Category "Dassault Systemes"

2019 solver has number of enhancements that spans from fracture mechanics to element formulation to material formulation. Let’s start with what’s there on the fracture mechanics side:

Fracture mechanics enhancements

  • Introduction of new linear elastic fatigue crack growth procedure: Allows for change in contact conditions while loading, allows non-linear geometry behavior, mixed mode fatigue loading and viewer improvement. It is currently available for constant amplitude loading only. The input deck for mixed mode behavior looks as follows:
  • Improvements in contour integrals pre-processing and solving time. This applies to both J-integrals as well as K-integrals.
  • XFEM improvement to increase smoothness of 3D non-planar crack front. This is achieved by introducing non-local stress averaging algorithms to predict crack direction. Also limit new crack propagation direction to a certain angle from previous direction.
  • Symmetric cohesive elements have been introduced. Plane of symmetry must be perpendicular to one of the global axis though.
  • Introduction of UDMGINI subroutine to incorporate varied crack initiation criteria for different enrichment zones.

Element technology enhancements

  • Poro-elastic acoustic elements have been introduced to study wave propagation in coupled isotropic poro-elastic medium. It is only available in steady state dynamics analysis.
  • Displacement acoustics pressure elements have been introduced: C3D8A, C3D6A, C3D4A. Primary unknows are structural displacement and pore pressure. Same shape function used for displacement and pressure.
  • Shear panel element SHEAR4 in Abaqus has been introduced to model thin reinforced panels such as in fuselage. Intended to model response of buckled plate. Use is limited to linear elastic only.
  • Variable beam radius element formulation now available in Abaqus that can be well visualized in viewer as well.

Material enhancements

  • Low density foam has been introduced in Abaqus standard in 2019x FD01. This material has already been present in explicit. This material is useful in modeling highly compressible elastomeric foams.
  • Output variable SROCK for rock mechanics effective stress.
  • Enhancements to super-elastic materials to improve convergence and performance of material model. This application would be of interest in healthcare industry. An environment variable should be introduced to activate the model. Available from 2018x FD04.
  • Transverse shear stiffness modulus has been introduced for shell and beam sections. This now obviates the user material model to deal with plates of spatially varying thickness or plates made of composites.
  • Damage in concrete due to plasticity can now be modeled by defining failure criteria and element deletion criteria.
  • Two new outputs introduced in explicit for cohesive elements: equivalent nominal strain NEEQ and equivalent nominal strain rare NEEQR

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Contacts and Constraints

While we introduce new functionalities in Abaqus 2019 in contacts and constraints like we have done for other functionalities in similar blogs, I would retrospect into 2018 and clarify an important point: what’s the difference between FD and FP (hot fix). Believe it or not, they are not the same and the table below clarifies it for 2018 release.

Now let’s look at enhancements

  • One of the biggest enhancement in contact is that 2D and axisymmetric models are now supported in general contact for explicit. This general contact capability was already available in standard. This has been done on many customer requests in the past. Please note that 3DX platform does not support 2D axisymmetric models yet.
  • Another major enhancement is that analytical rigid surfaces are now supported in general contact for standard. This capability was already available in explicit general contact. Most common benefit of analytical rigid surface is precise geometrical data of simple surfaces.
  • Threaded interface approximation has undergone correction to include effects of right handed or left handed threads. This is an enhancement to existing capability in *clearance, bolt keyword entry. The image below shows the effect of thread direction on contact normal.

Further enhancements have been made to differentiate between one way and two-way threads. A two-way thread can resist both tension as well as compression unlike one way thread.

  • Another major enhancement is the introduction of general contact in pure heat transfer as well as coupled thermal-electrical step. Moreover, general contacts defined in any one of these steps can be carried forward and used in subsequent steps such as general static.
  • New Output Variable: CEDGEACTIVE: Dynamic feature edge criteria. It is now possible to visualize active feature edges at any stage of the simulation. This can be of great use in explicit analysis for applications such as air bag deployment.

CSLIPEQ: Relative equivalent tangential slip while in contact. It was present in explicit but now has been introduced in standard as well.

CSLIP_PL: Introduced to quantify plastic slip when shear stress exceeds critical frictional stress.

CICPS: Integral of contact pressure over the surface. It is different from CFN because normal direction is not considered.

Perhaps key differentiator is the situation below in which CFN output is zero due to symmetry but CICPS has a finite value.

  • Moment correction due to shell offset: When shell offset is defined, nodes shift from shell midplane and so does any forces acting on shell edge thereby creating a false moment about the midplane. This affect has been corrected by introducing a counter moment at the nodal force location so that effective location of edge force is at the shell midplane.
  • Deprecate old contact controls: Changes in certain contact controls by user will now result in fatal error by default. These controls are approach, automatic tolerances, Lagrange Multiplier etc. It has been observed that changes in such controls often results in performance degradation. In earlier releases only warning messages were issued that users have tendency to ignore. The default settings can be changed by the user.
  • Initial contact stress: The initial contact stress is now equal to stress of underlying elements instead of being zero. This now obviates the use of penetrations and sliding to generate contact stresses. The feature can be of much use in geotechnical applications.
  • FRIC_COEF enhancement: This subroutine has been enhanced to pass user defined, solution dependent state variables. Now coefficient of friction can be defined as a function of user defined state variable. GETVRC utility routine can be accessed from within FRIC_COEF to access various state variables to define friction coefficient.

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Do any of the questions below apply to your organization:

  • Do you own existing Dassault Systemes software products and are up to date with maintenance?
  • Do you need to transform your digital engineering processes?
  • Are you interested in implementing the true Digital Twin concept?
  • Is the technology that you are using for Digital Product Definition out of date?
  • Does your company have strategic initiatives like Lean Manufacturing, Flawless Launch, Model Based Engineering or similar?
  • Is your company expanding or looking to put new products on the market?

If the answer to any of these questions is Yes, then you should be looking at the Customer Transformation Program (CTP) from Dassault Systemes.

Dassault Systemes  launched a Customer Transformation Program for 2019 which is designed to transform the businesses of all their existing customers. This is a limited-time sales initiative program starting January 21, 2019 and ending December 31, 2019.

The program offers existing customers a voucher that makes them eligible for a discount on qualified new purchases of software from Dassault Systemes extensive range of productivity enhancing solutions. Customers can earn up to 35% off purchase of qualified new software – an exciting incentive to get up to date with the latest technology.

The future focus of Dassault Systèmes is on the innovative 3DEXPERIENCE platform, a disruptive technology that can completely transform your business. As a result, the largest discounts are for platform products, on premise or in the cloud.

As an example, a customer may have an existing Dassault Systemes CATIA V5 software and his installed base entitles them to a voucher good for 35% discount on a new product up to an amount 0f $35,000. Assume a new opportunity arises and the customer requires SIMULIA to run advanced simulations. If the list price of what is required is $100,000, then this can be purchased for $65,000 by applying the voucher.

As a trusted advisor, Tata Technologies can help navigate through the CTP program. Dassault Systemes has been investing billions into innovative technologies and helping organizations face business challenges. Please engage us to discover how your business can be transformed.

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A quick recap of Fluid Mechanics solutions from Dassault Systemes. It’s not a one offering anymore. With recent acquisitions of world class technology such as XFlow, PowerFlow and Exa the offerings span across a wide range of application from Navier-Stokes formulation to Lattice-Boltzmann formulation. Let’s get started:

  • FLA and FMK unite together: FLA has been an analyst role and FMK the designer role till 2018x. Starting 2019 GA, FLA will merge into FMK. That means all the functionalities of FLA will now be available in FMK. As FMK is a designer role with its own assistant panel, using CFD feature would be a much easier starting 2019 GA.

Both on cloud and on-premise options remain available. However, the basic prerequisite will be SEI that can be upgraded to SPI in case of existing customers. The bonus is that FMK role comes with enough tokes to submit an 8 core job 😊. Additional on-premise or on-cloud tokens can be used if needed.

Enhancements in Physics of Flow

  • Radiation solver available: The combination of CFD and thermal is now enhanced by adding one prominent mode of heat transfer that is radiation. The surface to surface radiation module is available in 2019xGA and surface to ambient module will be available in 2019xFD01. Emissivity and ambient temperature are the key inputs.

  • General solver enhancements: Mesh size independent convergence rate, better shock capture for high Mach flows, buoyancy dominated natural convection flow.
  • Comfort and e-cooling: Number of cabin comfort parameters for whole human body have been added for T&M as well as A&D industry. These parameters are based on ASHRAE55 specifications.

Enhancements in Meshing

  • Intelligent feature capture: In case of complicated surfaces with lots of geometry, surface mesher initially created fine mesh over the surface where fine features need to be captured. In conventional approach, the same surface mesh creates extra fine volume mesh inside the fluid domain resulting in extremely large volume mesh. The new intelligent feature capture option allows mesher to obtain coarser volume mesh using fine surface mesh.

  • Partition hex mesher: This application can be of tremendous use in FSI applications on the 3D EXPERIENCE Platform. While Hybrid Hex mesher is still considered a piece of diamond for fluid meshing applications, user may have requirement of hex meshing for the structural counterpart. As a result, hex meshing using partition approach (just like in CAE) has been introduced in the platform as well.

Enhancements in Scenarios and post processing

  • Duplicating scenarios: This feature was requested multiple times by many customers. There is often a requirement for duplicating scenarios in situations where one or more of the scenario parameter should be changed such as mesh parameter or any fluid BC while the user wish to retain previous scenario for sake of comparisons. Earlier, user had to recreate scenario from scratch. Now a duplicate option exists along with option of activating/deactivating scenario.
  • FEM Rep option: When Scenario app is launched, the UI asks the user whether to create a new FEM Rep or use an existing one.
  • Uniformity index: Additional output on scale of 0 to 1 to quantify uniformity of flow across a given section.
  • User Field Expressions: User can now create customized field expressions using standard field expressions with mathematical operators. Our Abaqus CAE buddies know it is a very useful field output capability that is now available in 3DX for fluid applications.

Enhancements in performance and stability

  • Automatic solver configuration: Let CFD engineers perform simulations rather loosing time in juggling with numbers!

The solver has been made increasingly mesh agnostic when it comes to convergence. Earlier with change in mesh, user was expected to manually change solver under relaxation factors to avoid problems of slow convergence or no convergence. Starting 2019x, these factors are updated automatically by the solver with change in mesh. Available in all incompressible steady-state flow.

  • Bad cells treatment: Let’s not penalize the whole model due to presence of only few bad elements!

In case of bad mesh that cannot be fixed, solver parameters need to me modified for the whole mesh and that too manually to obtain a converged solution. Starting 2019x, solver automatically detects such bad cells and simplifies or alter solution parameters only in those cells to obtain a solution.

Enhancements in user documentation

  • Verification guide: Verification guide has been introduced that can be accessed either from the SWYM learning center or from the HELP option of rich client install.
  • Theory guide: Provided for every feature in 3D EXPERIENCE Help starting 2019x GA. In addition to how to set up, information on underlying formulation is available as well.
  • Assistant Panel is an added advantage by default that would provide additional text information as well.

 

 

 

From solver perspective, number of enhancements have been made but as additive manufacturing is gaining popularity these days, let’s start with what’s new is available at AM front.

Additive manufacturing functionality enhancement

  • Until past release, number of basic AM simulation features were not a part of main solver and required specific configuration to access. Starting 2018x all AM is in FD05 and in 2019x all AM is in GA.
  • Eigen strain has been added as an input/output in AM that can be accesses using existing subroutine UEPACTIVATIONVOL that now has eigenstrain as an argument. The material orientations can be defined as well as modified. As eigen strain is treated as instantaneous load, it can cause convergence problem. In such cases, eigen strain can be applied as a ramp input.

 

  • The conventional displacement of nodal output includes displacement prior to activation as well. New output variables UACT and URACT contain translational and rotational displacement only after activation.

  • Improved convergence of heat transfer analysis when linear elements are used with temperature dependent material properties.
  • The event series data is no longer limited to 53 million events. It has now been extended to 420 million events. Available from 2019xGA.
  • Property and parameter tables now available for Abaqus explicit as well starting 2019xFD01. Earlier this functionality was limited to standard only.
  • Number of heat energy outputs have been added for non-uniform moving flux. These are element internal heat energy called as EHUMDFLUX and element internal heat energy density called as EHUMDFLUXDEN. Both field and history outputs are available.
  • 2D and axisymmetric elements are not available that support *FILM parameter as well for convective heat transfer.

This blog is a part of series “what’s new in SIMULIA 2019”. Please follow our blog site regularly for next blog article on this topic.

Every year around this time, SIMULIA comes up with official declaration of new releases. That news is followed by discussion and buzzes around new functionalities and features. Last year we released a series of blog articles on new features in 2018 suite of products and we are following a similar pattern this year starting with Abaqus CAE.

  • Translation of parts and instances: Additional parameters have been introduced to ease this operation. Earlier CAE prompted to pick a start and end points to define direction vector. Now it possible to define the direction by picking global or local coordinate axis, datum axis as well as any straight edge. Moreover, the start and end point method is supplemented by a local coordinate system, if needed. Here is how user interface looks like:
  • CAE support for CAXA/SAXA element types: CAXA/SAXA element types are very useful in modeling structures that have axisymmetric geometry but not axisymmetric load. These element types are present in solver since long time but only option to use them was through manual keyword input. Now these element types are part of Abaqus CAE.
  • Optimization enhancement for additive manufacturing: Overhands can be difficult to print and they require support structures as well. It is advisable not to have overhand structures in the part subjected to AM process. Now an additional geometric restriction is available in optimization module of CAE to prevent overhangs formation.
  • Other optimization enhancements:
  • Shape optimization is often used after topology optimization to reduce hotspots. Earlier only controller based algorithm was supported for shape optimization that imposed many restrictions on choice of design responses. Now sensitivity based algorithm is also available in CAE for shape optimization. Moreover, for all types of optimization schemes, it is not possible to export the output in IGES format as well. Earlier this output feature was available only in form based native TOSCA GUI.
  • The envelop contours can not be created for complex stress values as well. Three types of complex stress contours are supported as shown below:
  • Another significant enhancement in viewer is the visualization of variable beam radius. This is applicable to the output of TOSCA sizing when beam elements are present in the structure. The name of field variable is BRADIUS.

This blog is a part of series “what’s new in SIMULIA 2019”. Please follow our blog site regularly for next blog article on this topic.

This year 2019 Abaqus release has seen number of potential enhancements in Abaqus explicit. Some are general purpose while others are tied to specific procedure and application. Let’s have a look at what’s new in the explicit basket.

  • Lumped Kinetic Molecular model: This model has been developed to simulate behavior of gases that can be of much use in air bag deployment simulation. The method is based on kinetic theory of gases which states that pressure exerted by a gas in closed chamber is a result of collisions between gas molecules as well as between gas and chamber surface. These collisions are perfectly elastic in nature. As number of molecules in a mole of gas is equal to Avogadro number (6.023e23) which is very large from computational perspective, lumped mass approach is used in Abaqus in which a gas particle is defined as a collection of many molecules. The method has been validated with analytical approaches. This method now replaces the Unified Pressure Method that cannot capture the change in pressure as the airbag expands. However, LKM is computationally more expensive than UPM. Best approach might be to use LKM during airbag expansion when pressure variation is large and then switch to UPM method. Switching time should be defined in such a case. Most expensive method is still CEL.

  • C3D10 element has been introduced in explicit that is a true second order element that offers larger stable time increment compared to C3D10M or linear element. It supports all the loads and BC’s supported by conventional continuum elements in explicit.
  • Limiting stop feature: It is not possible to stop the explicit analysis when a certain output parameter reaches a limiting value. These physical parameters may be node based such as reaction forces or element based such as equivalent plastic strains. The keyword is *FILTER.
  • Improved performance: Substantial decrease in solver time when performing large system level crash simulation over high performance cluster. Below is the example of a 5M DOF crash model on multiple cores.

This blog is a part of series “what’s new in SIMULIA 2019”. Please follow our blog site regularly for next blog article on this topic.

One of the noticeable change that has been made in 2019 solver is its capability to handle large models. SIMULIA has noticed that in recent past customers have shown increased interest in dealing with very large models with 2M degrees of freedom or more. There are multiple reasons for this requirement. First is scalability. More and more customers are interested in large system level simulations compared to part or assembly level. Second is fidelity and accuracy. Mesh size is getting finer to capture behavior at micro level instead of macro level.

When it comes to solving very large models, iterative solver has many advantages compared to direct solver such as less memory consumption, scalability and speed. A new hybrid iterative solver scheme has been introduced that offers more flexibility for choosing number of MPI ranks and number of threads per rank for a given node. These parameters can be defined in the abaqus_v6 environment file. This is equivalent to DMP+SMP allowing efficient memory management.

The iterative solver is available in 3DExperience 2018x FD05 and 2019x FD01 release. It supports many more Abaqus features compared to conventional iterative solver such as gaskets, friction, plasticity, creep, periodic boundary conditions etc.

This blog is a part of series “what’s new in SIMULIA 2019”. Please follow our blog site regularly for next blog article on this topic.

Simulations in Aerospace and Defense companies have a well-defined workflow. They have two separate teams for composites products: one for design and other for simulation. Composites ply design is primarily done by design engineers. These are the folks that determine the composites material as well as ply thicknesses and stackings in different regions of the composites part. CATIA composites design and manufacturing workbench has all sorts of tools to help designers achieve their objectives. We have discussed these workbenches in past.

However, because of FAA and other regulations in place, design has to be validated with FEA simulation and for most of the non linear workflows, Abaqus is the right solver choice. Though CATIA does provide an environment for Abaqus pre-processing, the preferred method in Aerospace industry is to use Abaqus CAE user interface. This is because of two reasons. First reason is better meshing capabilities offered by Abaqus CAE and second is tight coupling of Abaqus CAE with underlying solver. The obvious questions that arises is “how to move the ply information from CATIA to Abaqus CAE.”

The answer is composites link in collaboration with composites modeler for Abaqus CAE. The composites link exports the ply data from CATIA in form of layup file. Based on workflow, three options are possible.

  • Export only the ply data: When mesh is already in Abaqus CAE environment.
  • Export ply data with CATIA mesh: When meshing has been done in CATIA Analysis environment.
  • Export ply with external mesh file: When Abaqus input file needs to be merged with ply data.There are further options to export data either with or without taking change in orientations due to wrinkling into account as done by composites fiber modeler. Once the mesh and layup comes in Abaqus CAE environment, it is possible to explode the shell data based on ply thickness and create solid elements from shells. Abaqus CAE automatically creates section properties and assignments based on modified ply orientations. It is further possible to visualize ply orientations on each ply as well as ply stack plots on element by element bases. Once the data transfer and visualization is complete, the entire advanced analysis set up such as bird strike, fracture or delamination can be defined in Abaqus for analysis.

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