Towards the Design of Compliant Continuum Topologies With Geometric Nonlinearity

1999 ◽  
Author(s):  
A. Saxena ◽  
G. K. Ananthasuresh
Keyword(s):  
Finite Element ◽  
Linear Models ◽  
Compliant Mechanisms ◽  
Synthesis Method ◽  
Finite Element Models ◽  
Computationally Efficient ◽  
Mechanics Model ◽  
Nonlinear Design ◽  
Nonlinear Force ◽  
Synthesis Procedure

Abstract Optimal design methods that use continuum mechanics model for the deformation of the elastic body, are capable of generating suitable topology, shape, and dimensions of compliant mechanisms for desired specifications. Elastic analysis with linear finite element models employed in the synthesis procedures to date is not quantitatively accurate for large displacement situations. Also, the design specifications involving nonlinear force-deflection characteristics and generation of a curved path for the output port are difficult to realize with linear models. In this paper, the synthesis of compliant mechanisms is performed using geometrically nonlinear finite element models that appropriately account for large displacements. Frame elements are chosen for developing the synthesis procedure because of ease of implementation of the general approach and their ability to capture bending deformations. A computationally efficient method for computing the nonlinear design sensitivities is described. Examples are included to illustrate the usefulness of the synthesis method.

Topology Synthesis of Compliant Mechanisms for Nonlinear Force-Deflection and Curved Path Specifications

1999 ◽  
Vol 123 (1) ◽  
pp. 33-42 ◽  
Author(s):  
A. Saxena ◽  
G. K. Ananthasuresh
Keyword(s):  
Finite Element ◽  
Linear Models ◽  
Compliant Mechanisms ◽  
Synthesis Method ◽  
Design Sensitivity ◽  
Finite Element Models ◽  
Geometrically Nonlinear ◽  
Linear Elastic ◽  
Nonlinear Design ◽  
Nonlinear Force

Optimal design methods that use continuum mechanics models are capable of generating suitable topology, shape, and dimensions of compliant mechanisms for desired specifications. Synthesis procedures that use linear elastic finite element models are not quantitatively accurate for large displacement situations. Also, design specifications involving nonlinear force-deflection characteristics and generation of a curved path for the output port cannot be realized with linear models. In this paper, the synthesis of compliant mechanisms is performed using geometrically nonlinear finite element models that appropriately account for large displacements. Frame elements are chosen because of ease of implementation of the general approach and their ability to capture bending deformations. A method for nonlinear design sensitivity analysis is described. Examples are included to illustrate the usefulness of the synthesis method.

scholarly journals Computationally efficient reduction of modal data from finite element models by nested sets of B-splines

2015 ◽  
Vol 134 ◽  
pp. 549-564
Author(s):  
Diego Cárdenas ◽  
Hugo Elizalde ◽  
Oliver Probst ◽  
Walter Lacarbonara ◽  
Pier Marzocca ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Computationally Efficient ◽  
B Splines ◽  
Modal Data ◽  
Efficient Reduction ◽  
Nested Sets

scholarly journals Finite Element Modeling of K-Monel Bolts under Static Loading and Dynamic Shock Loading

2013 ◽  
Vol 20 (3) ◽  
pp. 575-589 ◽  
Author(s):  
Kevin Behan ◽  
Emily Guzas ◽  
Jeffrey Milburn ◽  
Stacy Moss
Keyword(s):  
Finite Element ◽  
High Resolution ◽  
Shock Loading ◽  
Future Research ◽  
Finite Element Models ◽  
Computationally Efficient ◽  
Bolted Connections ◽  
Bolted Connection ◽  
Physical Testing ◽  
Static Shear

The Naval Undersea Warfare Center has funded a project to investigate the accuracy of various bolt models used to represent actual shipboard bolted connections within an analytical shock survivability assessment. The ultimate goal within this project is to develop finite element bolt representations that are not only computationally efficient, but also accurate. A significant task within this effort involved the development of highly detailed finite element models of bolted connections under various load configurations. Accordingly, high-resolution bolt models were developed and incorporated into simulations of four bolted connection test arrangements: static shear, static tension, dynamic shear, and dynamic tension. These simulation results are validated against experimental data from physical testing of each configuration. Future research will focus on exploring simplified finite element bolt representations and comparing these against the high-resolution results.

A Comparison of Two Finite Element Reduction Techniques for Mistuned Bladed-Disks

2000 ◽  
Author(s):  
François Moyroud ◽  
Torsten Fransson ◽  
Georges Jacquet-Richardet
Keyword(s):  
Finite Element ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Computationally Efficient ◽  
Bladed Disks ◽  
Mode Localization ◽  
Reduced Order ◽  
Bladed Disk ◽  
Reduction Techniques ◽  
Modal Reduction

The high performance bladed-disks used in today’s turbomachines must meet strict standards in terms of aeroelastic stability and resonant response level. One structural characteristic that can significantly impact on both these area is that of bladed-disk mistuning. To predict the effects of mistuning, computationally efficient methods are necessary to make it feasible, especially in an industrial environment, to perform free vibration and forced response analyses of full assembly finite element models. Due to the size of typical finite element models of industrial bladed-disks, efficient reduction techniques must be used to systematically produce reduced order models. The objective of this paper is to compare two prevalent reduction methods on representative test rotors, including a modern design industrial shrouded bladed-disk, in terms of accuracy (for frequencies and mode shapes), reduction order, computational efficiency, sensitivity to inter-sector elastic coupling, and ability to capture the phenomenon of mode localization. The first reduction technique employs a modal reduction approach with a modal basis consisting of mode shapes of the tuned bladed-disk which can be obtained from a classical cyclic symmetric modal analysis. The second reduction technique is based on a Craig and Bampton substructuring and reduction approach. The results show a perfect agreement between the two reduced order models and the non-reduced finite element model. It is found that the phenomena of mode localization is equally well predicted by the two reduction models. In terms of computational cost, reductions from 1 to 2 orders of magnitude are obtained for the industrial bladed-disk, with the modal reduction method being the most computationally efficient approach.

Design of a Monolithic Constant-Force Compliant Mechanism for Extended Range of Motion and Minimal Force Variation

2021 ◽  
Author(s):  
Ching-Wei Lo ◽  
Yuan Chang ◽  
Mien-Li Wang ◽  
Cian-Ru Lin ◽  
Jyh-Jone Lee
Keyword(s):  
Finite Element ◽  
Range Of Motion ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Synthesis Method ◽  
Structural Deformation ◽  
Constant Force ◽  
Wide Range ◽  
Extended Range ◽  
Force Variation

Abstract Compliant mechanisms enable passive force control through induction of strain energy during deformation. This has been perceived as a desired factor for developing precise handling equipment of limited size where additional sensors and controls are inessential to its operation. In this paper, our objective is to design a monolithic constant-force compliant mechanism to be integrated in a constant-force gripper for extended range of bidirectional motion. A topology synthesis method has been proposed by means of domain definition, discrete parameterization, topology optimization, and nonlinear structural deformation evaluation. This article adapts a compliant topology of a homogeneous beam configuration that exhibits zero stiffness behavior over a pre-established effective region. The optimization by genetic algorithm generates discrete shaping parameters for formation of an optimal geometry. The structural deformation computation via vector form intrinsic finite element that accounts for large displacement motion quantifies an iterative series of load-displacement relations in the optimization. Results have been verified using a conventional finite element method. A conceptual gripper has been proposed with a pair of embedded constant-force compliant mechanisms. This procedure has prepared a general guideline for future development of passive compliant devices that require accurate force regulation over a wide range of motion.

Shape and Size Synthesis of Compliant Mechanisms Using Wide Curve Theory

2005 ◽  
Vol 128 (3) ◽  
pp. 551-558 ◽  
Author(s):  
Hong Zhou ◽  
Kwun-Lon Ting
Keyword(s):  
Cross Section ◽  
Optimization Problem ◽  
Compliant Mechanisms ◽  
Synthesis Method ◽  
Free Form ◽  
Control Parameters ◽  
Synthesis Procedure ◽  
Curve Theory ◽  
Practical Constraints ◽  
Shape And Size

A wide curve is a curve with width or cross section. This paper introduces a shape and size synthesis method for compliant mechanisms based on free-form wide curve theory. With the proposed method, detailed dimensions synthesis can be performed to further improve the performance after the topology is selected. Every connection in the topology is represented by a parametric wide curve in which variable shape and size are fully described and conveniently controlled by the limited number of parameters. The shape and size synthesis is formulated as the optimization of the control parameters of wide curves corresponding to all connections in the topology. Problem-dependent objectives are optimized and practical constraints are imposed during the optimization process. The optimization problem is solved by the constrained nonlinear programing algorithm in the MATLAB Optimization Toolbox. Two examples are included to demonstrate the effectiveness of the proposed synthesis procedure.

Sign in / Sign up

Export Citation Format

Share Document