Study of Notched MEMS Specimen: Elasto-Plastic Modeling and Experimental Testing

2021 ◽  
Author(s):  
Aurelio Soma' ◽  
Francesca Pistorio ◽  
Muhammad Mubasher Saleem
Keyword(s):  
Experimental Testing ◽  
Notch Root ◽  
Kinematic Model ◽  
Local Maximum ◽  
Experimental Tests ◽  
Tensile Loading ◽  
Plastic Behavior ◽  
Plastic Hinges ◽  
As Stress ◽  
Neuber's Rule

Abstract This paper investigates the effect of stress and strains concentration, due to the notch presence, on the elasto-plastic behavior of gold microstructures subjected to tensile loading under electrostatic actuation. A kinematic model for the test microstructure which relates the experimentally measured deflection to the induced stress in the central specimen with applied electrostatic load is developed. The local maximum stress and strains at the notch root are analytically estimated using the Neuber’s rule and verified through a detailed non-linear coupled-field electric-structural finite element method (FEM)-based analysis. Several experimental tests are carried out to analyze the accumulation of plastic strain and the consequent development of plastic hinges induced in the central notched specimen due to repeated cyclic tensile loading by measuring the corresponding deflection with each loading cycle. The comparison between the failure condition observed experimentally in the test notched specimens and the FEM-based simulation results shows that the notch acts as stress and strains raiser fostering the initiation and expansion of plastic hinges in the thin film gold specimen which can lead to the specimen breakdown.

Kinematic Precision Scaling With Physical Errors in Miniaturization of Four-Bar Polymer Compliant Machines

2006 ◽  
Vol 129 (5) ◽  
pp. 951-960
Author(s):  
R. J. Chang ◽  
Y. L. Wang
Keyword(s):  
Numerical Analysis ◽  
Material Properties ◽  
Compliant Mechanism ◽  
Experimental Testing ◽  
Signal To Noise Ratio ◽  
Kinematic Model ◽  
Experimental Tests ◽  
Signal To Noise ◽  
Compliant Joints ◽  
Noise Ratio

A precision-scaling kinematic model with the effects of physical error is investigated in the miniaturization of four-bar polymer machines with compliant joints. A pseudolinkages model (PLM) for the multiple-links compliant machine is formulated. A scaling formulation of the multiple-links compliant machine and its associated PLM is developed. A method for scaled-up test and scaled-down analysis of the compliant mechanism with the considerations of physical errors of fabrication processes, material properties, and experimental tests is proposed. By defining an index of signal-to-noise ratio, the performance of the miniature realization under physical errors is evaluated. The applications of the scaling PLM for the miniature realization of a compliant machine are illustrated by performing both numerical analysis and experimental testing on four-bar compliant polyethylene machines.

scholarly journals A New Approach of Soft Joint Based on a Cable-Driven Parallel Mechanism for Robotic Applications

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1468
Author(s):  
Luis Nagua ◽  
Carlos Relaño ◽  
Concepción A. Monje ◽  
Carlos Balaguer
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Experimental Tests ◽  
Humanoid Robots ◽  
Inverse Kinematic ◽  
Element Analysis ◽  
New Approach ◽  
Flexible Polymer ◽  
The Mathematical Model

A soft joint has been designed and modeled to perform as a robotic joint with 2 Degrees of Freedom (DOF) (inclination and orientation). The joint actuation is based on a Cable-Driven Parallel Mechanism (CDPM). To study its performance in more detail, a test platform has been developed using components that can be manufactured in a 3D printer using a flexible polymer. The mathematical model of the kinematics of the soft joint is developed, which includes a blocking mechanism and the morphology workspace. The model is validated using Finite Element Analysis (FEA) (CAD software). Experimental tests are performed to validate the inverse kinematic model and to show the potential use of the prototype in robotic platforms such as manipulators and humanoid robots.

On-Site Experimental Testing to Study the Vibration of Composite Floors

2014 ◽  
Vol 601 ◽  
pp. 231-234
Author(s):  
Cristian Lucian Ghindea ◽  
Dan Cretu ◽  
Monica Popescu ◽  
Radu Cruciat ◽  
Elena Tulei
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Testing ◽  
Concrete Slab ◽  
Human Perception ◽  
Experimental Tests ◽  
International Standards ◽  
Structural Element ◽  
Element Analysis ◽  
Floor Slabs ◽  
Composite Floors

As a general trend, in order to reduce material consumption or to reduce the mass of the structures, composite floor slabs solutions are used to achieve large spans floor slabs. This solutions led to floors sensitive to vibrations induced generally by human activities. As a verification of the design concepts of the composite floors, usually, it is recommended a further examination of the floor after completion by experimental tests. Although the experimental values of the dynamic response of the floor are uniquely determined, the processing can take two directions of evaluation. The first direction consist in determining the dynamic characteristics of the floor and their comparison with the design values. Another way that can be followed in the processing of the experimental results is to consider the human perception and comfort to the vibration on floors. The paper aims to present a case study on a composite floor, with steel beams and concrete slab, tested on-site. Both aspects of data processing are analyzed, in terms of the structural element, and in terms of the effect on human perception and comfort. Experimentally obtained values for the dynamic characteristics of the floor are compared with numerical values from finite element analysis, while the second type of characteristic values are compared with various human comfort threshold values found in international standards.

The Fictitious Radius as a Tool for Fatigue Life Estimation of Notched Elements

2012 ◽  
Vol 726 ◽  
pp. 27-32 ◽  
Author(s):  
Grzegorz Robak ◽  
Marcel Szymaniec ◽  
Tadeusz Łagoda
Keyword(s):  
Fatigue Life ◽  
Notch Root ◽  
Experimental Tests ◽  
Life Estimation ◽  
Fatigue Life Estimation

In this paper, the fictitious radius - according to Neuber’s method for determination of stresses at the notch root was used. Next, the fatigue lives of elements of the ring notches were calculated, and then compared with results of experimental tests of S235JR steel samples. However, the obtained fatigue lives did not bring satisfactory results. It has been demonstrated that the fictitious radius strongly depends on the expected fatigue life

Numerical and experimental performance estimation for a ExoFing - 2 DOFs finger exoskeleton

Robotica ◽  
2021 ◽  
pp. 1-13
Author(s):  
G Carbone ◽  
M Ceccarelli ◽  
C. E. Capalbo ◽  
G Caroleo ◽  
C Morales-Cruz
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Index Finger ◽  
Kinematic Model ◽  
Experimental Tests ◽  
Performance Estimation ◽  
Experimental Performance ◽  
Finger Motion ◽  
User Friendly ◽  
Operation Characteristics

Abstract This paper presents a numerical and experimental validation of ExoFing, a two-degrees-of-freedom finger mechanism exoskeleton. The main functionalities of this device are investigated by focusing on its kinematic model and by computing its main operation characteristics via numerical simulations. Experimental tests are designed and carried out for validating both the engineering feasibility and effectiveness of the ExoFing system aiming at achieving a human index finger motion assistance with cost-oriented and user-friendly features.

scholarly journals A New Multiparameter Model for Multiaxial Fatigue Life Prediction of Rubber Materials

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1194
Author(s):  
Rafael Tobajas ◽  
Daniel Elduque ◽  
Elena Ibarz ◽  
Carlos Javierre ◽  
Luis Gracia
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Experimental Testing ◽  
Experimental Tests ◽  
Relevant Information ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Proposed Model ◽  
Predicted Values

Most of the mechanical components manufactured in rubber materials experience fluctuating loads, which cause material fatigue, significantly reducing their life. Different models have been used to approach this problem. However, most of them just provide life prediction only valid for each of the specific studied material and type of specimen used for the experimental testing. This work focuses on the development of a new generalized model of multiaxial fatigue for rubber materials, introducing a multiparameter variable to improve fatigue life prediction by considering simultaneously relevant information concerning stresses, strains, and strain energies. The model is verified through its correlation with several published fatigue tests for different rubber materials. The proposed model has been compared with more than 20 different parameters used in the specialized literature, calculating the value of the R2 coefficient by comparing the predicted values of every model, with the experimental ones. The obtained results show a significant improvement in the fatigue life prediction. The proposed model does not aim to be a universal and definitive approach for elastomer fatigue, but it provides a reliable general tool that can be used for processing data obtained from experimental tests carried out under different conditions.

scholarly journals Framework for Fast Experimental Testing of Autonomous Navigation Algorithms

2019 ◽  
Vol 9 (10) ◽  
pp. 1997 ◽  
Author(s):  
Miguel Á. Muñoz–Bañón ◽  
Iván del Pino ◽  
Francisco A. Candelas ◽  
Fernando Torres
Keyword(s):  
Autonomous Navigation ◽  
Mobile Robotics ◽  
Experimental Testing ◽  
Autonomous Systems ◽  
Experimental Tests ◽  
Basic Structure ◽  
Satellite System ◽  
Outdoor Environments ◽  
Global Navigation Satellite ◽  
Abstraction Levels

Research in mobile robotics requires fully operative autonomous systems to test and compare algorithms in real-world conditions. However, the implementation of such systems remains to be a highly time-consuming process. In this work, we present an robot operating system (ROS)-based navigation framework that allows the generation of new autonomous navigation applications in a fast and simple way. Our framework provides a powerful basic structure based on abstraction levels that ease the implementation of minimal solutions with all the functionalities required to implement a whole autonomous system. This approach helps to keep the focus in any sub-problem of interest (i.g. localization or control) while permitting to carry out experimental tests in the context of a complete application. To show the validity of the proposed framework we implement an autonomous navigation system for a ground robot using a localization module that fuses global navigation satellite system (GNSS) positioning and Monte Carlo localization by means of a Kalman filter. Experimental tests are performed in two different outdoor environments, over more than twenty kilometers. All the developed software is available in a GitHub repository.

Experimental Tests of I Profile Made from UHPC Reinforced with Textile Glass Fibres

2016 ◽  
Vol 249 ◽  
pp. 261-266
Author(s):  
Tomáš Bittner ◽  
Petr Bouška ◽  
Šárka Nenadálová ◽  
Milan Rydval ◽  
David Čítek
Keyword(s):  
Experimental Testing ◽  
Experimental Tests ◽  
Loading Capacity ◽  
Test Results ◽  
Glass Fibres ◽  
Material Characteristics ◽  
Recorded Data ◽  
Glass Reinforcement ◽  
Metal Wires ◽  
3D Profile

This abstract is summarizing production and subsequent experimental testing of 3D profile of the symmetrical I shape concrete from UHPC matrix and reinforced with textile glass fibres. Upper and bottom covering strips of this profile are at the outside fibres reinforced with textile glass reinforcement. Position of this reinforcement is fixed in the distance of about 3 mm from outside fibres and is connected with reinforcement of the profile stem located in its axis. Such prepared beams were tested with four-point flexure evenly loaded until fracture. Course of the measurement was continuously recorded by the automatic logger, where mostly increase of the force in relation to deflection in the middle of the span and change of position of supports were recorded. From the recorded data were prepared graphic outputs compared with the same experiments performed on I profile which is not reinforced, i.e. only UHPC matrix, and for comparison also on the profile made from UHPC matrix with use of metal wires. In the conclusion were compared achieved test results. Mainly suitability and loading capacity of individual beam types was compared. Within the experiment were performed supporting tests based on which were determined material characteristics of tested matrix and textile glass reinforcement. Tests were performed in the Klokner Institute within solution of the grant project GACŘ 13-12676S.

An Elaborate Data Set for Mechanical Characterization of the Foot

2008 ◽  
Author(s):  
Pavana Sirimamilla ◽  
Ahmet Erdemir ◽  
Antonie J. van den Bogert ◽  
Jason P. Halloran
Keyword(s):  
Mechanical Response ◽  
Experimental Testing ◽  
Experimental Tests ◽  
Shear Loading ◽  
Data Set ◽  
Material Response ◽  
Heel Pad ◽  
Biaxial Tests

Experimental testing of cadaver specimens is a useful means to quantify structural and material response of tissue and passive joint properties against applied loading[1,4]. Very often, specific material response (i.e., stress-strain behavior of a ligament or plantar tissue) has been the goal of experimental testing and is accomplished with uniaxial and/or biaxial tests of prepared tissue specimens with uniform geometries[2,5]. Material properties can then be calculated directly and if testing data involves individual sets of multiple loading modes (e.g. compression only, shear only, volumetric) an accurate representation of the global response of the specimen may be possible. In foot biomechanics, however, it is practically impossible to perform isolated mechanical testing in this manner. The structural response, therefore the stiffness characteristics, of the foot have been quantified, usually using a dominant loading mode: e.g., whole foot compression [6], heel pad indentation [3]. This approach ignores the complexity of most in vivo loading conditions, in which whole foot deformation involves interactions between compression, shear (e.g. heel pad) and tension (e.g. ligaments). Therefore, the purpose of this study was to quantify the mechanical response of a cadaver foot specimen subjected to compression and anterior-posterior (AP) shear loading of isolated heel and forefoot regions as well as whole foot compression. Results from the experimental tests represent a novel methodology to quantify a complete structural biomechanical response. Combined with medical imaging, followed by inverse finite element (FE) analysis, the data may also serve for material characterization of foot tissue.

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