scholarly journals A DESIGN METHOD FOR OPTIMAL TRUSS STRUCTURES WITH REDUNDANCY BASED ON COMBINATORIAL RIGIDITY THEORY

2014 ◽  
Vol 79 (699) ◽  
pp. 583-592
Author(s):  
Rie KOHTA ◽  
Makoto YAMAKAWA ◽  
Naoki KATOH ◽  
Yoshikazu ARAKI ◽  
Makoto OHSAKI
Keyword(s):  
Design Method ◽  
Truss Structures ◽  
Rigidity Theory ◽  
Combinatorial Rigidity

Topology Optimization for Design of Origami-Based Active Mechanisms

2014 ◽  
Author(s):  
Kazuko Fuchi ◽  
Philip R. Buskohl ◽  
James J. Joo ◽  
Gregory W. Reich ◽  
Richard A. Vaia
Keyword(s):  
Topology Optimization ◽  
Mechanism Design ◽  
Design Method ◽  
Truss Structures ◽  
Systematic Design ◽  
Design Strategies ◽  
Foldable Structures ◽  
And Performance ◽  
2D And 3D ◽  
Additional Constraints

Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form of the structure and show potential for many engineering applications. However, the enormity of the design space and the complex relationship between origami-based geometries and engineering metrics place a severe limitation on design strategies based on intuition. The presented work proposes a systematic design method using topology optimization to distribute foldline properties within a reference crease pattern, adding or removing folds through optimization, for a mechanism design. Following the work of Schenk and Guest, foldable structures are modeled as pin-joint truss structures with additional constraints on fold, or dihedral, angles. The performance of a designed origami mechanism is evaluated in 3D by applying prescribed forces and finding displacements at set locations. The integration of the concept of origami in mechanism design thus allows for the description of designs in 2D and performance in 3D. Numerical examples indicate that origami mechanisms with desired deformations can be obtained using the proposed method. A constraint on the number of foldlines is used to simplify a design.

scholarly journals Optimum Design Method for Nonlinear Truss Structures based on Energy Principle considering Configuration and Sizing Variables

2002 ◽  
Vol 5 ◽  
pp. 121-131
Author(s):  
Kazuhiro TANIWAKI ◽  
Sadaji OHKUBO ◽  
Hiroshi MATSUTOMO ◽  
Yoshihiko KAZEKAWA
Keyword(s):  
Optimum Design ◽  
Design Method ◽  
Truss Structures ◽  
Energy Principle

An Improved Size, Matching, and Scaling Method for the Design of Deterministic Mesoscale Truss Structures

2011 ◽  
Author(s):  
Patrick S. Chang ◽  
David W. Rosen
Keyword(s):  
High Performance ◽  
Design Method ◽  
Weight Ratio ◽  
High Strength ◽  
Original Method ◽  
Topological Optimization ◽  
Truss Structures ◽  
Scaling Method ◽  
Element Analysis ◽  
And Performance

Mesoscale truss structures are cellular structures that have support elements on the order of centimeters. These structures are engineered for high performance and have applications in industries where a high strength-to-weight ratio is desired. However, design of mesoscale truss structures currently requires some form of topological optimization that slows the design process. In previous research, a new Size, Matching and Scaling method was presented that eliminated the need for topological optimization by using a solid-body finite element analysis combined with a library of lattice configurations to generate topologies. When compared to topological optimization, results were favorable: design times were significantly reduced and performance results were comparable. In this paper, we present a modified Size Matching and Scaling design method that addresses key issues in the original method. Firstly, we outline an improve methodology. Secondly, we expand the library of configurations in order to improve lattice performance. Finally, we test the updated method and library against design examples.

Origami Actuator Design and Networking Through Crease Topology Optimization

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Kazuko Fuchi ◽  
Philip R. Buskohl ◽  
Giorgio Bazzan ◽  
Michael F. Durstock ◽  
Gregory W. Reich ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Design Optimization ◽  
Design Method ◽  
Network Connectivity ◽  
Mechanical Analysis ◽  
Optimization Techniques ◽  
Truss Structures ◽  
Optimization Approach ◽  
Design Strategies ◽  
Multiple Actuators

Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form of the structure and show potential for many engineering applications. However, the enormity of the design space and the complex relationship between origami-based geometries and engineering metrics place a severe limitation on design strategies based on intuition. The presented work proposes a systematic design method using topology optimization to distribute foldline properties within a reference crease pattern, adding or removing folds through optimization, for a mechanism design. Optimization techniques and mechanical analysis are co-utilized to identify an action origami building block and determine the optimal network connectivity between multiple actuators. Foldable structures are modeled as pin-joint truss structures with additional constraints on fold, or dihedral, angles. A continuous tuning of foldline stiffness leads to a rigid-to-compliant transformation of the local foldline property, the combination of which results in origami crease design optimization. The performance of a designed origami mechanism is evaluated in 3D by applying prescribed forces and finding displacements at set locations. A constraint on the number of foldlines is used to tune design complexity, highlighting the value-add of an optimization approach. Together, these results underscore that the optimization of function, in addition to shape, is a promising approach to origami design and motivates the further development of function-based origami design tools.

scholarly journals A new hybrid method for size and topology optimization of truss structures using modified ALGA and QPGA

2016 ◽  
Vol 23 (2) ◽  
pp. 252-262 ◽  
Author(s):  
Nima NOII ◽  
Iman AGHAYAN ◽  
Iman HAJIRASOULIHA ◽  
Mehmet Metin KUNT
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Convergence Rates ◽  
Design Method ◽  
Optimization Methods ◽  
Cholesky Factorization ◽  
Truss Structures ◽  
Design Solution ◽  
Design Parameters ◽  
Traditional Design

Modified Augmented Lagrangian Genetic Algorithm (ALGA) and Quadratic Penalty Function Genetic Algo­rithm (QPGA) optimization methods are proposed to obtain truss structures with minimum structural weight using both continuous and discrete design variables. To achieve robust solutions, Compressed Sparse Row (CSR) with reordering of Cholesky factorization and Moore Penrose Pseudoinverse are used in case of non-singular and singular stiffness matrix, respectively. The efficiency of the proposed nonlinear optimization methods is demonstrated on several practical exam­ples. The results obtained from the Pratt truss bridge show that the optimum design solution using discrete parameters is 21% lighter than the traditional design with uniform cross sections. Similarly, the results obtained from the 57-bar planar tower truss indicate that the proposed design method using continuous and discrete design parameters can be up to 29% and 9% lighter than traditional design solutions, respectively. Through sensitivity analysis, it is shown that the proposed methodology is robust and leads to significant improvements in convergence rates, which should prove useful in large-scale applications.

scholarly journals Usefulness of Digital Serious Games in Engineering for Diverse Undergraduate Students

2022 ◽  
Vol 12 (1) ◽  
pp. 27
Author(s):  
Kimberly Cook-Chennault ◽  
Idalis Villanueva Alarcón ◽  
Gabrielle Jacob
Keyword(s):  
Technology Acceptance ◽  
Undergraduate Students ◽  
Design Method ◽  
Digital Games ◽  
Value Theory ◽  
Educational Game ◽  
Truss Structures ◽  
Exploratory Research ◽  
Course Content ◽  
Acceptance Model

The use of educational digital games as supplemental tools to course instruction materials has increased over the last several decades and especially since the COVID-19 pandemic. Though these types of instructional games have been employed in the majority of STEM disciplines, less is known about how diverse populations of students interpret and define the value of these games towards achieving academic and professional pursuits. A mixed-method sequential exploratory research design method that was framed on the Technology Acceptance Model, Game-Based Learning Theory and Expectancy Value Theory was used to examine how 201 students perceived the usefulness of an intuitive education game that was designed to teach engineering mechanics used in designing civil structures. We found that students had different expectations of educational digital games than games designed for entertainment used outside of classroom environments. Several students thought that the ability to design their own structures and observe structure failure in real-time was a valuable asset in understanding how truss structures responded to physical loading conditions. However, few students thought the educational game would be useful for exam (14/26) or job interview (19/26) preparation. Students associated more value with engineering games that illustrate course content and mathematical calculations used in STEM courses than those that do not include these elements.

Trust Region Augmented Lagrangian Methods With Secant Hessian Updating Applied to Structural Optimization

1996 ◽  
Author(s):  
J. E. Coster ◽  
N. Stander ◽  
J. A. Snyman
Keyword(s):  
Augmented Lagrangian ◽  
Optimization Problems ◽  
Design Method ◽  
Trust Region ◽  
Low Rank ◽  
Truss Structures ◽  
Augmented Lagrangian Methods ◽  
Penalty Term ◽  
Analysis And Design ◽  
Lagrangian Methods

Abstract The problem of determining the optimal sizing design of truss structures is considered. An augmented Lagrangian optimization algorithm which uses a quadratic penalty term is formulated. The implementation uses a first-order Lagrange multiplier update and a strategy for progressively increasing the accuracy with which the bound constrained minimizations are performed. The allowed constraint violation is also progressively decreased but at a slower rate so as to prevent ill-conditioning due to large penalty values. Individual constraint penalties are used and only the penalties of the worst violated constraints are increased. The scheme is globally convergent. The bound constrained minimizations are performed using the SBMIN algorithm where a sophisticated trust-region strategy is employed. The Hessian of the augmented Lagrangian function is approximated using partitioned secant updating. Each function contributing to the Lagrangian is individually approximated by a secant update and the augmented Lagrangian Hessian is formed by appropriate accumulation. The performance of the algorithm is evaluated for a number of different secant updates on standard explicit and truss sizing optimization problems. The results show the formulation to be superior to other implementations of augmented Lagrangian methods reported in the literature and that, under certain conditions, the method approaches the performance of the state-of-the-art SQP and SAM methods. Of the secant updates, the symmetric rank one update is superior to the other updates including the BFGS scheme. It is suggested that the individual function, secant updating employed may be usefully applied in contexts where structural analysis and optimization are performed simultaneously, as in the simultaneous analysis and design method. In such cases the functions are partially separable and the associated Hessians are of low rank.

scholarly journals A Novel Combinatorial Algorithm for Determining the Generic/Topological Mobility of Planar and Spherical Mechanisms

2013 ◽  
Author(s):  
Offer Shai ◽  
Andreas Müller
Keyword(s):  
Mathematical Proof ◽  
Mathematical Concept ◽  
Rigidity Theory ◽  
Combinatorial Algorithm ◽  
Spherical Mechanisms ◽  
Structural Mobility ◽  
Pebble Game ◽  
Spherical Mechanism ◽  
Combinatorial Rigidity

Structural mobility criteria, such as the well-known Chebychev-Kutzbach-Grübler (CKG) formula, give the correct generic mobility of a linkage (possibly of a certain class, e.g. planar, spherical, spatial) provided that it is not topologically overconstrained. As a matter of fact all known structural mobility criteria are prone to topological redundancies. In this paper a combinatorial algorithm is introduced that determines the correct generic/topological mobility of any planar and spherical mechanism. The algorithm also yields a set of independent links that can be used as input, as well as the redundantly constrained sub-linkages. A mathematical proof of the algorithm and the underlying mathematical concept is presented. The proposed method relies on an established algorithm developed within combinatorial rigidity theory, called pebble game, originally developed for checking the rigidity/immobility of constraint graphs. A novel theorem is introduced and later proved in the paper which in turn enables applying the algorithm to any holonomic planar or spherical mechanism with higher and lower kinematic pairs and multiple joints. A further important result of applying this algorithm is that it gives rise to a decomposition into Assur graphs, which is briefly discussed in this paper.

Sign in / Sign up

Export Citation Format

Share Document