Ballistic impact on concrete slabs: An experimental and numerical study

The ballistic perforation resistance of 50 mm thick concrete slabs impacted by 20 mm diameter ogive-nose steel projectiles is investigated experimentally and numerically. Three commercially produced concretes with nominal unconfined compressive strengths of 35, 75 and 110 MPa were used to cast material test specimens and slabs. After curing, ballistic impact tests were carried out to determine the ballistic limit curve and velocity for each slab quality. Material tests instrumented with digital image correlation (DIC) were conducted along the ballistic impact tests. DIC measurements were used to establish engineering stress-strain curves for calibration of a modified version of the Holmquist-Johnson-Cook concrete model. Finite element simulations of the impact tests gave good conservative predictions.

Dynamic Mechanical Damage and Non-Shock initiation of a New Polymer Bonded Explosive during Penetration

Complexities of heating mechanisms make it difficult to investigate the safety of a polymer bonded explosive (PBX) charge of earth-penetrating-weapons (EPWs) during penetration. In this paper, the dynamic damage and non-shock initiation of PBX1314 (60 wt % hexahydro-1, 3, 5-trinitro-1, 3, 5-s-triazine (RDX), 16 wt % aluminum, 24 wt % hydroxy-terminated polybutadiene (HTPB)) during penetration is investigated through experiments and simulations. In the experiments, steel projectiles filled with PBX1314 are launched to penetrate concrete targets. In the results, non-shock initiations occur on the tail surface of PBX1314 along with mechanical damage of the tail and middle part of PBX1314. A dynamic damage and initiation model is proposed to characterize the effects of microcracks on the mechanical and thermal responses of PBX1314. Investigation based on the model suggests that microcrack interfacial friction plays significant roles in damage, heat generation and localization in PBX1314. A non-shock initiation criterion is developed based on macroscale variables in PBX1314. Numerical simulations of the penetration experiments are performed by using the proposed model and criterion. The mechanical damage and non-shock initiation of PBX1314 in the experiments are successfully predicted. The simulation results indicate that the tail of PBX1314 impacts the projectile repeatedly during penetration. Finally, the initiation criterion is satisfied because of frictional heat localization near microcrack surfaces and initiation is activated in the tail of PBX1314.

Ballistic impact on fired clay masonry bricks

We perform an experimental and numerical study of ballistic impact on the German fired clay brick material VMz28. Parameters for the concrete material model applied in hydrocode simulations stem from material characterization experiments, especially planar plate impact experiments, engineering assumptions, and parameter studies. The performance of the numerical model is illustrated by a comparison of its results to ballistic data on penetration and perforation of spherical steel projectiles. Agreement is found between experiment and simulation for residual velocities and penetration depths. The experimental damage patterns are reproduced in the simulation with sufficient agreement. The application of the model to the impact of another differently shaped generic projectile reveals good predictive capabilities in a part of the impact velocity range. For the deviation found in the other part, limitations of the model concerning the full reproduction of the observed spall failure are discussed as a possible explanation. Overall, with moderate experimental effort, a numerical model with reasonably good predictive capabilities is obtained for engineering purposes.

Failure Behaviours of Steel Projectiles with Localised Melting Against Armour Plates

The surface remelting technology of high energy beam can locally weaken the case for controlled fragmentation, which may affect the survivability of the impacting projectiles. Failure behaviours of steel projectiles with melted layers grid normally perforating armour plates was investigated. The results reveal that shear fracture mainly occurs in the nose region of projectiles due to high loading, and the melting zone of projectiles can keep integrity with no damage, which means the survivability of projectile can be assured. Furthermore, an analytical model was proposed to the structural analysis of projectile, which is in accordance with the test results.