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1. A Method for Designing Multi-Layer Sheet-Based Lightweight Funicular Structure.

   Lu, Yao; Thamer Alsalem; Masoud Akbarzadeh (January 2022, IASS Annual Symposium 2022 – Innovation, Sustainability and Legacy)

   Multi-layer spatial structures usually take considerable external loads with very limited material usage at all scales, and Polyhedral Graphic Statics (PGS) provides a method to design multi-layer funicular polyhedral structures. The structural forms usually materialized as space frames. Our previous research shows that the intrinsic planarity of the polyhedral geometries can be harnessed for efficient fabrication and construction processes using flat-sheet materials. Sheet-based structures are advantageous over the conventional space frame systems because sheets can provide more load paths and constrain the kinematic degrees of freedom of the nodes. Therefore, they can take a wider range of load compared to space frames. Moreover, sheet materials can be fabricated to complex shapes using CNC milling, laser cutting, water jet cutting, and CNC bending techniques. However, not all sheets are necessary as long as the load paths are preserved, and the system does not have kinematic degrees of freedom. To find a reduced set of faces that satisfies the requirements, this paper incorporates and adapts the matrix analysis method to calculate the kinematic degree of freedom of sheet-based structure. Built upon this, an iterative algorithm is devised to help find the reduced set of faces with zero kinematic degree of freedom. To attest the advantage of this method over bar-node construction, a comparative study is carried out using finite element analysis. The result shows that, with the same material usage, the sheet-based system has improved performance than the framework system under a wide range of loading scenarios. 

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2. Kerf Bending and Zipper in Spatial Timber Tectonics

   Liu, Y.; Lu, Y.; Akbarzadeh, M. (September 2021, Proceedings of the Association for Computer-Aided Design in Architecture (ACADIA))

   Space frames are widely used in spatial constructions as they are lightweight, rigid, and efficient. However, when it comes to the complex and irregular spaces frames, they can be difficult to fabricate because of the uniqueness of the nodes and bars. This paper presents a novel timber space frame system that can be easily manufactured using 3-axis CNC machines, and therefore increase the ease of the design and construction of complex space frames. The form-finding of the space frame is achieved with the help of polyhedral graphic statics (PGS), and resulted form has inherent planarity which can be harnessed in the materialization of the structure. Inspired by the traditional wood tectonics kerf bending and zippers are applied when devising the connection details. This system's design approach and computational process are described, and a test fabrication of a single node is made via 3-axis CNC milling and both physically and numerically tested. The structural performance shows its potential for applications in large-scale spatial structures. 

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3. Funicular Glass Bridge Prototype: Design Optimization, Fabrication, and Assembly Challenges

   https://doi.org/10.1007/s40940-022-00177-x  

   Yao Lu; Alireza Seyedahmadian; Philipp Amir Chhadeh; Matthew Cregan; Mohammad Bolhassani; Jens Schneider; Joseph Robert Yost; Gareth Brennan; Masoud Akbarzadeh (January 2022, Glass structures engineering)

   Polyhedral Graphic Statics (PGS) is an effective tool for form-finding and constructing complex yet efficient spatial funicular structures. The intrinsic planarity of polyhedral geometries can be leveraged for efficient fabrication and construction using flat sheet materials, such as glass. Our previous research used PGS for the form-finding of a 3 m-span, modular glass bridge prototype to be built with thirteen unique hollow glass units (HGUs) in a compression-only configuration. This paper reports its design optimization, fabrication, and subsequent modular assembly process. The computational modeling of the geometries is facilitated with the efficient half-face data structure provided by PolyFrame, a software that implements PGS. Regular float glass and acrylic are selected as the main structural materials, and they are fabricated using 5-axis water jet cutting and CNC milling techniques. With the help of 3 M™ Very High Bond tape, the glass parts and acrylic parts are bonded as HGUs, which serve as the basic structural and assembly modules. Surlyn sheets are used as interface material to prevent glass-to-glass direct contact between HGUs. The digital model is also simulated using ANSYS to ensure the effectiveness of the design. Due to the lightweight of the HGUs, the assembly of the bridge can be done by one person without the requirement of any heavy construction machinery. 

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4. Neural Control Principles: Bernstein’s Insights from Biomechanics of Human Movement

   https://doi.org/10.4324/9780367816797  

   Prilutsky, Boris I; Zatsiorsky, Vladimir M. (January 2021, Bernstein's Construction of Movements: The Original Text and Commentaries)

   Latash, Mark L. (Ed.)

   This chapter reviews major principles of neural control of movement proposed by N. A. Bernstein based on his biomechanical studies of human movements and published in his 1947 book ‘On Construction of Movements’. These principles include the hierarchical organization of the motor control system; synergistic sensorimotor control; the principle of sensory corrections, and the principles of repetition without repetition and fixating and subsequent releasing kinematic degrees of freedom during motor skill acquisition. These principles simplify control of the musculoskeletal system with redundant degrees of freedom and unpredictable effects of reactive and muscle forces arising in multi-segment kinematic chains. We also discuss the relevant contemporary research that has been inspired by and further developed Bernstein’s ideas. We demonstrate, in particular, examples of complex muscle and kinematic synergies organized by different levels of the motor control system, consequences of loss of proprioceptive sensory corrections on movement coordination, and emergence of economical and stable kinematic and muscle invariant movement characteristics in the process of skill acquisition by trials and errors. We conclude this chapter with motor control related parables told by N. A. Bernstein to one of the authors (VMZ). 

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5. Tortuca: An Ultra-Thin Funicular Hollow Glass Bridge

   Lu Yao; Alireza Seyedahmadian; Philipp Amir Chhadeh; Matthew Cregan; Mohammad Bolhassani; Jens Schneider; Joseph Robert Yost; Gareth Brennan; Masoud Akbarzadeh. (January 2022, Proceedings of the 42nd Annual Conference of the Association for Computer-Aided Design in Architecture (ACADIA))

   Akbarzadeh, Masoud; Aviv, Dorit; Jamelle, Hina; Stuart-Smith, Robert (Ed.)

   Designed with Polyhedral Graphic Statics (PGS), a geometry- based structural form-finding method, Tortuca presents an efficient and innovative structural system constructed by the dry assembly of thirteen hollow glass units (HGU). It also proposes a new language for glass that is carefully treated, structurally informed, fabrication-aware, and environmentally responsible. Each HGU of Tortuca is made of 1 cm (3/8 inch) glass deck plates and 2 cm (0.7 inch) acrylic side plates precisely cut with 5-axis abrasive waterjet cutting and CNC milling to match the structural geometry. The structure spans 3.2 m (10.5 ft) with a mass of only 250 kg (550 lbs), where the float glass is the primary loadbearing material. Thanks to the efficiency and light weight of the construction system, a single person can assemble and disassemble the structure without needing a crane or additional labor. Moreover, this research explores the potential of using an extremely delicate material such as float glass for the primary structural system to encourage minimizing the material and energy demands in buildings and infrastructural projects. Additionally, it shows how utilizing the material in its purest format could simplify the recycling process after the life cycle of the structure has ended. Also, this research project is achieved by collaboration across different institutions, from design to engineering, from theoretical to practical, and from academia to industry. We appreciate the value of breaking disciplinary boundaries and joining forces from multiple fields. 

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