Project Description

The additive manufacturing of energetic materials holds tremendous promise for the creation of structures with precise geometric configurations and energy release profiles not readily achieved by any other manner. These in turn have great potential as next generation explosives and solid-rocket propellants. The creation of additively manufactured structures that can withstand aggressive service conditions has proven elusive. At the same time, there is a desire to improve range by reducing the mass associated with casings. The co-printing of a casing and fill can improve the performance of the energetic material and reduce the mass of the casing, while simultaneously allowing more precise engineering of the interface between the casing and the fill. In general, polymer additive manufacturing parts tend to fail at the interface or weld zones between subsequent layers. This interfacial weakness results from residual stresses, insufficient interpenetration of polymer chains from the newly deposited layer into the layer below, and relatively intrinsic intermolecular interactions across the interfacial zones. It is critical to measure the interfacial strength in additively manufactured (AM) parts, as a function of the interface architecture and composition so that the overall performance of the structure under loading can be accurately predicted. However, quantifying the mechanical properties of AM interfaces is particularly challenging. Typically, entire specimens are tested and differences in the bulk mechanical properties (modulus, fracture strength, etc.) are measured and the mechanisms governing interfacial toughness are inferred from the bulk performance. This work will systematically and independently vary the topographical configuration of the interface and the surface chemistry of the binder and casing, and will isolate key contributors to the stability of the integrated printed structures. This will, in turn, guide the development of design rules for producing high performance additively manufactured integrated casing/fill components.  

Start Date

Negotiable

Postdoc Qualifications

Ph.D. in engineering (i.e. mechanical, materials, civil, aerospace, chemical), physics, or related discipline
US citizenship
The project will involve instrument construction, laboratory experiments, and modeling/simulations. Candidates with experience in collaborative work at the experimental-theory interface are preferred.
Experience with MATLAB, LabView, and/or FEA software (i.e. Abaqus, Ansys, etc.) is preferred but not required.

Co-Advisors

Professor Chelsea Davis, School of Materials Engineering

Professor Jeff Rhoads, Ray W. Herrick Laboratories/School of Mechanical Engineering 

References

M.L. Rencheck, et al. Soft Matter. 2020. 16: 6230-6252. DOI: 10.1039/D0SM00465K.

J.E. Seppala, et al. Soft Matter. 2017. 4: 6761-6769. DOI: 10.1039/C7SM00950J.

C.S. Davis, et al. Additive Manufacturing. 2017. 6: 162-166. DOI: 10.1016/j.addma.2017.06.006.

I. E. Gunduz, et al. Additive Manufacturing. 2018. 22: 98-103. DOI: 10.1016/j.addma.2018.04.029