Structural optimisation of deployable scissor structures using new computational methods

A technique is introduced for the kinematic synthesis of deployable cable-stiffened truss structures. This technique, which is an extension of a prior procedure [l-21 for generating deployable truss structures, can be applied to generate all concepts of cable-stiffened truss structures as well as all their deployable derivatives. Examples illustrating the implementation of this new technique, along with a discussion of the results achieved. are included in this article. The primary function of a deployable structure is to maintain a stable configuration in its deployed state. This is reflected in current design practices of trading off decreased deployment or retraction performance for increased structural performance. As a result, various designs of deployable truss structures (with, and without cables) have been introduced that are over-constrained during deployment/retraction, i.e. deployment/retraction of these structures can only be achieved through the deformation of individual links or by exploiting symmetric features of the structure. The number of different conceptual designs of deployable structures that are based on a given structural configuration is unlimited, if deployable structures are permitted to be overconstrained during deploymenthetraction. For this reason, researchers in the area of deployable structures have given little attention to the systematic design of deployable truss structures and have instead devoted much of their attention to the introduction and discussion of novel concepts of deployable truss structures [3-171. If, on the other hand, it is assumed that the primary function of a deployable structure is to serve as a mechanism with a minimum number (i.e. at least one) of degrees-of-freedom, then the number of different conceptual designs that are based on a given structural configuration is finite. Hence, it is then possible to generate all possible designs for a given structural configuration. The assumption that a deployable structure is not constrained during deployment/retraction has enabled the development of a technique for the generation of all conceptual designs of deployable truss structures that can be used as building blocks (modules) of much larger structures [I-21. It should be noted that this technique, referred to as kinematic synthesis of * Sr. Mechanical Engineer, Member AIAA deployable structures, does not assume that the structural configuration is known but instead uses the characteristics of a given class of structures (i.e. truss modules) to generate all possible configurations of structures in this class. The limitation of this technique to truss modules has been avoided in the Explosion-Implosion technique [19], developed by the same authors, for the generation of allconceptual designs of deployable truss structures of which the locations of the nodes are known. Both techniques have been shown to result in the generation of an enormous, yet finite, number of novel conceptual designs as well as those that have been reported in the literature. Furthermore, by limiting the degrees-of-freedom available at individual joints, conceptual designs can be generated of deployable structures that are overconstrained during deployment/retraction. Although the kinematic synthesis technique and the explosionimplosion technique result in the generation of an enormous number of conceptual designs of deployable truss structures, they are not applicable to truss structures with cables. Yet, cable-stiffened truss structures have important advantages such as the reduction in mass and/or reduction in joints that can be achieved by replacing links in truss structures with cables. The objective of this article is to modify the technique introduced in [I-21 such that the new technique is also applicable to cablestiffened truss structures. This new approach can then be applied to generate novel concepts of deployablecable-stiffened truss structures as well as those that have been reported in the literature.

As a matter of fact, because of its unique portability and flexibility, the deployable structure can meet the needs of many fields of work, and has been widely used in various industries especially in recent years. With this in mind, this research will introduce the background of deployable structure, systematically introduce the basic principle as well as practical application of deployable structure. Based on the evaluations, the working principle of deployable structure represented by scissor structure, origami structure and scissor origami composite and how to work in practical applications are analyzed. According to the existing deployable structure, the limitations of deployable structure and the future development direction of deployable structure are pointed out and demonstrated. In this paper, the basic working principle and practical application of deployable structures are described by classifying deployable structures, and the types of existing deployable structures are summarized. Overall, these results pave a path for further exploration of deployable structure developments.

Static performances of scissor structures

This paper presents an innovative 5D origami-based structural design, exploring the application of origami technology across multiple dimensions (from 1D to 5D) and its potential in smart materials and deployable structures. The evolution of origami structures from 1D to 5D is discussed, emphasizing the increasing ability of origami structures to deform and adapt as the dimensions increase, particularly in 5D structures, where origami can achieve autonomous shape changes through adaptive mechanisms. In traditional 1D–4D origami structures, research has primarily focused on morphological deformations and responses to changes in the external environment. However, with advancements in technology, this study introduces the concept of 5D origami structures, innovatively incorporating a foundational dimension into the 4D structure. This new dimension not only extends the spatial adaptability of origami structures but also enables self-regulation through adaptive mechanisms, allowing the structure to adjust according to internal configurations, thereby enhancing its dynamic response capabilities. Moreover, compared to existing 4D origami structures, 5D structures offer greater flexibility and controllability in material self-regulation and shape transformations. Furthermore, a 5D cubic structure is proposed, combining origami technology with adaptive materials, and its potential application in smart antennas for dynamic electromagnetic property adjustment is analyzed. Additionally, the mechanical behaviors of origami unfolding deformations are studied, with a focus on the impact of creases on the unfolding process. The research reveals the mechanical characteristics, including geometric deformation, energy dissipation, and stiffness modulation, providing new insights for mechanical modeling and performance optimization of origami structures, promoting the application of origami technology in smart architecture and aerospace.

Structural design and optimization of large cable–rib tension deployable antenna structure with dynamic constraint

Computational methods have been successfully applied in structural analysis and drawings of large spatial structures. However, there are still huge challenges in performing conceptual design of structures using computers as what human brain is able to do. A computational method, named performance-based structural synthesis has been proposed and validated to generate and realize planar truss structures. However, it is insufficient for more general spatial truss structures whose geometries and load-carrying requirements are more complex compared with those of planar truss. Therefore, this computational synthesis method based on planar shape grammar was extended and presented in this paper to generate three-dimensional spatial truss structures through building 3D shape grammars and multi-objective hybridized optimization algorithm. Meanwhile techniques of load-generation were employed in the structural synthesis method to realize its engineering application. In the aspect of structural configuration, the method integrates structural topology, geometry and section size allocation; in the aspect of structural design and optimization, it takes into account the combining effects of safety, economy, construction and architectural elegance. Thus the structure generated by this synthesis method must be the best design in terms of the overall structural performance and cost compared with that obtained by traditional design method.

An experimental investigation on the Half Scissor-Like Elements (H-SLEs) mechanism deployable structure under compression axial load is presented. Two prefab cylindrical shape H-SLEs mechanism deployable steel structures namely M1 (Bolted base column) and model M2 (Unbolted base column) were tested on their performance in term of strength and stability performance. The model prototype consists coldformed and hot roll steel with bolted connection and tested at deployed vertical configuration. Compression axial load was applied at the middle top of loading platform, transferred equally to the six H-SLEs deployable mechanism through supporting beams. The experimental results obtained indicated that three types of failure modes, i.e. excessive bearing capacity failure at lipped C-section flange around bolt hole perimeter, instability due to horizontal displacement at mid-height of H-SLEs deployable mechanism (Bolted joint area) and member buckling. Among these failures, horizontal displacement nominated the overall structure stability while section thickness impacts member bucking and bearing capacity. The experimental ultimate load was 1.63% greater than BS EN 1993 design load resistance for M1 condition while 30% less for M2 condition. The applied load difference between these two model prototypes was 31.15%. Thus, M1 ultimate loads capacity was satisfactory since less than 15% acceptable level while M2 not satisfactory. Beside, horizontal displacement was identify highly impacted scissor mechanism deployable structure instability and suitable member thickness may avoid section premature failure.

Robust structural topology optimization considering boundary uncertainties

In the design process the main challenge of the designer is to generate an efficient project resulting from different objectives and associated criteria. These objectives are often conflicting and they are related to programmatic requirements, aesthetic, structural, and cost or energy performance. Multi-objective optimization (MOO) can guide the designer towards efficient design solutions. Parametric tools enable integrating MOO techniques and algorithms in 3D modeling environment. They allow the designers to take decisions during the design process. While the optimization tools are considering physical objectives (building energy, performance and daylighting, form generation, structural optimization …) the current applications often lack the evaluation of performance as perceived by occupants, e.g. based on post-occupancy evaluation studies. POE is defined as the evaluation of the building performance by users. Implementing POE in a parametric environment can improve the design and in particular the reorganization of an interior layout space design.

Time series forecasting is fundamental for various use cases in different domains such as energy systems and economics. Creating a forecasting model for a specific use case requires an iterative and complex design process. The typical design process includes five sections (1) data preprocessing, (2) feature engineering, (3) hyperparameter optimization, (4) forecasting method selection, and (5) forecast ensembling, which are commonly organized in a pipeline structure. One promising approach to handle the ever‐growing demand for time series forecasts is automating this design process. The article, thus, reviews existing literature on automated time series forecasting pipelines and analyzes how the design process of forecasting models is currently automated. Thereby, we consider both automated machine learning (AutoML) and automated statistical forecasting methods in a single forecasting pipeline. For this purpose, we first present and compare the identified automation methods for each pipeline section. Second, we analyze these automation methods regarding their interaction, combination, and coverage of the five pipeline sections. For both, we discuss the reviewed literature that contributes toward automating the design process, identify problems, give recommendations, and suggest future research. This review reveals that the majority of the reviewed literature only covers two or three of the five pipeline sections. We conclude that future research has to holistically consider the automation of the forecasting pipeline to enable the large‐scale application of time series forecasting.This article is categorized under:Technologies > Machine LearningTechnologies > PredictionAlgorithmic Development > Spatial and Temporal Data Mining

An automatic optimization approach for the structural design of turbine blade shroud is presented and applied to the optimal design of a zigzag shroud in this paper. It integrates commercial CAD and CAE softwares into optimization procedure iSIGHT. According to the normal rules of the shroud design and experience, this paper advises a zigzag shroud which is fit for a kind of turbine blade. The parametric model of the shroud is established and the pre-twist angle parameter is taken into consideration. The structural intensity performance of the shroud, which is used to compute the optimal objective and constraints during optimization, is determined by conducting coupled thermal-structural analysis of shrouded turbine blade using the commercial Finite Element code ANSYS. Two application examples of the optimization approach are presented, with optimal objective functions of shrouded blade mass and maximum shroud contact pressure respectively. The latter includes the pre-twist angle as one of design variables. Mechanical and geometry constraints are applied on the design to ensure that the optimized design meets requirements for feasibility of engineering criteria. Simulation results from shroud optimizations by means of the optimization approach prove that the performance of the shroud can be improved significantly through structure optimization. The optimization approach provides an effective method to design and optimize the similar complicated models.

Much has been written by scholars about how kinematics of mechanisms came into existence in the middle of the nineteenth century spurred by the first industrial revolution, thrived for many decades as a scientific discipline pursued by mathematicians of yore, and then became an integral part of mechanical engineering. Abstraction of machine elements gathered momentum with the efforts of Franz Reuleaux in the late nineteenth century, geometric analysis and graphical design methods flourished in the early twentieth century primarily in Europe, and analytical and computational methods were developed in the United States and elsewhere giving birth to modern kinematics. All of these have influenced the way kinematics is taught and practised today. The constructive elements of mechanisms got established more than a century ago but they have not changed or expanded much since then. As we look back, kinematics of mechanisms in the later part of twentieth century has given rise to robotics and compliant mechanisms. Arguably, studies on kinematics of open-chain manipulators laid the foundation for robotics but the field quickly became multidisciplinary with control, sensing, and actuation becoming more prominent than kinematics. The subfield of compliant mechanisms, on the other hand, has significantly added to the repertoire of elements of mechanisms and ushered in a new era of growth leading to the use of a wider variety of materials, miniaturization, wearables, and soft robotics. Some scholars of the past had anticipated this development in the early twentieth century. After giving an overview of the development of kinematics of mechanisms over the last two centuries, we wonder what the future holds. Biohybrid mechanisms appear as a natural next milestone. This too was contemplated by Robert Thurston at the turn of the twentieth century. We end this article by speculating on how kinematics might thrive in the coming decades and thus stay alive and not become obsolete. We also discuss how mechanisms ought to be taught to the current generation of students even as modern topics creep into the curriculum.

Structural optimization and form finding of light weight structures

The objective of the present study is to reveal a dynamic calculation method for a deployable scissor structure in space as an unstable structure without boundaries, by generalizing its dynamic modeling to predict the relationship between its deployment motion and input moment generated by an actuator. The purpose is to study the construction process of space structures such as a solar power satellite in future. Whereas our previous study demonstrated a specific derivation sequence of a dominant equation of a scissors unit, the present paper shows the generalized derivation sequence and its numerical calculation examples of more extended analysis models.

Drawing from my experience as a hybrid practitioner-educator, this pedagogical statement examines how we teach the invisible dimensions of transformative design. While traditional design process diagrams and metaphors—from squiggles to diamonds—effectively structure design activities, they fall short in teaching students how to facilitate transformative design processes. I propose braiding as a complementary cross-cultural metaphor that illuminates the concurrent processes woven through design work. I define four fundamental strands that expert practitioners weave into complex design processes: learning (growing capacity), narrative (weaving stories), relationships (growing connections and trust), and change (rehearsing transformation). This framework emerged from my practice of teaching students not just what to design, but how to orchestrate processes that transform products and services, and people and organizations. The metaphor of braiding also emphasizes the facilitative or holding skills design practitioners must develop to guide processes in contexts of crisis or change. This statement offers fellow design educators new language and invitations for teaching the social dimensions of design, particularly crucial for preparing students to work in complex, cross-cultural social contexts.