Department Of Physics

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Blast mitigation properties of porous nano-carbon
(Elsevier Ltd, 2021-11-03T00:00:00) Chinke, Shamal L.; Sandhu, Inderpal S.; Alegaonkar, Prashant S.
Designing and development of a superior shock mitigation nano�material shield is an emerging armour building technology. We report, the effect of Kolsky bar simulated blast waves, onto the shock damping characteristics of the porous nano�carbon (abbreviation: PNC), synthesized by pyrolysis of biomass precursor. Measurement of stress (?)�strain (?), constitutive variables reveal the elasto�plastic behaviour suggesting moderate built�up, and accumulation of stress; independent of applied strain before reaching a yield ~50 MPa. Gruneisen fatigue parameter is estimated to be less (~0.92) over a theoretical Rayleigh limit with >80% post impact damage of porous component. The loci of dictated shock states derived from Rankine�Hugoniot formulism demonstrates the hydrodynamic interplay between pressure (P), volume (V), shock (US) and particle (UP) velocity. For PNC, Rayleigh slope is observed to be reduced, whereas, US became pressure independent over 10 GPa. Behaviour of P�UP hydrodynamic equation displays 30% variation in shock states and predicts a reduction of sound speed by a factor of ~0.25 in porous matrix. Behind the shock wavefront, matrix particles attend a max�speed of 100 km�s?1. The value of elastic limit for PNC is ~8.62 GPa as obtained by analysing the actual shock profile, with an evidence of phase transformation. Electron and force microscopy studies show reduction in an area, effectively, by 20�30%, thickness by six�fold factors with a rise in topological disorder. Hydro�physical variables inferred from Raman, scanning electron, transmission electron, and atomic force microscopy is comparatively discussed for PNC and other nano�carbons. Shock topology obtained by pressure�time signal processing shows ~30% impact of the shock onto PNC and manifested as shock echo. Details of the analysis are presented. � 2021 Elsevier B.V.
High Speed Projectile Sensor: Design, Development and System Engineering
(Institute of Electrical and Electronics Engineers Inc., 2021-10-15T00:00:00) Chinke, Shamal L.; Berhe, Solomon; Alegaonkar, Prashant S.
Chronography is a muzzle velocity and position sensor for a small metallic projectile (bullet) used for the military training purpose. We report on design, development, and performance testing of a conductor-insulator-conductor (CIC) sensory panel integrated with chronograph hardware and portable bullet speedometer. The established system is capable of dual recharging by alternating current mains as well as by battery support. The sensory mechanism is based on a short circuit voltage pulse developed while onset passage of the bullet from the screens. The pulse time is suitably registered, transferred, and communicated to a data storage unit interfaced to a multiport readout using the developed hardware. The whole sensor circuitry was, initially, simulated followed by optimization and final assembly of the hardware. Moreover, measured read out is taken onto a handheld speedometer with a capability to connect to personnel computer/laptop or cell phone using a state-of-the-art wireless fidelity communication interface. Three-dimensional printing technology was used to package the integrated sensor, after finalizing isometric engineering drawings. Details of fabrication, integration, and performance evaluation is demonstrated. System is real time, portable, power, and cost effective. Sensor is capable to measure the muzzle velocity 1000 m/s more than 98% accuracy when compared with a standard doppler radar and an acoustic sensor. Details are presented. � 2001-2012 IEEE.
Shock wave hydrodynamics of nano-carbons
(Elsevier Ltd, 2021-02-02T00:00:00) Chinke, Shamal L.; Sandhu, Inperpal S.; Bhave, Tejashree M.; Alegaonkar, Prashant S.
Dynamic deformation of nano-carbons by shock waves is an important object in technological applications as well as in basic sciences. We report, on hydrodynamic response of two types of nano-carbon systems: graphene nano-flakes (GNF) and carbon nano-spheres (CNS) by subjecting them to the Klosky bar shock test (at strain rate 102�104/s). Data of stress (?), strain (?), and strain rate (?) were obtained with time to analyse the behaviour of constitutive parameter (?�?). In elastic region GNF showed superior stress sensitivity at least by fivefold over CNS, whereas, stress accumulation ability of CNS was found to be ten times better than GNF. In plastic region both the systems were behaved quiet complexly. They comprised of various stages of deformation like inter�particle separation, micro�structure gliding, fracture, and perforation. To obtain hydrodynamic variables a few thermodynamic assumptions like matrix homogeneity, linear volume deformity, negligible temperature rise were made to set up the Lagrange�Rankine�Hugoniot model. Interplay of built�in pressure (P), particle velocity (UP), shock velocity (US), specific volume (V/VO), density (?), shock energy (E), behind and ahead of the shock wavefront led to the establishment of the equation of state for the system. Theoretical shock profile was vis-�-vis compared with the experimentally obtained shock results. Distribution of impulse pressure over the topology of the nano-carbons was examined that exhibited non-uniform shock energy dissipation pattern with peak pressure ~250 N/m2. Our calculations revealed that, almost ~65% shock energy was damped within GNF and ~89% in CNS. Details of the analysis are presented. � 2021 Elsevier B.V.

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