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Assessment of the ballistic response of honeycomb sandwich structures subjected to offset and normal impact

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Defence Technology（防务技术） 2023年第10期28卷 56-73页

作者： Nikhil Khaire Gaurav Tiwari Vivek Patel m.a.iqbal Department of mechanical Engineering Indian Institute of Technology DelhiNew Delhi110016India Department of mechanical Engineering Visvesvaraya National Institute of TechnologyNagpur440026India School of mechanical Engineering Dr.Vishwanath Karad MIT World Peace UniversityPune411038India Department of Civil Engineering Indian Institute of Technology RoorkeeRoorkee247667India

In the present study,experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb *** high velocity impact tests were carried out using a compressed air gun.A sharp conical nosed projectile was impacted normally and with some offset distance(20 mm and 40 mm).The deformation,failure mode and energy dissipation characteristics were obtained for both kinds of ***,the explicit solver was run in Abaqus to create the finite element *** numerically obtained test results were compared with the experimental to check the accuracy of the *** numerical result was further employed to obtain strain energy dissipation in each element by externally running user-defined code in ***,the influence of inscribe circle diameter and cell wall and face sheet thickness on the energy dissipation,deformation and failure mode was *** result found that ballistic resistance and deformation were higher against offset impact compared to the normal impact *** panel impacted at 40 mm offset distance required 3 m/s and 1.9 m/s more velocity than 0 and 20 mm offset ***,increasing the face sheet and wall thickness had a positive impact on the ballistic resistance in terms of a higher ballistic limit and energy ***,inscribe circle diameter had a negative influence on the ballistic ***,the geometrical parameters of the sandwich structure had a significant influence on the energy dissipation in the different deformation *** energy dissipation in plastic work was highest for circumferential direction,regardless of impact condition followed by tangential,radial and axial directions.

关键词： Honeycomb sandwich structure Offset impact Energy dissipation characteristic Deformation and failure mode Geometry effect

Ballistic response of skin simulant against fragment simulating projectiles

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Defence Technology（防务技术） 2023年第12期30卷 70-82页

作者： Punit Kumar Pandey Atul Harmukh m.K.Khan m.a.iqbal S.G.Ganpule Department of mechanical and Industrial Engineering Indian Institute of Technology Roorkee247667India Department of Civil Engineering Indian Institute of Technology Roorkee247667India Department of Design Indian Institute of Technology Roorkee247667India

The response of biological phantoms against high velocity impact is actively sought for applications in defense,space,soft robotics and *** this end,we study the ballistic response of silicone based skin simulant against fragment *** a pneumatic gas gun setup,six chisel-nosed and three regular shaped(sphere,cylinder,and cube)fragments were impacted on the skin *** resulting skin simulant response was studied in terms of ballistic limit velocities,energy densities,failure pattern,and the mechanics of *** results indicate that the shape of the fragment affects the ballistic limit *** ballistic limit velocities,energy densities of the chisel-nosed fragment simulating projectiles were relatively insensitive to the size(mass),except for the smallest(0.16 g)and largest(2.79 g)chisel-nosed *** the same size(1 g),ballistic limit velocities and failure are dependent on the shape of the *** skin simulant failed by combined plugging and elastic hole *** in the spherical fragment was dominated by the elastic hole enlargement,whereas plugging failure was dominant in all other *** spherical,cylindrical,and chisel-nosed fragments created circular cavities,and the cubical fragment created a square *** the case of the spherical fragment,slipping of the fragment within the skin simulant was *** fragments created lateral cracks emanating from the corners of the square ***,for all the fragments,the maximum deformation corresponding to the perforation was lower than the non-perforation indicating rate dependent,stress driven *** maximum deformation was also dependent on the shape of the ***,these results provide unique insights into the mechanical response of a soft simulant against ballistic *** have utility in the calibration and validation of computational models,design of personal protective equipment,and antipersonnel syste

关键词： Skin simulant Fragment Impact Ballistic limit velocity Energy density Failure

Advances in healthcare wearable devices

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npj Flexible Electronics 2021年第1期5卷 73-86页

作者： Sheikh m.a.iqbal Imadeldin mahgoub E Du mary Ann Leavitt Waseem Asghar Department of Computer and Electrical Engineering&Computer Science Florida Atlantic UniversityBoca RatonFLUSA Asghar-Lab Micro and Nanotechnology in MedicineCollege of Engineering and Computer ScienceBoca RatonFLUSA Department of Ocean and mechanical Engineering Florida Atlantic UniversityBoca RatonFLUSA Christine E.Lynn College of Nursing Florida Atlantic UniversityBoca RatonFLUSA Department of Biological Sciences(Courtesy appointment) Florida Atlantic UniversityBoca RatonFLUSA

Wearable devices have found numerous applications in healthcare ranging from physiological diseases,such as cardiovascular diseases,hypertension and muscle disorders to neurocognitive disorders,such as Parkinson’s disease,Alzheimer’s disease and other psychological *** types of wearables are used for this purpose,for example,skin-based wearables including tattoobased wearables,textile-based wearables,and biofluidic-based ***,wearables have also shown encouraging improvements as a drug delivery system;therefore,enhancing its utility towards personalized *** wearables contain inherent challenges,which need to be addressed before their commercialization as a fully personalized healthcare *** paper reviews different types of wearable devices currently being used in the healthcare *** also highlights their efficacy in monitoring different diseases and applications of healthcare wearable devices(HWDs)for diagnostic and treatment ***,current challenges and limitations of these wearables in the field of healthcare along with their future perspectives are also reviewed.

关键词： wear healthcare challenges

Soliton formation in electron-temperature-gradient-driven magnetoplasma

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Plasma Science and Technology 2018年第2期20卷 82-86页

作者： m Yaqub KHAN Javed iqbal Department of mathematics Riphah International University

Electron-temperature-gradient（ETG）-driven solitons are studied in a *** derive the linear dispersion relation and an admitted solitary wave solution Korteweg–de Vries-typeequation（Kd V）for the ETG mode in the nonlinear regime by using the Braginskii model and a *** is found that the ETG mode supports only rarefactive *** is also observed that the ratio of electron-to-ion temperature t=T T,e ithe ratio of gradient scale lengths h=L L,（en） Tand the magnetic field B affect both the amplitude and width of a *** is found that the soliton profile changes with variation in these *** apply the homotopy perturbation method to the derived Kd V *** is found this method is computationally attractive and the results are very *** work may be useful to study the low electrostatic modes in inhomogeneous electron–ion plasma with density and *** illustration,the model has been applied to tokamak plasma.

关键词： ETG mode KdV equation HPm

Effect of Lanthanum on Nodule Count and Nodularity of Ductile Iron

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Journal of Rare Earths 2007年第5期25卷 533-536页

作者： m. Ashraf Sheikh Javed iqbal University of Engineering & Technology

The present study aims at finding out the effect of the addition of a single rare earth element, that is, lanthanum on the nodularity and nodule count of ductile iron under controlled conditions. For this purpose, four melts with different compositions were made, using a 28 kg inductotherm medium frequency induction furnace. The temperature was carefully maintained between 1400 and 1450 ℃ for these heats. A good quality charge consisting of Sorel metal, ferrosilicon, Swedish iron, ferrosilicon magnesium, and ferrosilicon lanthanum was used for the production of melts. A vertically parted sand mould was used for casting of 10 test bars made from local silica sand. Standard coin samples were chill-cast to conduct chemical analysis of the ductile iron. mierostructure study of the samples was conducted using a Leica optical microscope. Nodule count and nodularity of the samples were carried out using an image analyzer. The results obtained indicated that with the increased addition of lanthanum the nodule count of ductile iron increased, thus making it evident that it played a significant role in increasing the mechanical properties. The highest nodule count of 467 was obtained with the addition of 0.03% lanthanum. However, the effect of lanthanum on nodularity was negligible with nodularity ranging from 81% to 83 %.

关键词： ductile iron mischmetal nodulization nodulafity nodule count rare earths

An Improved Perturb and Observe maximum Power Point Tracking Algorithm for Photovoltaic Power Systems

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Journal of modern Power Systems and Clean Energy 2023年第4期11卷 1165-1175页

作者： Rasool Kahani mohsin Jamil m.Tariq iqbal Department of Electrical and Computer Engineering Memorial University of NewfoundlandSt.John’sA1B 3X5Canada

This paper aims to improve the performance of the conventional perturb and observe(P&O)maximum power point tracking(mPPT)*** the oscillation around the maximum power point(mPP)is the main disadvantage of this technique,we introduce a modified P&O algorithm to conquer this *** new algorithm recognizes approaching the peak of the photovoltaic(PV)array power curve and prevents the oscillation around the *** key to achieve this goal is testing the change of output power in each cycle and comparing it with the change in array terminal power of the previous *** a decrease in array terminal power is observed after an increase in the previous cycle or in the opposite direction,an increase in array terminal power is observed after a decrease in the previous cycle;it means we are at the peak of the power curve,so the duty cycle of the boost converter should remain the same as the previous ***,an optimized duty cycle is introduced,which is adjusted based on the operating point of PV ***,a DC-DC boost converter powered by a PV array simulator is used to test the proposed *** the irradiance changes,the proposed algorithm produces an averageηmPPT of nearly 3.1%greater than that of the conventional P&O algorithm and the incremental conductance(In C)*** addition,under strong partial shading conditions and drift avoidance tests,the proposed algorithm produces an averageηmPPT of nearly 9%and 8%greater than that of the conventional algorithms,respectively.

关键词： Photovoltaic system maximum power point tracking(mPPT) perturb and observe(P&O) boost converter steady-state performance

A study on stochastic longitudinal wave equation in a magneto-electro-elastic annular bar to find the analytical solutions

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Communications in Theoretical Physics 2023年第8期75卷 78-86页

作者： m mamun miah m Ashik iqbal m S Osman Department of mathematics Khulna University of Engineering and TechnologyKhulna-9203Bangladesh Division of mathematical and Physical Sciences Kanazawa UniversityKakumaKanazawa 920-1192Japan Department of mathematics and Physics Khulna Agricultural UniversityKhulna-9100Bangladesh Department of mathematics Faculty of ScienceCairo UniversityGiza 12613Egypt

In this paper,we set up dynamic solitary perturb solutions of a unidirectional stochastic longitudinal wave equation in a magneto-electro-elastic annular bar by a feasible,useful,and influential method named the dual(G’/G,1/G)-expansion *** software,like mathematica,is used to complete this *** obtained solutions of the proposed equation are classified into trigonometric,hyperbolic,and rational types which play an important role in searching for numerous scientific *** technique employed here is an extension of the(G’/G)-expansion technique for finding all previously discovered *** illustrate our findings more clearly,we provide 2D and 3D charts of the various recovery *** then contrasted our findings with those of past *** graphical illustrations of the acquired solutions are singular periodic solitons and kink solitons which are added at the end of this paper.

关键词： dual(G'/G,1/G)-expansion method stochastic longitudinal wave equation dynamic solitary perturb solutions magneto-electro-elastic annular bar

Characterization of ion irradiated silicon surfaces ablated by laser-induced breakdown spectroscopy

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Chinese Physics B 2018年第8期27卷 505-510页

作者： T iqbal m Abrar m B Tahir m Seemab A majid S Rafique Department of Physics Faculty of Sciences University of Gujrat Hafiz Hayat Campus Department of Physics Hazara University Mansehra Department of Physics University of Engineering and Technology (UET)Lahore Pakistan

Low energy metallic ions, generated by a Q-switched Nd：YAG laser （1064-nm wavelength, 10-mJ energy, 9-nm 12-ns-pulse width, 1011 W/cm2 intensity） irradiated on a silicon substrate to modify various properties, such as electrical, morphological, and structural modifications. Thomson parabola technique is used to calculate the energy of these metallic ions whereas the electrical conductivity is calculated with the help of Four-point probe. Interestingly circular tracks forming chain like damage trails are produced via these energetic ions which are carefully examined by optical microscopy. It is observed that excitation, ionization, and cascade collisions are responsible for surface modifications of irradiated samples. Four-point probe analysis revealed that the electrical conductivity of substrate has reduced with increasing trend of atomic number of irradiated metallic ions （A1, Ti, Cu, and Au）. The x-ray diffraction analysis elucidated the crystallographic changes leading to reduction of grain size of N-type silicon substrate, which is also associated with the metallic ions used. The decreasing trend of conductivity and grain size is due to thermal stresses, scattering effect, structural imperfections, and non-uniform conduction of energy absorbed by substrate atoms after the ion irradiation.

关键词： ablation Thomson parabola technique four-point probe

Energy transport for ion acoustic waves in a spin polarized quantum plasma

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Communications in Theoretical Physics 2020年第1期72卷 124-129页

作者： m Ayub Z iqbal H A Shah G murtaza Salam Chair Department of PhysicsG.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics G.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics Mirpur University of Science and TechnologyMirpur-10250(AJK)Pakistan

The separate spin evolution quantum hydrodynamics(SSE-QHD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum *** results show that the energy flow speed decreases with spin polarization *** is also shown that it decreases with the increasing rate up to a certain range of wave number and then it goes to zero *** is observed that Bohm potential suppresses the energy flow *** is also noticed that the energy flow speed deviates from the group velocity even in the absence of Bohm potential ***,the contribution of of Bohm poential effect in spin polarized plasma reduces the extent of deviation.

关键词： spin polarization quantum plasma ion acoustic wave energy flow speed