A New Cohesive Parametric High-Fidelity-Generalized-Method-of-Cells Micromechanical Model
"ZOOM" SEMINAR
SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Monday, December 28, 2020 at 14:00
A New Cohesive Parametric High-Fidelity-Generalized-Method-of-Cells Micromechanical Model
Ido Meshi
Ph.D. student under the supervision of Prof. Rami Haj-Ali
According to the U.S. Department of commerce, advanced composite structures are at the forefront of innovative solutions for the challenges facing leading industries and communities, e.g. rebuilding old infrastructure, building new climate resilience public utilities, and improving the fuel-efficiency of airplanes and vehicles. The main advantage of composites is their light weight and increased strength compared to traditional materials.
Accurate local and global analysis of mechanical behavior of composites, including damage under various loading conditions, is critical to predicting material and structural performance and durability. It is customary to classify damage in composites by location of occurrence, such as fiber and matrix intra-laminar modes, and delamantion as inter-laminar. However, damage progression emanating at fiber-matrix interfaces is also critical as it can significantly reduce the load-carrying capacity of the material and structure. To that end, the Parametric High-Fidelity-Generalized-Method-of-Cells (PHFGMC) micromechanical model, Haj-Ali and Aboudi (2013), is extended to include cohesive zone models and intra-laminar damage. The nonlinear PHFGMC is a dedicated micromechanical method, extending its HFGMC predecessor. The microstructure is discretized into volumetric subcells that form the repeating unit cell (RUC) and representing the composite's periodic microstructure. The traction and displacement continuity between the subcells are satisfied in an average sense. The direct incremental formulation has been developed in the past. In the current formulation, the linearized governing equations are obtained from a virtual work principle applied to both the local and far-field variables and solved using a new incremental-iterative formulation. The proposed formulation yields an overall symmetric system of equations and also enables the implementation of advanced traction-separation laws available in the literature. The material and cohesive properties are calibrated with experimental data. Predictions of the cohesive PHFGMC for damage initiation, its evolution, and the overall stress-strain response are shown to be in good agreement with those from a finite-element (FE) analysis for various structural configurations and loading patterns.
In addition, a multiscale FE-PHFGMC analysis is formulated and implemented to complement the Cohesive PHFGMC for compression loading. This is necessary since no damage occurs on the repeating-unit-cell level and since the kink-band is a mesoscale phenomenon. The multiscale model predicts the strength and damage evolution under compression and multi-axial loading of a multi-directional laminate. The predicted values are compared to experimental results.
https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09 The meeting will be recorded and made available on the School’s site.
