Programmable Constant-Force Multistable Mechanisms

2018 ◽  
Author(s):  
Mohamed Zanaty ◽  
Simon Henein
Keyword(s):  
Numerical Simulations ◽  
Reaction Force ◽  
Experimental Measurements ◽  
Constant Force ◽  
Stable States ◽  
Zero Force ◽  
Stability Behavior ◽  
Analytical Results ◽  
Potential Applications ◽  
Axially Loaded

Programmable multistable mechanisms exhibit stability behavior whereby the stiffness and the number of stable states can be controlled via programming inputs. In this paper, we report the zero stiffness behavior of a 2-degree of programming (DOP) T-combined, axially loaded double parallelogram multistable mechanism. We demonstrate zero force monostability, constant force monostability, zero force bistability, constant force bistability and zero force tristability behaviors by tuning the programming input. We derive analytically the reaction force of the mechanism for each configuration and verify our analytical results using numerical simulations and experimental measurements, showing less than 10% discrepancy. The concept of constant-force programming can be extended to N-DOP T-combined, serial combined and parallel combined programmable multistable mechanisms. Finally, we present potential applications of stability programming.

Experimental Characterization of a T-Shaped Programmable Multistable Mechanism

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Mohamed Zanaty ◽  
Simon Henein
Keyword(s):  
Numerical Simulations ◽  
Reaction Force ◽  
Experimental Measurements ◽  
Experimental Characterization ◽  
Stable States ◽  
Stability Behavior ◽  
The Stability ◽  
Force Characteristics ◽  
Good Agreement

Programmable multistable mechanisms (PMM) exhibit a modifiable stability behavior in which the number of stable states, stiffness, and reaction force characteristics are controlled via their programming inputs. In this paper, we present experimental characterization for the concept of stability programing introduced in our previous work (Zanaty et al., 2018, “Programmable Multistable Mechanisms: Synthesis and Modeling,” ASME J. Mech. Des., 140(4), p. 042301.) A prototype of the T-combined axially loaded double parallelogram mechanisms (DPM) with rectangular hinges is manufactured using electrodischarge machining (EDM). An analytical model based on Euler–Bernoulli equations of the T-mechanism is derived from which the stability behavior is extracted. Numerical simulations and experimental measurements are conducted on programming the mechanism as monostable, bistable, tristable, and quadrastable, and show good agreement with our analytical derivations within 10%.

Optimal Design of Bi- and Multi-Stable Compliant Cellular Structures

2018 ◽  
Author(s):  
Quantian Luo ◽  
Liyong Tong
Keyword(s):  
Optimal Design ◽  
Virtual Work ◽  
Reaction Force ◽  
Nonlinear Finite Element ◽  
Cellular Structures ◽  
Stress And Strain ◽  
Principle Of Virtual Work ◽  
Stable States ◽  
Threshold Method ◽  
Element Analysis

This paper presents optimal design for nonlinear compliant cellular structures with bi- and multi-stable states via topology optimization. Based on the principle of virtual work, formulations for displacements and forces are derived and expressed in terms of stress and strain in all load steps in nonlinear finite element analysis. Optimization for compliant structures with bi-stable states is then formulated as: 1) to maximize the displacement under specified force larger than its critical one; and 2) to minimize the reaction force for the prescribed displacement larger than its critical one. Algorithms are developed using the present formulations and the moving iso-surface threshold method. Optimal design for a unit cell with bi-stable states is studied first, and then designs of multi-stable compliant cellular structures are discussed.

scholarly journals CFD Simulation and Experimental Measurements of Radon Distribution in a Traditional Hammam

2021 ◽  
Vol 39 (3) ◽  
pp. 963-968
Author(s):  
Rabi Rabi ◽  
Lhoucine Oufni ◽  
El-Hocine Youssoufi ◽  
Khamiss Cheikh ◽  
Hamza Badry ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Numerical Simulations ◽  
Indoor Air ◽  
Meteorological Parameters ◽  
Rate Increase ◽  
Cfd Simulation ◽  
Ventilation Rate ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
The Public

Radon natural is the main cause of lung cancer in non-smokers. Therefore, the study of the behavior of radon and its descendants in indoor air is of the highest importance, in order to limit the risk of radiation dose due to inhalation of radon by members of the public. This article focuses to study the effects of meteorological parameters on the concentration and distribution of radon in a traditional hammam by both numerical simulations and experiments. The results of the numerical simulations are qualitative and show that the concentration and distribution of radon decrease when the ventilation rate increase, as well as, when the temperature increases, however, it increases with the increase in relative humidity. The results obtained by the numerical simulations were in agreement with those obtained experimentally with a maximum deviation of 7%. Numerical simulations allow a better estimate of the distribution of radon in indoor air.

scholarly journals Metode Iterasi Tiga Langkah untuk Menyelesaikan Persamaan NonLinear dengan Menggunakan Matlab

2019 ◽  
Vol 4 (2) ◽  
pp. 34
Author(s):  
Deasy Wahyuni ◽  
Elisawati Elisawati
Keyword(s):  
Numerical Simulations ◽  
Nonlinear Equations ◽  
Newton Method ◽  
Iteration Method ◽  
Newton's Method ◽  
Order Of Convergence ◽  
Higher Order ◽  
Convergence Order ◽  
Matlab Program ◽  
Analytical Results

Newton method is one of the most frequently used methods to find solutions to the roots of nonlinear equations. Along with the development of science, Newton's method has undergone various modifications. One of them is the hasanov method and the newton method variant (vmn), with a higher order of convergence. In this journal focuses on the three-step iteration method in which the order of convergence is higher than the three methods. To find the convergence order of the three-step iteration method requires a program that can support the analytical results of both methods. One of them using the help of the matlab program. Which will then be compared with numerical simulations also using the matlab program.  Keywords : newton method, newton method variant, Hasanov Method and order of convergence

scholarly journals Mathematical modeling and numerical simulation of heat dissipation in led bulbs

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1877-1884 ◽  
Author(s):  
Diego Alarcón ◽  
Eduardo. Balvís ◽  
Ricardo Bendaña ◽  
Alberto Conejero ◽  
de Fernández ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
The Common

We present a detailed study of heating and cooling processes in LED luminaires with passive heat sinks. Our analysis is supported by numerical simulations as well as experimental measurements, carried on commercial systems used for outdoor lighting. We have focused our analysis on the common case of a single LED source in thermal contact with an aluminum passive heat sink, obtaining an excellent agreement with experimental measurements and the numerical simulations performed. Our results can be easily expanded, without loss of generality, to similar systems.

A Simple Approach to Characterize Finite Compressibility of Elastomers

2003 ◽  
Vol 76 (4) ◽  
pp. 912-922 ◽  
Author(s):  
Mark R. Gurvich ◽  
Thomas S. Fleischman
Keyword(s):  
Carbon Black ◽  
Bulk Modulus ◽  
Experimental Verification ◽  
Material Properties ◽  
Numerical Approach ◽  
Simple Approach ◽  
Experimental Measurements ◽  
Axially Loaded ◽  
Different Levels

Abstract A hybrid experimental-numerical approach is proposed for accurate dimensionless characterization of rubber finite compressibility. Rubber specimens in the form of bonded rubber disks are considered as elastomeric structures with unknown material properties. These properties are calculated by matching results of FEA with experimental measurements of radial deformations of the axially-loaded disks. The approach may be used for reliable characterization of Poisson's ratio, bulk modulus, or other characteristics of interest. Implementation of the approach is considered for two representative elastomeric compounds with different levels of carbon black. Good experimental verification of the approach is shown at different levels of loading. Moreover, the same parameters of finite compressibility are independently obtained using both compressive and tensile loads. Higher compressibility is observed for a compound with larger content of carbon black as expected.

Multifidelity Recursive Cokriging for Dynamic Systems' Response Modification

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Luigi Bregant ◽  
Lucia Parussini ◽  
Valentino Pediroda
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Dynamic Systems ◽  
System Optimization ◽  
The Other ◽  
Experimental Measurements ◽  
Reciprocal Influence ◽  
Tests And Measurements ◽  
Invaluable Tool ◽  
Mixed Approach

In order to perform the accurate tuning of a machine and improve its performance to the requested tasks, the knowledge of the reciprocal influence among the system's parameters is of paramount importance to achieve the sought result with minimum effort and time. Numerical simulations are an invaluable tool to carry out the system optimization, but modeling limitations restrict the capabilities of this approach. On the other side, real tests and measurements are lengthy, expensive, and not always feasible. This is the reason why a mixed approach is presented in this work. The combination, through recursive cokriging, of low-fidelity, yet extensive, numerical model results, together with a limited number of highly accurate experimental measurements, allows to understand the dynamics of the machine in an extended and accurate way. The results of a controllable experiment are presented and the advantages and drawbacks of the proposed approach are also discussed.

Mesoscale Dynamic Ice Formation and Breaking on a Vibrating Thin Membrane

1999 ◽  
Author(s):  
Jeff Fullilove ◽  
Norman Miller ◽  
Mark Shannon ◽  
Michael Philpot ◽  
Alexander Vakakis ◽  
...  
Keyword(s):  
Average Rate ◽  
Ice Formation ◽  
Experimental Measurements ◽  
Thin Membrane ◽  
Laser Vibrometry ◽  
Membrane Interaction ◽  
Analytical Results ◽  
Vibrating Membrane

Abstract We study dynamic ice formation and breaking (IF/B) on a thin vibrating membrane. The complicated discontinuous dynamics of the membrane is studied experimentally using laser vibrometry. Although the fluid- and coolant-membrane interaction with simultaneous ice forming and breaking is a complicated dynamical phenomenon, the average rate of ice formed and broken can be approximately quantified. The analytical results are compared to experimental measurements.

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