The Effect of Blast Exposure Distance on Hardness and Reduced Modulus Properties of Lead-Free Solder

This study discussed the effect of blast exposure distance of lead-free solder on micromechanical properties. Sn-Ag-Cu solder samples were exposed to 1000 g of Plastic Explosive. The soldered samples were placed at a distance of 1 m, 2 m and 4 m distance from the blast source. In order to study micromechanical properties in localized and more details, the nanoindentation approach was used. The indentation was performed at the center of the solder to examine the hardness and reduced modulus properties. The load-depth curve of indentation for 1 m distance from the blast source has apparent the discontinuity during loading as compared to the control sample. The hardness value increased as the distance from the blast source increased. The shortest distance from the blast source gives a high impact on the degradation of hardness properties as compared to others. This result is important in assessing the effect of exposure distance from the blast source.

EVALUATION OF THE CHARACTERISTICS OF PLASTIC EXPLOSIVE ADHERED BY LIQUID NATURAL RUBBER

Plastic explosive (PBX) is an explosive that a polymer binder is used to reduce the sensitivity of high explosives for various applications. This paper presents the characteristics of the PBXs based on liquid natural rubber (LNR) and hexogen (RDX). The PBXs are prepared according to a modified formulation of the Composition C-4. The plasticity of the PBXs is determined according to the MIL-STD-650 method 211.1. The uniaxial compression of the PBXs examined by the STANAG 4443. The test of the sensitivity of PBXs to friction is carried out by STANAG 4487. The thermal stability is tested by the STANAG 4556 at 100 oC for 40 hours. The results indicated that the plasticity is found to be more than 0.018 in accordance with the MIL-C-45010A. Further, the modulus of elasticity, yield strength, and strain can be adjusted by the composition of the LNR binder. In addition, the frictional sensitivity of the PBXs is significantly reduced to more 360 N of the load. The thermal stability is in the range of 0.156 to 0.225 ml.g-1 and completely meets technical requirements. Therefore, the direction of using LNR as a binder for PBXs gives acceptable results for further researches.

EPS foam blast attenuation in full-scale field test of reinforced concrete slabs

Predicting explosion parameters is an important step when planning for blast tests or the design of blast resistant buildings. This paper presents a comparison of recorded pressure that was reflected on the surface of reinforced concrete slabs with and without EPS (Expanded Polystyrene) foam retrofit measured from a detonation of 2.7 kg of non-confined plastic explosive. Two 50 MPa reinforced concrete slabs measuring 1.0x1.0x0.08 m, simply supported on two sides were tested. The explosive was suspended at a distance of 2.0 m from the upper surface of the slabs; one of the slabs had 5.0 cm thick foam on the top side. Eight piezoelectric pressure sensors were positioned at a distance of 2.0 m from the explosive. Results showed that the foam retrofit reduced the reflected pressure by approximately 57% when compared to the slab without EPS foam retrofit.

Experimental Investigations Regarding the Behaviour of Composite Panels Based on Polyurea and Kevlar or Dyneema Layers Under Blast and Fragments

This paper presents an experimental study to determine the behaviour of composite panels, made of polyurea sprayed on Kevlar or Dyneema support layers, under blast and fragments produced by an improvised explosive device (IED). The fragments used for tests were steel bearing balls of 8 and 10 mm propelled by a plastic explosive charge and bullets cal. 7.62 mm, type Full Metal Jacketed Armor Piercing (FMJ AP) and Hollow Point Boat Tail (HPBT), with impact velocity greater than 500 m/s. To determine the fragments attenuation, their velocities before and after the impact with the composite panel were measured and compared. In order to assess the blast attenuation, the reflected pressures measured by two face-on sensors, one of which was covered by the composite panel, were compared. Also, to explain the behaviour of composite panels under blast, the shock polars of materials in the panel�s composition were plotted. The results have shown that the composite panels have a low rate of attenuation of fragment velocities but a very good ability to attenuate the pressure and impulse associated with the shock wave.

Preparation and Characterization of a New High-Performance Plastic Explosive in Comparison with Traditional Types

EPX-2R is a high-performance plastic explosive produced for different applications. EPX-2R is based on RDX (1,3,5-trinitro-1,3,5-triazinane) bonded by the elastic matrix of the softened styrene butadiene binder. A computerizing mixer plastograph was used for the production of EPX-2R. The internal energy of combustion was measured and used to determine the enthalpy of formation. Friction and impact sensitivities were measured. The velocity of detonation was determined experimentally, and the detonation properties were calculated by the EXPLO 5 code. For comparison, traditional plastic explosives, composition C-4, Semtex 10, Formex P1, EPX-1, and Sprängdeg m/46, were studied. It was concluded that the velocity of detonation of EPX-2R was higher than the studied samples except composition C-4, while its sensitivity is the lowest. Interesting inversely proportional relationship between the measured internal energy of combustion and the calculated heat of detonation was observed.

Mitigation of Blast Induced Acceleration using open cell natural rubber and Synthetic Foam

In addition to high pressure generated by explosion, the induced high acceleration can also cause severe injuries to occupants and structural damage, especially in anti-vehicular land mine blast scenario. This problem has not been studied well and only few techniques to reduce the deadly effect of high acceleration are reported in literature. In the present work, the mitigation of blast induced acceleration using add-on layers of open cell natural rubber and synthetic foam on rigidly fixed composite plate has been studied experimentally under increasing blast wave strengths. The blast wave strength was varied by increasing quantity of plastic explosive from 0.150 kg to 0.550 kg. The induced vibration in the composite plate due to impingement of blast wave was measured in terms of acceleration using piezoelectric accelerometer. It was observed that the sharp rising acceleration signals were transformed into a slowly rising and low amplitude signals with the addition of foam. The mitigation of high frequencies and amplitude of acceleration signals was also verified with the fast Fourier transform study. The rubber foam shows better acceleration mitigation than synthetic foam. This study has suggested that the material like rubber and synthetic foam can be used for mitigating the acceleration resulting from the impact of blast wave.

The Influence of the Explosive Ordnance Disposal Suit on the Bomb Squad Safety

The article presents a study on the influence of shock wave on a Hybrid III anthropomorphic test device (ATD HIII) equipped with an explosive ordnance disposal (EOD) suit. The shock wave was generated by the detonation of SEMTEX 1A plastic explosive, formed in the shape of a 250 g, 500 g, and 840 g sphere, at a distance of 0.5 m, 1 m, and 2 m. The use of ATD allowed for determining parameters of damage to the human body as a result of the impact of overpressure wave. The experiments also included a measurement of such parameters as forces and moments on lower extremi-ties, acceleration of head and pelvis, and forces and moments on a neck simulator. Chest Wall Velocity Predictor (CWVP), calculated from the pressure measured on ADT’s chest, was adopted as the most critical parameter. It was revealed that the allowed distance of explosion of a 500 g pure explosive, which does not cause exceeding the allowed parameters, is 1 m.