<p>For polymers, inelastic deformation and failure under dynamic loading is largely dependent on temperature, strain rate and stress multiaxiality. Consequently, modelling their impact behavior requires several experiments and time-consuming determination of material parameters. In this work, a calibration strategy to reduce calibration times and experimental workloads based on neural networks and genetic algorithms is presented. The method is demonstrated on Charpy- and puncture experiments at 23&#xa0;<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\( ^{\circ }\text {C}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> <mtext>C</mtext> </mrow> </math></EquationSource> </InlineEquation> and 50&#xa0;<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\( ^{\circ }\text {C}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> <mtext>C</mtext> </mrow> </math></EquationSource> </InlineEquation> with two additional tensile tests at <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(-\)</EquationSource> <EquationSource Format="MATHML"><math> <mo>-</mo> </math></EquationSource> </InlineEquation>&#xa0;30&#xa0;<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\( ^{\circ }\text {C}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> <mtext>C</mtext> </mrow> </math></EquationSource> </InlineEquation> and 23&#xa0;<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\( ^{\circ }\text {C}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mo>∘</mo> </mmultiscripts> <mtext>C</mtext> </mrow> </math></EquationSource> </InlineEquation>. In many cases, these experiments are conducted for datasheet specifications and are readily available. To achieve a balance between precision, ability to generalize and numerical simplicity, the strain-rate and temperature dependence was mapped via a Johnson–Cook model that creates tabular inputs for a general J2 plasticity model in Abaqus. Similarly, failure behavior was modelled using ductile-damage in Abaqus. The traditional fitting methodology based on inverse analysis using finite element simulations was replaced by the use of neural network surrogate models which allow for calibration in a matter of minutes. This approach was validated against four-point bending experiments with geometry, velocity and temperatures different to those used to calibrate the model on. Here, simulated toughness and limit loads on average differed by 19% and 5% from experimental results.</p>

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Modelling Polymers Under Impact Loading: A Fast Calibration Strategy Using Machine Learning

  • F. Kiehas,
  • M. Reiter,
  • F. Rueda,
  • J. P. Torres,
  • M. Jerabek,
  • Z. Major

摘要

For polymers, inelastic deformation and failure under dynamic loading is largely dependent on temperature, strain rate and stress multiaxiality. Consequently, modelling their impact behavior requires several experiments and time-consuming determination of material parameters. In this work, a calibration strategy to reduce calibration times and experimental workloads based on neural networks and genetic algorithms is presented. The method is demonstrated on Charpy- and puncture experiments at 23  \( ^{\circ }\text {C}\) C and 50  \( ^{\circ }\text {C}\) C with two additional tensile tests at \(-\) -  30  \( ^{\circ }\text {C}\) C and 23  \( ^{\circ }\text {C}\) C . In many cases, these experiments are conducted for datasheet specifications and are readily available. To achieve a balance between precision, ability to generalize and numerical simplicity, the strain-rate and temperature dependence was mapped via a Johnson–Cook model that creates tabular inputs for a general J2 plasticity model in Abaqus. Similarly, failure behavior was modelled using ductile-damage in Abaqus. The traditional fitting methodology based on inverse analysis using finite element simulations was replaced by the use of neural network surrogate models which allow for calibration in a matter of minutes. This approach was validated against four-point bending experiments with geometry, velocity and temperatures different to those used to calibrate the model on. Here, simulated toughness and limit loads on average differed by 19% and 5% from experimental results.