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.

Finite Element Simulation of High Speed Machining of Ti6Al4V Alloy and the Corresponding Experimental Study

2016 ◽  
Vol 836-837 ◽  
pp. 444-451 ◽  
Author(s):  
Long Hui Meng
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Finite Element Simulation ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Ti6al4v Alloy ◽  
Machining Process ◽  
High Speed Machining ◽  
Hopkinson Pressure Bar ◽  
Element Simulation

Finite element simulation of high speed machining of Ti6Al4V alloy was carried out based on the software of Abaqus. The Johnson-Cook constitutive model was chosen for the material of Ti6Al4V, the parameters of the model were obtained through the SHPB (Split Hopkinson Pressure Bar) experiment. The similarity of the chips obtained from the simulation and that obtained from the experiment indicated that the parameters of the Johnson-Cook constitutive model for Ti6Al4V alloy were reliable. Different cutting parameters and different tool geometric parameters were used in the simulations to find out their effects to the simulation results. Also a comparison was made between the results got form the simulations results and the experimental results, a good agreement between them indicated that the finite element simulation of high speed machining of Ti6Al4V is reliable, so it can be concluded that the finite element simulations of high speed machining can be widely used in practice to study the more about the machining process and reduce the experimental expenses.

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.

Confinement device to assess dynamic crushability of wood material

2017 ◽  
Vol 232 (8) ◽  
pp. 1418-1432 ◽  
Author(s):  
J Wouts ◽  
G Haugou ◽  
M Oudjene ◽  
H Naceur ◽  
D Coutellier
Keyword(s):  
Finite Element ◽  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Hybrid Approach ◽  
Hopkinson Pressure Bar ◽  
Wood Material ◽  
Element Analysis ◽  
Multiaxial Stress State ◽  
Split Hopkinson ◽  
Pressure Bar

Cellular materials such as wood are widely and advantageously used as shock absorbers in various transport applications. The design and manufacturing of structures made of these materials require the knowledge of their dynamic compressive properties at various strain rates and stress states. Therefore, it is challenging to conduct dynamic multiaxial stress state experiments and especially on split-Hopkinson pressure bar apparatus where stress hardening increases as a function of velocity. This paper presents the so-called verification and validation methodology for confining solutions dedicated to impact on viscoelastic split-Hopkinson pressure bar system with large diameter bars. The method is a hybrid approach combining finite element analysis and an original experimental validation. Based on finite element results, particular attention is given to the mass, the material and the geometry to minimize the confining device influence on the propagation of elastic waves and thus on the material response of the tested specimens. It is essential to avoid spurious reflected waves at the new interfaces of the system in order to ensure the validity of the experimentation. The numerically predicted solutions are experimentally validated and preliminary results in the context of dynamic loadings using wood material are presented.

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.

A Numerical Verification of the Reliability of a Split Hopkinson Pressure Bar with a Total Bar Length of 3 m and a Diameter of 1 Inch

2015 ◽  
Vol 799-800 ◽  
pp. 681-684 ◽  
Author(s):  
Hyun Ho Shin ◽  
Ho Yun Lee ◽  
Jong Bong Kim ◽  
Yo Han Yoo
Keyword(s):  
Numerical Experiment ◽  
Numerical Experiments ◽  
Split Hopkinson Pressure Bar ◽  
Strain Curve ◽  
Hopkinson Bar ◽  
Numerical Verification ◽  
Hopkinson Pressure Bar ◽  
Stress Strain Curve ◽  
Split Hopkinson ◽  
Pressure Bar

A short split Hopkinson bar system with a total bar length of 3 m (a 2 m input bar plus a 1 m output bar), a striker length of 254 mm, and a diameter of 25.4 mm, is designed. Through numerical experiments, the stress vs. strain curve and the rate vs. strain curve of the specimen are obtained from the bar signals. These measured curves are reasonably consistent with the input stress-strain curve of the specimen for the numerical experiment and the prediction by the recently reported rate equation, respectively, verifying the reliability of the designed SHPB system.

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