The Experts below are selected from a list of 87414 Experts worldwide ranked by ideXlab platform
N K Naik - One of the best experts on this subject based on the ideXlab platform.
-
Energy absorption capability of carbon nanotubes dispersed in resins under compressive High Strain Rate loading
Composites Part B: Engineering, 2015Co-Authors: Kedar S. Pandya, N K NaikAbstract:Abstract The focus of the present study is on energy absorption capability (EA) of carbon nanotubes (CNTs) dispersed in thermoset epoxy resin under compressive High Strain Rate loading. Toward this objective, High Strain Rate compressive behavior of multi-walled carbon nanotube (MWCNT) dispersed epoxy is investigated using a split Hopkinson pressure bar. The amount of MWCNT dispersion is varied up to 3% by weight. Calculation methodology for the evaluation of EA of individual CNTs and CNTs dispersed in resins/composites is presented. Quantitative data on EA of individual CNTs and CNTs dispersed in resins under quasi-static and High Strain Rate loading is given.
-
Shear properties of acrylic under High Strain Rate loading
Journal of Applied Polymer Science, 2011Co-Authors: Tamrat Abishu Gelu, Suhas S. Joshi, N K NaikAbstract:Acrylic is being used in structural applications because of its Higher resistance to projectile impacts. High Strain Rate shear loading is one of the critical conditions. In the present study, properties of typical acrylic under High Strain Rate shear loading are presented. Torsional Split Hopkinson Bar apparatus was used for the studies in the shear Strain Rate range of 290 per sec to 791 per sec. Thin-walled tubular specimens with hexagonal flanges were used for the experimental studies. Details of specimen configuration, data acquisition, and processing are presented. Shear strength is presented as a function of shear Strain Rate. It is observed that the shear strength at High Strain Rate is enhanced up to 25% compared with that at quasi-static loading in the range of parameters considered. Comparison of torque versus time behavior derived from signals obtained from Strain gauges mounted on incident bar and transmitter bar is also presented. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
-
High Strain Rate tensile behavior of woven fabric e glass epoxy composite
Polymer Testing, 2010Co-Authors: N K Naik, P Yernamma, Narasimha Moorthy Thoram, R Gadipatri, Venkateswara Rao KavalaAbstract:Abstract High Strain Rate tensile behavior is presented along thickness, warp and fill directions for a typical plain weave fabric E-glass/epoxy composite. Studies were carried out on tensile Split Hopkinson Pressure Bar (SHPB) apparatus in the Strain Rate range of 140–400/s. For comparison, quasi-static properties were also geneRated on a universal testing machine. An increase of 75–93% was observed in through the thickness High Strain Rate tensile strength compared with quasi-static tensile strength. In the range of Strain Rate considered, as the Strain Rate was increased, the tensile strength increased up to 11% along the thickness direction. An increase of 63–88% was observed in High Strain Rate tensile strength along the fill compared with quasi-static tensile strength. In the range of Strain Rate considered, as the Strain Rate was increased, the tensile strength increased up to 16% along the fill direction. Since the plain weave fabric used was balanced, the properties along warp and fill are nearly identical.
-
High Strain Rate behavior of woven fabric composites under compressive loading
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: N K Naik, Venkateswara Rao KavalaAbstract:Abstract Investigations on High Strain Rate behavior of composites under compressive loading are presented. Compressive split Hopkinson pressure bar (SHPB) apparatus was used for the studies. Compressive properties of typical plain weave E-glass/epoxy and plain weave carbon/epoxy were evaluated along all the principal directions in the Strain Rate range of 680–2890 s−1. It is generally observed that the compressive strength is enhanced at High Strain Rate loading compared with that at quasi-static loading. During SHPB testing of the specimens, it was observed that the peak force obtained from the Strain gage mounted on the transmitter bar is lower than the peak force obtained from the Strain gage mounted on the incident bar. The explanation for this is provided based on stress wave attenuation studies.
Venkateswara Rao Kavala - One of the best experts on this subject based on the ideXlab platform.
-
High Strain Rate tensile behavior of woven fabric e glass epoxy composite
Polymer Testing, 2010Co-Authors: N K Naik, P Yernamma, Narasimha Moorthy Thoram, R Gadipatri, Venkateswara Rao KavalaAbstract:Abstract High Strain Rate tensile behavior is presented along thickness, warp and fill directions for a typical plain weave fabric E-glass/epoxy composite. Studies were carried out on tensile Split Hopkinson Pressure Bar (SHPB) apparatus in the Strain Rate range of 140–400/s. For comparison, quasi-static properties were also geneRated on a universal testing machine. An increase of 75–93% was observed in through the thickness High Strain Rate tensile strength compared with quasi-static tensile strength. In the range of Strain Rate considered, as the Strain Rate was increased, the tensile strength increased up to 11% along the thickness direction. An increase of 63–88% was observed in High Strain Rate tensile strength along the fill compared with quasi-static tensile strength. In the range of Strain Rate considered, as the Strain Rate was increased, the tensile strength increased up to 16% along the fill direction. Since the plain weave fabric used was balanced, the properties along warp and fill are nearly identical.
-
High Strain Rate behavior of woven fabric composites under compressive loading
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: N K Naik, Venkateswara Rao KavalaAbstract:Abstract Investigations on High Strain Rate behavior of composites under compressive loading are presented. Compressive split Hopkinson pressure bar (SHPB) apparatus was used for the studies. Compressive properties of typical plain weave E-glass/epoxy and plain weave carbon/epoxy were evaluated along all the principal directions in the Strain Rate range of 680–2890 s−1. It is generally observed that the compressive strength is enhanced at High Strain Rate loading compared with that at quasi-static loading. During SHPB testing of the specimens, it was observed that the peak force obtained from the Strain gage mounted on the transmitter bar is lower than the peak force obtained from the Strain gage mounted on the incident bar. The explanation for this is provided based on stress wave attenuation studies.
Nikhil Gupta - One of the best experts on this subject based on the ideXlab platform.
-
Quasi-Static and High Strain Rate Compressive Response of Injection-Molded Cenosphere/HDPE Syntactic Foam
JOM, 2016Co-Authors: B. R. Bharath Kumar, Mrityunjay Doddamani, Ashish Kumar Singh, Dung D Luong, Nikhil GuptaAbstract:High Strain Rate compressive properties of High-density polyethylene (HDPE) matrix syntactic foams containing cenosphere filler are investigated. Thermoplastic matrix syntactic foams have not been studied extensively for High Strain Rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10^−4 s^−1, 10^−3 s^−1 and 10^−2 s^−1 Strain Rates. Further, a split-Hopkinson pressure bar is utilized for characterizing syntactic foams for High Strain Rate compression. The compressive strength of syntactic foams is Higher than that of HDPE resin at the same Strain Rate. Yield strength shows an increasing trend with Strain Rate. The average yield strength values at High Strain Rates are almost twice the values obtained at 10^−4 s^−1 for HDPE resin and syntactic foams. Theoretical models are used to estimate the effectiveness of cenospheres in reinforcing syntactic foams.
-
quasi static and High Strain Rate compressive response of injection molded cenosphere hdpe syntactic foam
JOM, 2016Co-Authors: B Bharath R Kumar, Ashish Kumar Singh, Mrityunjay Doddamani, Dung D Luong, Nikhil GuptaAbstract:High Strain Rate compressive properties of High-density polyethylene (HDPE) matrix syntactic foams containing cenosphere filler are investigated. Thermoplastic matrix syntactic foams have not been studied extensively for High Strain Rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10−4 s−1, 10−3 s−1 and 10−2 s−1 Strain Rates. Further, a split-Hopkinson pressure bar is utilized for characterizing syntactic foams for High Strain Rate compression. The compressive strength of syntactic foams is Higher than that of HDPE resin at the same Strain Rate. Yield strength shows an increasing trend with Strain Rate. The average yield strength values at High Strain Rates are almost twice the values obtained at 10−4 s−1 for HDPE resin and syntactic foams. Theoretical models are used to estimate the effectiveness of cenospheres in reinforcing syntactic foams.
-
Post-impact residual High Strain Rate compressive properties of carbon fiber laminates
Journal of Reinforced Plastics and Composites, 2013Co-Authors: Ronald L. Poveda, Nikhil GuptaAbstract:The purpose of the present study is to investigate the residual High Strain Rate compressive properties of cross-ply carbon fiber laminates after drop-weight impact. The tested laminate is divided into four quadrants and specimens are extracted from each quadrant for High Strain Rate compression testing using a split–Hopkinson pressure bar. The testing is conducted in the Strain Rate range of 1000–1450 s−1. A comparison between pre- and post-impact carbon fiber laminates subjected to High Strain Rate compression suggested that there is a maximum decrease of 76.1% and 71.6% in the peak stress and absorbed energy of the laminate, respectively, at High Strain Rate compression. Microscopy was conducted on the failed specimens to determine the failure mode. Extensive delamination observed at the impact point causes significant decrease in compressive strength and energy absorption of the laminate.
-
High Strain Rate response of rabbit femur bones.
Journal of biomechanics, 2010Co-Authors: Vasanth Chakravarthy Shunmugasamy, Nikhil Gupta, Paulo G. CoelhoAbstract:Strain Rate dependence of the mechanical response of hard tissues has led to a keen interest in their dynamic properties. The current study attempts to understand the High Strain Rate characteristics of rabbit femur bones. The testing was conducted using a split-Hopkinson pressure bar equipped with a High speed imaging system to capture the fracture patterns. The bones were also characterized under quasi-static compression to enable comparison with the High Strain Rate results. The quasi-static compressive moduli of the epiphyseal and diaphyseal regions were measured to be in the range of 2–3 and 5–7 GPa, respectively. Under High Strain Rate loading conditions the modulus is observed to increase with Strain Rate and attains values as High as 15 GPa for epiphyseal and 30 GPa for diaphyseal regions of the femur. The strength at High Strain Rate was measured to be about twice the quasi-static strength value. A large number of small cracks initiated on the specimen surface close to the incident bar. Coalescence of crack branches leading to fewer large cracks resulted in specimen fragmentation. In comparison, the quasi-static failure was due to shear cracking.
Ezio Cadoni - One of the best experts on this subject based on the ideXlab platform.
-
High Strain Rate response of s355 at High temperatures
Materials & Design, 2016Co-Authors: Daniele Forni, Bernardino Chiaia, Ezio CadoniAbstract:Abstract In this paper the High Strain Rate behaviour in tension and in a wide range of elevated temperatures of the S355 structural steel is presented. A Split Hopkinson Tensile Bar for the mechanical characterisation at High Strain Rates, equipped with a water-cooled induction heating system is used. These data are collected with the purpose of evaluating the extreme combined effect of dynamic loadings and elevated temperatures (200 °C, 400 °C, 550 °C, 700 °C and 900 °C), e.g., a fire load followed by an explosion. The reduction factors for the main mechanical properties are reported. The novelty of our data is the addition of the Strain Rate dependency to the temperature. High Strain Rate tests at 550 °C Highlighted the phenomenon known as blue brittleness where an increase of strength and a decrease of ductility were ascribed to the dynamic Strain ageing. Focusing the attention on the thermal softening parameter, m , the widely used constitutive law proposed by Johnson and Cook during the eighties is critically reviewed Highlighting some weaknesses. The results can be of great interest for the assessment of robustness in structures where a fire induced progressive collapse should be evaluated focusing the attention to the extreme combined effects.
-
High Strain Rate behaviour in tension of steel B500A reinforcing bar
Materials and Structures, 2014Co-Authors: Ezio Cadoni, Matteo Dotta, Daniele Forni, Nicoletta TesioAbstract:In reinforced concrete structures under severe dynamic loading, as impact and blast, both concrete and reinforcing bars are subjected to High Strain-Rates. While the dynamic tensile behaviour of concrete is the subject of many researches, the behaviour of the reinforcing steel under High Strain Rate has been not completely considered yet. Such behaviour is of capital importance in the structural assessment under the abovementioned loading conditions. This is the reason why an experimental program on rebar, stirrup and wire steels under High Strain Rate in tension is running at the DynaMat Laboratory. In this study the effect of High Strain Rate on the mechanical properties of B500A steel reinforcing bars in tension has been analysed. The steel of three different bars having diameter of 6, 8 and 10 mm have been investigated. The experiments have been carried out by means of a Split Hopkinson Tensile Bar at 250, 500 and 1000 s−1. Finally the parameters of the well-known Johnson–Cook and Cowper–Symonds materials models have been obtained.
Erhong Song - One of the best experts on this subject based on the ideXlab platform.
-
High Strain Rate compressive response of the Cf/SiC composite
Ceramics International, 2019Co-Authors: Kun Luan, Jianjun Liu, Baozhong Sun, Wei Zhang, Xiaomeng Fang, Chen Ming, Erhong SongAbstract:Abstract Carbon fiber reinforced ceramic owns the properties of lightweight, High fracture toughness, excellent shock resistance, and thus overcomes ceramic's brittleness. The researches on the advanced structure of astronautics, marine have exclusively evaluated the quasi-static mechanical response of carbon fiber reinforced ceramics, while few investigations are available in the open literature regarding elastodynamics. This paper reports the dynamic compressive responses of a carbon fiber reinforced silicon carbide (Cf/SiC) composite (CFCMC) tested by the material test system 801 machine (MTS) and the split Hopkinson pressure bar (SHPB). These tests were to determine the Rate dependent compression response and High Strain Rate failure mechanism of the Cf/SiC composite in in-plane and out-plane directions. The in-plane compressive Strain Rates are from 0.001 to 2200 s−1, and that of the out-plane direction are from 0.001 to 2400 s−1. The compressive stress-Strain curves show the Cf/SiC composite has a property of Strain Rate sensitivity in both directions while under High Strain Rate loadings. Its compressive stiffness, compressive stress, and corresponding Strain are also Strain Rate sensitive. The compressive damage morphologies after High Strain Rate impacting show different failure modes for each loading direction. This study provides knowledge about elastodynamics of fiber-reinforced ceramics and extends their design criterion with a reliable evaluation while applying in the scenario of loading High Strain Rate.