Topology Optimization of Large Motion Rigid Body Mechanisms With Nonlinear Kinematics

2009 ◽  
Vol 4 (2) ◽  
Author(s):  
Kai Sedlaczek ◽  
Peter Eberhard
Keyword(s):  
Topology Optimization ◽  
Rigid Body ◽  
Design Process ◽  
Combinatorial Problem ◽  
Optimization Techniques ◽  
Dimensional Synthesis ◽  
Ground Structure ◽  
Geometrical Properties ◽  
Manual Task ◽  
Large Motion

The modern design process of mechanical structures is increasingly influenced by highly sophisticated methods of topology optimization that can automatically synthesize optimal design variants. However, the typically finite-element-based methods are limited to design tasks with comparably small deflections and simple kinematics. They are not directly applicable to the difficult development process of large motion mechanisms, which remains mainly a manual task based on the engineer’s experience, intuition, and ingenuity. There, optimization techniques are only, if at all, used in the process of dimensional synthesis, where the geometrical properties and the orientation of individual links of a fixed mechanism topology are determined. In this work, two different approaches to optimization-based topology synthesis of large motion rigid body mechanisms are presented and investigated. The goal is to automatically synthesize a combination of linkage topology and joint types that represent the most suitable mechanism layout for a particular task. The first approach is based on a trusslike ground structure that represents an overdetermined system of rigid bars from which the most appropriate topology can be extracted from this ground structure by means of gradient-based optimization algorithms. In the second approach, a genetic algorithm is used to solve the intrinsically combinatorial problem of topology synthesis. Along with several examples, both approaches are explained, their functionality is shown, and their advantages, limitations, and their capability to improve the overall design process is discussed.

Design Optimization of Rigid Body Mechanism Topology

2007 ◽  
Author(s):  
Kai Sedlaczek ◽  
Peter Eberhard
Keyword(s):  
Rigid Body ◽  
Development Process ◽  
Combinatorial Problem ◽  
Optimization Techniques ◽  
Dimensional Synthesis ◽  
Ground Structure ◽  
Overall Design ◽  
Modern Computer ◽  
Gradient Based ◽  
Computer Based

Despite modern computer based design tools, the development process of new mechanisms is still based on the engineer’s experience, intuition and ingenuity. The goal of this work is to find a combination of linkage topology and joint types that represent the most suitable mechanism layout for a particular task. Optimization techniques are hardly used for this design problem except for the task of dimensional synthesis of a given mechanism type. This study presents and compares two different approaches to topology or type optimization of planar rigid body mechanisms that can be used to improve the overall design process. The first approach is based on a truss-like ground structure that represents an over-determined system of rigid bars where the most appropriate topology can be extracted from this ground structure by means of gradient based optimization algorithms. In the second approach, we use a genetic algorithm for the intrinsically combinatorial problem of topology synthesis. We explain both approaches and show their capabilities, their advantages and drawbacks.

Topology Optimization in the Conceptual Design: Take the Frame of a Bender as Example

2011 ◽  
Vol 267 ◽  
pp. 297-301
Author(s):  
Yong Wang ◽  
Guo Niu Zhu ◽  
Bo Yu Sun
Keyword(s):  
Topology Optimization ◽  
Design Process ◽  
Mechanical Design ◽  
Cost Effective ◽  
Optimization Techniques ◽  
Structural Topology Optimization ◽  
Structural Topology ◽  
Effective Manner ◽  
Stress And Deformation ◽  
Design Proposal

The paper is concerned with topology optimization in the mechanical design process. The disadvantage of current process of mechanical design is discussed and a new design process based on structural topology optimization is presented. The design process with structural topology optimization in mechanical design is discussed by the example of the frame of a bender. Static analysis is made to the original model first according to the whole structure and working characteristic of the machine, the stress and deformation distribution are obtained and then topology optimization is carried out. On the basis of topology optimization, the layout of the initial design proposal is obtained and the weight of the frame is substantially reduced while the performance enhanced. The application of the method demonstrates that through innovative utilization of the topology optimization techniques, the conceptual proposals can be obtained and the overall mechanical design process can be improved substantially in a cost effective manner.

Dimensional Synthesis of Planar Eight-Bar Linkages Based on a Parallel Robot With a Prismatic Base Joint

2013 ◽  
Author(s):  
Gim Song Soh ◽  
Fangtian Ying
Keyword(s):  
Rigid Body ◽  
Design Process ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
End Effector ◽  
Prismatic Joint ◽  
Serial Chain ◽  
Different Types

This paper details the dimensional synthesis for the rigid body guidance of planar eight-bar linkages that could be driven by a prismatic joint at its base. We show how two RR cranks can be added to a planar parallel robot formed by a PRR and 3R serial chain to guide its end-effector through a set of five task poses. This procedure is useful for designers who require the choice of ground pivot locations. The results are eight different types of one-degree of freedom planar eight-bar linkages. We demonstrate the design process with the design of a multifunctional wheelchair that could transform its structure between a self-propelled wheelchair and a walking guide.

Automatic Design in Matlab Using PDE Toolbox for Shape and Topology Optimization

2019 ◽  
Author(s):  
Yilun Sun ◽  
Lingji Xu ◽  
Jingru Yang ◽  
Tim C. Lueth
Keyword(s):  
Topology Optimization ◽  
Design Process ◽  
High Efficiency ◽  
Mechanical Performance ◽  
Optimization Techniques ◽  
Automatic Design ◽  
Medical Robots ◽  
Shape And Topology Optimization ◽  
And Topology ◽  
Material Layout

Abstract In this paper, we present a novel concept of using Matlab’s Partial Differential Equation (PDE) Toolbox to achieve shape and topology optimization during the automatic mechanical design process. In our institute, we are developing a toolbox called Solid Geometry (SG) Library in Matlab to achieve automatic design of medical robots and mechanisms. The entire design process is performed in one developing environment without additional data input and output. And those robots and mechanisms can be quickly manufactured by different kinds of 3D printers. Recently, we have also integrated the shape and topology optimization techniques into our automatic design process by using the PDE Toolbox of Matlab for finite element analysis because of its high efficiency and compactness. For optimization algorithms, we have already implemented two bionic structural optimization methods called Computer Aided Optimization (CAO) and Soft Kill Option (SKO) to optimize the stress distribution in the structure. Since the complicated material layout in the optimization results can be easily realized by the 3D printing technology, the mechanical performance of our medical robots and mechanisms can be greatly improved with the work presented in this paper.

On the Design of Spatial 4C Mechanisms for Rigid-Body Guidance Through 4 Positions

1995 ◽  
Author(s):  
Pierre M. Larochelle
Keyword(s):  
Rigid Body ◽  
Design Process ◽  
Design Procedure ◽  
Design Parameters ◽  
Two Dimensional ◽  
Dimensional Synthesis ◽  
Numerical Example ◽  
Cylindrical Joint ◽  
Free Parameters

Abstract This paper presents a procedure for determining the fixed and moving congruences associated with four finitely separated spatial positions. Furthermore, a methodology is derived for selecting the lines from the congruences which define the joint axes of a 4C mechanism. The result is a design procedure for performing the kinematic dimensional synthesis of spatial 4C mechanisms for four position rigid body guidance. Associated with four finitely separated positions in space are a fixed and a moving congruence. These congruences are a two dimensional set of lines, where each line defines the axis of a cylindrical joint that guides a body through the four prescribed positions. In order to uniquely determine a 4C mechanism from the congruences four free parameters must be specified. We present procedures for determining these free design parameters which result in mechanisms with joint axes that are nearest to some desired location. Moreover, included is a detailed numerical example illustrating the design process.

scholarly journals A Sequential Approach for Aerodynamic Shape Optimization with Topology Optimization of Airfoils

2021 ◽  
Vol 26 (2) ◽  
pp. 34
Author(s):  
Isaac Gibert Martínez ◽  
Frederico Afonso ◽  
Simão Rodrigues ◽  
Fernando Lau
Keyword(s):  
Topology Optimization ◽  
Shape Optimization ◽  
Volume Fraction ◽  
Optimization Techniques ◽  
Free Form ◽  
Aerodynamic Shape Optimization ◽  
Sequential Approach ◽  
Airfoil Surface ◽  
Aerodynamic Shape ◽  
Design Variables

The objective of this work is to study the coupling of two efficient optimization techniques, Aerodynamic Shape Optimization (ASO) and Topology Optimization (TO), in 2D airfoils. To achieve such goal two open-source codes, SU2 and Calculix, are employed for ASO and TO, respectively, using the Sequential Least SQuares Programming (SLSQP) and the Bi-directional Evolutionary Structural Optimization (BESO) algorithms; the latter is well-known for allowing the addition of material in the TO which constitutes, as far as our knowledge, a novelty for this kind of application. These codes are linked by means of a script capable of reading the geometry and pressure distribution obtained from the ASO and defining the boundary conditions to be applied in the TO. The Free-Form Deformation technique is chosen for the definition of the design variables to be used in the ASO, while the densities of the inner elements are defined as design variables of the TO. As a test case, a widely used benchmark transonic airfoil, the RAE2822, is chosen here with an internal geometric constraint to simulate the wing-box of a transonic wing. First, the two optimization procedures are tested separately to gain insight and then are run in a sequential way for two test cases with available experimental data: (i) Mach 0.729 at α=2.31°; and (ii) Mach 0.730 at α=2.79°. In the ASO problem, the lift is fixed and the drag is minimized; while in the TO problem, compliance minimization is set as the objective for a prescribed volume fraction. Improvements in both aerodynamic and structural performance are found, as expected: the ASO reduced the total pressure on the airfoil surface in order to minimize drag, which resulted in lower stress values experienced by the structure.

scholarly journals Hybrid Optimization Based Mathematical Procedure for Dimensional Synthesis of Slider-Crank Linkage

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1581
Author(s):  
Alfonso Hernández ◽  
Aitor Muñoyerro ◽  
Mónica Urízar ◽  
Enrique Amezua
Keyword(s):  
Genetic Algorithm ◽  
Fitness Function ◽  
Linear Equations ◽  
Optimization Procedure ◽  
Optimization Techniques ◽  
Dimensional Synthesis ◽  
Hybrid Strategy ◽  
Dimensional Parameters ◽  
Optimization Methodology ◽  
Crank Mechanism

In this paper, an optimization procedure for path generation synthesis of the slider-crank mechanism will be presented. The proposed approach is based on a hybrid strategy, mixing local and global optimization techniques. Regarding the local optimization scheme, based on the null gradient condition, a novel methodology to solve the resulting non-linear equations is developed. The solving procedure consists of decoupling two subsystems of equations which can be solved separately and following an iterative process. In relation to the global technique, a multi-start method based on a genetic algorithm is implemented. The fitness function incorporated in the genetic algorithm will take as arguments the set of dimensional parameters of the slider-crank mechanism. Several illustrative examples will prove the validity of the proposed optimization methodology, in some cases achieving an even better result compared to mechanisms with a higher number of dimensional parameters, such as the four-bar mechanism or the Watt’s mechanism.

Structural Analysis and Optimal Design of Lightweight Skate for Loading and Unloading

2013 ◽  
Vol 785-786 ◽  
pp. 1258-1261
Author(s):  
In Pyo Cha ◽  
Hee Jae Shin ◽  
Neung Gu Lee ◽  
Lee Ku Kwac ◽  
Hong Gun Kim
Keyword(s):  
Topology Optimization ◽  
Structural Analysis ◽  
Optimal Design ◽  
Optimization Techniques ◽  
Normal Operation ◽  
Stress And Strain ◽  
Initial Model ◽  
Design Variables ◽  
Model Set ◽  
Main Frame

Topology optimization and shape optimization of structural optimization techniques are applied to transport skate the lightweight. Skate properties by varying the design variables and minimize the maximum stress and strain in the normal operation, while reducing the volume of the objective function of optimal design and Skate the static strength of the constraints that should not degrade compared to the performance of the initial model. The skates were used in this study consists of the main frame, sub frame, roll, pin main frame only structural analysis and optimal design was performed using the finite element method. Simplified initial model set design area and it compared to SM45C, AA7075, CFRP, GFRP was using the topology optimization. Strength does not degrade compared to the initial model, decreased volume while minimizing the stress and strain results, the optimum design was achieved efficient lightweight.

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