DOI: 10.5281/zenodo.15836252
title: Deciphering elastoplastic properties from atomistic structure: Reactive coarse-grained MD for epoxies - Dataset

description:  

Abstract:from [1]

Adhesive joints provide a better strength-to-weight ratio than traditional fastening methods and thus play a vital role in lightweight and cost-efficient engineering designs. The interaction of adherend and adhesive causes a region with different local resin-to-hardener ratios, e.g., due to demixing or sterically hindered diffusion during curing. Consequently, this interphase exhibits a mechanical behavior that differs from that of the bulk adhesive, immediately implying thickness-dependent properties of the joint, which should be, but are not yet, addressed in engineering.Additionally, these local gradients of structural and especially mechanical properties are, if at all, very difficult to assess by  experimental methods.As a remedy, we derive the elastoplastic material parameters for bulk adhesives covering a wide range of mixing ratios. To this end, we simulate the curing and deformation of pure epoxy with reactive, coarse-grained molecular dynamics (CGMD) and introduce an extrapolation scheme to obtain the quasi-static material response.The latter removes the viscous contributions, which facilitates the comparison of ultra-fast MD with conventional mechanical testing. Based on these results, we calibrate elastoplastic constitutive models with VOCE-type hardening and obtain mixing ratio-dependent Young's modulus, Poisson's ratio, yield stress, and hardening parameters. Finally, we obtain the correlation between these material parameters and structural characteristics, such as density and curing degree, for a wide range of mixing ratios.With these results, we can then conclude on the local mechanical properties of interphases, based on CGMD simulations of the curing of adhesive joints, which inherently provide the local structure gradients in the vicinity of the adherends.

Contact:

Maximilian RiesInstitute of Applied MechanicsFriedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 591058 Erlangen

Software:

All MD simulations were performed with LAMMPS [2,3], version: 2 Aug 2023 - Update 3, with REACT package [4,5]

Compiled withCompiler: GNU C++ 11.2.0 with OpenMP not enabledC++ standard: C++11

including packages: BPM CLASS2 DPD-BASIC EXTRA-DUMP EXTRA-FIX EXTRA-MOLECULE EXTRA-PAIR INTEL KSPACE MANYBODY MC MISC MOLECULE MOLFILE MPIIO NETCDF OPT REACTION

Post-processing Matlab R2019b, Abaqus CAE

License:

Creative Commons Attribution 4.0 International

Context:

Data set supplementing  journal paper:[1] M. Ries, J, Tiefenthäler, M. Losert, G. Possart, “Deciphering elastoplastic properties from atomistic structure: Reactive coarse-grained MD for epoxies,” International Journal of Adhesion and Adhesives, 104196, 2025.

Content:

structure of data set:

    - mixing_ration_experiment    - degree_of_cure_experiment    - size_of_system_experiment    - strainrate_experiment    - temperature_experiment

naming convention for simulation folders

    calculation-{investigated parameter}-{replica number}        - replica number from 00 to 09 for averaging        - investigated parameter, i.e., mixing ratio, temperature, ...

 

Each simulation directory contains:

    data files (*.data) containing the sample configuration in LAMMPS data format    dat files (*.dat)   containing simulation output, format explained below    meta.info             containing metadata of each simulation

    lammps_out:            simulation results     out_EQU:            results from equilibration run    out_UT:                results from uniaxial tension     out_RELAX:            results from relaxation runs (data files are omitted here to reduce the overall file size)                - neat_Epoxy.data                                sample configuration at end of respective run        - thermo_COOL.dat                                thermodynamic output of cooldown (see below)        - thermo_EQU.dat                                thermodynamic output of whole equilibration run (see below)        - thermo_UT.dat                                    thermodynamic output of uniaxial tensile run (see below)        - thermo_RELAX.dat                                thermodynamic output of relaxation runs (see below)                    - thermo_COOL.dat                tabulated thermodynamic output during cooldown in columns, containing            TimeStep                     timestep            c_thermo_temp                 temperature in K            v_MassDensity                density of simulation box in g/cm^3                    -thermo_EQU.dat                    tabulated thermodynamic output during cooldown in columns, containing            TimeStep                     timestep            c_thermo_temp                 temperature in K            c_thermo_press                 pressure in atm            v_DCDensity                    curing density in 1/cm^3            v_MassDensity                density of simulation box in g/cm^3            v_DC                        curing degree            v_HardenerReact                crosslinking degree            v_numBonds                    number of bonds                    - thermo_UT.dat                             tabulated thermodynamic output during deformation in columns, containting             TimeStep                     timestep            v_MassDensity                density of simulation box in g/cm^3            v_Strain_xx                 strain component in xx direction            v_Strain_yy                  strain component in yy direction            v_Strain_zz                  strain component in zz direction            v_Stress_xx                    stress component in xx direction in MPa            v_Stress_yy                 stress component in yy direction in MPa            v_Stress_zz                 stress component in zz direction in MPa            v_Stress_xy                 stress component in xy direction in MPa            v_Stress_xz                 stress component in xz direction in MPa            v_Stress_yz                 stress component in yz direction in MPa            v_numBonds                    number of bonds                    - thermo_RELAX.dat                 tabulated thermodynamic output during relaxtion in columns, containting             TimeStep                     timestep            v_MassDensity                density of simulation box in g/cm^3            v_Strain_xx                 strain component in xx direction            v_Strain_yy                  strain component in yy direction            v_Strain_zz                  strain component in zz direction            v_Stress_xx                    stress component in xx direction in MPa            v_Stress_yy                 stress component in yy direction in MPa            v_Stress_zz                 stress component in zz direction in MPa            v_Stress_xy                 stress component in xy direction in MPa            v_Stress_xz                 stress component in xz direction in MPa            v_Stress_yz                 stress component in yz direction in MPa            v_numBonds                    number of bonds

                

References:

[1] M. Ries, J, Tiefenthäler, M. Losert, G. Possart, “Deciphering elastoplastic properties from atomistic structure: Reactive coarse-grained MD for epoxies,” International Journal of Adhesion and Adhesives, 104196, 2025.

[2] S. Plimpton, “Fast parallel algorithms for short-range molecular dynamics,” Journal of computational physics, 1995, 117, 1-19.

[3] A. P. Thompson et al., “LAMMPS - a flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales,” Computer Physics Communications, vol. 271, p. 108171, 2022.

[4] J. R. Gissinger, B. D. Jensen, and K. E. Wise, “Modeling chemical reactions in classical molecular dynamics simulations,” Polymer, vol. 128, pp. 211–217, 2017.

[5] J. R. Gissinger, B. D. Jensen, and K. E. Wise, “Reacter: A heuristic method for reactive molecular dynamics,” Macromolecules, vol. 53, no. 22, pp. 9953–9961, 2020.