Elastic–plastic characterization of microstructures through pull-in 4 point bending test

Somà, Aurelio; Saleem, Muhammad Mubasher

doi:10.1088/1361-6439/aaf60d

Cited by 4 publications

(5 citation statements)

References 45 publications

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“…Moreover, for the first three cycles the plastic zone is localized near the notch root, whereas further from this region the gold material remains unyielded and, thus, all the three specimens fully recovered to their initial positions after each loading cycle. As authors have already shown in [19], the progressive variation in the vertical deflection values of the three specimens each loading cycle can be attributed to the elasto-plastic behavior of the gold material with the initiation and progressive expansion of the plastic hinge in the critical locations of concentration, i.e. near the notch root of the specimens.…”

Section: Experimental Elasto-plastic Behavior Of the Notched Specimen...supporting

confidence: 55%

“…The Fogale-Zoomsurf 3D optical profiling system is based on non-contact optical interferometry. The recorded light intensity is detected by a CCD pixel as a function of the specimen height, thus defining either the profile of the monitored specimen or its vertical position [19]. The optical view of sample is converted to an elevation map using interferogram processing techniques.…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, the development of test structures at micro-scale is a challenging task due to the need to have a stress-free fabrication, gripping, correct alignment, and accurate loading of the specimens. To solve these issues, test microstructures have been designed, for both loading of the test specimens and measuring the corresponding deflection, on the same chip [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Study of notched MEMS specimen: elasto-plastic modeling and experimental testing

Somà¹,

Pistorio²,

Saleem³

2022

J. Micromech. Microeng.

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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.

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Section: Experimental Elasto-plastic Behavior Of the Notched Specimen...supporting

confidence: 55%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of notched MEMS specimen: elasto-plastic modeling and experimental testing

Somà¹,

Pistorio²,

Saleem³

2022

J. Micromech. Microeng.

Self Cite

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“…A test microstructure is specifically designed and built to characterize the fatigue fracture in gold-based MEMS notched specimen with on-chip testing. The design of the test microstructure, as well as its fabrication process and the advantages over other designs proposed in the literature, are extensively reported in authors' previous works [32,33,[45][46][47], thus just a brief description is given below for the sake of clarity.…”

Section: Test Microstructure Designmentioning

confidence: 99%

“…A summary of RFS microfabrication process steps is widely described in [28,50,51]. It is important to point out that the fabrication process is designed to limit the onset of residual stress, as explained in detail in previous authors' works [45,46,52]. The design of the test microstructure is addressed to correlate the degradation of the specimen stiffness due to cycling to the variation in the device deflection, as previously reported in [32,33,47].…”

Section: Test Microstructure Designmentioning

confidence: 99%

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

Pistorio

Somà

2023

J. Micromech. Microeng.

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The characterization of fatigue fracture mechanics in gold-MEMS notched specimens is presented in this work. A test microstructure with a central notched specimen is specifically designed and built to perform on-chip fatigue test. The central specimen undergoes cyclic loading due to the application of alternating voltage. The variation in the microstructure deflection is measured using an optical profilometer and is attributed to the crack growth in the gold material, causing the variation in the specimen stiffness. The occurrence of pull-in condition is used as a fracture detector, then the fracture of the specimen can be recognized without performing scanning electron microscope inspections during the fatigue test. Crack propagation in the test specimen is simulated through a coupled-field electromechanical fracture finite element model and the computed crack path is compared to the results obtained from scanning electron microscope analyses. Finally, Paris' law is applied and the number of cycles to failure is computed by exploiting the results of the fracture model and experimental measurements. Both experimental and numerical results demonstrate that the notch acts as a stress and strain raiser, fostering crack nucleation from the notch root, and that the linear elastic fracture mechanics theory is still valid to describe crack propagation in micro-size samples.

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A survey of Mechanical failure and design for Reliability of MEMS

Somà

2020

IOP Conf. Ser.: Mater. Sci. Eng.

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In this paper, several experimental mechanical investigation techniques are presented to evaluate the reliability of micro-electro-mechanical systems (MEMS). Microsystems in recent years have spread in many everyday devices. We find micro-scale sensors and actuators in automotive, biomedical and aerospace applications where are demanded very strict performance requirements. Electromechanical non-linear coupling is often a crucial problem both in design and also for the reliability of the system. Mechanism of failure and failure modes has to be taken into account in order to evaluate the reliability of the final system. Focusing on device failure, it emerges that mechanical damage is the most significant source. In this paper a survey of recent advance in mechanical testing of MEMS is presented including: mechanical fatigue, mechanical strength and plasticity, surface and contact failure and creep. Different design of testing specimens is discussed to identify the material properties and failure modes behavior in order to obtain design rules and strategies.

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Elastic–plastic characterization of microstructures through pull-in 4 point bending test

Cited by 4 publications

References 45 publications

Study of notched MEMS specimen: elasto-plastic modeling and experimental testing

Study of notched MEMS specimen: elasto-plastic modeling and experimental testing

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

A survey of Mechanical failure and design for Reliability of MEMS

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