Bazle A. Gama
University of Delaware
Composite numberEngineeringCeramicFinite element methodStrain rateComposite materialEpoxyCompression (physics)Materials scienceBallistic impactPlain weaveMetal foamProjectileMechanicsStructural engineeringDelaminationArmourSplit-Hopkinson pressure barStress (mechanics)Shear (geology)
46Publications
18H-index
1,923Citations
Publications 45
Newest
#1A.F. Manzella (UD: University of Delaware)H-Index: 1
#2Bazle A. Gama (UD: University of Delaware)H-Index: 18
Last. John W. Gillespie (UD: University of Delaware)H-Index: 70
view all 3 authors...
Abstract The behavior of composite materials under transverse loading is often characterized using quasi-static experimental methods. A complete characterization requires experimentation for a range of specimen and impactor dimensions, necessitating a sizeable test matrix. However, if dimensional effects on specimen damage behavior can be understood, the number of tests required can be reduced. The present study considers confined compression testing of an S-2 glass/SC15 resin composite under qu...
17 CitationsSource
#1Stephan Fell (GM: General Motors)H-Index: 1
#2Thorsten Schuetz (GM: General Motors)H-Index: 1
Last. Bazle A. Gama (UD: University of Delaware)H-Index: 18
view all 5 authors...
3 CitationsSource
#1Bazle A. Gama (UD: University of Delaware)H-Index: 18
#2John W. Gillespie (UD: University of Delaware)H-Index: 70
Abstract Impact, damage evolution and penetration of thick-section composites are investigated using explicit finite element (FE) analysis. A full 3D FE model of impact on thick-section composites is developed. The analysis includes initiation and progressive damage of the composite during impact and penetration over a wide range of impact velocities, i.e., from 50 m/s to 1000 m/s. Low velocity impact damage is modeled using a set of computational parameters determined through parametric simulat...
113 CitationsSource
#1Sergey L. Lopatnikov (UD: University of Delaware)H-Index: 15
#2Bazle A. Gama (UD: University of Delaware)H-Index: 18
Last. John W. GillespieH-Index: 9
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Dynamics of a rigid plate impacting a glass plate is presented considering failure-wave and shock-wave propagations in the target material in addition to an elastic precursor. A generalized one dimensional theoretical failure-shock-elastic (FSE) model is developed and later simplified to study different impact scenarios on glass. While the nonlinear equations of the FSE model is solved numerically, an analytical solution is obtained for the failure-elastic submodel. In solving the failure-shock ...
1 CitationsSource
#1Bazle A. GamaH-Index: 18
#2Travis A. BogettiH-Index: 26
Last. John W. GillespieH-Index: 1
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Progressive damage of plain weave S-2 Glass/SC15 composites under in-plane tension, compression, and shear, through-thickness tension and compression, and transverse interlaminar and punch shear loading is presented for a unit single element using the MAT162 composite damage model in LSDyna. While the detail formulation of the MAT162 material model can be found in the Keyword user's manual [1], the main objective of this paper is to describe a methodology to determine a set of softening paramete...
4 Citations
#1Bazle A. Gama (UD: University of Delaware)H-Index: 18
#2John W. Gillespie (UD: University of Delaware)H-Index: 70
Abstract Ballistic damage and penetration mechanics of thick-section composites are presented. In order to correlate the ballistic penetration damage mechanisms with quasi-static penetration, experiments are designed to maintain similar boundary conditions. It has been found that the ballistic damage mechanisms can be mimicked by conducting a series of quasi-static punch shear experiments at different support spans. A quasi-static punch shear test (QS-PST) methodology is developed to quantify an...
117 CitationsSource
#1Bazle A. Gama (UD: University of Delaware)H-Index: 18
#2Sergey L. Lopatnikov (UD: University of Delaware)H-Index: 15
Last. John W. Gillespie (UD: University of Delaware)H-Index: 70
view all 3 authors...
Recent advances in SHPB technique are discussed. A compliance calibration technique together with an exact 1-D Hopkinson bar theory has been developed to accurately measure the rate dependent elastic modulus in the small strain range. A right circular cylinder (RCC) specimen with chamfered edges is found to minimize the stress concentration at the edges and thus provide a more uniform uni-axial stress state in the specimen. A new SHPB experimental methodology using an equal diameter RCC specimen...
Source
#1J.R. Xiao (UD: University of Delaware)H-Index: 21
#2Bazle A. Gama (UD: University of Delaware)H-Index: 18
Last. John W. Gillespie (UD: University of Delaware)H-Index: 70
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Abstract Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a right circular cylinder punch. Load–unload tests are performed to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Energies absorbed at different levels of damage are obtained from the load–unload curves. Two different support spans of 25.4 mm (1 in.) and 101.6 mm (4 in.) diameter w...
253 CitationsSource
#1Sergey L. Lopatnikov (UD: University of Delaware)H-Index: 15
#2Bazle A. Gama (UD: University of Delaware)H-Index: 18
Last. John W. Gillespie (UD: University of Delaware)H-Index: 70
view all 3 authors...
Abstract Quasi-static axial compression behavior of cellular materials can be explained by two ideal deformation scenarios: homogeneous deformation and progressive collapse. An elastic–plastic–rigid (E–P–R) foam model is used to derive the energy absorbed under these two deformation scenarios. It has been identified that the progressive collapse mode of deformation can absorb more energy than homogeneous deformation prior to full densification. The additional energy is shown to be proportional t...
33 CitationsSource
#1J.R. Xiao (UD: University of Delaware)H-Index: 21
#2Sergey L. Lopatnikov (UD: University of Delaware)H-Index: 15
Last. John W. Gillespie (UD: University of Delaware)H-Index: 70
view all 4 authors...
Abstract In this paper, the deformation of single- and multi-walled carbon nanotubes under radial pressure has been studied by using an analytical molecular structural mechanics model. The elastic in-plane properties (in-plane stiffness in the hoop direction, Y θ ) and Poisson's ratio ( v θ z ) of single-walled carbon nanotubes (SWCNTs) has been derived and shown to be equal to the axial direction in-plane properties ( Y z , v z θ ) for all tube diameters. In-plane properties are sensitive to tu...
30 CitationsSource