Topology Optimization for Additive Manufacturing

This paper gives an overview of the issues and opportunities for the application of topology optimization methods for additive manufacturing (AM). The main analysis issues discussed are: how to achieve the maximum geometric resolution to allow the fine features easily manufacturable by AM to be represented in the optimization model; the manufacturing constraints to be considered, and the workflow modifications required to handle the geometric complexity in the post optimization stages. The main manufacturing issues discussed are the potential for realizing intermediate density regions, in the case of the solid isotropic material with penalization (SIMP) approach, the use of small scale lattice structures, the use of multiple material AM processes, and an approach to including support structure requirement as a manufacturing constraint.Mechanical Engineerin

Multiple-Material Topology Optimization of Compliant Mechanisms Created via Polyjet 3D Printing

Compliant mechanisms are able to transfer motion, force, and energy using a monolithic structure without discrete hinge elements. The geometric design freedoms and multi-material capability offered by the PolyJet 3D printing process enables the fabrication of compliant mechanisms with optimized topology. The inclusion of multiple materials in the topology optimization process has the potential to eliminate the narrow, weak, hinge-like sections that are often present in single-material compliant mechanisms. In this paper, the authors propose a design and fabrication process for the realization of 3-phase, multiple-material compliant mechanisms. The process is tested on a 2D compliant force inverter. Experimental and theoretical performance of the resulting 3-phase inverter is compared against a standard 2-phase design.Mechanical Engineerin

Unshackling evolution: evolving soft robots with multiple materials and a powerful generative encoding

In 1994 Karl Sims showed that computational evolution can produce interesting morphologies that resemble natural organisms. Despite nearly two decades of work since, evolved morphologies are not obviously more complex or natural, and the field seems to have hit a complexity ceiling. One hypothesis for the lack of increased complexity is that most work, including Sims’, evolves morphologies composed of rigid elements, such as solid cubes and cylinders, limiting the design space. A second hypothesis is that the encodings of previous work have been overly regular, not allowing complex regularities with variation. Here we test both hypotheses by evolving soft robots with multiple materials and a powerful generative encoding called a compositional pattern-producing network (CPPN). Robots are selected for locomotion speed. We find that CPPNs evolve faster robots than a direct encoding and that the CPPN morphologies appear more natural. We also find that locomotion performance increases as more materials are added, that diversity of form and behavior can be increased with di↵erent cost functions without stifling performance, and that organisms can be evolved at di↵erent levels of resolution. These findings suggest the ability of generative soft-voxel systems to scale towards evolving a large diversity of complex, natural, multi-material creatures. Our results suggest that future work that combines the evolution of CPPNencoded soft, multi-material robots with modern diversityencouraging techniques could finally enable the creation of creatures far more complex and interesting than those produced by Sims nearly twenty years ago

Fictional Proto-architecture as an Introduction to Biologic Design: Challenging the Concept of Morphogenesis of Neo-architectural Organism

The architecture is based on a dialectical search for new ways of matter representation. We deal with the form of contemporary architecture under two approaches: expression and content. The article examines how mathematical principles based on natural growth can be applied in architectural design to create a dynamic, not static, structure. The dynamic process of the cell and its growth provides the basic structure. The continuity of the domain is exemplified by the impact of the new forms on the society that has already begun to emerge from the obscurity. The paper argues that without a deeper and more receptive connection between geometry and performance from a bio-morphogenetic perspective of complex systems. The experimental design methods are applied both to generate and to evaluate an architecture of the futuristic lines. These methodological frameworks focus on cyclically restated themes in the field of parametrises, which are identified as endemic to architecture: the realization of buildings, of multifunctional volumes and customized per se through a gradual approach of the architectural properties and the exploitation of a "concept construction" integrated as a process, obtained through innovative modelling environments. And so, and the reconstruction of architecture as an organ of nature is demonstrated. The new vanguard of proto architecture describes difficulties and inconsistencies in the relationship between theories and structures, difficulties arising from the very idea of "virtually" itself. It becomes difficult to say that a drawing in cyberspace is an architectural form or just a graph of architectural theory; in the virtual space, there is no difference between the particular structure and the general principle. Therefore, the form is first designed, only after to be constructed. Naturally, it is impossible (theoretically or technically) for design and construction processes to take place simultaneously. Predictably, bio-morphosis leads to multiple forms of expression, defined and transmitted in geometric terms. Doi: 10.28991/esj-2020-01248 Full Text: PD

A hybrid additive and subtractive manufacturing approach for multi-material components

This research introduces a hybrid additive and subtractive method for producing multiple material components consisting of metal and polymer regions. The method expands the notion of hybrid beyond multiple processes, to include multi-materials, taking advantages from each process and material. An AMBIT PE-1 polymer screw extrusion tool has been integrated into a HAAS machining center, bringing large scale additive manufacturing in-envelope with subtractive manufacturing. In this thesis, the effect of cooling time on the ability to reproduce overhanging geometry and on the strength of the interlayer bonding is investigated. This evaluation provides the baseline needed to evaluate the strength of the material transition. A mechanically interlocking root structure is developed to join regions of dissimilar materials into a single component. Two geometries of this root structure are evaluated for their mechanical strength. This method of creating a mechanical bond between substrates can be applied in hybrid additive and subtractive applications where dissimilar materials have limited chemical compatibility. Expanding the material capabilities of hybrid manufacturing enables a future of rapid manufacturing where a wide range of complex components can be produced on a single piece of hardware without the need for part-specific tooling

Evolutionary Developmental Soft Robotics As a Framework to Study Intelligence and Adaptive Behavior in Animals and Plants

In this paper, a comprehensive methodology and simulation framework will be reviewed, designed in order to study the emergence of adaptive and intelligent behavior in generic soft-bodied creatures. By incorporating artificial evolutionary and developmental processes, the system allows to evolve complete creatures (brain, body, developmental properties, sensory, control system, etc.) for different task environments. Whether the evolved creatures will resemble animals or plants is in general not known a priori, and depends on the specific task environment set up by the experimenter. In this regard, the system may offer a unique opportunity to explore differences and similarities between these two worlds. Different material properties can be simulated and optimized, from a continuum of soft/stiff materials, to the interconnection of heterogeneous structures, both found in animals and plants alike. The adopted genetic encoding and simulation environment are particularly suitable in order to evolve distributed sensory and control systems, which play a particularly important role in plants. After a general description of the system some case studies will be presented, focusing on the emergent properties of the evolved creatures. Particular emphasis will be on some unifying concepts that are thought to play an important role in the emergence of intelligent and adaptive behavior across both the animal and plant kingdoms, such as morphological computation and morphological developmental plasticity. Overall, with this paper, we hope to draw attention on set of tools, methodologies, ideas and results, which may be relevant to researchers interested in plant-inspired robotics and intelligence

Design for additive manufacturing: Trends, opportunities, considerations, and constraints

The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry

Design for additive manufacturing: trends, opportunities, considerations, and constraints

© 2016 CIRP. The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry

Computational Design of Compositionally Graded Alloys

In this work, a new computational methodology is presented for the design of compositionally graded alloys. Compositionally graded alloys are a class of functionally graded materials, or materials which exhibit spatially varying properties. While the introduction of additive manufacturing has accelerated interest in these materials, there are many challenges that impede their development like the formation of deleterious phases and material compositions that are incompatible with manufacturing processes. Previous design methods have attempted to design gradients that avoid these issues, but such methods have been limited to the analysis and interpretation of two-dimensional diagrams and are therefore hindered by the limits of human visualization and ideation. The proposed methodology is made possible by the novel formulation of gradient design as a path planning problem. This formulation allows the use of path planning algorithms to optimize gradient paths in composition space. Such algorithms can optimize gradients with any number of constituent elements to meet specified design requirements or objectives. To make the gradient design problem tractable for such algorithms, surrogate modeling techniques are employed to represent design constraints and objectives. Constraints, like deleterious phase formation, can be predicted by CALPHAD software and then modeled by a machine learning classifier. Similarly, regression models can be trained to evaluate cost functions in an efficient manner. Several unique problem formulations are demonstrated to showcase the advantages of the methodology in gradient design. Among these are constraints to avoid deleterious phase regions and other regions of the state space with poor predicted manufacturability. Common cost functions in the path planning community, like path length and obstacle clearance, are shown to be useful for some problems, while including constraint violation as penalty term is demonstrated to satisfy constraints that might otherwise be unachievable. Lastly, a novel cost function is proposed to design gradients with monotonic properties, which can achieve nearly any bounded property distribution on a gradient part. All proposed problem formulations are demonstrated in the design of authentic compositionally graded alloys and experiments are used to validate predicted results

Rules for Making: Kinematic Design, Shape and Structure

The thesis examines the role of making rules, within the creative exploration of kinematic design spaces. As a process of searching within a conceptual space, creative exploration can be described using rules. When applied to design, this model for creativity affords the application of computational techniques. In shape grammars, shape rules for ‘seeing’ and ‘doing’ apply a descriptive approach to the visual recognition, composition and modification of pictorial representations. This formalism can provide generative specifications and reveal the synthetic reasoning underlying iterative trajectories of design development. Making rules extend this approach to the tactile-visual representations of physical models and prototypes. When instantiating design representations within the material world, actions to construct and alter descriptions are grounded in material algebras. This thesis has a focus in Kinematics, where physical models provide a synthetic alternative to analytic techniques for modelling motions. In this context, making rules describe how to construct designs, make alterations, and manipulate models. Kinematic connections afford variable spatial relations between kinematic parts, and rules for physically manipulating models elicit their motions. Single closed-loop kinematic chains with full cycle mobility provide case studies for experimenting with making rules in design exploration, using both physical models and abstract geometric descriptions. An existing design creates a point of entry, where rules then afford the exploration of a surrounding kinematic design space. Applying alterations and transformations to physical models can identify the boundaries within which kinematic properties are preserved. The experimental cases inform theoretical development of exploratory making, with special reference to the variable spatial relations in kinematic designs and the integration of visual and tactile sensing. The main conclusion is that: as making rules construct models, rules are abstracted into schema by comparing properties of similar designs. The schema explain the results of exploration, initiating new explorations and new designs