potential for Liquids, Electrolytes and Polymers (APPLE&P) that is currently being commercialized by Wasatch Molecular Inc. This potential will be compatible with several commonly used simulation packages including Lucretius, AMBER, LAMMPS and TINKER, and will be marketed both alone and in conjunction with Lucretius. Non-polarizable versions of the potential will be marketed in forms compatible with all major simulation packages. We are actively seeking to develop marketing relationships for both APPLE&P and Lucretius with various modeling software firms.

Industrial Projects

 

Government laboratories