Review of experimental techniques for high rate deformation and shock studies

Local impact effects of hard missiles on concrete targets

An empirical equation for penetration depth of ogive-nose projectiles into concrete targets

This article presents a computational constitutive model for glass subjected to large strains, high strain rates and high pressures. The model has similarities to a previously developed model for brittle materials by Johnson, Holmquist and Beissel (JHB model), but there are significant differences. This new glass model, presented in Fig. 1, provides a material strength that is dependent on the location and/or condition of the material. Provisions are made for the strength to be dependent on whether it is in the interior, on the surface (different surface finishes can be accommodated), adjacent to failed material, or if it is failed. The intact and failed strengths are also dependent on the pressure and the strain rate. Thermal softening, damage softening, timedependent softening, and the effect of the third invariant are also included. The shear modulus can be constant or variable. The pressure-volume relationship includes permanent densification and bulking. Damage is accumulated based on plastic strain, pressure and strain rate. Significant features of the model are the ability to compute size effects (small scales are stronger than large scales), surface effects (smooth surfaces are stronger than rough surfaces), and high internal tensile strength (as demonstrated by spall plate-impact experiments). Simple (single-element) examples are presented to illustrate the capabilities of the model. Several example computations are presented in Figs. 2-4 to demonstrate the ability to compute more complex, high-velocity-impact conditions. Figure 2 presents computed results for a gold projectile impacting a borosilicate target with a copper buffer attached to the impact surface. The computed results produce interface defeat (no glass penetration) at Vs = 800 m/s and prompt penetration at Vs = 900 m/s. This is consistent with the test results provided by Anderson et al. [1]. Behner et al. [2] performed experiments using no buffer (gold rod impacting bare glass) which produced penetration at much lower impact velocities. For these experiments the penetration velocities were determined using a series of flash x-rays and are presented as a function of impact velocity in the lower protion of Fig. 3. Also shown are the computed penetration velocities for Vs = 900 m/s and Vs = 2400 m/s. The computed results are in good agreement with the experiments. Anderson et al. [3] also performed experiments using a pointed steel projectile impacting thin plates of borosilicate glass at three different scales. The smaller scale targets were stronger than the larger scale targets. Figure 4 demonstrates the capability to compute size effects. Computed results are presented for the 0.50-cal (scale = 1.0) and the 0.22cal (scale = 0.44) projectile for Vs = 300 m/s and Vs = 400 m/s. At 300 m/s the 0.50-cal projectile exits the target at Vr = 22 m/s but the smaller scale 0.22-cal projectile is stopped. As the impact veloicty is increased the computed size effect diminshes as shown at Vs = 400 m/s. The ability for the computations to produce size effects is due to the time-dependent features in the model.

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A Computational Constitutive Model for Glass Subjected to Large Strains, High Strain Rates and High Pressures

Penetration of grout and concrete targets with ogive-nose steel projectiles

Glass bars and plates were subjected to impact loading. Failure waves were observed to propagate behind the compression waves. Material traversed by the failure wave suffers total loss of tensile strength and substantial drop in shear strength. Failure wave propagation velocities exceed the maximum crack propagation speed, but are not constant. In bars, failure wave speed range from 2.3 to 5.2 mm/μs, increasing with increasing impact velocity; in plates, the wave speed is about 2 mm/μs. The failure is ‘‘explosive’’ in nature, leading to radial expansion in bars and an increase in mean stress in plates.

Impact‐induced failure waves in glass bars and plates

Penetration of 7075-T651 aluminum targets with ogival-nose rods

The dynamic properties of hot‐pressed aluminum nitride ceramics were determined in a series of plate impact experiments using longitudinal and transverse in‐material manganin gauges. The Hugoniot curve for hot pressed specimens was determined in the range of 0–190 kbar with a value of 94±2 kbar for the Hugoniot elastic limit (HEL). Using both gauge orientations, the stress deviator in the specimens was determined as the difference between longitudinal and transverse stresses. It was found that the stress deviator remains relatively constant above the HEL, and is about 10% higher than the value at the HEL point. The inferred Hugoniot converges to the extrapolation of the hydrostat. Since the convergence is not due to loss of strength, it may be due to a phase change in the AlN from low‐pressure (wurtzite) structure to high‐pressure (rocksalt) structure.

Dynamic high-pressure properties of AlN ceramic as determined by flyer plate impact

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. SPALL STRENGTH AND FAILURE WAVES IN GLASS N. Brar, Z. Rosenberg, S. Bless

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N.S. Brar

Papers

Penetration of grout and concrete targets with ogive-nose steel projectiles

Impact‐induced failure waves in glass bars and plates

Penetration of 7075-T651 aluminum targets with ogival-nose rods

Dynamic high-pressure properties of AlN ceramic as determined by flyer plate impact

Spall strength and failure waves in glass