a b s t r a c tTopologically interlocked materials (TIMs) are a class of materials made by a structured assembly of an array of identically shaped and sized unit elements that are held in a confining framework. The assembly can resist transverse forces in the absence of adhesives between the unit elements. The present study focuses on topologically interlocked materials with cellular unit elements. The resulting materials achieve their properties by a combination of deformation of the individual unit elements and their contact interaction. Drop tower tests were conducted to characterize the mechanical behavior of the cellular TIMs made of an intrinsically brittle base material. The TIMs were found to exhibit perfect softening, independent of the relative density of the cellular units. The analysis of the experiments revealed a positive correlation between strength and toughness in contrast to more conventional materials. An analytical model for the prediction of the observed material behavior is developed. Model predictions are in agreement with experimental data. The implications of the present findings for the design of these novel materials are discussed.

The high sound transmission loss (STL) metamaterials that have been suggested to-date commonly require the introduction of relatively heavy resonating or constraining components which limit the applicability of these solutions in typical noise control applications where it is desirable to minimize the treatment mass at a given STL. Here it is proposed that a panel consisting of an array of cellular unit structures can possess a high STL within a specified low frequency range without an undue mass penalty. The cellular acoustical metamaterial considered comprises a periodic arrangement of unit cells consisting of plates held in a grid-like frame (which itself is unsupported). It is suggested here that such a cellular panel can yield enhanced STL if the unit cell mass is apportioned appropriately between the unit cell plate and the surrounding grid-like frame, the effect being similar to the high STL observed in the low frequency range for a plate clamped along its edges. A finite element-model of a single unit cell was used to predict the normal incidence transmission loss of the periodic array by im-1 posing boundary conditions that enforce spatial periodicity. Two material designs were compared: one in which the densities of the materials used for the unit plate panel and the grid were changed relative to each other, and a second where the relative thicknesses of the unit plate panel and the grid frame were varied. The numerical simulations indicate that benefits can be achieved in either case. However, the design based on density variations appears to be more effective than the approach based on geometry alteration in creating a relatively broad range of low frequency transmission loss enhancement.

A kinematic analysis technique is introduced to find the angular velocities of all links in bevel epicyclic gear trains. The method relies on previous work in graph theory. It improves on existing techniques used for analysis of planar geared mechanisms in its ability to accurately solve the kinematics of spatial geared mechanisms, particularly bevel gear trains, in a simpler manner. Usefulness of the method is demonstrated through its application to power-flow and efficiency analyses as well as its implementation in computer software. This discussion is limited to gear trains whose input and output axes are collinear, such as automotive automatic transmissions.

PurposeTopologically interlocked materials are a class of materials in which individual unit elements interact with each other through contact only. Cracks and other defects occurring due to external loading are contained in the individual unit elements. Thus, topologically interlocked materials are damage tolerant and provide high structural integrity. The purpose of this paper is to investigate the concepts of remanufacturing in the context of a material for which the intended use is structural such that the material's structural integrity is of concern. In particular, the study is concerned with the mechanical behavior of a topologically interlocked material.Design/methodology/approachA topologically interlocked material based on tetrahedron unit elements is investigated experimentally. Manufacturing with aid of a robotically controlled end‐effector is demonstrated, and mechanical properties are determined for a plate configuration. A conceptual mechanical model for failure of topologically interlocked materials is developed and used to interpret the experimental results.FindingsIt is demonstrated that remanufacturing of the topologically interlocked material is possible with only a limited loss of material performance. The proposed model predicts trends in agreement with the experimental findings.Research limitations/implicationsWhile the model predictions are qualitatively in agreement with experiments, more detailed finite element models are needed to predict the material performance accurately. Experiments were conducted on a model material obtained from a 3D printer and should be verified on other solids.Practical implicationsThe authors demonstrate that damage containment together with the absence of binders or adhesives enables reuse through remanufacturing without loss of structural integrity.Social implicationsTopologically interlocked materials emerge as attractive materials for sustainable engineering once their material performance are weighted with an environmental impact factor.Originality/valueRemanufacturing experiments on a novel class of materials were conducted and a new model for the characterization of the structural integrity of topologically interlocked materials is proposed and successfully evaluated against experiments in at least qualitative form.

Topologically interlocked materials (TIMs) are a class of 2D mechanical crystals made by a structured assembly of an array of polyhedral elements. The monolayer assembly can resist transverse forces in the absence of adhesive interaction between the unit elements. The mechanical properties of the system emerge as a combination of deformation of the individual unit elements and their contact interaction. The present study presents scaling laws relating the mechanical stiffness of monolayered TIMs to the system characteristic dimensions. The concept of thrust line analysis is employed to obtain the scaling laws, and model predictions are validated using finite element simulations as virtual experiments. Scaling law powers were found to closely resemble those of classical plate theory despite the distinctly different underlying mechanics and theory of TIM deformation.

Topologically interlocked material (TIM) systems are load-carrying assemblies of unit elements interacting by contact and friction. TIM assemblies have emerged as a class of architectured materials with mechanical properties not ordinarily found in monolithic solids. These properties include, but are not limited to, high damage tolerance, damage confinement, adaptability, and multifunctionality. The review paper provides an overview of recent research findings on TIM manufacturing and TIM mechanics. We review several manufacturing approaches. Assembly manufacturing processes employ the concept of scaffold as a unifying theme. Scaffolds are understood as auxiliary support structures employed in the manufacturing of TIM systems. It is demonstrated that the scaffold can take multiple forms. Alternatively, processes of segmentation are discussed and demonstrated. The review on mechanical property characteristics links the manufacturing approaches to several relevant material configurations and details recent findings on quasi-static and impact loading, and on multifunctional response.

As an ancient paper craft originating from Japan, origami has been naturally embedded and contextualized in a variety of applications in the fields of mathematics, engineering, food packaging, and biological design. The computational and manufacturing capabilities today urge us to develop significantly new forms of folding as well as different materials for folding. In this paper, by allowing line cuts with crease patterns and creating folded hinges across basic structural units (BSU), typically not done in origami, we achieve a new multiprimitive folding framework such as using tetrahedral, cuboidal, prismatic, and pyramidal components, called “Kinetogami.” “Kinetogami” enables one to fold up closed-loop(s) polyhedral mechanisms (linkages) with multi-degree-of-freedom and self-deployable characteristics in a single build. This paper discusses a set of mathematical and design theories to enable design of 3D structures and mechanisms all folded from preplanned printed sheet materials. We present prototypical exploration of folding polyhedral mechanisms in a hierarchical manner as well as their transformations through reconfiguration that reorients the material and structure. The explicit 2D fabrication layout and construction rules are visually parameterized for geometric properties to ensure a continuous folding motion free of intersection. As a demonstration artifact, a multimaterial sheet is 3D printed with elastomeric flexure hinges connecting the rigid plastic facets.

A method is presented for calibration of a robot to correct position and orientation errors due to manufacturing. The method is based on the shape matrix robot kinematic description. Each joint is individually and successively moved in order to explicitly calculate the shape matrix of each link. In addition, methods to correct for the errors in both the forward and inverse kinematic solutions are presented. The modification of the forward solution is a simple task. The modification of the inverse kinematic solution is a difficult problem and is achieved by an iterative technique which supplements the closed-form solution. An example of the calibration and inverse solution is presented to show the improvement in the accuracy of the robot.