A Novel Compliant Bistable Mechanism Incorporating a Fixed-Guided Flexural Member

Volume 10: 44th Mechanisms and Robotics Conference (MR) ◽

10.1115/detc2020-22420 ◽

2020 ◽

Author(s):

James J. Joo ◽

David H. Myszka

Keyword(s):

Inflection Point ◽

Operation Mode ◽

Stable Configuration ◽

Preliminary Design ◽

Element Simulation ◽

Simple Geometry ◽

Flexural Member ◽

Bistable Mechanism ◽

Monolithic Structure ◽

Displacement Measurements

Abstract This paper presents the design of a novel compliant bistable mechanism. Bistable mechanisms are commonly used in switches and other devices that operate in two distinct modes. This mechanism is a single monolithic structure with simple geometry and does not require external components or post-manufacture assembly. As such, the design is ideally suited for additive manufacturing at large, or micro, scales. The design features a fixed-guided flexural member with surrounding geometry. When a load is applied to the mechanism in a stable configuration, the flexural member exhibits an inflection point that enables bifurcated behavior. As a result, the mechanism snaps between two stable positions in an on-off operation mode. This paper describes the mechanism geometry and its operation. Preliminary design modeling equations are formulated. A finite element simulation is presented that verifies the design equations. Lastly, a prototype is presented to confirm the operation and facilitate force and displacement measurements.

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Calibrating a New Constitutive Tension Model to Extract a Simplified Nonlinear Sectional Analysis of Reinforced Concrete Beams

Applied Sciences ◽

10.3390/app11052292 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2292

Author(s):

Alaaeldin Abouelleil ◽

Hayder A. Rasheed

Keyword(s):

Reinforced Concrete ◽

Concrete Beams ◽

Compressive Strain ◽

Design Criterion ◽

Reinforced Concrete Beams ◽

Secondary Outcome ◽

Shear Stresses ◽

Structural Members ◽

Flexural Member ◽

Smeared Crack

Nonlinear analysis of structural members is vital to understand the behavior and the response of reinforced concrete members. Even though most design procedures concentrate on the ultimate stage of response towards the end of the post-yielding zone as the decisive design criterion, the structural members usually function at the service load levels within the post-cracking zone. Therefore, cracking is a critical aspect of concrete behavior that affects the overall response of reinforced concrete beams. The initiation and the propagation of the cracks are affected directly by the tension and shear stresses in the beam. In flexural beams, the tensile stresses dominate the crack onset and its growth. Cracks in reinforced concrete flexural beams leave non-cracked regions in between the cracked sections. In order to apply a consistent analysis strategy, the smeared crack approach averages the behavior of these different cracked sections and uncracked in between regions to generate an accurate global response of the entire beam. This study presents a numerical constitutive tensile model that captures the complete tensile response of the reinforced concrete flexural member, in terms of averaged/smeared crack response. As a second step, this model was examined against a large pool of experimental data to validate its accuracy. Overall, the main objective of this study is to develop a representative constitutive tensile model for reinforced concrete flexural members and validate its accuracy against experimental results. The full nonlinear sectional response is analytically realized, based on the assumed trilinear moment–curvature response and the assumed trilinear moment–extreme fiber compressive strain response. This is considered as the secondary outcome of the present study.

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Achieving Multistability Through Use of a Single Bistable Compliant Mechanism

Volume 2: 34th Annual Mechanisms and Robotics Conference, Parts A and B ◽

10.1115/detc2010-28388 ◽

2010 ◽

Author(s):

Guimin Chen ◽

Yanjie Gou ◽

Aimei Zhang

Keyword(s):

Stable Equilibrium ◽

Compliant Mechanism ◽

Power Input ◽

Successful Operation ◽

New Approaches ◽

Reconfigurable Robots ◽

Bistable Mechanism

A compliant multistable mechanism is capable of steadily staying at multiple distinct positions without power input. Many applications including switches, valves, relays, positioners, and reconfigurable robots may benefit from multistability. In this paper, two new approaches for synthesizing compliant multistable mechanisms are proposed, which enable designers to achieve multistability through the use of a single bistable mechanism. The synthesis approaches are described and illustrated by several design examples. Compound use of both approaches is also discussed. The design potential of the synthesis approaches is demonstrated by the successful operation of several instantiations of designs that exhibit three, four, five, and nine stable equilibrium positions, respectively. The synthesis approaches enable us to design a compliant mechanism with a desired number of stable positions.

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Preparation and Basic Mechanical Properties of Self-Compacting Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.150-151.354 ◽

2010 ◽

Vol 150-151 ◽

pp. 354-357

Author(s):

Heng Yan Xie ◽

Xin Zheng

Keyword(s):

Strain Curve ◽

Self Compacting Concrete ◽

Stress Strain ◽

Mixture Ratio ◽

Concrete Members ◽

Compression Strain ◽

Stress Strain Relation ◽

Steel Bar ◽

Flexural Member ◽

Good Flow

Self- compacting concrete (SCC) has characteristics of good flow-ability, non-vibrating and self-compacting. It is the optimum to be used in concrete members with densely distributed steel bar and concrete is inconvenient to be vibrated. The mixture ratio of design grade of C20 and C40 SCC commonly used in project is given after trial mix. The compression stress-strain relation of SCC prism is obtained by MTS. The Mechanical property indexes of SCC are got. The ultimate compression strain of the extreme fiber is acquired by testing beam made of SCC, and the relation between the ultimate compression strain of the extreme fiber in flexural member and the strain at the peak of the stress-strain curve subjected to uniaxial compression is given.

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Bistable Compliant Four-Bar Mechanisms With a Single Torsional Spring

Volume 2: 30th Annual Mechanisms and Robotics Conference, Parts A and B ◽

10.1115/detc2006-99453 ◽

2006 ◽

Cited By ~ 2

Author(s):

Adarsh Mavanthoor ◽

Ashok Midha

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Mechanism Design ◽

Compliant Mechanisms ◽

Compliant Mechanism ◽

Stored Energy ◽

Element Analysis ◽

Bistable Behavior ◽

Torsional Spring ◽

Bistable Mechanism

Significant reduction in cost and time of bistable mechanism design can be achieved by understanding their bistable behavior. This paper presents bistable compliant mechanisms whose pseudo-rigid-body models (PRBM) are four-bar mechanisms with a torsional spring. Stable and unstable equilibrium positions are calculated for such four-bar mechanisms, defining their bistable behavior for all possible permutations of torsional spring locations. Finite Element Analysis (FEA) and simulation is used to illustrate the bistable behavior of a compliant mechanism with a straight compliant member, using stored energy plots. These results, along with the four-bar and the compliant mechanism information, can then be used to design a bistable compliant mechanism to meet specified requirements.

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Identification of Compliant Pseudo-Rigid-Body Four-Link Mechanism Configurations Resulting in Bistable Behavior

Journal of Mechanical Design ◽

10.1115/1.1625399 ◽

2003 ◽

Vol 125 (4) ◽

pp. 701-708 ◽

Cited By ~ 65

Author(s):

Brian D. Jensen ◽

Larry L. Howell

Keyword(s):

Energy Storage ◽

Rigid Body ◽

Mechanism Design ◽

Bistable Behavior ◽

Strongly Coupled ◽

Present Design ◽

Stable Equilibria ◽

Motion Characteristics ◽

Bistable Mechanism ◽

Design Challenges

Bistable mechanisms, which have two stable equilibria within their range of motion, are important parts of a wide variety of systems, such as closures, valves, switches, and clasps. Compliant bistable mechanisms present design challenges because the mechanism’s energy storage and motion characteristics are strongly coupled and must be considered simultaneously. This paper studies compliant bistable mechanisms which may be modeled as four-link mechanisms with a torsional spring at one joint. Theory is developed to predict compliant and rigid-body mechanism configurations which guarantee bistable behavior. With this knowledge, designers can largely uncouple the motion and energy storage requirements of a bistable mechanism design problem. Examples demonstrate the power of the theory in bistable mechanism design.

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