Deciphering elastoplastic properties from atomistic structure: Reactive coarse-grained MD for epoxies - Dataset

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.