Monte Carlo simulation of effective elastic constants of polycrystalline thin films

Mullen, Robert L.; Ballarini, Roberto; Yin, Yue; Heuer, A. H.

doi:10.1016/s1359-6454(96)00366-7

Cited by 90 publications

(60 citation statements)

References 2 publications

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“…Given the 650 nm average grain size of SUMMiT polysilicon, a material domain that includes 15x15=225, or more, columnar grains behaves isotropically with a statistical scatter of less than 5%. This experimental assessment of the RVE is in agreement with computational results in [15] for <100> textured polysilicon. It also provides a measure of the number of grains in the RVE rather than an absolute length scale which could be used to obtain estimates for the physical size of an RVE of polysilicon with different grain size but the same grain structure and orientation distributions as the samples used here.…”

Section: Cu-j)supporting

confidence: 87%

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Fatigue and Fracture of Polycrystalline Silicon and Diamond MEMS at Room and Elevated Temperatures

Chasiotis¹

2006

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2 14. ABSTRACT A high-resolution Atomic Force Microscopy (AFM)/Digital Image Correlation (DIC) method was developed to investigate the deformation and fracture of tetrahedral amorphous diamond-like carbon (ta-C) and polycrystalline silicon (polysilicon) for microelectromechanical systems (MEMS). Polysilicon and ta-C test structures were fabricated at the Sandia National Laboratories (SNL) and at MCNC-Cronos. Their Young's modulus, Poisson's ratio, strength, and fracture toughness were obtained, many of them for the first time. Compared to polysilicon, ta-C was found to have superior mechanical properties: Its fracture toughness and strength were 3.5 times and two times that of polysilicon, respectively. Its elastic modulus was 4.5 times that of polysilicon and its Poisson's ratio was 30% smaller than polysilicon. The mode I and mixed mode I/I fracture toughness of polysilicon showed 50% scatter due to its polycrystallinity. On the contrary, the mixed mode I/I fracture of the amorphous ta-C was described wellf by deterministic theories for brittle fracture. The stochastic failure of polysilicon was treated by a finite element model that combined NASA's code CARES Life (Ceramics Analysis and Reliability Evaluation of Structures Life). This model provided failure predictions for devices with arbitrary geometries. Finally, the multi-grain nature of polysilicon was found to present a potential risk in the accurate determination of its effective mechanical behavior, especially in MEMS with dimensions equal to a small multiple of the grain size. In general, devices with dimensions larger than 15x 15 grains can be described by using the isotropic properties reported in literature and presented in this report. DI-STRIBUT1O•! STAT,47EWTAApproved for Public Release Distribution Unlimited SUMMARY A high-resolution experimental method was developed to investigate the deformation and fracture properties of tetrahedral amorphous diamond-like carbon (ta-C) and polycrystalline silicon (polysilicon) for microelectromechanical systems (MEMS). The method employed an Atomic Force Microscope (AFM) to record stra...

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Section: Cu-j)supporting

confidence: 87%

“…, [14], while according to [15] when the specimen contains less than 200 grains crystalline anisotropy becomes important resulting in statistical variation of the measured properties.…”

Section: Xmentioning

confidence: 99%

Fatigue and Fracture of Polycrystalline Silicon and Diamond MEMS at Room and Elevated Temperatures

Chasiotis¹

2006

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“…[55][56][57] A lot of average isotropic elastic moduli for isotropic polycrystalline materials have been calculated using the Voigt-Reuss-Hill averaging scheme from the elastic stiffness coefficients of the single crystals that were determined not only from the firstprinciples calculations but also from the experimental mesuments. 27,[35][36][37][38][39][40][41][52][53][54][55][57][58][59] In many cases, the values of the average isotropic elastic moduli have been in good agreement with the values measured on polycrystalline specimens experimentally. [53][54][55] However, they were not always in good agreement with the experimental values.…”

Section: Resultsmentioning

confidence: 99%

Elastic Constants of AlLi from First Principles

2005

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The elastic stiffness coefficients of single crystal AlLi with cubic NaTl (B32) structure were calculated at 0 K from the first principles. The obtained elastic stiffness coefficients, in units of GPa, were c 11 ¼ 66:9, c 12 ¼ 38:2 and c 44 ¼ 51:7. Then the bulk modulus, Young's modulus, shear modulus and Poison's ratio were estimated for polycrystalline AlLi from the elastic stiffness coefficients. The Young's modulus for single crystal AlLi was the highest in the h111i direction. The formation of the sp 3 -like bond connecting the nearest-neighbor Al atoms was confirmed from the charge density distribution. The elastic anisotropy of AlLi was compared with those of the sp 3 bonded semiconductors such as Si and GaAs.

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“…In particular, it has been shown that auxetic behavior can be achieved in a variety of highly porous materials [10], including foams with re-entrant [11][12][13][14][15] and chiral [16,17] microstructure, microporous polymeric materials [18], networks of rigid units [19] and skeletal structures [20]. Moreover, negative Poisson's ratio has also been shown in non-porous systems, such as laminates [21,22], sheets assemblies of carbon nanotubes [23], composites [24] and polycrystalline thin films [25].…”

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confidence: 99%

Low Porosity Metallic Periodic Structures with Negative Poisson's Ratio

et al. 2013

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Auxetic behavior in low porosity metallic structures is demonstrated via a simple system of orthogonal elliptical voids. In this minimal 2D system, the Poisson's ratio can be effectively controlled by changing the aspect ratio of the voids. In this way, large negative values of Poisson's ratio can be achieved, indicating an effective strategy for designing auxetic structures with desired porosity.

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Monte Carlo simulation of effective elastic constants of polycrystalline thin films

Cited by 90 publications

References 2 publications

Fatigue and Fracture of Polycrystalline Silicon and Diamond MEMS at Room and Elevated Temperatures

Fatigue and Fracture of Polycrystalline Silicon and Diamond MEMS at Room and Elevated Temperatures

Elastic Constants of AlLi from First Principles

Low Porosity Metallic Periodic Structures with Negative Poisson's Ratio

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