Use of High-Speed Photography to Augment Split Hopkinson Pressure Bar Measurements of Energetic Materials

2002 ◽  
Author(s):  
Richard J. Lee
Keyword(s):  
Energetic Materials ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
High Speed Photography ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

An improved method for compressive stress-strain measurements at very high strain rates

1992 ◽  
Vol 438 (1902) ◽  
pp. 153-170 ◽  
Keyword(s):  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Pure Copper ◽  
High Strength ◽  
Tungsten Alloy ◽  
High Speed Photography ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

This paper describes a modification of the split Hopkinson pressure bar, to allow compression testing of high strength metals at a strain rate of up to about 10 5 s –1 . All dimensions are minimized to reduce effects of dispersion and inertia, with specimens of the order of 1 mm diameter. Strain is calculated from the stress record and calibrated with high-speed photography. Particular attention has been paid to the accuracy of the technique, and errors arising from nonlinearity in the instrumentation, dispersion, frictional restraint and inertia have all been quantitatively assessed. Stress–strain results are presented of Ti 6A14V alloy, a high strength tungsten alloy, and pure copper.

Thermo-Mechanical Aspects of Adiabatic Shear Failure of AM50 and Ti6Al4V Alloys

2008 ◽  
Author(s):  
D. Rittel ◽  
Z. G. Wang
Keyword(s):  
High Speed ◽  
Shear Failure ◽  
Split Hopkinson Pressure Bar ◽  
Adiabatic Shear ◽  
Maximum Temperature ◽  
Hopkinson Pressure Bar ◽  
Gauge Section ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Deformation Patterns

The thermo-mechanical aspects of adiabatic shear band (ASB) formation are studied for two commercial alloys: Mg AM50 and Ti6Al4V. Tests are carried out on shear compression specimens (SCS). The evolution of the temperature in the deforming gauge section is monitored in real time, using an array of high speed infrared detectors synchronized with a Kolsky apparatus (split Hopkinson pressure bar). The evolution of the gage temperature is found to comprise 3 basic stages, in agreement with Marchand and Duffy’s simultaneous observations of mechanical data and gauge deformation patterns (1988). The onset and full formation stages of ASB are identified by combining the collected thermal and mechanical data. Full development of the ASB is identified as the point at which the measured and calculated temperature curves intersect and diverge thereon. At that stage, the homogeneous strain assumption used in calculating the maximum temperature rise is no longer valid.

A texture and microstructure analysis of high speed rolling of AZ31 using split Hopkinson pressure bar results

2013 ◽  
Vol 48 (19) ◽  
pp. 6656-6672 ◽  
Author(s):  
M. Sanjari ◽  
A. Farzadfar ◽  
T. Sakai ◽  
H. Utsunomiya ◽  
E. Essadiqi ◽  
...  
Keyword(s):  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Microstructure Analysis ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

scholarly journals The dynamic compressive behavior of beryllium bearing bulk metallic glasses

1996 ◽  
Vol 11 (2) ◽  
pp. 503-511 ◽  
Author(s):  
H. A. Bruck ◽  
A. J. Rosakis ◽  
W. L. Johnson
Keyword(s):  
Metallic Glass ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Testing ◽  
Adiabatic Heating ◽  
Nominal Composition ◽  
Hopkinson Pressure Bar ◽  
Thermal Detector ◽  
Split Hopkinson ◽  
Pressure Bar

In 1993, a new beryllium bearing bulk metallic glass with the nominal composition Zr41.25Ti13.75Cu12.5Ni10Be22.5 was discovered at Caltech. This metallic glass can be cast as cylindrical rods as large as 16 mm in diameter, which permitted specimens to be fabricated with geometries suitable for dynamic testing. For the first time, the dynamic compressive yield behavior of a metallic glass was characterized at strain rates of 102 to 104/s by using the split Hopkinson pressure bar. A high-speed infrared thermal detector was also used to determine if adiabatic heating occurred during dynamic deformation of the metallic glass. From these tests it appears that the yield stress of the metallic glass is insensitive to strain rate and no adiabatic heating occurs before yielding.

Finite Element Simulation for Design Verification of a Small Size Split Hopkinson Pressure Bar

2013 ◽  
Author(s):  
Mohamad Dyab ◽  
Payam Matin ◽  
Yuanwei Jin
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Bar ◽  
Hopkinson Pressure Bar ◽  
Element Simulation ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
High Speed Deformation

Split Hopkinson Pressure Bar is an apparatus that is used to study materials behavior under high speed deformation, where strain rate is very high. Hopkinson bars are usually custom made based on the needs of customers, who are mostly researchers in universities or research labs. In this work, the authors designed a small size split Hopkinson pressure bar. The objectives of this project are 1) to design a well-structured Hopkinson bar by means of solid mechanics fundamentals 2) to implement finite element simulation to verify the design. The designed Split Hopkinson bar consists of two metallic bars with a specimen placing in between, a striker assembly, an air compressor, instrumentation and a data acquisition system. The solid model of the apparatus is built using CAD software SolidWorks. The design is validated by extensive finite element simulation using ABAQUS. A working prototype is physically built and tested. High speed deformation experiments are developed using the prototype fabricated. The experiments are conducted as an impact is made by the striker on one of the bars, which generates stress wave through the specimen and the other bar. During the experiments, strain in specimen is determined by measuring strains on the bars using strain gauges mounted on the bars. Preliminary tests demonstrate that the performance of the apparatus is as predicted by the FEM simulation. This work is supported by an NSF’s CMMI (Civil, Mechanical and Manufacturing Innovation) program.

scholarly journals ‘Seeing’ Strain in Soft Materials

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 542 ◽  
Author(s):  
Zhiyong Xia ◽  
Vanessa D. Alphonse ◽  
Doug B. Trigg ◽  
Tim P. Harrigan ◽  
Jeff M. Paulson ◽  
...  
Keyword(s):  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Color Change ◽  
Soft Materials ◽  
Image Correlation ◽  
High Rate ◽  
Hopkinson Pressure Bar ◽  
Dimethyl Siloxane ◽  
Split Hopkinson ◽  
Pressure Bar

Several technologies can be used for measuring strains of soft materials under high rate impact conditions. These technologies include high speed tensile test, split Hopkinson pressure bar test, digital image correlation and high speed x-ray imaging. However, none of these existing technologies can produce a continuous 3D spatial strain distribution in the test specimen. Here we report a novel passive strain sensor based on poly(dimethyl siloxane) (PDMS) elastomer with covalently incorporated spiropyran (SP) mechanophore to measure impact induced strains. We have shown that the incorporation of SP into PDMS at 0.25 wt% level can adequately measure impact strains via color change under a high strain rate of 1500 s−1 within a fraction of a millisecond. Further, the color change is fully reversible and thus can be used repeatedly. This technology has a high potential to be used for quantifying brain strain for traumatic brain injury applications.

The Effect of Stress Wave on Dynamic Response of Square Thin-Walled Tube

2014 ◽  
Vol 590 ◽  
pp. 63-68 ◽  
Author(s):  
Zhu Hua Tan ◽  
Bo Zhang ◽  
Peng Cheng Zhai
Keyword(s):  
Wave Propagation ◽  
Dynamic Response ◽  
Stress Wave ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Stress Wave Propagation ◽  
Hopkinson Pressure Bar ◽  
Thin Walled Tube ◽  
Split Hopkinson ◽  
Pressure Bar

The effect of stress wave propagation on dynamic response of square tube was investigated by the experimental and numerical simulation methods in the present paper. The square tubes were subjected to the axial impact by split Hopkinson pressure bar. And the deformation process of each square tube was recorded by a high speed camera. Typical dynamic plastic buckling phenomena were observed in the experiments. And the numerical calculation of the experimental load case was conducted to analyze the effect of the stress wave propagation on the initial buckling of the square tube. The results show that there is obvious stress wave propagation in the square tube before the buckling of the square tube. And the initial buckling starts from the rear end of the tube due to the propagation of the stress wave. The relation between the stress wave propagation and initial buckling of the square tube was also discussed.

Features of Meso-Deformation and Failure of Aluminum Foam under Impact

2012 ◽  
Vol 602-604 ◽  
pp. 2235-2240
Author(s):  
Bao Yang ◽  
Li Qun Tang ◽  
Yi Ping Liu ◽  
Ze Jia Liu ◽  
Zhen Yu Jiang
Keyword(s):  
High Speed ◽  
Aluminum Foam ◽  
Split Hopkinson Pressure Bar ◽  
Digital Camera ◽  
Fe Model ◽  
Hopkinson Pressure Bar ◽  
Camera System ◽  
Deformation And Failure ◽  
Split Hopkinson ◽  
Pressure Bar

Deformation and failure of meso-structures take great effect on the loading and energy absorption of aluminum foam under impact. We designed a split Hopkinson pressure bar (SHPB)-high speed digital camera system to monitor the meso-deformation and failure features, and measure the nonuniformity of deformation of aluminum foam under impact. The meso-deformation and failure of aluminum foam were observed successfully by the system, and it showed that there does exist remarkable nonuniform deformation along the specimen. In order to expand the experimental results, the specimen of aluminum foam with meso-structures is modeled by 3D Voronoi technique. The numerical results show that the FE model can simulate the experiment well, and shows that nonuniformity of deformation appears in aluminum foam specimen significantly. The analysis indicates that the assumption of uniform deformation of specimen in SHPB cannot be strictly satisfied for the material of aluminum foam.

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