Publications

Aguilo Valentin, Miguel A.; Beghini, Lauren L.; Clark, Brett W.; Quadros, William R.; Robbins, Joshua R.; Sneed, Brett S.; Voth, Thomas E.

Abstract not provided.

Davis, Jean-Paul D.; Lane, James M.; Thompson, Aidan P.; Drake, Richard R.; Weirs, Vincent G.; Flicker, Dawn G.; Robbins, Joshua R.; Lemke, Raymond W.; Martin, Matthew; Alexander, Charles S.; Haill, Thomas A.; Ao, Tommy A.; Dolan, Daniel H.

Abstract not provided.

Brewer, Luke N.; Robbins, Joshua R.

Abstract not provided.

Ferroelectrics

Robbins, Joshua R.

Abstract not provided.

Dong, Wen D.; Robbins, Joshua R.

Abstract not provided.

Jared, Bradley H.; Kozuch, Christopher D.; Tappan, Alexander S.; Cook, Adam W.; Bishop, Joseph E.; Adams, David P.; Maguire, Michael C.; Robinson, David R.; Hall, Aaron C.; Carrillo, Lawrence R.; Sego, Abraham L.; Leathe, Nicholas L.; Fuller, Nathan F.; Robbins, Joshua R.; Clark, Brett W.

Abstract not provided.

Scripta Materialia

Jared, Bradley H.; Aguilo, Miguel A.; Beghini, Lauren L.; Boyce, Brad B.; Clark, Brett W.; Cook, Adam W.; Kaehr, Bryan J.; Robbins, Joshua R.

Additive manufacturing offers unprecedented opportunities to design complex structures optimized for performance envelopes inaccessible under conventional manufacturing constraints. Additive processes also promote realization of engineered materials with microstructures and properties that are impossible via traditional synthesis techniques. Enthused by these capabilities, optimization design tools have experienced a recent revival. The current capabilities of additive processes and optimization tools are summarized briefly, while an emerging opportunity is discussed to achieve a holistic design paradigm whereby computational tools are integrated with stochastic process and material awareness to enable the concurrent optimization of design topologies, material constructs and fabrication processes.

Robbins, Joshua R.

Abstract not provided.

Wong, Michael K.; Brunner, Thomas A.; Garasi, Christopher J.; Haill, Thomas A.; Mehlhorn, Thomas A.; Drake, Richard R.; Hensinger, David M.; Robbins, Joshua R.; Robinson, Allen C.; Summers, Randall M.; Voth, Thomas E.

ALEGRA is an arbitrary Lagrangian-Eulerian multi-material finite element code used for modeling solid dynamics problems involving large distortion and shock propagation. This document describes the basic user input language and instructions for using the software.

Robinson, Allen C.; Petney, Sharon P.; Drake, Richard R.; Weirs, Vincent G.; Adams, Brian M.; Vigil, Dena V.; Carpenter, John H.; Garasi, Christopher J.; Wong, Michael K.; Robbins, Joshua R.; Siefert, Christopher S.; Strack, Otto E.; Wills, Ann E.; Trucano, Timothy G.; Bochev, Pavel B.; Summers, Randall M.; Stewart, James R.; Ober, Curtis C.; Rider, William J.; Haill, Thomas A.; Lemke, Raymond W.; Cochrane, Kyle C.; Desjarlais, Michael P.; Love, Edward L.; Voth, Thomas E.; Mosso, Stewart J.; Niederhaus, John H.

Abstract not provided.

Boucheron, Edward A.; Haill, Thomas A.; Peery, James S.; Petney, Sharon P.; Robbins, Joshua R.; Robinson, Allen C.; Summers, Randall M.; Voth, Thomas E.; Wong, Michael K.; Brown, Kevin H.; Budge, Kent G.; Burns, Shawn P.; Carroll, Daniel E.; Carroll, Susan K.; Christon, Mark A.; Drake, Richard R.; Garasi, Christopher J.

ALEGRA is an arbitrary Lagrangian-Eulerian finite element code that emphasizes large distortion and shock propagation. This document describes the user input language for the code.

Ibanez-Granados, Daniel A.; Hansen, Glen H.; Voth, Thomas E.; Love, Edward L.; Overfelt, James R.; Roberts, Nathan V.; Mota, Alejandro M.; Robbins, Joshua R.; Aguilo Valentin, Miguel A.

Abstract not provided.

Robbins, Joshua R.; Aguilo Valentin, Miguel A.

This report provides detailed documentation of the algorithms that were developed and implemented in the Plato software over the course of the Optimization-based Design for Manufacturing LDRD project.

AIP Conference Proceedings

Robbins, Joshua R.; Voth, Thomas E.

The extended Finite Element Method (X-FEM) is a finite-element based discretization technique developed originally to model dynamic crack propagation [1]. Since that time the method has been used for modeling physics ranging from static meso-scale material failure to dendrite growth. Here we adapt the recent advances of Vitali and Benson [2] and Song et. al. [3] to model dynamic loading of a polycry stalline material. We use demonstration problems to examine the method's efficacy for modeling the dynamic response of polycrystalline materials at the meso-scale. Specifically, we use the X-FEM to model grain boundaries. This approach allows us to i) eliminate ad-hoc mixture rules for multi-material elements and ii) avoid explicitly meshing grain boundaries. © 2007 American Institute of Physics.

Robbins, Joshua R.; Voth, Thomas E.

Abstract not provided.

Jared, Bradley H.; Boyce, Brad B.; Battaile, Corbett C.; Lim, Hojun L.; Tran, Hy D.; Robbins, Joshua R.; Clark, Brett W.; Blacker, Ted D.

Abstract not provided.

Proceedings - ASPE 2015 Spring Topical Meeting: Achieving Precision Tolerances in Additive Manufacturing

Jared, Bradley H.; Boyce, Brad B.; Battaile, Corbett C.; Lim, Hojun L.; Tran, Hy D.; Robbins, Joshua R.; Clark, Brett W.; Blacker, Ted D.

Abstract not provided.

Robbins, Joshua R.; Alberdi, Ryan A.; Clark, Brett W.

The typical topology optimization workflow uses a design domain that does not change during the optimization process. Consequently, features of the design domain, such as the location of loads and constraints, must be determined in advance and are not optimizable. A method is proposed herein that allows the design domain to be optimized along with the topology. This approach uses topology and shape derivatives to guide nested optimizers to the optimal topology and design domain. The details of the method are discussed, and examples are provided that demonstrate the utility of this approach.

Computer Methods in Applied Mechanics and Engineering

Voth, Thomas E.; Mosso, Stewart J.; Robbins, Joshua R.

Here, we examine the coupling of the patterned-interface-reconstruction (PIR) algorithm with the extended finite element method (X-FEM) for general multi-material problems over structured and unstructured meshes. The coupled method offers the advantages of allowing for local, element-based reconstructions of the interface, and facilitates the imposition of discrete conservation laws. Of particular note is the use of an interface representation that is volume-of-fluid based, giving rise to a segmented interface representation that is not continuous across element boundaries. In conjunction with such a representation, we employ enrichment with the ridge function for treating material interfaces and an analog to Heaviside enrichment for treating free surfaces. We examine a series of benchmark problems that quantify the convergence aspects of the coupled method and examine the sensitivity to noise in the interface reconstruction. Finally, the fidelity of a remapping strategy is also examined for a moving interface problem.

Walsh, Timothy W.; Bishop, Joseph E.; Brown-Shaklee, Harlan J.; Hammetter, Christopher H.; Robbins, Joshua R.; Sinclair, Michael B.; Aquino, Wilkins A.

Abstract not provided.

Clark, Brett W.; Aguilo Valentin, Miguel A.; Voth, Thomas E.; Robbins, Joshua R.

Abstract not provided.

Robbins, Joshua R.

Abstract not provided.

Journal of the Mechanics and Physics of Solids

Alberdi, Ryan A.; Robbins, Joshua R.; Walsh, Timothy W.; Dingreville, Remi P.

Metamaterials are artificial structures that can manipulate and control sound waves in ways not possible with conventional materials. While much effort has been undertaken to widen the bandgaps produced by these materials through design of heterogeneities within unit cells, comparatively little work has considered the effect of engineering heterogeneities at the structural scale by combining different types of unit cells. In this paper, we use the relaxed micromorphic model to study wave propagation in heterogeneous metastructures composed of different unit cells. We first establish the efficacy of the relaxed micromorphic model for capturing the salient characteristics of dispersive wave propagation through comparisons with direct numerical simulations for two classes of metamaterial unit cells: namely phononic crystals and locally resonant metamaterials. We then use this model to demonstrate how spatially arranging multiple unit cells into metastructures can lead to tailored and unique properties such as spatially-dependent broadband wave attenuation, rainbow trapping, and pulse shaping. In the case of the broadband wave attenuation application, we show that by building layered metastructures from different metamaterial unit cells, we can slow down or stop wave packets in an enlarged frequency range, while letting other frequencies through. In the case of the rainbow-trapping application, we show that spatial arrangements of different unit cells can be designed to progressively slow down and eventually stop waves with different frequencies at different spatial locations. Finally, in the case of the pulse-shaping application, our results show that heterogeneous metastructures can be designed to tailor the spatial profile of a propagating wave packet. Collectively, these results show the versatility of the relaxed micromorphic model for effectively and accurately simulating wave propagation in heterogeneous metastructures, and how this model can be used to design heterogeneous metastructures with tailored wave propagation functionalities.

Dong, Wen D.; Robbins, Joshua R.; DiAntonio, Christopher D.

Abstract not provided.

Aguilo Valentin, Miguel A.; Voth, Thomas E.; Clark, Brett W.; Robbins, Joshua R.

Abstract not provided.