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  • Feb
    21

    Level Excursion Analysis of Probabilistic Quasibrittle Fracture

    McCormick - Mechanical Engineering

    11:00 AM A230, Technological Institute

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    TAM Seminar Series Presents

    Speaker: Jia-Liang Le

    University of Minnesota

    Host: Professor Zdenek Bazant

    Abstract
    It is widely acknowledged that no structures can be designed to be risk free, and therefore reliability analysis plays a central role in the design of engineering structures. The recent focus has been placed on structures made of brittle heterogenous (a.k.a. quasibrittle) materials, such as ceramics, composites, concrete, and many more at the microscale. We recently developed a level excursion model for analyzing the probabilistic failure of quasibrittle structures, in which the structural failure statistics is calculated as a first passage probability. The main feature of the model is that it captures both the spatial randomness of local material resistance and the random stress field induced by microstructures (e.g. randomly distributed flaws). It is shown that the model represents a continuum generalization of the classical weakest-link model, which recovers the Weibull distribution as an asymptotic distribution function. In this talk, I will discuss two applications of this model:

    1) Modeling of strength distribution of polycrystalline silicon (poly-Si) MEMS structures based on 1D level excursion analysis. We show that the model agrees well with the experimentally measured strength distributions of poly-Si MEMS specimens of different sizes. The model predicts a complete size effect curve of the mean structural strength, which transitions from a vanishing size effect at the small-size limit to the classical Weibull size effect at the large-size limit.

    2) Investigation of the tail distribution of strength of brittle and quasibrittle structures by extending the level excursion analysis to high dimensions. We show that the power-law tail distribution of structural strength stems from the tail distribution of material strength. Flaw statistics introduces additional randomness to the overall failure statistics of the structure, but does not dictate the power-law form of its tail distribution.

    Biography
    Dr. Jia-Liang Le is currently an associate professor in the Department of Civil, Environmental, and Geo- Engineering at the University of Minnesota. He earned his Bachelor of Engineering (First Class Honors) and Master of Engineering from the National University of Singapore, and a Ph.D. in structural engineering from Northwestern University. He is a registered professional engineer and a member of ASCE, ACI and SES. His research interests include fracture mechanics, probabilistic mechanics, scaling, computational mechanics, and structural reliability. He received the Army Research Office Young Investigator Award, the EMI Leonardo da Vinci Award from the American Society of Civil Engineers, and the Society of Engineering Sciences Young Investigator Medal.

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    TIME Thursday, February 21, 2019 at 11:00 AM - 12:00 PM

    LOCATION A230, Technological Institute    map it

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    CONTACT Alison Rodriguez    alison.rodriguez@northwestern.edu EMAIL

    CALENDAR McCormick - Mechanical Engineering

  • Apr
    22

    ME512 Distinguished Speaker Seminar Marcia K. O'Malley

    McCormick - Mechanical Engineering (ME)

    3:00 PM LR3, Technological Institute

    EVENT DETAILS

    TIME Monday, April 22, 2024 at 3:00 PM - 4:00 PM

    LOCATION LR3, Technological Institute    map it

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    CONTACT Jeremy Wells    jeremywells@northwestern.edu EMAIL

    CALENDAR McCormick - Mechanical Engineering (ME)

  • Apr
    30

    ME Alumni Seminar Series- Apostolos Karafillis

    McCormick - Mechanical Engineering (ME)

    2:00 PM 1.350, Ford Motor Company Engineering Design Center

    EVENT DETAILS

    TIME Tuesday, April 30, 2024 at 2:00 PM - 3:00 PM

    LOCATION 1.350, Ford Motor Company Engineering Design Center    map it

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    CONTACT Jeremy Wells    jeremywells@northwestern.edu EMAIL

    CALENDAR McCormick - Mechanical Engineering (ME)

  • May
    3

    Russ Tedrake, MIT and Toyota Research Institute, "Dexterous Manipulation with Diffusion Policies"

    Center for Robotics and Biosystems (CRB)

    11:30 AM M416, Technological Institute

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    TIME Friday, May 3, 2024 at 11:30 AM - 12:30 PM

    LOCATION M416, Technological Institute    map it

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    CONTACT Amy Nedoss    amy.nedoss@northwestern.edu EMAIL

    CALENDAR Center for Robotics and Biosystems (CRB)

  • May
    8

    Extending Care: A Conversation about Conservation and Futurity

    Block Museum of Art

    6:00 PM Block Museum of Art, Mary and Leigh

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    TIME Wednesday, May 8, 2024 at 6:00 PM - 7:30 PM

    LOCATION Block Museum of Art, Mary and Leigh    map it

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    CONTACT Block Museum of Art    block-museum@northwestern.edu EMAIL

    CALENDAR Block Museum of Art

  • Jun
    10

    Northwestern Engineering PhD Hooding and Master's Degree Recognition Ceremony

    McCormick School of Engineering and Applied Science

    9:00 AM Welsh-Ryan Arena

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    TIME Monday, June 10, 2024 at 9:00 AM - 11:00 AM

    LOCATION Welsh-Ryan Arena   

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    CONTACT Amy Pokrass    amy.pokrass@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science

  • Jun
    10

    Northwestern Engineering Undergraduate Convocation

    McCormick School of Engineering and Applied Science

    2:00 PM Welsh-Ryan Arena

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    TIME Monday, June 10, 2024 at 2:00 PM - 4:00 PM

    LOCATION Welsh-Ryan Arena   

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    CONTACT Amy Pokrass    amy.pokrass@northwestern.edu EMAIL

    CALENDAR McCormick School of Engineering and Applied Science