- History of bar technology and new theories.
- Exercise on signal processing: from bar signals to stress vs. strain & strain rate vs. strain curves.
- Exercise on designing the Split Hopkinson Bar (SHB) Experiment Using the Strain Rate Equation.
- Exercise on verifying the results of the SHB experiment using the Strain Rate Equation.
- Exercise on dispersion correction using Shin's Pochhammer-Chree equation solver.
- Exercise on calibrating co, nu, E, and rho of the bar and frequency analysis.
- Friction correction in SHPB experiment.
- SHBs with different bar materials (SHB-DBM) for soft materials; the strain rate equation for the SHB-DBM.
- Dynamic increase factor of geomaterials.
- Challenges in using high-strain-rate torsion test results to calibrate constitutive and fracture models.
- Current status and future directions in SHB technology.
- Framework of the Johnson-Cook constitutive model
- Review of more complicated constitutive models.
- Meaning of the reference strain rate and reference temperature.
- Realities and illusions of high-temperature testing.
- Managing the Inelastic Heat Fraction (Taylor–Quinney Coefficient).
- Exercise on the calibration of a strain rate- and temperature-dependent constitutive model.
- Describing the stress upturn phenomenon by modifying the strain rate factor.
- Voce-Polynomial and Ludwik Polynomial models and their fortran user subroutines.
- Extracting equivalent stress–equivalent plastic strain curve of a necking material in a tensile test.
- Importance of accurate tensile test on damage–fracture model calibration (the topic in Day 3).
- Inverse calibration of the strain rate and temperature factors using the 'SHPB' test data.
- How should we handle constitutive parameter values for a large element (approximately 1.5 cm) in large-scale structural analyses?
- Current status and future directions in strain rate-dependent constitutive models and their calibration.
- Classification and extensive review of fracture models up to recent models such as Energetic / Non-local models.
- Fracture envelopes, damage evolution, and coupling schems of various models .
- Detailed comparisons of (1) the original JC damage–fracture model, (2) Mat 15 , (3) Mat 224, (4) DIEM, and (5) GISSMO in LS-DYNA, and (6) Progressive Damage–Fracture Model in ABAQUS under the damage initiation types of JC, ductile, shear, and MSDFLD.
- Realities of coupled damage models for shell and bulk structures.
- Accounting for the variable nature of triaxiality during loading when calibrating D1–D3.
- Exercise on the calibration of fracture model parameters including the strain rate and temperature oarameters.
- Coupling scheme for materials exhibiting non-zero fracture strength and its calibration.
- The necessity of modifying the first JC factor, involving D1–D3, to realistically simulate penetration/protection phenomena under conditions of highly negative triaxiality.
- How can the fracture strain locus be determined in the highly negative triaxiality regime?
- Inverse calibration of temperature and strain rate parameters of a damage-facture model using the 'SHPB' test data.
- How should we handle the fracture model paranmeters for a large element (approximately 1.5 cm) in large-scale structural analyses?
- Current status and future directions in strain rate-dependent damage-fracture models and their calibration.
In this short course, we provide virtual or ground-truth experimental data, then practice processing the data and discuss related theories. Equipment handling and laboratory data acquisition are not included.
The software developed by the presenter will be freely distributed to attendees in its latest version.
* Two types of open-source solvers for the Pochhammer–Chree equation: one designed for n = 1 and another capable of handling up to n = 20.
* An iterative dispersion correction program written in MATLAB, available as open-source software.
* An Excel Macro program implementing the strain rate equation to predict the curves of stress-strain and strain rate-atrain measured in an SHB test.
* Excel templates for calibrating theJC constitutive model under isothermal and adiabatic assumptions.
* An Excel template designed to calibrate the JC damage–fracture model by incorporating the varying characteristics of triaxiality throughout the loading process.
* Fortran user subroutine programs for the JC constitutive model and JC damage–fracture model for major commercial FE codes.
* Executable files for data intrerval control.
* Three programs introduced above. These programs are assigned to a specific MAC address provied by the user.
The course will primarily cover metal materials using J2 plasticity theory based on von-Mises yield criterion, while additionally covering the pressure-dependent material models for geomaterials (ceramics, concrete, rocks, soil, and foam), and hyperelastic models for rubber and elastomers.
The scope of this short course on the Split Hopkinson Bar focuses on exploiting the advantages of the Split Hopkinson Pressure Bar and the Split Hopkinson Tension Bar, while simultaneously leveraging their disadvantages.
Please bring a notebook with Excel installed, as laptops will not be provided for this short course. We believe that achieving results using Excel demonstrates a true understanding of the calibration process. It is preferable to maximize what can be accomplished with Excel while minimizing reliance on more advanced optimization tools, which should be used only after fully comprehending the calibration process established through Excel. If MATLAB is also installed, attendees will find the exercises on related topics more engaging and beneficial.
The course includes the presentation of results obtained using commercial software, such as finite element (FE) packages and MATLAB, but does not cover the methods for operating the software itself. This topic is addressed in classes offered by authorized training agencies affiliated with the software companies.
The course fee includes printed handouts, lunch, coffee, tea, and snacks. Attendees will receive Excel macro programs, MATLAB scripts, executable files, and Excel templates developed by the presenter as gifts from the Short Course, including the three software illustrated in the General Information page.
09:00–09:20 Registration (08:30 – 09:20 for Day 1)
09:20–12:00 Morning session with Q&A and one coffee break.
12:00–13:10 Lunch break.
13:10–17:40 Afternoon session with Q&A and two coffee breaks.
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