Introduction
Methodology
Experimental Setup
Analytical Estimation of Dynamic Yield Stress
Numerical Investigations of Impacts
Analysis Type
Modeling Material Behavior
Modeling of Contact Conditions
Experimental Investigations
Impact | Drop height, cm | V, m/s | \(\dot{\varepsilon }\), s−1 | V′, m/s | σΥ′, N/mm2 |
---|---|---|---|---|---|
3A | 22.1 | 2.082 | 6120 | 1.098 | 647 |
3B | 47.4 | 2.991 | 6998 | 1.403 | 607 |
3C | 76.9 | 3.882 | 8991 | 1.339 | 618 |
3D | 76.9 | 3.882 | 8991 | 1.553 | 547 |
Numerical Investigations
Simulation of the Drop Tests Strain Rates with the FE Method
Simulation of the HFMI
Model | σy, MPa | H, GPa | D, – | q, – | Calibrated based on | Goodness of fit | |||
---|---|---|---|---|---|---|---|---|---|
SSE, – | R-square, – | Adjusted R-square, – | RMSE, – | ||||||
Tensile | 450 | 0.9 | 353,500 | 5 | Foehrenbach et al. (Ref 12) | 3584 | 0.8197 | 0.8197 | 34.56 |
Compressive | 450 | 0.9 | 613,500 | 4 | Drop Tests and Cadoni et al. (Ref 21) | 21,620 | 0.7126 | 0.7126 | 29.15 |
Results and Discussion
Summary and Conclusions
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Strain rate dependency is according to initial expectations predominant for the accurate modeling of the HFMI RS profiles.
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Force-based modeling of the HFMI pin’s vertical movement is confirmed to be appropriate for simulations considering strain rate dependency.
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Dynamic yield stress estimated with the drop tests shows that for a single HFMI impact, lies closer to the ones extracted with compressive high strain rate testing, confirming as well initial expectations about the predominance of compressive viscosity during a single impact.
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In contrast to the previous argument, FE analysis of HFMI considering the tensile viscous material model provided better agreement with the respective measurements. Assumptions for this incompatibility were stated ,and appropriate future investigations were proposed.