Structural Metamaterials: On-Demand Oral Presentations
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Additive Manufacturing Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Amy Wat, Lawrence Livermore National Laboratory; Brad Boyce, Sandia National Laboratories; Xiaoyu Zheng, University of California, Los Angeles; Fabrizio Scarpa, University of Bristol; Robert Ritchie, University of California, Berkeley
Monday 8:00 AM
March 14, 2022
Room: Mechanics & Structural Reliability
Location: On-Demand Room
High-stiffness Metamaterial Composite Structure with Plate Reinforced Strut-microlattice: Manash Baishya1; Bikram Sahariah1; Nelson Muthu1; Prasenjit Khanikar1; 1Indian Institute of Technology Guwahati
A novel metamaterial lattice composite structure inspired by the particle reinforced composite materials was designed by combining the plate and strut microlattice topologies to achieve high stiffness. The previously published literature has shown that the plate-lattice exhibits much higher stiffness than that of the strut-lattice, and the stiffness values of the plate-lattice can even exceed the maximum theoretical stiffness limit, i.e., Hashin-Shtrikman upper bound. However, the plate lattices are difficult to be fabricated using additive manufacturing because of the powder entrapment in the enclosed space of the plate lattice. In this study, high stiffness plate-lattice substructures were added as reinforcements in the matrix of strut-lattice to achieve high stiffness. The quasi-static compression behavior of the metamaterial composite structures was predicted using finite element analysis of the heterogeneous lattice structure and equivalent material obtained through the homogenization technique. The results showed that the metamaterial lattice composite with plate reinforcement exhibited considerable improvement in stiffness and elastic strain energy absorption compared to the parent strut lattice of the same relative density.
Sensitivity and Uncertainty Quantification Analysis in Phononic Metamaterials through Complex-Variable Finite Element Method: David Restrepo1; Juan Navarro1; Juan Velasquez1; Harry Millwater1; Matthew Balcer1; 1University of Texas at San Antonio
Phononic metamaterials exhibit frequency band gaps. This property is found to be useful in various applications, such as noise absorption and seismic wave abatement. However, the bandgap behavior is sensitive to small variations in the unit cell. Current techniques used to produce periodic metamaterials, such as additive manufacturing, do not ensure mechanical or geometric consistency to preserve theoretical predictions. Therefore, it is of primal importance to investigate the band gaps' sensibility to different parameter variations to close the breach between the scientific predictions and the industrial applications. In this talk, we will present a new computational methodology to perform parameter sensibility and uncertainty quantification in these materials. The method is based on the complex-variable finite element method (ZFEM) coupled with Bloch's periodic boundary. Preliminary results show that our method can reproduce probability density functions with the same accuracy as Monte Carlo modeling but at a fraction of the computational cost.
Engineering Splat Based Features for Improved Damage Tolerance in Brittle Metamaterials: Deepesh Yadav1; Tanmayee More1; B N Jaya1; 1IIT Bombay, Powai
The objective of this study is to improve damage tolerance in brittle materials inspired by defect features in thermal spray splats, to create low-density metamaterials. Globular and ellipsoidal features have been laser micro-machined in a brittle Poly(methyl methacrylate) polymer, with the objective to optimize the size, volume fraction, spacing, and arrangements of these features for best damage tolerance. Influence of single features size, spacing between two features (to understand interactions between features), and their primary unit cell architecture on the crack tip energy release rate have been determined by numerical simulations. Three-point bending experiment has been used to determine damage tolerance of full-fledge architecture in terms of work of fracture and GIC. Strain around the features has been determined by digital image correlation and correlated with the stress fields from the finite element model to understand interactions between the features in full fledge architectures.
Structural Locking in Multimodal Origami Metamaterials: Damiano Pasini1; 1McGill University
Origami crease patterns have inspired the design of reconfigurable materials that can rigidly fold and provide structural stiffness in certain directions. Their deployability, however, can occur only in one direction along which they lose load-bearing capacity. Here, we introduce a multimodal class of rigid-foldable materials that can deploy into multiple directions and lock up into several stiff states due to panel self-contact. Hallmarks include omnidirectional structural resistance under compression, access to multiple flat-foldable and lockable folding paths, and capacity to undergo topological changes each with its own set of structural properties. Their high versatility can be used for structural applications across the length-scale spectrum, such as in-situ deployment of load-bearing structures, reconfigurable packaging, and miniaturized mechanical memories.
Viscoelastic Dynamics of Polymeric Phononic Materials: Anastasiia Krushynska1; 1University of Groningen
Phononics are a sub-class of metamaterials capable of manipulating acoustic waves in solids. In the case of polymer constituents, the dynamic characteristics of phononic structures are dependent on the viscoelastic properties of the polymers. In this talk, we analyze these dependencies for phononic plates made of pristine polymer sheets and for additively manufactured three-dimensional phononic configurations produced by means of commercial FDM, SLS, and MJF techniques. We propose a general finite-element framework to characterize the wave dispersion and transmission in polymer phononic materials with different architectures and validate the obtained results experimentally. The key findings of our study provide useful guidelines for modeling phononics in broad frequency ranges for a variety of applications.
Design of 2D-Mechanical Metamaterials with Spinodal Topologies: Kiara McMillan1; Doğacan Öztürk2; Pinar Acar1; 1Virginia Tech; 2University of Alaska Fairbanks
This study investigates the design of a subset of mechanical metamaterials that demonstrate enhanced material performance through their spinodal topologies. They are generated through spinodal decomposition modeled by the Cahn–Hilliard equation. Instead of utilizing the inefficient method of modeling this time-dependent equation, formulation introduced by Kumar and co-workers, which uses Gaussian random fields to generate a special form of spinodal microstructures called spinodoids, is followed. With this approach, 2D-spinodoid images are generated by controlling their topology with orientation parameters. Principal Component Analysis (PCA) is applied to reduce the high dimensionality of this image representation and present an efficient means of characterizing this dataset. Physics-based simulations will be conducted to determine the homogenized mechanical properties as a function of the spinodoid topology. After characterizing the generated spinodoids, an inverse problem with uncertainty will be considered to find the corresponding 2D-spinodoid that provide prescribed values of properties using the PCA representation.
Investigation on Mechanical Properties of Honeycomb-based Cellular Solids and Cylindrical Shells with Structural Hierarchy: Ching-Han Hsu1; Cheng-Che Tung1; Po-Yu Chen1; 1National Tsing Hua University
Honeycombs feature outstanding lightweight characteristics, excellent energy absorption capacity, and tailorable mechanical properties. This study aims to propose novel designs which composed of conventional cellular structures, structural hierarchy, and re-entrant honeycombs with negative Poisson’s ratio, and investigate the uniaxially compressive behavior of the sheets and the rolled-up cylindrical shells. The 3D printing technology and simulation come in handy for an integrated approach to verify theoretical and experimental results. To elucidate the fundamental structure-property relations of the honeycomb lattice cylindrical shells, systematic parametric studies of different wall thickness, the number of repeating units, and Poisson’s ratio are evaluated. The investigation methods include compression test, cyclic test, digital image correlation, and finite element analysis. The novel designs can be used as the cores of sandwich composites morphed into cylindrical shapes and may be practical in various applications ranging from aerospace to domestic as impact resistance structures with lightweight and recoverable properties.
Controlling Failure with Fractal Chiral Metamaterials: Fabrizio Scarpa1; Wenjiao Zhang2; Robin Neville1; Dayi Zhang3; 1University of Bristol; 2Northeast Agricultural University; 3Beihang University
Metamaterials with fractal and perforated periodic patterns feature dramatic changes of static and dynamic properties that depend on the fractal order of the periodic pattern characteristic of their unit cells. The failure characteristics of those metamaterials have been seldom explored. We present experimental and numerical results related to the tensile and shear failure of fractal chiral metamaterial perforated plates with up to 3 fractal orders. The fractal metamaterials have been built by laser cutting techniques over PMMA substrates. Analytical, full scale and periodic unit cells Finite Element models have been also developed. These metamaterials show interactions between their fractal architecture and friction-induced dissipative mechanisms when components of the fractal pattern enter in contact during loading. Both experiments and models show that failure stresses exhibit a linear logarithmic scale dependence versus the fractal order of the pattern; crack propagation is also dependent upon the fractal design of the unit.