Reactive coarse-grained MD models to capture interphase formation in epoxy-based structural adhesive joints - dataset

Abstract:from [1] Adhesive joints offer a superior strength-to-weight ratio compared to conventional fastening methods, making them essential for achieving cost-efficiency and sustainability goals. The adherends influence the adhesive in their immediate vicinity, creating regions with altered microstructures. These regions, known as interphases, exhibit material properties that differ from those of the bulk adhesive and are not fully understood from an engineering perspective.To address this issue, we introduce a novel coarse-grained molecular dynamics (CGMD) model for adhesive joints, which aims to study the interphase formation and its resulting properties at the molecular level. We utilize a reactive epoxy model from the literature for the adhesive and implement matching aluminium substrates, along with the necessary adherend-adhesive interaction parameters. The resulting adhesive joint model allows us to investigate the formation of the adhesive's microstructure during the curing process and the mechanical properties of the joint. We conduct a parameter study on the adherend-adhesive interaction parameters, unravel the role of grafting bonds and their distribution, and examine the impact of the adhesive's thickness. Additionally, we identify an interphase based on variations in the local microstructure, estimate its size, and determine the influencing parameters. In this first contribution, we demonstrate the capabilities of our model in evaluating the mechanical behavior of the interphase, which is crucial for gaining a better understanding of adhesive joints. 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 Post-processing Matlab R2023b License: Creative Commons Attribution 4.0 International Context: Data set supplementing journal paper:[1] V. Dötschel, E. M. Richter, G. Possart, P. Steinmann, M. Ries, "Reactive coarse-grained MD models to capture interphase formation in epoxy-based structural adhesive joints." European Journal of Mechanics-A/Solids (2025): 105801. Content: structure of data set (follows sections of [1]): - 3.1 Adherend-adhesive interaction parameters - 3.2.1 Grafting bond density - 3.2.2 Grafting bond heterogeneities - 3.3 Adhesive layer thickness - A2 Case III: no grafting naming convention for simulation folders - case_I, case_II, case_III: refers to the different force field parameter sets discussed in the paper - surf_react: gives the grafting density in percent - hole05: indicates an inert region of 50percent - EQ: contains equilibration files - UT: contains uniaxial tensile files - _double, _half: indicates the adhesive joint thickness, double or half of the standard presented in 3.1 - _01 to _05: number of the replica - bins Each simulation directory contains: data files (*.data) containing the sample configuration in LAMMPS data format dat files (*.dat) containing simulation output, format explained below LAMMPS_out: simulation results - ReadyForCuring.data sample configuration directly before curing - Sandwich_Sim_Curing1.data sample configuration after curing stage I - Sandwich_Sim_Curing2.data sample configuration after curing stage II - Sandwich_Sim_Curing3.data sample configuration after curing stage III - Sandwich_Sim_Curing4.data sample configuration after curing stage IV (end of curing) - Sandwich_Sim_finalEquil_afterBC_change.data sample at end of equilibration, i.e., ready for deformation - Sandwich_Sim_afterDeformation.data sample after deformation - thermo.dat tabulated thermodynamic output during equilibration in columns, containing TimeStep timestep c_thermo_temp temperature in K c_thermo_press[1] pressure component pxx in atm c_thermo_press[2] pressure component pyy in atm c_thermo_press[3] pressure component pzz in atm c_thermo_press[4] pressure component pxy in atm c_thermo_press[5] pressure component pxz in atm c_thermo_press[6] pressure component pyz in atm v_PACM_react fraction of reacted PACM (linear and network reactions) v_DC fraction of reacted DGEBA excluding grafting reactions v_DGEBA_react fraction of reacted DGEBA including grafting reactions v_Surf_react fraction of reacted substrate surface atoms v_Etot total energy in kcal/mol v_Epair nonbonded energy in kcal/mol v_Ebond bond energy in kcal/mol v_Eangle angle energy in kcal/mol v_Epot potential energy in kcal/mol v_Ekin kinetic energy in kcal/mol v_Stress_xx_MPa stress component in xx direction in MPa v_Density density of simulation box in g/cm^3 v_Lx length of simulation box in x direction v_Ly length of simulation box in y direction v_Lz length of simulation box in z direction v_Stress_yy_MPa stress component in yy direction in MPa v_Stress_zz_MPa stress component in zz direction in MPa v_Stress_xy_MPa stress component in xy direction in MPa v_Stress_xz_MPa stress component in xz direction in MPa v_Stress_yz_MPa stress component in yz direction in MPa - thermo_UT.dat tabulated thermodynamic output during deformation in columns, containting TimeStep timestep c_thermo_temp temperature in K c_thermo_press[1] pressure component pxx in atm c_thermo_press[2] pressure component pyy in atm c_thermo_press[3] pressure component pzz in atm c_thermo_press[4] pressure component pxy in atm c_thermo_press[5] pressure component pxz in atm c_thermo_press[6] pressure component pyz in atm v_Etot total energy in kcal/mol v_Epair nonbonded energy in kcal/mol v_Ebond bond energy in kcal/mol v_Eangle angle energy in kcal/mol v_Epot potential energy in kcal/mol v_Ekin kinetic energy in kcal/mol v_Stress_xx_MPa stress component in xx direction in MPa v_Density density of simulation box in g/cm^3 v_Lx length of simulation box in x direction v_Ly length of simulation box in y direction v_Lz length of simulation box in z direction 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_Strain_xy strain component in xy direction v_Strain_xz strain component in xz direction v_Strain_yz strain component in yz direction v_Stress_xx_MPa stress component in xx direction in MPa v_Stress_yy_MPa stress component in yy direction in MPa v_Stress_zz_MPa stress component in zz direction in MPa v_Stress_xy_MPa stress component in xy direction in MPa v_Stress_xz_MPa stress component in xz direction in MPa v_Stress_yz_MPa stress component in yz direction in MPa v_Volume_Epoxy1 polymer volume via substrate volume in A^3 v_Volume_Epoxy2 polymer volume via box lenghts in A^3 v_Cauchy_xx_MPa_Epoxy1 stress component in xx direction in MPa with respect to Volume_Epoxy1 (only polymer) v_Cauchy_yy_MPa_Epoxy1 stress component in yy direction in MPa with respect to Volume_Epoxy1 (only polymer) v_Cauchy_zz_MPa_Epoxy1 stress component in zz direction in MPa with respect to Volume_Epoxy1 (only polymer) v_Cauchy_xy_MPa_Epoxy1 stress component in xy direction in MPa with respect to Volume_Epoxy1 (only polymer) v_Cauchy_xz_MPa_Epoxy1 stress component in xz direction in MPa with respect to Volume_Epoxy1 (only polymer) v_Cauchy_yz_MPa_Epoxy1 stress component in yz direction in MPa with respect to Volume_Epoxy1 (only polymer) c_ForceLeft resulting force acting on left substrate in kcal/(mol A) c_ForceRight resulting force acting on right substrate in kcal/(mol A) c_ForceBothSurfaces resulting force acting on both substrates in kcal/(mol A) v_NominalStressLeft nominal tensile stress via force acting on left substrate in MPa v_NominalStressRight nominal tensile stress via force acting on right substrate in MPa v_TrueStressLeft true tensile stress via force acting on left substrate in MPa v_TrueStressRight true tensile stress via force acting on left substrate in MPa v_Cauchy_xx_MPa_Epoxy2 stress component in xx direction in MPa with respect to Volume_Epoxy2 (only polymer) v_Cauchy_yy_MPa_Epoxy2 stress component in yy direction in MPa with respect to Volume_Epoxy2 (only polymer) v_Cauchy_zz_MPa_Epoxy2 stress component in zz direction in MPa with respect to Volume_Epoxy2 (only polymer) v_Cauchy_xy_MPa_Epoxy2 stress component in xy direction in MPa with respect to Volume_Epoxy2 (only polymer) v_Cauchy_xz_MPa_Epoxy2 stress component in xz direction in MPa with respect to Volume_Epoxy2 (only polymer) v_Cauchy_yz_MPa_Epoxy2 stress component in yz direction in MPa with respect to Volume_Epoxy2 (only polymer) - Bins*.dat output for spatial binning of atom type *, i.e, 3, 5, 8, 9, 10, or 11; containing Chunk ID for ith binning Coord1 center coordinate of binning Ncount number of atom of atom type * in current bin density/number number density of atom type * in current bin References: [1] V. Dötschel, E. M. Richter, G. Possart, P. Steinmann, M. Ries, "Reactive coarse-grained MD models to capture interphase formation in epoxy-based structural adhesive joints." European Journal of Mechanics-A/Solids (2025): 105801. [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.