The Experts below are selected from a list of 3480 Experts worldwide ranked by ideXlab platform
Heping Xie - One of the best experts on this subject based on the ideXlab platform.
-
dynamic split tensile test of flattened brazilian disc of rock with shpb setup
Mechanics of Materials, 2009Co-Authors: Qi Wang, Heping XieAbstract:The Flattened Brazilian Disc (FBD) specimens were impacted diametrically by a pulse shaping split Hopkinson pressure Bar to measure dynamic tensile strength of a brittle rock. With application of strain gauge technique, the stress waves traveling through the Incident Bar, the transmission Bar as well as the FBD specimen were recorded and analyzed. The loading history was determined based on the one-dimensional stress wave theory. The dynamic equilibrium condition in the specimen was approximately satisfied, this claim was supported by the numerical simulation of dynamic stress evolution in the specimen, with the conclusion that a short time after impact the pattern of dynamic stress distribution in the specimen was symmetric and similar to that of the counterpart static loading. The validity of the test was further verified experimentally, as the waveforms acting on the two flat ends of the FBD specimen, respectively, were of nearly the same shape, and the rupture modes of the specimens were generally such that crack first initiated at the center of the disc and subsequently propagated along the loading diameter, whereas crush zones were implied to form lastly near the two flat ends of the broken specimen. The dynamic tensile strength of marble was measured at the critical point when the tensile strain wave recorded at the disc center got peak value of the strain derivative with respect to time.
N K Naik - One of the best experts on this subject based on the ideXlab platform.
-
Stress Wave Attenuation in Aluminum Alloy and Mild Steel Specimens Under SHPB Tensile Testing
'Wiley', 2018Co-Authors: Ravikumar G, Arya H, Cs Yerramalli, N K NaikAbstract:Investigations on the effect of intensity of Incident pressure wave applied through the striker Bar on the specimen force histories and stress wave attenuation during split Hopkinson pressure Bar (SHPB) tensile testing are presented. Details of the tensile SHPB along with Lagrangian x-t diagram of the setup are included. Studies were carried out on aluminum alloy 7075 T651 and IS 2062 mild steel. While testing specimens using the tensile SHPB setup, it was observed that the force calculated from the transmitter Bar strain gauge was smaller than the force obtained from the Incident Bar strain gauge. This mismatch between the forces in the Incident Bar and the transmitter Bar is explained on the basis of stress wave attenuation in the specimens. A methodology to obtain force histories using the strain gauges on the specimen during SHPB tensile testing is also presented. Further, scanning electron microscope images and photomicrographs are given. Correlation between the microstructure and mechanical properties is explained. Further, uncertainty analysis was conducted to ascertain the accuracy of the results
-
High Strain Rate and High Temperature Behavior of Ti-6Al-4V Alloy Under Compressive Loading
'Wiley', 2018Co-Authors: Nb Bhalerao, Ss Joshi, N K NaikAbstract:The titanium alloy (grade 5) is a two-phase material, which finds significant applications in aerospace, medical, marine fields, owing to its superior characteristics like high strength-to-weight ratio, excellent corrosion resistance, and good formability. Hence, the dynamic characteristics of the Ti-6Al-4V alloy are an important area to study. A compressive split Hopkinson pressure Bar (SHPB) was used to evaluate the dynamic properties of Ti-6Al-4V alloy under various strain rates between 997 and 1898s(-1), and at temperatures between -10 degrees C and 320 degrees C. It was evident that the material strength is sensitive to both strain rate and temperature; however, the latter is more predominant than the former. The microstructure of the deformed samples was examined using electron back-scattered diffraction (EBSD). The microscopic observations show that the dynamic impact characteristics of the alloy are higher at higher strain rates than at quasi-static strain rates. The SHPB tests show that the force on the transmitter Bar is lower than the force on the Incident Bar. This indicates that the dynamic equilibrium cannot be achieved during high rate of damage evolution. Various constants in Johnson-Cook (JC) model were evaluated to validate the results. An uncertainty analysis for the experimental results has also been presented
-
high strain rate mechanical behavior of epoxy under compressive loading experimental and modeling studies
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: N K Naik, Venkateswara Rao Kavala, Parimi Jaya Shankar, G Ravikumar, Jayaram R Pothnis, Hemendra AryaAbstract:Abstract Investigations on high strain rate behavior of epoxy LY 556 under compressive loading are presented. Compressive Split Hopkinson Pressure Bar (SHPB) apparatus was used for the experimental investigations. The studies are presented in the strain rate range of 683–1890 per second. It was 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 gauge mounted on the transmitter Bar is lower than the peak force obtained from the strain gauge mounted on the Incident Bar. Further, an analytical method is presented based on variable rate power law for the prediction of compressive strength at high strain rate loading for epoxy LY 556. Using the analytical method, high strain rate compressive stress–strain behavior is presented up to strain rate of 10,000 per second.
-
shear properties of epoxy under high strain rate loading
Polymer Engineering and Science, 2010Co-Authors: N K Naik, Ravikumar Gadipatri, Narasimha Moorthy Thoram, Venkateswara Rao KavalaAbstract:Shear properties of epoxy LY 556 under high strain rate loading are presented. Torsional Split Hopkinson Bar apparatus was used for the studies in the shear strain rate range of 385–880 per sec. Experimental details, specimen configuration and development, data acquisition, and processing are presented. Shear strength, shear modulus, and ultimate shear strain are presented as a function of shear strain rate. For comparison, studies are presented at quasi-static loading. It is observed that the shear strength at high strain rate is enhanced up to 45% compared with that at quasi-static loading in the range of parameters considered. Further, it is observed that, in the range of parameters considered, the change in shear properties with the change in shear strain rate is not significant. Comparison of torque versus time behavior derived from signals obtained from strain gauges mounted on Incident Bar and transmitter Bar is also presented. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
-
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.
Qi Wang - One of the best experts on this subject based on the ideXlab platform.
-
dynamic split tensile test of flattened brazilian disc of rock with shpb setup
Mechanics of Materials, 2009Co-Authors: Qi Wang, Heping XieAbstract:The Flattened Brazilian Disc (FBD) specimens were impacted diametrically by a pulse shaping split Hopkinson pressure Bar to measure dynamic tensile strength of a brittle rock. With application of strain gauge technique, the stress waves traveling through the Incident Bar, the transmission Bar as well as the FBD specimen were recorded and analyzed. The loading history was determined based on the one-dimensional stress wave theory. The dynamic equilibrium condition in the specimen was approximately satisfied, this claim was supported by the numerical simulation of dynamic stress evolution in the specimen, with the conclusion that a short time after impact the pattern of dynamic stress distribution in the specimen was symmetric and similar to that of the counterpart static loading. The validity of the test was further verified experimentally, as the waveforms acting on the two flat ends of the FBD specimen, respectively, were of nearly the same shape, and the rupture modes of the specimens were generally such that crack first initiated at the center of the disc and subsequently propagated along the loading diameter, whereas crush zones were implied to form lastly near the two flat ends of the broken specimen. The dynamic tensile strength of marble was measured at the critical point when the tensile strain wave recorded at the disc center got peak value of the strain derivative with respect to time.
Venkateswara Rao Kavala - One of the best experts on this subject based on the ideXlab platform.
-
high strain rate mechanical behavior of epoxy under compressive loading experimental and modeling studies
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: N K Naik, Venkateswara Rao Kavala, Parimi Jaya Shankar, G Ravikumar, Jayaram R Pothnis, Hemendra AryaAbstract:Abstract Investigations on high strain rate behavior of epoxy LY 556 under compressive loading are presented. Compressive Split Hopkinson Pressure Bar (SHPB) apparatus was used for the experimental investigations. The studies are presented in the strain rate range of 683–1890 per second. It was 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 gauge mounted on the transmitter Bar is lower than the peak force obtained from the strain gauge mounted on the Incident Bar. Further, an analytical method is presented based on variable rate power law for the prediction of compressive strength at high strain rate loading for epoxy LY 556. Using the analytical method, high strain rate compressive stress–strain behavior is presented up to strain rate of 10,000 per second.
-
shear properties of epoxy under high strain rate loading
Polymer Engineering and Science, 2010Co-Authors: N K Naik, Ravikumar Gadipatri, Narasimha Moorthy Thoram, Venkateswara Rao KavalaAbstract:Shear properties of epoxy LY 556 under high strain rate loading are presented. Torsional Split Hopkinson Bar apparatus was used for the studies in the shear strain rate range of 385–880 per sec. Experimental details, specimen configuration and development, data acquisition, and processing are presented. Shear strength, shear modulus, and ultimate shear strain are presented as a function of shear strain rate. For comparison, studies are presented at quasi-static loading. It is observed that the shear strength at high strain rate is enhanced up to 45% compared with that at quasi-static loading in the range of parameters considered. Further, it is observed that, in the range of parameters considered, the change in shear properties with the change in shear strain rate is not significant. Comparison of torque versus time behavior derived from signals obtained from strain gauges mounted on Incident Bar and transmitter Bar is also presented. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
-
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.
Fengchun Jiang - One of the best experts on this subject based on the ideXlab platform.
-
analyzing stress wave propagation in a hollow Bar loaded three point bend fracture test using numerical methods
Applied Mechanics and Materials, 2015Co-Authors: Raja Ahsan Javed, Chun Huan Guo, Shi Fan Zhu, Fengchun JiangAbstract:Modified Hopkinson pressure Bar apparatus is widely used to investigate the dynamic fracture behavior of materials at higher rate loading. While using a small sample for fracture toughness testing, plane strain conditions are compromised. In the current work, a large diameter two-Bar/ three-point bend fracture setup is used to analyze stress wave propagation behavior within a larger cracked specimen. The experimental setup model consists of striker, Incident Bar, loading pin, cracked three-point specimen, span and transmission Bar. The model is prepared using ANSYS software and the transient dynamic analysis technique is used to simulate the dynamic load. The effects of increased transient time on the stress wave propagation behavior within the cracked sample and the stress and strain values at the crack tip of the three-point bend specimen are analyzed. In addition, the effects of the hollow striker, the hollow Incident Bar and the specimen span are studied. It is found that during large specimen testing, an increase in the transient time results in the lower stress and strain values in the specimen crack-tip. The relationship of the specimen span, the striker and the Incident Bars with the strain values in the specimen is analyzed and a method for the three-point bend specimen testing at the higher strain rates is also proposed.
-
investigation into dynamic response of a three point bend specimen in a hopkinson Bar loaded fracture test using numerical methods
Advances in Mechanical Engineering, 2015Co-Authors: Raja Ahsan Javed, Kenneth S Vecchio, Chun Huan Guo, Zhu Shifan, Fengchun JiangAbstract:Dynamic fracture toughness of engineering materials at loading rates greater than 106MPam/s is widely investigated using the modified Hopkinson pressure Bar apparatus. For accurate measurement of dynamic fracture toughness, it is essential to thoroughly understand the dynamic effects excited by the stress wave, such as stress wave propagation characteristics in Bars/cracked specimen, the contact situation between the specimen and loading point or supports, and the dynamic response of the fracture specimen. In this work, full transient dynamic analysis techniques are used to comprehend “loss of contact” situation of cracked fracture specimen with an Incident Bar (impactor) and a transmission Bar (supports) in a Hopkinson Bar loaded two-Bar/three-point bend test. A modified Hopkinson Bar loaded experimental setup, including striker, Incident, and transmission Bars and three-point bend fracture specimen, is modeled using the commercial software ANSYS. The dynamic responses of the specimens made of titanium a...
-
numerical investigation of the stress wave propagation in the Incident Bar and the specimen
Applied Mechanics and Materials, 2014Co-Authors: Raja Ahsan Javed, Chun Huan Guo, Shi Fan Zhu, Fengchun JiangAbstract:Hopkinson pressure Bar apparatus is extensively used for the measurement of the dynamic fracture properties. For accurate measurement of the dynamic fracture properties we need to understand concepts and principles associated with the test setup. The understanding of stress wave in the Bar and specimen is also very important. In the current work, ANSYS LS-DYNA software is used to simulate the propagation behavior of the time based loading and generation of stress wave. The stress and strain plots in the specimen and the Incident Bar are obtained as an output of the analysis. The analysis of the plots suggest that, for the same time duration the rising trend is observed for the plots of stress and strain of Incident Bar whereas a sine wave trend is observed for the plots in the specimen.
