Recently we published a paper in Composite Structures. It can be freely downloaded from the link

http://authors.elsevier.com/a/1RGr0x-7hNgCX

Abstract of the article is below:

Inclusions in short fiber reinforced composites (SFRC) suffer from debonding and cannot be directly modeled using Eshelby based mean field methods. This paper proposes a method of treatment of inclusions with debonded interface by replacing them with a fictitious “equivalent bonded inclusion” (EqBI) whose properties are calculated based on the reduced load bearing capacity of the inclusion due to the debonded interface. Approximate expressions are derived for stress redistribution in an inclusion due to the presence of debonded interface for the six elementary loading cases and the corresponding terms in the stiffness tensor are estimated as a function of the reduced average stress in the inclusion. Mechanical equivalence of the EqBI is confirmed by comparison with finite element models having inclusions with debonded interface and the overall stress strain response of a SFRC composite is validated against experimental data.

Comments and feedback are welcome

Liu, M., & Chen, C. (2015). A micromechanical analysis of the fracture properties of saturated porous media. International Journal of Solids and Structures, 63, 32-38.

Abstract: A two-dimensional single edge crack problem is employed to investigate the fracture behavior of saturated poroelastic media. The media are mimicked by a micromechanical model consisting of elastic matrix and square arrays of voids with prescribed uniform pore pressure. Finite element method is used to simulate the fracture responses of the model subject to remote stress and pore pressure loading. The stress extrapolation method is extended for the porous media to calculate the nominal stress intensity factor (SIF) from the crack tip stress field. By adopting the tensile strength criterion and assuming either brittle or ductile failure of the constituent solid skeleton of the porous media, lower and upper bounds of the fracture toughness are obtained. Theoretical expressions for the stress intensity factor and the toughness are derived, agreeing well with numerical results. The effects of the arrangement of pores and the non-uniform pore pressure on the cracking of porous media are discussed and are found to only have moderate effects on the obtained results.

Hello All,

I am new to the field of Micromechanincs and continum mechanics and my first assignment is FEM modeling of a unit cell or RVE using abaqus. My RVE is rectangular matrix with single fiber in the centre. No symmetry is being used. I have read research papers and the general principal seen was using normal and shear loads individually on unit cell to obtain colums of stiffness matrix. But, as always, none of the research paper talked of ground rules or step by step approach towards finding a constitutive law from a micromechanics analysis.
This may seem trivial, but for a started like me, is a conundrem and can save me lot of time that i can use to explore continum mechanics.
so can we establish a step by step approach for newbess.

looking forward to replies...

I am interested in developing a global-local finite element model (micro/macro) to simulate flexural testing of a composite material. Flexural loading will be applied on global model (macro) and crack propagation will be simulated in the local model (micro). I want to compare stress intensity factor or any other fracture property obtained from local model (micro) with that of experimental results.

I would appreciate if anyone could suggest some references/literature in this area. Any kind of suggestions would be great!

Venkata

Hi,

I was going though papers related to micromechanical modeling of composites using unit cell approach. Usually in this procedure, a unit cell is isolated from the material and to ensure the compatabilty of the unit cell boundary, periodic boundary conditions are applied.

To ensure the compatabilty of the boundary and to apply loads, can we use submodeling techniques available in ABAQUS.

Thank you

Regards

Ghouse