On the Design of a Long-Stroke Beam-Based Compliant Mechanism Providing Quasi-Constant Force

Author(s):  
Pietro Bilancia ◽  
Alessandro Geraci ◽  
Giovanni Berselli

Abstract In this paper the design of a linear long-stroke quasi-constant force compliant mechanism (CM) is presented and discussed. Starting from a flexure-based slider-crank mechanism, providing the required constant force within a rather limited deflection range, the paper reports about the shape optimization carried out with the specific aim of extending the available CM operative range. The proposed device is suitable in several precision manipulation systems, which require to maintain a constant-force at their contact interface with the manipulated object. Force regulation is generally achieved by means of complex control algorithms and related sensory apparatus, resulting in a flexible behavior but also in high costs. A valid alternative may be the use of a purposely designed CM, namely a purely mechanical system whose shape and dimensions are optimized so as to provide a force-deflection behavior characterized by zero stiffness. In the first design step, the Pseudo-Rigid Body (PRB) method is exploited to synthesize the sub-optimal compliant configuration, i.e. the one characterized by lumped compliance. Secondly, an improved design alternative is evaluated resorting to an integrated software framework, comprising Matlab and ANSYS APDL, and capable of performing non-linear structural optimizations. The new embodiment makes use of a variable thickness beam, whose shape and dimensions have been optimized so as to provide a constant reaction force in an extended range. Finally, a physical prototype of the beam-based configuration is produced and tested, experimentally validating the proposed design method.

Author(s):  
Zhongtian Xie ◽  
Lifang Qiu

Compliant constant-force mechanisms (CFM) are a type of compliant mechanism which produce a reaction force at the output port that does not change for a large range of input motion. This paper describes a new compliant CFM, introduces its design and configuration-improvement process. A finite element analysis (FEA) model of the compliant CFM was created to evaluate its constant force behavior. The FEA result shows that when the displacement is Δ = 4 mm, the compliant CFM maintains a nearly constant force in the operational displacement range of 1.31 mm to 4 mm with an error of 5.05%. The operational range accounts for 67% of the total motion. This compliant CFM can be used to regulate the contact force of a robot end-effector or as an electrical connector.


Author(s):  
Qingsong Xu

This paper presents the design and analysis a flexure-guided compliant micropositioning stage with constant force and large stroke. The constant force output is achieved by combining a bistable flexure mechanism with a positive-stiffness flexure mechanism. In consideration of the constraint of conventional tilted beam-based bistable mechanism, a new type of bistable structure based on tilted-angle compound parallelogram flexure is proposed to achieve a larger range of constant force output while maintaining a compact physical size. To facilitate the parametric design of the flexure mechanism, analytical models are derived to quantify the stage performance. The models are verified by carrying out nonlinear finite-element analysis. Results demonstrate the effectiveness of the proposed ideas for a long-stroke, constant-force compliant mechanism dedicated to precision micropositioning applications.


2019 ◽  
Vol 111 ◽  
pp. 06052
Author(s):  
Seok-Hyun Kim ◽  
Soo Cho ◽  
Young-Hum Cho

In South Korea, the evaluation criteria for the shading devices installation are defined by regulations, but the standards of design methods are not clearly established. The installation of shading device is used to solar control in building. It has become mandatory for some public buildings due to revised regulations. Generally this device mean is horizontal shading at upper window. Therefore, a design of horizontal shading device which takes into account the energy consumption of the building is required, and indoor environmental problems which may occur due to the installation of them should also be taken into consideration. This research studied to propose a design which takes into account the energy consumption which may occur if the horizontal shading device is installed, and suggest an improved design method of horizontal shading devices on the basis of the analysis of the problems that may occur when they are installed. Consequently, it was confirmed that as the length of the horizontal shading device becomes longer, the incoming daylight is reduced and the indoor intensity of illumination becomes lower, and thus, more lighting energy may be consumed in a room where the shading device is installed than in the one where it is not. Therefore, annual energy consumption was calculated by applying the lighting control and it was found that the total energy consumption decreased as a result of the reduction in energy consumption for air conditioning and fans and further decrease in lighting energy consumption.


Author(s):  
Giovanni Berselli ◽  
Rocco Vertechy ◽  
Gabriele Vassura ◽  
Vincenzo Parenti Castelli

The interest in actuators based on dielectric elastomer films as a promising technology in robotic and mechatronic applications is increasing. The overall actuator performances are influenced by the design of both the active film and the film supporting frame. This paper presents a single-acting actuator which is capable of supplying a constant force over a given range of motion. The actuator is obtained by coupling a rectangular film of silicone dielectric elastomer with a monolithic frame designed to suitably modify the force generated by the dielectric elastomer film. The frame is a fully compliant mechanism whose main structural parameters are calculated using a pseudo-rigid-body model and then verified by finite element analysis. Simulations show promising performance of the proposed actuator.


1960 ◽  
Vol 38 (1) ◽  
pp. 78-99 ◽  
Author(s):  
A. Ishimaru ◽  
G. Held

Part I considers the problem of determining the source distribution over a circular aperture required to produce a prescribed radiation pattern. In particular, the problem of optimizing the narrow broadside pattern from a circular aperture is discussed in detail and an improved design method over Taylor's for line source is devised. Numerical examples are given.Part II deals with the analysis of the radiation pattern from a circular aperture from γ1 to γ2 with the traveling wave type source functions. Expressions suitable to the analysis and the synthesis are obtained and the narrow-beam and shaped-beam synthesis are discussed.


Author(s):  
Andrea Spaggiari ◽  
Eugenio Dragoni

This paper explores the merits of shape memory Negator springs as powering elements for solid state actuators. A Negator spring is a spiral spring made of strip of metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbour. The unique characteristic of Negator springs is the nearly-constant force needed to unwind the strip for very large, theoretically infinite deflections. Moreover the flat shape, having a high area over volume ratio, grants improved bandwidth compared to any solution with solid wires or helical springs. The SMA material is modelled as elastic in austenitic range while an exponential continuum law is used to describe the martensitic behaviour. The mathematical model of the mechanical behaviour of SMA Negator springs is provided and their performances as active elements in constant-force, long-stroke actuators are assessed. The SMA Negator spring is also simulated in a commercial finite element software, ABAQUS, and its mechanical behaviour is estimated through FE analyses. The analytical and the numerical prediction are in good agreement, both in martensitic and in austenitic range.


Author(s):  
Seok-Won Lee ◽  
Wan Gi Jeon ◽  
Kyeong-Han Jeong ◽  
Hyun-Ho Ahn ◽  
Ju Hyoung Lee

Food Research ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 298-305
Author(s):  
B. Yudhistira ◽  
A.K. Putri ◽  
S. Prabawa

Marshmallow belongs to a high-calorie food that requires a low-calorie substitute for sucrose, one of which is sorbitol. Marshmallow has the potential to become a functional food with the addition of inulin contained within white sweet potatoes. Inulin refers to a type of fructan carbohydrate which contains fiber and has the potential as a prebiotic that is beneficial for the human’s body. This study aims to determine the effect of the addition of white sweet potato (Ipomea batatas L.) inulin extract and sorbitol on the physical, chemical and organoleptic characteristic of marshmallows and to obtain the best marshmallow’s formula through white sweet potato (Ipomea batatas L.) inulin extract and sorbitol addition. The completely randomized design method (CRD) applied in this study consisted of one factor, namely the difference in formulation between the concentration of white sweet potato inulin extract (2% and 3%) and the concentration of sorbitol (25%, 50%, and 75%). The statistical analysis utilized the One Way Analysis of Variance (ANOVA) method using SPSS. The results of this study indicated that the addition of white sweet potato inulin extract and sorbitol had a significant effect on tensile strength, density, moisture content, ash content, total calories, dietary fiber, and organoleptic characteristics of marshmallows. The best formula for marshmallows was formula 4 with the addition of 2% white sweet potato inulin extract and 50% sorbitol.


2005 ◽  
Vol 41 (8) ◽  
pp. 461 ◽  
Author(s):  
S. Reekmans ◽  
J. De Maeyer ◽  
P. Rombouts ◽  
L. Weyten

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