Nonlinear Phenomena in the Single-Mode Dynamics in an AFM Cantilever Beam

2016 ◽  
Author(s):  
Laura Ruzziconi ◽  
Stefano Lenci ◽  
Mohammad I. Younis
Keyword(s):  
Numerical Simulations ◽  
Cantilever Beam ◽  
Separation Distance ◽  
Global Perspective ◽  
Structural Safety ◽  
Nonlinear Phenomena ◽  
Practical Case ◽  
Dynamical Integrity ◽  
Sample Separation ◽  
Integrity Analysis

This study deals with the nonlinear dynamics arising in an atomic force microscope cantilever beam. After analyzing the static behavior, a single degree of freedom Galerkin reduced order model is introduced, which describes the overall scenario of the structure response in a neighborhood of the primary resonance. Extensive numerical simulations are performed when both the forcing amplitude and frequency are varied, ranging from low up to elevated excitations. The coexistence of competing attractors with different characteristics is analyzed. Both the non-resonant and the resonant behavior are observed, as well as ranges of inevitable escape. Versatility of behavior is highlighted, which may be attractive in applications. Special attention is devoted to the effects of the tip-sample separation distance, since this aspect is of fundamental importance to understand the operation of an AFM. We explore the metamorphoses of the multistability region when the tip-sample separation distance is varied. To have a complete description of the AFM response, comprehensive behavior charts are introduced to detect the theoretical boundaries of appearance and disappearance of the main attractors. Also, extensive numerical simulations investigate the AFM response when both the forcing amplitude and the tip-sample separation distance are considered as control parameters. The main features are analyzed in detail and the obtained results are interpreted in terms of oscillations of the cantilever-tip ensemble. However, we note that all the aforementioned results represent the limit when disturbances are absent, which never occurs in practice. Here comes the importance of overcoming local investigations and exploring dynamics from a global perspective, by introducing dynamical integrity concepts. To extend the AFM results to the practical case where disturbances exist, we develop a dynamical integrity analysis. After performing a systematic basin of attraction analysis, integrity profiles and integrity charts are drawn. The curves of constant percentage of integrity measure are detected, highlighting that they provide valuable quantitative information about the changes in the structural safety. Robustness as well as vulnerability to disturbances is examined. The practical range of existence of each branch is observed to be smaller, and sometimes remarkably smaller than the theoretical one. The issue of the dynamical integrity analysis in the AFM design is addressed, showing that these curves may be used to establish safety factors in order to operate the AFM according to the desired outcome, depending on the expected disturbances. Physical meaning and practical relevance of the nonlinear phenomena in the AFM engineering design are discussed.

AN IMPERFECT MICROBEAM UNDER AN AXIAL LOAD AND ELECTRIC EXCITATION: NONLINEAR PHENOMENA AND DYNAMICAL INTEGRITY

2013 ◽  
Vol 23 (02) ◽  
pp. 1350026 ◽  
Author(s):  
LAURA RUZZICONI ◽  
STEFANO LENCI ◽  
MOHAMMAD I. YOUNIS
Keyword(s):  
Axial Load ◽  
Single Mode ◽  
Quantitative Information ◽  
Structural Safety ◽  
Nonlinear Phenomena ◽  
Practical Case ◽  
Electric Excitation ◽  
Dynamic Voltage ◽  
Final Response ◽  
Dynamical Integrity

This work deals with the nonlinear dynamics of a microelectromechanical system constituted by an imperfect microbeam under an axial load and an electric excitation. The device is characterized by a bistable static configuration. We analyze the single-mode dynamics and describe the overall scenario of the response, up to the inevitable escape, when both the frequency and the electrodynamic voltage are considered as driving parameters. We observe the presence of several competing attractors leading to a considerable versatility of behavior, which may have many feasible applications. Extensive numerical simulations are performed. The frequency-dynamic voltage behavior chart is obtained, which detects the theoretical boundaries of appearance and disappearance of the main attractors. Taking into account the erosion of the double well, we investigate the final response when each attractor vanishes. All these results represent the limit when disturbances are absent, which never occurs in practice. To extend them to the practical case where disturbances exist, we develop a dynamical integrity analysis. This is performed via curves of constant percentage of local integrity measure, which give quantitative information about the changes in the structural safety. For each attractor, we examine both the practical disappearance, by analyzing the robustness of its basin along the range of existence, and the practical final response, by detecting where safe jump to another attractor may be ensured and where instead dynamic pull-in may arise. These curves may be used to establish safety factors in order to operate the device according to the desired outcome, depending on the expected disturbances.

Occupational and Environmental Health

2017 ◽  
Keyword(s):  
Public Health ◽  
Occupational Health ◽  
Environmental Health ◽  
Health And Safety ◽  
Practical Experience ◽  
Global Perspective ◽  
Clear Understanding ◽  
Practical Case ◽  
Environmental Sciences ◽  
Wide Range

This thoroughly updated seventh edition is a comprehensive, clearly written, and practical textbook that includes information on both occupational health and environmental health, providing the necessary foundation for recognizing and preventing work-related and environmentally induced diseases and injuries. National and international experts share their knowledge and practical experience in addressing a wide range of issues and evolving challenges in their fields. A multidisciplinary approach makes this an ideal textbook for students and practitioners in public health, occupational and environmental medicine, occupational health nursing, epidemiology, toxicology, occupational and environmental hygiene, safety, ergonomics, environmental sciences, and other fields. Comprehensive coverage provides a clear understanding of occupational and environmental health and its relationships to public health, environmental sciences, and government policy. Practical case studies demonstrate how to apply the basic principles of occupational and environmental health to real-world challenges. Numerous tables, graphs, and photographs reinforce key concepts. Annotated Further Reading sections at the end of chapters provide avenues for obtaining further infomation. This new edition of the book is thoroughly updated and also contains new chapters on climate change, children’s environmental health, liver disorders, kidney disorders, and a global perspective on occupational health and safety.

scholarly journals Ventilated cladding systems: structural and drainability performance criteria

2018 ◽  
Vol 18 (3) ◽  
pp. 341-358 ◽  
Author(s):  
Luiz Fernando Batista da Silva ◽  
Ercio Thomaz ◽  
Luciana Alves de Oliveira
Keyword(s):  
Vertical Wall ◽  
Impact Resistance ◽  
Residential Building ◽  
Test Methods ◽  
Performance Criteria ◽  
Structural Safety ◽  
Practical Case ◽  
Performance Requirements ◽  
Efficient Measure ◽  
Building Facades

Abstract Cladding systems have significant effect on the performance and durability of building façades, contributing to the building watertightness, property valuation, aesthetic finishing, and decoration. Non-adherent cladding, also named rainscreen cladding or ventilated cladding, is currently used in residential and commercial buildings, new constructions, or retrofit operations, and it is considered an efficient measure to improve the moisture safety of building envelopes. Therefore, the absence of Brazilian normalization to ventilated cladding systems is one of the difficulties limiting its increased local application. In Brazil, a technical standard, NBR 15575, parts 1-6, (2013), establish the general performance requirements and test methods to evaluate residential building systems including structure, wall, floor, coverage, and hydraulic installation. However, this standard cannot be integrally applied to the cladding systems because it was developed considering the vertical wall system as a whole. In this study, we propose the criteria and test methods for assessing ventilated cladding systems while taking into account the structural safety (wind loads resistance, hard and soft impact resistance) and drainability requirements. The following activities are performed: literature review, practical case study, and tests on prototypes for validation of the proposal. The tests allow verification of the feasibility of the criteria and tests methods proposed. In addition, the proposal makes it possible to guide design, construction, and maintenance needs, thereby inducing the growth of this technology in Brazil.

Identification and Analysis of Artifacts in Amplitude Modulated Atomic Force Microscopy Array Operation

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
Samuel Jackson ◽  
Stefanie Gutschmidt
Keyword(s):  
Atomic Force Microscopy ◽  
Separation Distance ◽  
Constant Frequency ◽  
Single Beam ◽  
Force Microscopy ◽  
Atomic Force ◽  
Close Proximity ◽  
Output Amplitude ◽  
Sample Separation ◽  
The Relationship

To increase measurement throughput of atomic force microscopy (AFM), multiple cantilevers can be placed in close proximity to form an array for parallel throughput. In this paper, we have measured the relationship between amplitude and tip-sample separation distance for an array of AFM cantilevers on a shared base actuated at a constant frequency and amplitude. The data show that discontinuous jumps in output amplitude occur within the response of individual beams. This is a phenomenon that does not occur for a standard, single beam system. To gain a better understanding of the coupled array response, a macroscale experiment and mathematical model are used to determine how parameter space alters the measured amplitude. The results demonstrate that a cusp catastrophe bifurcation occurs due to changes in individual beam resonant frequency, as well as significant zero-frequency coupling at the point of jump-to-contact. Both of these phenomena are shown to account for the amplitude jumps observed in the AFM array.

scholarly journals Study on the impulsive pressure of tank oscillating by force towards multiple degrees of freedom

2018 ◽  
Vol 180 ◽  
pp. 02034
Author(s):  
Shigeyuki Hibi
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Experimental Results ◽  
Nonlinear Phenomena ◽  
Multiple Degrees Of Freedom ◽  
Impulsive Loads ◽  
Impulsive Pressure ◽  
Specific Phase ◽  
Fft Analysis ◽  
Phase Differences

Impulsive loads should be excited under nonlinear phenomena with free surface fluctuating severely such as sloshing and slamming. Estimating impulsive loads properly are important to recent numerical simulations. But it is still difficult to rely on the results of simulations perfectly because of the nonlinearity of the phenomena. In order to develop the algorithm of numerical simulations experimental results of nonlinear phenomena are needed. In this study an apparatus which can oscillate a tank by force was introduced in order to investigate impulsive pressure on the wall of the tank. This apparatus can oscillate it simultaneously towards 3 degrees of freedom with each phase differences. The impulsive pressure under the various combinations of oscillation direction was examined and the specific phase differences to appear the largest peak values of pressure were identified. Experimental results were verified through FFT analysis and statistical methods.

A Comparative Study on the Impact Damage of Membrane Type LNGC Insulation System

2009 ◽  
Author(s):  
Min Sung Chun ◽  
Yong Suk Seo ◽  
Ito Hisasi ◽  
Wha Soo Kim ◽  
Byeong Jae Noh ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Failure Mode ◽  
Impact Load ◽  
Impact Damage ◽  
Structural Response ◽  
Structural Safety ◽  
Structural Behavior ◽  
Insulation System ◽  
Membrane Type ◽  
The Impact

To verify the structural safety under impact load caused by sloshing of LNG is one of the main issues in the design of membrane type LNG cargo containment system of LNG carrier. In order to estimate structural response under sloshing impact load, many kinds of studies including experimental test and numerical simulation have been done by various research groups such as shipyards, oil companies, universities as well as classification societies. In spite of these efforts, many uncertainties still exist to predict the structural behavior of LNG insulation system under sloshing impact load. Therefore, it can be regarded as a challenge to investigate dynamic response of LNG cargo insulation system against sloshing load. In this paper, Cooperative research results obtained by SHI-HHI-PNU-Lloyd-ABS-DNV JDP focused on the impact damage or failure mode of membrane type LNG cargo insulation system are summarized. A systematic experimental research is carried out to find out failure mode of the insulation system under impact load and criteria which can be applied for the design of LNG carrier. A series of dry drop tests as well as static compressive tests are carried out. The structural behavior of the specimen under impact load is recorded using ultrahigh-speed camera and reaction force is measured using load cells which are installed under bottom of the test facility. By analyzing recorded video, deformation history of the specimen at impact moment is obtained. The numerical simulations are also carried out for the dry drop test for verification purpose, It is expected that the insights observed from the systematic experiments and numerical simulations for the structural response of the LNG cargo insulation system subjected to the impact load can be effectively used as design guide for evaluation of the integrity of structural components of LNG cargo hold system.

Metal whisker growth induced by localized, high-intensity DC electric fields

MRS Advances ◽  
2018 ◽  
Vol 3 (57-58) ◽  
pp. 3367-3372
Author(s):  
Vamsi Borra ◽  
Osama Oudat ◽  
Daniel G. Georgiev ◽  
Victor G. Karpov ◽  
Diana Shvydka
Keyword(s):  
Electric Fields ◽  
Whisker Growth ◽  
Dielectric Breakdown ◽  
Extended Period ◽  
Growth Direction ◽  
Separation Distance ◽  
Vertical Orientation ◽  
Conductive Afm ◽  
Sample Separation ◽  
Very High

ABSTRACTIn this work, a very high, locally applied electric field was used to induce whisker nucleation on an Sn film. The field was generated by using a conductive AFM tip and applying a voltage bias between the sample and the conductive cantilever. The tip-sample separation distance was thus controllable, and any dielectric breakdown could be avoided. At locations where the AFM tip was positioned for an extended period, minuscule whiskers were observed, whose growth direction matched vertical orientation of the field.

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