Rethinking of timber joinery in 21st-century architecture The computation of a timber joinery through complex geometry

Master of ScienceDepartment of ArchitectureMajor Professor Not ListedIn recent years, there has been a renewed interest in timber joinery in contemporary architecture. With the introduction of digital fabrication technologies and computational design, it is now possible to create complex timber structures with more complex shapes and designs. One of the critical advantages of timber as a building material is its ability to be combined in various ways. Timber joinery can create solid and durable connections between structural members while providing an aesthetically pleasing finish. In the 21st century, architects and designers are exploring new ways to use timber joinery to create unique and innovative structures. Computational design tools allow designers to create complex geometries that can be fabricated precisely using computer numerical control (CNC) machines and other digital fabrication technologies. Designers who are well-versed in programs like Rhino, Grasshopper, or Revit have the ability to utilize parametric modeling software that can calculate timber joinery that is based on intricate geometry. These tools allow designers to create 3D models of the structure and conduct experiments with different joinery options and configurations. Once the joinery is designed, it can be fabricated using CNC machines or other digital fabrication tools. It allows for high precision and accuracy in the fabrication process, ensuring the joint perfectly fits together. The use of complex timber joinery in contemporary architecture provides functional benefits and a unique aesthetic that cannot be achieved with other materials. By rethinking traditional joinery techniques and embracing digital technologies, architects and designers can create structures that push the boundaries of what is possible through timber construction. This thesis will investigate and explore the timber joinery system and fabrication methods, one of the old wooden structure techniques used in the age of digital technologies that rejuvenate the usage of conventional construction processes in timber buildings. The main aim of this thesis was to study computational design in creating complex wooden segmental base structures that rely on interlocking timber joints as the primary form of connection. This involved analyzing the role of wooden joinery and exploring complex systems made using this technique. The second objective was to create a digital model of several types of parametric wood joineries, such as halve and lap joint, Tenon and mortise joint, and finger joints. A digital model of a complex segmental plate structure with three fundamental parametric joints was also developed. The three basic types include finger, halve and lap clip, and Mortise and Tenon joints. The third objective is a structural and shape optimization of the basic mesh for specified complex geometry, which will be a digital model to evaluate the applicability of the generated joints, and will be determined because of this investigation

ACM Transactions on Graphics

We present FlexMolds, a novel computational approach to automatically design flexible, reusable molds that, once 3D printed, allow us to physically fabricate, by means of liquid casting, multiple copies of complex shapes with rich surface details and complex topology. The approach to design such flexible molds is based on a greedy bottom-up search of possible cuts over an object, evaluating for each possible cut the feasibility of the resulting mold. We use a dynamic simulation approach to evaluate candidate molds, providing a heuristic to generate forces that are able to open, detach, and remove a complex mold from the object it surrounds. We have tested the approach with a number of objects with nontrivial shapes and topologies

ReciprocalShell: A hybrid timber system for robotically-fabricated lightweight shell structures

Reciprocal timber systems have been widely studied, however they have never been directly applied to the segmented timber shell structures as cross bracing of the polygonal topologies. For the first time, this paper presents an innovative hybrid timber system developed for design and construction of the robotically-fabricated lightweight timber shell structures. The paper integrates two configurations of wood beams: polygonal framing and reciprocal bracing. While, the polygonal topology of facets enables a constant distance offset for the thickness of the shell, the reciprocal configuration allows for cross bracing of polygonal frames where diagonals within the polygons cannot directly connect corners due to geometric constraints resulted by the free-form surface structure of shell shapes. Joining the cross-bracing elements in the center of the polygons with a reciprocal node reduces the complexity of the connection system at nodes while demonstrating the high load-bearing capacity of joints to withstand structural loads throughout the structure, compared to connecting 5, 6 or 7 beams in a single point. The article discusses the application and limitations of the timber system while presenting the design-to-assembly process of a case study of the small-scale shell demonstrator with the maximum span of 7.5 meters made of 144 wood elements for each polygonal and reciprocal configurations. The results show that the timber system has a great capacity for the rapid and precise assembly and disassembly of prefabricated timber structures. Generation of similar but different solid elements, allowed for the development of a custom CAD data interface for the automated production of numerous pieces, where simple joint details are applied for both alignment and attachment of beams, reducing the design complexity and facilitate the construction phase. As the result, the fabrication process was completely carried out with only a saw blade in a multi-axis robotic fabrication set up that enables the rapid, precise, and accurate cuts and grooves. Both timber configurations generate a uniform distribution of beam size, meaning that the production process created only a minimal amount of offcuts that allows for the use of simple and cost-efficient, short solid wood pieces

Remote Collaborative 3D Printing - Process Investigation

The Remote Collaborative 3D Printing project is a collaboration between Strategic System Programs (SSP), the Naval Postgraduate School (NPS), NAVFAC Headquarters Asset Management - Facilities Integrated Product Support (IPS) Program, and the NAVFAC Engineering and Expeditionary Warfare Center (EXWC). The intent of the project was to investigate the end-to-end process of transferring, receiving, manipulating, and printing a digital 3D model into an additively manufactured component. Several digital models were exchanged, and the steps, barriers, workarounds, and results have been documented.Strategic System Programs, Naval Postgraduate SchoolNAVFAC Headquarters Asset Managemen

ACM Transactions on Graphics

We present a computational approach for designing CurveUps, curvy shells that form from an initially flat state. They consist of small rigid tiles that are tightly held together by two pre-stretched elastic sheets attached to them. Our method allows the realization of smooth, doubly curved surfaces that can be fabricated as a flat piece. Once released, the restoring forces of the pre-stretched sheets support the object to take shape in 3D. CurveUps are structurally stable in their target configuration. The design process starts with a target surface. Our method generates a tile layout in 2D and optimizes the distribution, shape, and attachment areas of the tiles to obtain a configuration that is fabricable and in which the curved up state closely matches the target. Our approach is based on an efficient approximate model and a local optimization strategy for an otherwise intractable nonlinear optimization problem. We demonstrate the effectiveness of our approach for a wide range of shapes, all realized as physical prototypes

Tree-inspired dendriforms and fractal-like branching structures in architecture: A brief historical overview

Abstract The shapes of trees are complex and fractal-like, and they have a set of physical, mechanical and biological functions. The relation between them always draws attention of human beings throughout history and, focusing on the relation between shape and structural strength, architects have designed a number of treelike structures, referred as dendriforms. The replication and adoption of the treelike patterns for constructing architectural structures have been varied in different time periods based on the existing and advanced knowledge and available technologies. This paper, by briefly discussing the biological functions and the mechanical properties of trees with regard to their shapes, overviews and investigates the chronological evolution and advancements of dendriform and arboreal structures in architecture referring to some important historical as well as contemporary examples

Computational design of steady 3D dissection puzzles

Dissection puzzles require assembling a common set of pieces into multiple distinct forms. Existing works focus on creating 2D dissection puzzles that form primitive or naturalistic shapes. Unlike 2D dissection puzzles that could be supported on a tabletop surface, 3D dissection puzzles are preferable to be steady by themselves for each assembly form. In this work, we aim at computationally designing steady 3D dissection puzzles. We address this challenging problem with three key contributions. First, we take two voxelized shapes as inputs and dissect them into a common set of puzzle pieces, during which we allow slightly modifying the input shapes, preferably on their internal volume, to preserve the external appearance. Second, we formulate a formal model of generalized interlocking for connecting pieces into a steady assembly using both their geometric arrangements and friction. Third, we modify the geometry of each dissected puzzle piece based on the formal model such that each assembly form is steady accordingly. We demonstrate the effectiveness of our approach on a wide variety of shapes, compare it with the state-of-the-art on 2D and 3D examples, and fabricate some of our designed puzzles to validate their steadiness

IST Austria Thesis

Fabrication of curved shells plays an important role in modern design, industry, and science. Among their remarkable properties are, for example, aesthetics of organic shapes, ability to evenly distribute loads, or efficient flow separation. They find applications across vast length scales ranging from sky-scraper architecture to microscopic devices. But, at the same time, the design of curved shells and their manufacturing process pose a variety of challenges. In this thesis, they are addressed from several perspectives. In particular, this thesis presents approaches based on the transformation of initially flat sheets into the target curved surfaces. This involves problems of interactive design of shells with nontrivial mechanical constraints, inverse design of complex structural materials, and data-driven modeling of delicate and time-dependent physical properties. At the same time, two newly-developed self-morphing mechanisms targeting flat-to-curved transformation are presented. In architecture, doubly curved surfaces can be realized as cold bent glass panelizations. Originally flat glass panels are bent into frames and remain stressed. This is a cost-efficient fabrication approach compared to hot bending, when glass panels are shaped plastically. However such constructions are prone to breaking during bending, and it is highly nontrivial to navigate the design space, keeping the panels fabricable and aesthetically pleasing at the same time. We introduce an interactive design system for cold bent glass façades, while previously even offline optimization for such scenarios has not been sufficiently developed. Our method is based on a deep learning approach providing quick and high precision estimation of glass panel shape and stress while handling the shape multimodality. Fabrication of smaller objects of scales below 1 m, can also greatly benefit from shaping originally flat sheets. In this respect, we designed new self-morphing shell mechanisms transforming from an initial flat state to a doubly curved state with high precision and detail. Our so-called CurveUps demonstrate the encodement of the geometric information into the shell. Furthermore, we explored the frontiers of programmable materials and showed how temporal information can additionally be encoded into a flat shell. This allows prescribing deformation sequences for doubly curved surfaces and, thus, facilitates self-collision avoidance enabling complex shapes and functionalities otherwise impossible. Both of these methods include inverse design tools keeping the user in the design loop

Recent developments in tensile properties of friction welding of carbon fiber-reinforced composite: A review

In this review article, the joining of carbon fiber-reinforced polymer composite with metallic materials by using friction welding techniques was discussed and the effects of process parameters on the weld properties were evaluated. Major parameters involved in this process were plunge depth (PD), dwell time, joining time, and tool rotational speed. A successful friction joint of carbon fiber-reinforced poly composite laminate (CF-PPS)-metal was formed with an interlayer film of additional polyphenylene sulfide. In addition, a detailed overview of the friction techniques was discussed, such as friction stir spot welding (FSSW), friction stir welding (FSW), and refill friction stir spot welding (RFSSW). In this current work, we had focused on the parameters, process, and their development during friction welding of similar and dissimilar metals with CFRP joint. Regarding the FSSW review, the best tensile shear load was 7.1 kN obtained from AA5182 and CFRP at a rotational speed of 3,000 rpm and 5 s welding time. The thickness for AA5182 and CFRP are 1.2 and 3 mm, respectively. The most efficient parameters are rotational speed, PD, dwell time, and shoulder penetration depth. In addition, the heat generated during the process parameters, its influence on mechanical and microstructure properties along with the possible defects and internal cracks of the similar and dissimilar welded joints will be reviewed and discussed