Spherical and cylindrical cavity expansion models based prediction of penetration depths of concrete targets

<div><p>The cavity expansion theory is most widely used to predict the depth of penetration of concrete targets. The main purpose of this work is to clarify the differences between the spherical and cylindrical cavity expansion models and their scope of application in predicting the penetration depths of concrete targets. The factors that influence the dynamic cavity expansion process of concrete materials were first examined. Based on numerical results, the relationship between expansion pressure and velocity was established. Then the parameters in the Forrestal’s formula were fitted to have a convenient and effective prediction of the penetration depth. Results showed that both the spherical and cylindrical cavity expansion models can accurately predict the depth of penetration when the initial velocity is lower than 800 m/s. However, the prediction accuracy decreases with the increasing of the initial velocity and diameters of the projectiles. Based on our results, it can be concluded that when the initial velocity is higher than the critical velocity, the cylindrical cavity expansion model performs better than the spherical cavity expansion model in predicting the penetration depth, while when the initial velocity is lower than the critical velocity the conclusion is quite the contrary. This work provides a basic principle for selecting the spherical or cylindrical cavity expansion model to predict the penetration depth of concrete targets.</p></div

The expansion process of the spherical cavity under an expansion pressure of 1.5 GPa.

<p>The expansion process of the spherical cavity under an expansion pressure of 1.5 GPa.</p

Radial stress in spherical and cylindrical cavity models at t = 5 us.

<p>Radial stress in spherical and cylindrical cavity models at t = 5 us.</p

Comparison of penetration depths predicted by spherical cavity expansion model and test data.

<p>Comparison of penetration depths predicted by spherical cavity expansion model and test data.</p

Simulation model: (a) spherical cavity and (b) cylindrical cavity.

<p>Simulation model: (a) spherical cavity and (b) cylindrical cavity.</p

Comparison of numerical and theoretical results of radial stress after expanded for 5 us under an expansion pressure of 1.5 GPa.

<p>Comparison of numerical and theoretical results of radial stress after expanded for 5 us under an expansion pressure of 1.5 GPa.</p

Response regions of the spherical cavity expansion model.

<p>Response regions of the spherical cavity expansion model.</p

Comparison between the best-fit value of <i>B</i>* and the numerical results for cylindrical cavity expansion.

<p>Comparison between the best-fit value of <i>B</i>* and the numerical results for cylindrical cavity expansion.</p

Comparison between the best-fit value of <i>B</i>* and the numerical results for spherical cavity expansion.

<p>Comparison between the best-fit value of <i>B</i>* and the numerical results for spherical cavity expansion.</p

Expansion velocity of cavity wall with different pressures.

<p>Expansion velocity of cavity wall with different pressures.</p