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Explicit Dynamics Brochure  Download 
Based on the robust and timetested Lagrange (STRuctural) solver of the ANSYS AUTODYN analysis program, ANSYS Explicit STR software is fully integrated into the unified ANSYS Workbench environment. This framework enables convenient and seamless use of a range of multiphysics solutions, including electrical, thermal, mechanical and computational fluid dynamics (CFD).
ANSYS Explicit STR extends the range of problems that can be conveniently and easily solved by the powerful ANSYS mechanical suite by efficiently and accurately simulating shortduration severe loadings and complex contact problems. The graphical user interface for Explicit STR is the same as for ANSYS Mechanical software. Users will find that setting up problems is even easier than for the mechanical suite as contact surfaces are handled automatically and need not be defined. Sophisticated, material models can simply be selected from the explicit material library without having to specify any of the properties. Highly transient phenomena can easily be modeled with detailed resolution of the materials response.
ANSYS Explicit STR is well suited to a number of different types of problems including:
Product Features Include:
Wide Range of Capabilities
ANSYS explicit dynamics helps engineers to explore a wide range of simulation challenges.
Superior Bidirectional CAD Interface
Existing native CAD geometry can be used directly with ANSYS explicit dynamics solutions with no need for translations to intermediate geometry formats such as IGES to ensure that parameters and other design information are not lost. ANSYS has provided native, bidirectional, integration with the most popular CAD systems for more than 10 years and also provides integration directly into the CAD menu bar making it very simple to launch worldclass ANSYS simulation directly from a CAD system. Because the geometry import mechanism from ANSYS is common to all CAD systems, the user has the flexibility to work within a single, common simulation environment while using multiple CAD packages and multiple ANSYS solution methods including explicit dynamics, structural mechanics, fluid dynamics and electromagnetics.
ANSYS supports the following CAD systems: Autodesk® Inventor®, Autodesk Mechanical Desktop®, Autodesk Inventor Professional Stress, CATIA® v4 and v5, Pro/ENGINEER®, Solid Edge®, SolidWorks®, Unigraphics®, CoCREATE Modeling™ and SpaceClaim®. The ANSYS Workbench environment also supports the neutral format files of IGES, Parasolid®, ACIS® (SAT) and STEP to which any CAD system can export.
Geometries created with CAD tools are not always well suited for explicit dynamic simulations. For example, surfaces that do not meet or overlap may need to be corrected. Very small features may need to be removed to so that meshes can be created that can be used to generate accurate results efficiently. These operations can be done easily and conveniently with the ANSYS DesignModeler and ANSYS SpaceClaim Direct Modeler tools.
Robust Automatic Meshing
ANSYS provides a wide range of highly robust automated meshing tools — from tetrahedral meshes to pure hexahedral meshes and highquality meshes for surface and line bodies. Using the explicit preference in meshing will generate meshes well suited for explicit dynamics. Additional productivity tools include the ability to control element size, to defeature unnecessary details, to generate swept hex dominant meshes, to use smoothing controls for gradual element size transitions and to apply multizone meshing for parts consisting of multiple bodies that need to be meshed uniformly. Multizone meshing also automatically will “slice and dice” parts to enable the generation of high quality hex meshes.
Auto Contact Detection for Parts
Once the geometry has been imported, the software automatically detects and performs setup for contacts, bonded contacts and interface definition for coupling between Euler and Lagrange regions for problems involving fluid–structure Interaction (FSI). Contact settings can be modified to improve computation speed by excluding parts or surfaces that are known not to come in contact.
Comprehensive Element Technology
The current generation of ANSYS element technologies used in explicit dynamics provides rich functionality with a consistent theoretical foundation coupled with the most advanced algorithms. ANSYS Explicit Dynamics solutions provide a variety of elements for use with line bodies, surfaces and solid elements. Element types include 8node hex, 6node penta or 4node tet elements in 3D as well as 4node hex and 3node tet in 2D. The speed of calculations can be further improved with the use of 2D axis symmetry, 2D planer symmetry as well as 3D quarter or half symmetry. These options can be easily set up in the ANSYS Workbench platform. Complex geometries are often difficult to mesh with all hex elements, which are generally desirable due to their accuracy and efficiency. Tet elements facilitate the meshing of complicated geometries, but have been avoided in the past for explicit solutions, because they tend to be too stiff and lock up. The recently implemented NBS tet eliminates problems with both volume and shear locking and enables easier problem setup without sacrificing accuracy.
Extensive Library of Material Models
It is vital to understand and accurately characterize material behavior while designing or analyzing an engineering application. ANSYS Explicit Dynamics solutions provide a vast library of mathematical material models to aid the user in simulating virtually all kinds of material behavior as shown in the table below. In addition, in order to aid in finding parameters for these materials models, ANSYS also provides a set of curvefitting tools.
Class of Materials  Material Effects 
Metal  Elasticity Plasticity Isotropic Strain Hardening Isotropic Thermal Softening Ductile Fracture Brittle Fracture (Fracture Energy Based) Dynamic Failure (Spall) 
Concrete/Rock  Elasticity Porous Compaction Plasticity Strain Rate Hardening in Compression Strain Rate Hardening in Tension Pressure Dependent Plasticity Lode Angie Dependent Plasticity Shear Damage/Fracture Tensile Damage/Fracture 
Soil/Sand  Elasticity Porous Compaction Plasticity Pressure Dependent Plasticity Shear Damage/Fracture Tensile Damage/Fracture 
Rubber/Polymer  Elasticity Viscoelasticity Hyperelasticity 
Orthotropic  Orthotropic Elasticity 
Material Models  
Linear Elastic  Isotropic Elasticity Orthotropic Elasticity Visoelastic 
Experimental Stress Strain Data  Uniaxial Test Data Biaxial Test Data Shear Test Data Volumetric Test Data 
Hyperelastic  NeoHookean MooneyRivlin 2 Parameter MooneyRivlin 3 Parameter MooneyRivlin 5 Parameter MooneyRivlin 9 Parameter Polynomial 1st Order Polynomial 2nd Order Polynomial 3rd Order Yeoh 1st Order Yeoh 2nd Order Yeoh 3rd Order Ogden 1st Order Ogden 2nd Order Ogden 3rd Order 
Plasticity  Bilinear Isotropic Hardening Multilinear Isotropic hardening Bilinear Kenematic Hardening Multilinear Kinematic Hardening Johnson Cook Strength Cowper Symonds Strenght Steinberg Guinan Strength Zerilli Armstrong Strength 
Thermal  Specific Heat 
Brittle/Granular  Drucker– Prager Strength Linear Drucker– Prager Strength Stassi Drucker– Prager Strength Piecewise Johnson– Holmquist Strength Continuour Johnson– Holmquist Strength Segmented RHT Concrete Strength MO Granular 
Equations of State  Bulk Modulus Shear Modulus Polynomial EOS Shock EOS Linear Shock EOS Bilinear 
Porosity  Crushable Foam Compaction Linear Compaction EOS nonlinear Palpha EOS 
Failure  Plastic Strain Failure Principal Stress Failure Principal Strain Failure Stochastic Failure Tensile Pressure Failure Crack Softening Failure Johnson Cook Failure Grady Spall Failure 
The engineering data library included with the ANSYS Workbench platform not only contains an extensive list of material models but displays the material response properties in a tabular and graphical form.
Advanced Numerical Methods for Nonlinear Dynamics
With a solid foundation of element and material technology, ANSYS Explicit dynamics solutions offer various advanced solver technologies to best simulate a comprehensive list of dynamic applications. The multiple solution methods described and pictured below can be combined in several ways through the use of part interaction. The interactions can be through contact, bonded contact and coupling between Euler and Lagrange regions for problems involving fluid–structure interaction (FSI). For parts that interact via contact, the contact surfaces that are automatically redefined as elements on the surface are removed through erosion. The table below shows the solvers that are available with each of the three explicit dynamics products, through the ANSYS Workbench interface.
ANSYS Product  
Available Solution Method 
LSDYNA 
Explicit Dynamics (STR) 
Autodyn 
Lagrange (including shell & beam) 

SPH 

EULER 

EULER FCT 

ALE 

Implicit Prestress 
Available Solution Methods
The Lagrange solver utilizes a mesh that moves and distorts with the material it models as a result of forces from neighboring elements. This is the most efficient solution methodology with accurate pressure history definition. If however, there is too much deformation of any element, it results in a very slowly advancing solution and is usually terminated because the smallest dimension of an element results in a time step that is below the threshold level. For problems with too much deformation involving gases and liquids, the Euler solver is better suited.
The Euler (multimaterial) solver utilizes a fixed mesh, allowing materials to flow (advect) from one element to the next. The Euler solver is very well suited for problems involving extreme material movement, such as those involving fluids and gases. Euler is generally more computationally intensive than Lagrange and requires higher resolution (smaller elements) to accurately capture sharp pressure peaks that often occur with shocks.
The ALE (Arbitrary Lagrange, Euler) solver utilizes the advantages of both the Lagrange and Euler solvers. It works as a Lagrangian solver but periodically repairs the mesh as it becomes distorted. This solver is well suited for problems that lie between the Lagrange and Euler sweet spots.
The Euler–FCT solver, used for ideal gases, is a specialpurpose Euler solver that is very fast and highly accurate. It is best suited for use in problems simulating blast loadings.
SPH (smooth particle hydrodynamic) meshfree method is ideally suited for certain types of problems with extensive material damage and separation such as cracking. This type of response often occurs with brittle materials and with hypervelocity impacts.
The Shell solver is assigned to twodimensional parts such as membranes. It enables efficient computation in spite of the very small dimension of the membrane.
The Beam solver is used for onedimensional parts such as reinforcements. When used in conjunction with solid elements, beams can be located inside a solid element and need not be aligned with the nodes of the Lagrangian elements, making their use unlimited, while requiring very little effort to setup.
Lagrange (structures) 

Euler (fluids) 

ALE (auto remesh) 

SPH (brittle) 

Shell/Surface (thin 2D) 

Beam  Reinforcement (long 1D) 
Efficiency Tools
The interactive user interfaces offered by ANSYS Explicit STR and ANSYS AUTODYN software offer a powerful collection of tools for increasing productivity by reducing the effort to set up, run and analyze simulations. This increases accuracy, reduces simulation time and makes the jobs of the engineer or scientist easier and more enjoyable. The list below contains just a few of the numerous tools available to the user.
Tool/Description  Picture 
Interactive problem setup (preprocessing) solution and analysis (postprocessing) Working interactively with a graphical user interface, instead of preparing a text input file, makes it easy and convenient to immediately identify and correct bad input values, thus resulting in a working solution in the shortest possible time. 

Remapping in space High resolution fast running 1D problems can be mapped into 2D or 3D, enabling highly accurate results to be created extremely fast. The remapping is accomplished with just a few clicks of the mouse. 3D problems can also be remapped into 3D for extending the physical size of the problem. 

Remapping solution method The solution method for a part can be changed when the problem requires a different methodology. In the example to the right a 2D axissymmetric Euler solution is mapped into a 3D Lagrange solution enabling the simulation of an oblique impact. Running this problem in 3D with the same result resolution and accuracy would require 1,000 times as much computer time. 

Import of data from Geographic Information System (GIS) services For modeling large city structures information from a GIS data base can be imported, making the creation of a mesh and solution space virtually automatic. Manual setup of this type of a problem would make it totally unpractical. 

Mass scaling Mass is artificially added to individual elements to ensure their timestep is at least equal to a user defined value. This is a valuable technique for problems with a limited number of small elements. A contour plot of the time step for each element enables quick identification of the scope of the problem and whether this technique is practical and safe. 

Dezoning Parts using the Euler solver can be “dezoned” increasing the size of each element and reducing the number of elements. This process tool provides a way to increase the computational speed during the later stages of a calculation when less resolution might be required. 

Erosion Erosion is a numerical method to eliminate elements that have become degenerate, or have caused the time step to be reduced below a minimum value. Erosion criteria can be based on minimum time step values, strain or material failure. The eroded element can optionally be retained as a point mass, enabling more accurate momentum conservation and potential loading from the eroded nodes. 

Natural Fragmentation Natural fragmentation provides a statistical way to model failure due to impurities. This technique is invaluable when modeling symmetrical parts under uniform strain, where normally all elements would fail at the same time. Natural fragmentation introduces minor variance in the failure criteria randomly in the elements that make up the part, resulting in “natural fragmentation.” 
Advanced PostProcessing
ANSYS provides a comprehensive set of postprocessing tools to display results as contours or vector plots and provide summaries of the results (like min/max values and locations). Powerful and intuitive slicing techniques allow the user to obtain more detailed results over given parts of the geometries. All the results can also be exported as text data or to a spreadsheet for further calculations. Animations are provided for static cases as well as for nonlinear or transient histories. Any result or boundary condition can be used to create customized charts.
Automatic Report Generation
A design can be explored in multiple ways. Then the results must be efficiently documented. ANSYS provides instantaneous report generation to gather all input data specifications, material models used and a copy of all the images and graphs that were generated in the setup and postprocessing of the model in a convenient format (HTML, Microsoft Word®, Microsoft PowerPoint®).
Advanced PreProcessing for Composites
Setting up parts consisting of complex layups for modeling composites is greatly simplified with the use of the ANSYS Composite PrepPost program. Explicit dynamics can now use the results of ANSYS Composite PrepPost and simulate the response of composites exposed to impact or other severe loadings.
Solving Large and Complex Models Efficiently
ANSYS Explicit Dynamics solutions offer a comprehensive set of tools that facilitate reduction of solution time and increase in accuracy of the results generated. Parallel processing using domain decomposition can reduce the solution time for large problems. Parallel solutions can be used with any computer configuration, such as multicore, multiCPU or networked computers.
Solution Customization and Open Architecture
ANSYS Explicit Dynamics solutions offer an open architecture that enables customers to extend the standard capabilities of the program easily and conveniently. Customization capabilities through userdefined subroutines are available for a list of functions, such as materials equation of state, material failure model, erosion model, strength model, boundary conditions, input and output functions and many more. Templates are provided for all user definable subroutines with documentation on how they can be used, the variables available for use and the variables that must be defined within the subroutine.


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ANSYS 14.5 Capabilities Chart  Download 
Explicit Dynamics Goes Mainstream  Download 