New M@TE! model:

we have provided a summary of your model as a starting point for the README, feel free to edit

Section 1: Summary of your model

Model Submitter:

Melanie Finch (0000-0001-9699-2769)

Model Creator(s):

• Melanie Finch (0000-0001-9699-2769)
• Paul D. Bons (0000-0002-6469-3526)
• Florian Steinbach
• Albert Griera Artigas (0000-0003-4598-8385)
• Maria-Gema Llorens (0000-0002-6148-2600)
• Enrique Gomez-Rivas (0000-0002-1317-6289)
• Hao Ran (0000-0002-8639-3890)
• Tamara de Riese (0000-0001-5828-8711)

Model slug:

finch-2024-cprime

(this will be the name of the model repository when created)

Model name:

The ephemeral development of C′ shear bands: A numerical modelling approach

License:

Creative Commons Attribution 4.0 International

Model Category:

• model published in study

Model Status:

• completed

Associated Publication title:

The ephemeral development of C′ shear bands: A numerical modelling approach

Short description:

This model simulates the development of C' shear bands in ductile shear zones. The model begins with an equigranular texture of three phases: a strong phase (e.g., feldspar) an intermediate-strength phase (e.g., quartz) and an anisotropic weak phase (e.g., mica). Dextral shearing stretches and rotates the microstructure, forming S-C fabric, asymmetric folds and C' shear bands.

Abstract:

Funder(s):

• Alexander von Humboldt Foundation (https://ror.org/012kf4317)
• Ministerio de Ciencia, Innovación y Universidades (https://ror.org/05r0vyz12)

Section 2: your model code, output data

No embargo on model contents requested

Include model code:

True

Model code notes:

The starting microstructure for the model is an .Elle file that can be viewed and edited in notepad or similar. The microstructure can be viewed with the showelle program. To run the simulation the program Elle can be downloaded from elle.ws.

Include model output data:

True

Model output data notes:

Output data consists of 900 files that are 21 Mb each and an avi movie that is 80 Mb

Section 3: software framework and compute details

Software Framework DOI/URL:

Found software: Elle Numerical Simulation Platform

Software Repository:

https://sourceforge.net/p/elle/git/ci/master/tree/

Name of primary software framework:

Elle Numerical Simulation Platform

Software framework authors:

• Paul D. Bons (0000-0002-6469-3526)
• Tamara de Riese (0000-0001-5828-8711)
• Lynn Evans (0000-0002-0954-6072)
• Melanie Finch (0000-0001-9699-2769)
• Robyn Gardner (0000-0001-8707-8537)
• Enrique Gomez-Rivas (0000-0002-1317-6289)
• Albert Griera Artigas (0000-0003-4598-8385)
• Baoqin Hao (0000-0003-3762-1655)
• mark jessell (0000-0002-0375-7311)
• Daniel Koehn (0000-0002-2276-2626)
• Ricardo Lebensohn (0000-0002-3152-9105)
• Maria-Gema Llorens (0000-0002-6148-2600)
• Sandra Piazolo (0000-0001-7723-8170)
• Till Sachau (0000-0002-3790-1385)
• Yuanchao Yu (0009-0000-4868-3152)

Software & algorithm keywords:

• VPFFT
• Elle

Section 4: web material (for mate.science)

Landing page image:

Filename: Fig 3.png
Caption: Stages of microstructural development in a model with 15% weak phase (black) and a medium phase strength contrast. (a) Starting microstructure, (b) stage 1: grain elongation and rotation. Note the distribution of maximum strain rate (red arrows) localised to tips of WP grains that are parallel to the C plane, (c) stage 2: S-C fabric development. Stress is highest in the IP+SP adjacent to high strain rate layers of interconnected WP (red and orange arrows). (d) stage 3: shear band development and strain partitioning. Maximum stress in the model is in the gap in the shear band (red arrow). Green arrows highlight areas that have been asymmetrically folded (c.f. Fig. 1a). The first column shows the grain microstructure, the second column shows the normalised von Mises strain rate and the third column shows the von Mises stress. Images in the same row correspond to the same model and step.

Animation:

Filename:

Graphic abstract:

Filename: Fig 5.png
Caption: The formation of C' shear bands by the rotation of a C plane forwards due to high strain rate in the shear band and high stress at the tip of the shear band. (a) Discontinuous shear band with section parallel to the SZB at high strain rate (red arrow) and high stress in the IP+SP region at the end of the shear band (orange arrow). (b) A low strain rate section in the shear band is bracketed on either side by high strain rate sections (red arrows) and begins to rotate forwards. (c) C' shear band forms in low strain rate section (red dashed line). (d) Strain rate reduces in the shear band and the C' shear band has rotated back into parallelism with the SZB and C planes. The first column shows the grain microstructure, the second column shows the normalised von Mises strain rate and the third column shows the von Mises stress. Model shown contains 15% weak phase and a high phase strength contrast. Images in the same row correspond to the same model and step.

Model setup figure:

Filename: Fig 2.png
Caption: Basic process of microstructure simulation. (a) The starting microstructure consists of three grain types that undergo one increment of γ = 0.02 dextral shear. (b) The microstructure is deformed with wrapping boundaries. (c) The microstructure is repositioned back to a square before the next increment of strain. (d) Zoom in of (a) showing the three flynn (grain) types: strong phase (SP), intermediate-strength phase (IP), and weak phase (WP). (e) Zoom-in of (d) showing that flynn grain boundaries are defined by double (blue) and triple (red) bnodes joined by straight lines. An additional grid of unconnected nodes (unodes, black) is overlain on flynns and stores state variables and flynn properties.
Description: A three-phase microstructure was used with 15% weak phase (WP), 42.5% intermediate-strength phase (IP) and 42.5% strong phase (SP). The starting model was square and defined by 2,748 equant grains with a random distribution of the three phases. Velocity boundary conditions with constant strain rate were applied with top-to-the-right (dextral) simple shear in increments of Δγ = 0.02, up to a finite shear strain of γ=18 in 900 steps. After each deformation step, the model was repositioned to the initial square unit cell and grain properties mapped back on to the grid before the next deformation step. A power-law viscous rheology was employed with n = 3. Each phase was associated with a mineral model that specified the slip systems and their effective strength or resistance to shear. The mineral models employed attempted to broadly approximate the most important features of mica (WP), quartz (IP), and feldspar (SP) in order to more closely correspond to previous experimental work. To model the WP we used a mineral model with hexagonal symmetry and three slip systems (basal, prismatic, and pyramidal) because, although mica is monoclinic, it is pseudohexagonal and its most important mechanical feature is an easy glide plane since shear in mica is easier parallel to the basal plane than in any other direction. Accordingly we set the basal plane of the WP to one tenth of the non-basal WP planes, producing a mechanically anisotropic WP. Feldspar is also pseudohexagonal, so we employed a hexagonal mineral model for the SP, but with all slip systems at the same effective strength. For the IP we used the crystal model of quartz with four slip systems (basal, prismatic, pyramidal and pyramidal <c+a>) and gave the effective strength of all four slip systems the same value, making the IP effectively mechanically isotropic. The IP was 25x stronger than the WP basal plane and the SP was 2x stronger than the IP.