TITLE:

Ensuring Mesh Objectivity in Multiscale Progressive Failure Analysis of Advance Composites

DATE:

Friday, February 24th, 2017

TIME:

3:30 PM

LOCATION:

GMCS 314

SPEAKER:

Dr. Evan Pineda, Aerospace Research Engineer at NASA Glenn Research Center.

ABSTRACT:

Composite materials contain numerous inherent length scales. The globally observed damage and failure mechanisms are a culmination of the mechanisms that accrue at the lower scales. Moreover, the damage mechanisms are highly interactive at and across multiple length scales. Thus, multiscale modeling is a useful computational tool for progressive failure analysis (PFA) of composite materials and structures. However a prominent challenge in PFA is the numerical modeling of failure due to strain localization. When strain localization is present, special energetic considerations must be made at and across the various length scales in the model to avoid pathological (non-convergent) mesh dependence.

In this presentation, an overview of multiscale modeling strategies is given (hierarchical, concurrent, and synergistic). Then, the use of NASA’s Integrated Multiscale Micromechanics Analysis Code (ImMAC) software suite, which utilizes the generalized method of cells (GMC) and high fidelity GMC (HFGMC) micromechanics theories, for PFA is demonstrated at the microscale and across two scales. The focus of this work is ensuring mesh objectivity when there is strain localization. As such, a method for regularizing the energy dissipated during failure (crack band theory) is presented. Moreover, a homogenization (“handshaking”) technique for ensuring proper energy preservation across disparate length scales is postulated.

HOST:

Dr. Satchi Venkataraman

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