New Theory and Calibration of the Split Hopkinson Bar, and Calibration of Constitutive and Fracture Models up to High Strain Rates and Tempearures
February 2-4, 2028
Presenter: Prof. Hyunho Shin, Kangwon National University
Venue: Kangwon National University, Gangneung, South Korea
Hosted by Dyn Tech Inc., Gangneung, South Korea
This short course is designed to equip professional engineers, researchers, and postgraduate students with practical knowledge in Mechanical Material Modeling for Simulation—specifically focusing on the split Hopkinson bar (SHB) and the calibration of the constitutive models and damage–fracture models up to high strain rates and temperatures.
NOTE THAT CALIBRATING A FRACTURE MODEL, FOR INSTANCE, IS OFTEN MORE CHALLENGING THAN DEVELOPING IT. In this context, the detailed objectives of this short course are to equip participants with practical skills to verify and utilize the SHB data for innovative applications introduced in this course, based on recent scientific advances in SHB theory (see the Presenter page and below); to calibrate the constitutive model using deformation test results up to high strain rates and temperatures; and to calibrate the damage–fracture model using damage and fracture outcomes up to high strain rates and temperatures.
The modeling results using quasistatic tests and SHB tests are essential for simulation-based design and analysis of large structural deformations, fractures, impacts, crashworthiness, high-speed machining, penetration, explosions, blasting, protective structures, and disaster prevention strategies.
From February 4 to 6, 2026, the First Int'l Short Course on Mechanical Material Modeling and Simulation (3MS): The Split Hopkinson Bar and Calibration of the Johnson-Cook Constitutive and Danage-Fracture Models was successfully held at the same venue with the same presenter.
The attendees of the previous meeting received the following course notes free of charge. The attendees of the next short course will receive the revised versions. DO NOT FALL BEHIND THE INNOVATIVE METHODOLOGIES AND THEORIES PRESENTED IN THIS COURSE.
Day 1: The Split Hopkinson Bar: New Theory, Calibration, and Applications—Course Notes on Mechanical Material Modeling for Simulation (ISBN: 979–11–996810–0–2)
The book begins with the fundamentals of mechanical materials and provides a brief history of the split Hopkinson bar, including existing one-dimensional theories. It then introduces new theories and methods developed by the author, such as the strain rate equation, the striker-bar impact equation, the principles and applications of the Pochhammer-Chree open-source solver, iterative dispersion correction for determining the sound speed and Poisson's ratio of the bar, an iterative simulation method to ascertain the elastic modulus and density of the bar, and the one-dimensional nature of the bar's sound speed for diameters up to 200 mm. The in-person short course includes exercises on signal processing and the aforementioned new theories, which facilitate the verification and calibration of split Hopkinson bar properties. The book further deepens its content by covering an innovative method that leverages the advantages of both the split Hopkinson pressure bar and the split Hopkinson tension bar, while simultaneously addressing their drawbacks by combining the split Hopkinson pressure bar with Compression-to-Tension Converting (CTC) structures and an inverse simulation method. Note that this innovative methodology can be implemented only through the precise calibration of bar properties—such as the elastic modulus, Poisson's ratio, one-dimensional sound speed, and density—using iterative dispersion correction and finite element analyses (FEA).
Day 2: Review and Calibration of Constitutive Models up to High Strain Rates and Temperatures: Course Notes on Mechanical Material Modeling for Simulation (ISBN: 979–11–996810–1–9)
The book begins with fundamental concepts of mechanical materials and the framework of the Johnson-Cook constitutive model. The in-person short course includes exercises on calibrating this model under both isothermal and adiabatic conditions. It then reviews twelve strain-rate-dependent constitutive models, highlighting the realities of several well-known complex models. The book further enriches its content by presenting an innovative method for accurately measuring the stress-strain (σ-ε) curve of a necking material without assuming a constitutive model. This approach employs a slightly geometrically tapered (flawed) tensile specimen in both experimental tests and iterative finite element analyses. Additionally, it explores cutting-edge techniques for accurately and economically determining parameters such as strain rate, temperature, and the inelastic heat fraction (Taylor-Quinney coefficient) by combining the Type I Compression-to-Tension Converting (CTC) structure, a split Hopkinson pressure bar, and an inverse simulation method. This approach enables the determination of these constitutive constants through a single split Hopkinson pressure bar test at ambient temperature. This innovative methodology can be implemented only through the precise calibration of bar properties and the accurate measurement of the equivalent stress–equivalent strain (σ–ε) curve for a necking material under quasistatic strain rates. This curve serves as the reference for comparison with the curve obtained using the CTC-SHPB method.
Day 3: Classification, Review, and Calibration of Danage–Fracture Models up to High Strain Rates and Temperatures: Course Notes on Mechanical Material Modeling for Simulation (ISBN: 979–11–996810–2–6)
The book begins with fundamental concepts of mechanical materials, the concept of damage, and the framework of the Johnson-Cook damage-fracture model. The in-person short course includes exercises on calibrating the fracture envelope in a damage-based fracture model, described as functions of both triaxiality and the Lode parameter. The book then discusses the roles of implicit and explicit finite element analyses in determining the equivalent stress versus equivalent plastic strain curve and in determining the fracture equivalent strain under various stress states. It considers the case where an accurately measured stress-strain curve is available by the method described in the previous book (Review and Calibration of Constitutive Models up to High Strain Rates and Temperatures) and discusses, within this context, the significance of the weakly coupled damage model for shell elements and 3D elements within the framework of the J2 plasticity model based on the von Mises yield criterion. The book further deepens its content by introducing a new coupling scheme for materials with non-zero fracture strength, which applies to the majority of materials in practice. Additionally, it explores cutting-edge techniques for accurately and economically determining both constitutive and damage-fracture models that depend on strain rate and temperature by combining Type II and Type III compression-to-tension converting (CTC) structures, a split Hopkinson pressure bar, and an inverse simulation method. This approach enables the determination of both constitutive and fracture model constants through a single split Hopkinson pressure bar test at ambient temperature. This innovative methodology can be implemented only through (1) precise calibration of bar properties, (2) accurate measurement of the equivalent stress–equivalent strain (σ–ε) curve for a necking material under quasistatic strain rates, and (3) accurate calibration of the damage-fracture model using methods such as the "∑(individual calibration)" method developed by the presenter. The results obtained under quasistatic conditions—namely, the (σ–ε) curve and the calibrated damage-fracture model—serve as references for comparison with those obtained using the CTC-SHPB method.
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 for the strain rate equation.
* 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.
* Other Excel templates for calibrating theJC constitutive model.
* Executable files for data intreval control and data interval syncronization.
* An SHB executable software per person for a specific MAC address.
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 materials (rubber and polymers).
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 one executable software per person for a specific MAC address.
We expect that the executable software alone, linked to a MAC address, will demonstrate to attendees that the registration fee is justified.
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