Dana Mcgraw Dattelbaum

Additive manufacturing (AM) has provided a new paradigm of control not only on material microstructure but also on structural assembly. The promise of AM lies in tailoring properties through this exquisite microstructural and topological design and fabrication, and the possibility of “metamaterial” properties simply not possible through conventional manufacturing. Relevant to mechanical properties and dynamic performance, the application of AM has resulted in many examples in which control of deformation mechanics and structural instabilities has led to novel properties, such as high strength-to-weight ratios, tailored thermal management, and auxetic properties. This chapter will provide an overview of the dynamic behaviors of additively manufactured polymers and metals and provide a perspective on future directions in the area.

Accurate modeling and prediction of damage induced by dynamic loading in materials have long proved to be a difficult task. Examination of postmortem recovered samples cannot capture the time-dependent evolution of void nucleation and growth, and attempts at analytical models are hindered by the necessity to make simplifying assumptions, because of the lack of high-resolution, in situ, time-resolved experimental data. We use absorption contrast imaging to directly image the time evolution of spall damage in metals at ∼1.6-μm spatial resolution. We observe a dependence of void distribution and size on time and microstructure. The insights gained from these data can be used to validate and improve dynamic damage prediction models, which have the potential to lead to the design of superior damage-resistant materials. Spall-induced void damage is observed in situ, providing insights into void evolution, which can be used to improve dynamic damage.

We have performed shock compression experiments at the Los Alamos Neutron Science Center (LANSCE) at the proton radiography (pRad) facility on a porous, low-Z material: APO-BMI. APO-BMI is a carbon micro-balloon filled foam that has homogenous pore sizes that measure 20-50 µm. The motivation for these experiments was to advance our understanding of uncertainties inherent in the shock compression of porous materials. We were able to concurrently collect dynamic radiography images with the traditional velocimetry data to directly compare these diagnostics and to, perhaps, better understand experimental uncertainties inherent to shock compression of these low-Z, porous foams.

Trinitrotoluene (TNT) is an explosive of historical importance with a wide variability of reported performance due to the number of ways to prepare it. In this work, we focus on making a consistent data set for an Arrhenius Wescott-Stewart-Davis (AWSD) burn model for pressed TNT at 1.630 g/cm3. We look at a variety of data for the calibration of the reactant and product equations of state (EOS) and produce a Davis form for each EOS. We perform the rate law calibrations based on recent gas gun experiments and historical diameter effect data. We begin to explore several different choices made in the modeling.