TECHNOLOGY AREA(S): Information Systems, Materials/Processes

ACQUISITION PROGRAM: Strategic Systems Program (SSP) Trident D5 Missile

OBJECTIVE: Develop modeling framework of design and analysis for the development of scalable lattice (or cellular) architectures to optimize the weight, dynamic response and robustness of structural components for missile applications.� Deliver a tool that can analyze the additive manufacturing process and verify within specific criteria. Also, be able to compare products to existing designs and critically analyze the components.� Framework should be applicable for metals and composites.

DESCRIPTION: Advances in Additive Manufacturing (AM), Topological Optimization (TO), and Digital Imaging Correlation (DIC) technologies offer a unique opportunity to create a synergistic impact in developing efficient structural designs that can adapt to evolving technology elements and operational environments.� For example, AM facilitates rapid prototyping, and alleviates the design and logistics constraints of the current manufacturing processes.� Combination of AM and TO using generative design allows for biologically-inspired designs such as lattice (or cellular) that use highly ordered unit cells (trusses) to create efficient structures oriented along the force field, rather than the properties of the parent material.� Furthermore, recent developments in measurement technology such as DIC allow for better understanding of the structural response of the complex topology of the lattice (unit cells) under static and dynamic loading and provide for better model validation of such complex structures.� Overall, the coupling between these three technology areas may potentially allow reduction in qualification time of these repeatable units.

Adoption of these technologies through the development of such framework is key to evolving the current missile design to a future capability with viable missile components to meet its affordability goals.� While there have been considerable developments and all the benefits point to the attractive proposition for these technologies, some key issues have yet to be addressed such as the accuracy, reproducibility, and reliability of the AM, and the verification and validation challenges that remain for qualification for space flight.

This task will focus on the primary structural components, currently machined out of metal billets using designs to optimize the weight of the missile, using conventional manufacturing techniques, which drive the location of interfaces (i.e., joints) and impact part-count and weight.� The use of AM and TO simplify the design and manufacture of complex structures thus eliminating some of these interfaces and aligning lattice elements along force fluxes to minimize weight.� This SBIR topic is focused on developing an integrated framework of design, analysis, and test and evaluation methodologies to design the structural components using a lattice (cellular) design using AM processed aluminum or titanium alloys.� Since significant work has already been performed on TO [1,2], AM property definition and process [3,4], qualification, and part strain measurements using DIC [5,6,7], what remains a technical challenge is the ability to model and predict AM lattice structures at various scales and the kind of failure process�catastrophic or graceful�and define the path to flight acceptance.� The proposed framework is expected to perform integrated system design (i.e., balance system requirements with component and part design, shape, material, and manufacture using a confidence/uncertainty based evaluation).� The expected solution would be a departure from the conventional A-basis properties and margin-based evaluation.� However, an evaluation of the framework will be based on comparing this outcome with the components developed with the conventional process on an equal uncertainty confidence level basis.� To accomplish this will require leveraging lessons learned on past AM and TO experience coupled with the development of models for predictive modeling of lattice structure behavior under all mechanical (structural, thermal and dynamic (vibration/shock)) loading at various scales, evaluation, and statistical basis of experimental measurements and test data, modes of failure propagation and reliability predictions, and criteria of acceptance on risk-based decision process to reduce qualification costs.

Ultimately, the product of this effort is expected to be folded into a larger Model Based Engineering framework as a lean tool for successfully designing, manufacturing, and qualifying topology optimized missile components.
Proposals are solicited that address the following capabilities:
� Providing an optimized process of design and analysis for structural components in relation to the previous design process.� This includes time, cost, implantation, structural integrity, etc.
� Focusing modeling framework on structural components of lattice or cellular design
� Allowing application for both metals and composites

Proposed solutions should support the following:
� Parts ranging from 2in up to 3ft (depending on AM capability)
� Mechanical Loads
o Load factors:� less than 100g
o Temperature range: 160�F up to 3,000�F
o Shock/Vibration: 40-500g (20-2kHz) / 0.04-01g2/Hz (20-2kHz)
� Materials:
o Metal: Aluminum, Ti, Steel, other high-temperature material
o Composites: Metal Matrix Composite (MMC), Polymer Matrix Composite (PMC), etc.
� Wire and powder-based AM
� Standards and certification

PHASE I: Develop a proof of concept modeling framework that can optimize missile structural component design using various scales of lattice (or cellular) designs to minimize weight; achieve a required stiffness, strength, and reliability; and meet system structural and dynamic performance objectives with confidence levels.� Demonstrate the concept, for various scales, on a missile component object provided by the Contracting Officer�s Representative (COR).� Phase I will include plans for a concept prototype to be developed during Phase II.

PHASE II: Mature concept system architecture into a working design and analysis tool that will be used to demonstrate optimized manufacturing concepts for missile structural components.� Focus initially on a single material for which AM processes are mature, and expand the work to other materials as the offeror�s manufacturing technology matures.� Demonstrate the applicability of the Phase I-developed framework/tool by designing, fabricating, and testing three different scales of the missile component object.� The Phase II effort will result in a final certification-ready tool.

PHASE III DUAL USE APPLICATIONS: Manufacture full-scale structural missile component object using this new lattice structure and AM modeling framework and subject them to flight acceptance test program to develop a process for future use of this framework.

REFERENCES:

1. Suard, M. "Characterization and Optimization of Lattice Structures made by Electron Beam Melting." University of Grenoble Thesis. November 2015.

2. Nguyen, J., Park, S., Rosen, D., Folgar, L., and Williams, J. "Conformal Lattice Structure Design and Fabrication." https://sffsymposium.engr.utexas.edu/Manuscripts/2012/2012-10-Nguyen.pdf.

3. Campbell, T., and Ivanova, O. "Additive Manufacturing as a Disruptive Technology: Implications of Three-Dimensional Printing.� Technology and Innovation, 2013, Vol. 15, pp. 67-79. http://www.ingentaconnect.com/contentone/cog/ti/2013/00000015/00000001/art00008

4. Ford, Sharon L. N. "Additive Manufacturing Technology: Potential Implications for U.S. Manufacturing Competitiveness." United States Trade Commission, Journal of International Commerce and Economics, Web version: September 2014. https://www.usitc.gov/journals/Vol_VI_Article4_Additive_Manufacturing_Technology.pdf

5.� Sutton, M. Orteu, JJ and Schreier, H. "Image-based Measurements in Solid Mechanics: A Brief History, Static and Dynamic Application Examples and Recent Developments." Published electronically at bssm.org. https://books.google.com/books?hl=en&lr=&id=AlkqMxpQMLsC&oi=fnd&pg=PA1&ots=5VdTgfvE_F&sig=gx4_kmU5t6zF5LzJ5DG0_sCdsV8#v=onepage&q&f=false

6. Reu, L., Sutton, M., Wang, Y., and Miller, T. "Uncertainty quantification for digital image correlation." Proceedings of the SEM Annual Conference, June 1-4 2009. https://sem.org/uncertainty-quantification-for-digital-image-correlation-7-pages/

7.� Ghadbeigi, H., Goodall, R., Khodadadi, M., and Jones, E. "Damage and deformation analysis of Ti-6Al-4V Diamond lattice structures."� http://www.bssm.org/uploadeddocuments/Conference%202015/2015papers/Damage_and_deformation_analysis_of_Ti-6Al-4V_Diamond_lattice_structures.pdf

KEYWORDS: Additive Manufacturing; Topological Optimization; Digital Imaging Correlation (DIC) Technologies; D5 Missile; Lattice Structures; Material Design; Model-based Engineering; Material and Processes