A novel method combining Monte Carlo–FEM simulations and experiments for simultaneous evaluation of the ultrathin film mass density and Young׳s modulus

Zapoměl, Jaroslav; Stachiv, Ivo; Ferfecki, Petr

doi:10.1016/j.ymssp.2015.06.022

Cited by 11 publications

(7 citation statements)

References 21 publications

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“…where u * is the local coordinate in the lateral direction, i is the i-th region of cantilever beam cross section [36]. The general form of the hydrodynamic force obtained by solving the Fourier-transformed continuity and Navier-Stokes equations (i.e., computations are in the time domain Fourier-transform), for an incompressible fluid as…”

Section: Flexural Oscillations Of Two-layered (Multi-layered) Microcamentioning

confidence: 99%

“…The resonant frequency and Q-factor of a two(multi)-layered microcantilever vibrating in air can be obtained in the same way as done in the previous section for flexural oscillations. Briefly, by accounting for the membrane analogy proposed by Prandtl in 1903, similarities with the theoretical model for flexural oscillations of a multilayered beam in vacuum given in Zapomel et al [36] and theory of Green and Sader [41], the general governing equation and boundary conditions for torsional oscillations of a two-layered microcantilever (see Figure 1b) operating in air takes the following form:…”

Section: Torsional Oscillations Of Two-layered (Multi-layered) Microcmentioning

confidence: 99%

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Simple Non-Destructive Method of Ultrathin Film Material Properties and Generated Internal Stress Determination Using Microcantilevers Immersed in Air

Stachiv

Gan

2019

Coatings

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Recent progress in nanotechnology has enabled to design the advanced functional micro-/nanostructures utilizing the unique properties of ultrathin films. To ensure these structures can reach the expected functionality, it is necessary to know the density, generated internal stress and the material properties of prepared films. Since these films have thicknesses of several tens of nm, their material properties, including density, significantly deviate from the known bulk values. As such, determination of ultrathin film material properties requires usage of highly sophisticated devices that are often expensive, difficult to operate, and time consuming. Here, we demonstrate the extraordinary capability of a microcantilever commonly used in a conventional atomic force microscope to simultaneously measure multiple material properties and internal stress of ultrathin films. This procedure is based on detecting changes in the static deflection, flexural and torsional resonant frequencies, and the corresponding quality factors of the microcantilever vibrating in air before and after film deposition. In contrast to a microcantilever in vacuum, where the quality factor depends on the combination of multiple different mechanical energy losses, in air the quality factor is dominated just by known air damping, which can be precisely controlled by changing the air pressure. Easily accessible expressions required to calculate the ultrathin film density, the Poisson’s ratio, and the Young’s and shear moduli from measured changes in the microcantilever resonant frequencies, and quality factors are derived. We also show that the impact of uncertainties on determined material properties is only minor. The validity and potential of the present procedure in material testing is demonstrated by (i) extracting the Young’s modulus of atomic-layer-deposited TiO2 films coated on a SU-8 microcantilever from observed changes in frequency response and without requirement of knowing the film density, and (ii) comparing the shear modulus and density of Si3N4 films coated on the silicon microcantilever obtained numerically and by present method.

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Section: Flexural Oscillations Of Two-layered (Multi-layered) Microcamentioning

confidence: 99%

Section: Torsional Oscillations Of Two-layered (Multi-layered) Microcmentioning

confidence: 99%

Simple Non-Destructive Method of Ultrathin Film Material Properties and Generated Internal Stress Determination Using Microcantilevers Immersed in Air

Stachiv

Gan

2019

Coatings

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“…For the vibrational amplitude that is much smaller than any of the cantilever length scale, the governing equation for the elastic deformation of the multilayered cantilever beam performing the flexural oscillations takes the following general form [ 45 ]:

…”

Section: Theorymentioning

confidence: 99%

Nanocantilevers with Adjustable Static Deflection and Significantly Tunable Spectrum Resonant Frequencies for Applications in Nanomechanical Mass Sensors

Stachiv

Šittner

2018

Nanomaterials

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Nanocantilevers have become key components of nanomechanical sensors that exploit changes in their resonant frequencies or static deflection in response to the environment. It is necessary that they can operate at a given, but adjustable, resonant frequency and/or static deflection ranges. Here we propose a new class of nanocantilevers with a significantly tunable spectrum of the resonant frequencies and changeable static deflection utilizing the unique properties of a phase-transforming NiTi film sputtered on the usual nanotechnology cantilever materials. The reversible frequency tuning and the adjustable static deflection are obtained by intentionally changing the Young’s modulus and the interlayer stress of the NiTi film during its phase transformation, while the usual cantilever elastic materials guarantee a high frequency actuation (up to tens of MHz). By incorporating the NiTi phase transformation characteristic into the classical continuum mechanics theory we present theoretical models that account for the nanocantilever frequency shift and variation in static deflection caused by a phase transformation of NiTi film. Due to the practical importance in nanomechanical sensors, we carry out a complete theoretical analysis and evaluate the impact of NiTi film on the cantilever Young’s modulus, static deflection, and the resonant frequencies. Moreover, the importance of proposed NiTi nanocantilever is illustrated on the nanomechanical based mass sensors. Our findings will be of value in the development of advanced nanotechnology sensors with intentionally-changeable physical and mechanical properties.

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“…Of course, this is not the only possible approach, there are other computational methods, such as RBD analysis, 7 Markov analysis, 8 and Monte Carlo method, which is also successfully utilized in the area of functional safety probabilistic assessment of mechanical components. 9,10 The important part of vehicle safety also by mechanical components must be covered, 11,12 but this important problematic is not described in this paper. Also, the utilization of random vector as a very suitable computational method for functional safety assessment is possible.…”

mentioning

confidence: 99%

Application of hardware reliability calculation procedures according to ISO 26262 standard

Famfulík

Richtář

Rehak

et al. 2020

Quality & Reliability Eng

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The second edition of standard ISO 26262 (ed. 2018) for functional safety assessment in the automotive industry requires a hardware evaluation using the probabilistic metric for random hardware failures (P MHF). The standard for mentioned purpose highly recommends the fault tree analysis (FTA) utilization but does not give any specific calculation example. Therefore, this article describes computational procedures with derivation and explanation of mathematical formulas for various hardware architectures of electronic systems. Described formulas consider impact of multiple failures and impact of elf-tests, but formulas are relatively simple. This simplicity allows them to be used in the early stages of hardware development when frequent hardware design changes can be expected. Thus, the article with attached case study is intended not only for scientists but also for developers of critical safety-related electronic systems in the automotive industry. K E Y W O R D S car functional safety, fault tree analysis (FTA), hardware assessment, hardware development, ISO 26262, P MHF 1 | INTRODUCTION As in all other areas of industry, the number of electronic systems in car design is constantly growing. This is closely related to the implementation of industry standards in the field of functional safety, based on the principles described in the basic safety standard EN 61508. In the automotive industry, standard ISO 26262:2018 is already established for vehicles up to 3.5 tons. One of the objectives of this standard is to adjust the procedures for Automotive Safety Integrity Level (ASIL) assessment. Generally, standard ISO 26262 assumes for electrical/electronic systems possibility of occurrence of two types of failures, the systematic failures and the random failures, and standard also sets the procedures for failures elimination. However, random failures cannot be completely eliminated, because of their stochastic nature, but it is possible to assess their expected frequency, respectively probability of occurrence, by applying appropriate computational methods. The standard requirement for validation of hardware of assessed system according to ISO 26262 is to perform a quantitative analysis to demonstrate compliance with specific target values depending on the desired ASIL level in two areas. The first area is the diagnostic coverage, thus the ability to detect dangerous system failures robustly and timely. Diagnostic coverage procedures are well described in ISO 26262 and are complemented by a sample example to help developers. Therefore, in the article, this issue will only be mentioned to the extent necessary to understand other texts.

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A novel method combining Monte Carlo–FEM simulations and experiments for simultaneous evaluation of the ultrathin film mass density and Young׳s modulus

Cited by 11 publications

References 21 publications

Simple Non-Destructive Method of Ultrathin Film Material Properties and Generated Internal Stress Determination Using Microcantilevers Immersed in Air

Simple Non-Destructive Method of Ultrathin Film Material Properties and Generated Internal Stress Determination Using Microcantilevers Immersed in Air

Nanocantilevers with Adjustable Static Deflection and Significantly Tunable Spectrum Resonant Frequencies for Applications in Nanomechanical Mass Sensors

Application of hardware reliability calculation procedures according to ISO 26262 standard

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