Extensive research activities in the field of blast loads have taken place in the last few decades. There are many experimental results related to underground explosions. The mechanism of crater formation is complex and it is related to the dynamic physical properties of air, soil and soil-air interface. Studies concerned with the characteristics of craters caused by explosions usually resort to dimensional analysis and statistics. Some empirical equations proposed for the evaluation of crater dimensions can be found in the literature. Nevertheless, they were obtained for particular type of soils, shapes of explosives, ranges of explosive mass and depth of explosive and they present considerable variability. The main objective of this paper is to prove the accuracy of numerical simulation of craters produced by underground explosions. For this purpose, the numerical analysis of crater formation due to underground explosions is performed with a hydrocode. Several numerical approaches are carried out using different models and processors for the soil. Moreover, different alternatives for the constitutive model of the soil are used. In order to validate the numerical approach and prove its ability to model the crater formation, comparison with experimental results is performed. Many simulations of the same physical model lead to the same crater dimensions and a good agreement between the test results and the predicted crater measures is achieved.
A jet of material was observed exiting from the rear of the remnants of an initially semi‐hollow explosively formed projectile, which perforated a finite thickness composite armour panel. The observation of this phenomenon was made by means of flash‐X‐ray photography at two different sub‐millisecond times for a copper EFP that impacted the panel at above 2000 m/s. The jet exhibited remarkably similar characteristics to what is typically observed for shaped charge jets for similar liner materials. Progressive necking was observed in the jet and the velocity differences between necked sections were characterized. Simulation of a similar generic event by the ANSYS Autodyn hydrocode showed that reverse jet formation is possible for specific EFP geometries and impact conditions. The relatively low velocities of the jet elements in terms of the laboratory coordinates, holds promise for the soft recovery of the jetted particles.
The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) AUTHOR(S)Dr IM Snyman 5f. WORK UNIT NUMBER PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) CSIR, DPSS PERFORMING ORGANIZATION REPORT NUMBER DPSS 2005/158 SPONSOR/MONITOR'S ACRONYM(S)AMB, ERO, ARL SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Aero-Mechanics Branch, European Research Office, Army Research Laboratory 223 Old Marylebone Road, London, NW1 5TH UK SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for Public Release; distribution unlimited SUPPLEMENTARY NOTES ABSTRACTUse the theoretical knowledge of shock attenuation and advance with experimental evidence to the point where the results can be used in practical scenario. Our first objective is to characterise the material with respect to shock attenuation from a blast load. This achieved by the design and development of a test rig that can be used to evaluate, analyse and eventually understand the parameters in a material that influence shock attenuation with verification of the existing theory. SUBJECT TERMS AbstractUse the theoretical knowledge of shock attenuation and advance with experimental evidence to the point where the results can be used in practical scenario. Our first objective is to characterise the material with respect to shock attenuation from a blast load. This achieved by the design and development of a test rig that can be used to evaluate, analyse and eventually understand the parameters in a material that influence shock attenuation with verification of the existing theory Objective:The objective of this project is to use the theoretical knowledge of shock attenuation and advance with experimental evidence to the point where the results can be used in practical scenario.Our first objective is to characterise the material with respect to shock attenuation from a blast load. Methodology:Design and develop a test rig that can be used to evaluate, analyse and eventually understand the parameters in a material that influence shock attenuation with verification of the existing theory. Conclusions:The first phase of the design of the rig was successful with regard to the fitment...
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