Category "Simulation"

In previous blog articles on 3D Experience simulation roles, we primarily discussed platform configurations, concept of personas and roles as well as simulation capacity of the platform. In this blog article contains detailed information about three primary structural simulation roles: MDS, DRD and SMU.

To begin with, lets recapitulate that simulation roles are categorized in groups based on personas of users working on such roles. In terms of complexity and functionality, offerings range from based to intermediate to advanced.

 

Engineer profile: The is the simplest and easiest to use simulation offering primarily meant for designers with low to intermediate simulation knowledge. Their primary job is product design and they perform simulations very occasionally. Roles for this profile are CAD centric and are associated with a guided workflow. Simulation tokens are embedded in the role.

Analysis engineer profile: This profile is one level above the engineer profile and is suitable for structural analysis engineers associated with product engineering. Their simulation knowledge is of intermediate level which means they understand simulation process in terms of meshing, BC, Loads, result visualization etc. but don’t have any hands-on experience of advanced simulation tools. Usually there is no guided workflow. Simulation tokens are embedded in the role.

Analyst profile: This role is for full time analysts who primarily perform intermediate to advanced level simulations. They have in depth expertise in at-least one simulation domain and often hold Masters or Doctorate level credentials. This role requires extensive knowledge of pre-processing, solver terminologies such as statics, dynamics, non-linearity, convergence schemes, as well as post processing etc. There is no guided workflow. Simulation tokens are procured separately.

 Research Specialist profile: This is a complex simulation offering primarily for experts who develop novel simulation workflows and processes. The simulation requirements often span across multiple physical domains and involves advanced Physics such as vibrations and noise. The pre-processing aspect may include complex meshing of assemblies and assemblies of meshes.

Let’s look at one role from each of first three profiles:

Stress Engineer role (MDS)

 

It’s a role from engineer profile and has a guided workflow. The snapshot shows apps available in MDS role. It performs routine strength and deflection calculations under static loading conditions. It can also compute product fatigue life for very simple loads. The CATIA and SOLIDWORKS associativity is well maintained. Local solver execution up to 4 cores is included.

Structural analysis Engineer role (DRD)

 

It’s a role from analysis engineer profile that has no guided workflow. It is used to access the structural integrity of products subjected to wide range of loading conditions. The snapshot above shows available apps in this role. It works on MSR concept available in advanced simulation tools i.e.  Model-Scenario-Results. Many advanced settings are exposed to the user. This role can perform multi step simulations. Local job execution of up to 8 cores is available.

Mechanical Analyst role (SMU)

 

It’s a role from analyst profile and it does not include a guided workflow. The snapshot above shows available apps in this role.  It uses advanced finite element techniques to simulate and validate complex engineering problems. It offers multiple advanced meshing techniques such as Octree, surface, sweep and RBM. Both single step as well as multi step scenarios are included. Supported analysis steps include static perturbation, non-linear static, frequency, buckling, implicit dynamics, explicit dynamics, steady state heat transfer, transient heat transfer etc. Most of the non-linear materials and complex engineering connections are included.

While we discussed one prominent role from each profile, the south quadrant of 3D Experience platform offers numerous simulation roles. To know more, please contact us.

One thing common between SIMULIA roles of 3DExperience platform and the standalone Abaqus products is that both require an Abaqus solver to perform computations. It further means that both solutions require Abaqus tokens to complete or speed up the computation part of the simulation. For standalone abaqus product, we know that the calculation is straight forward. Abaqus requires a minimum of five tokens to execute a single core non-linear job. Large models require more number of cores to solve in real time and more number of cores require more tokens as follows:

The computation capacity of 3D Experience platform, however, cannot be defined by a single equation. Unlike Abaqus solver, that is available as an integrated all-in-one license for all types of simulations such as standard, CFD, explicit etc., 3D Experience offerings are in form of roles. Each role is a sellable license that includes either some or all Abaqus solver capabilities. Offers are made further flexible by on premise vs. on cloud offerings. Let’s have a look at solver offerings in different configurations and roles.

    Engineer role vs. Analyst role

While most of design engineer roles have embedded Abaqus tokens, most of the analyst roles do not have any compute capacity at all. The number of tokens embedded in designer role depends on the level of simulation complexity a role can accommodate. For example

Stress Engineer role has 8 embedded tokens to accommodate up-to 4 cores job

Structural analysis engineer role has 12 embedded tokens to accommodate up-to 8 cores job

It is possible to submit jobs on more number of cores than what embedded solver permits but in that situation external tokens need to be utilized and embedded solver takes no credit at all.

                Tokens vs. Credits

In case of analyst roles such as stress analyst, fluid mechanics analyst etc., the role itself does not have any compute capacity which should be procured either in the form of tokens or credits. Tokens are renewable form of compute capacity which means they can be used over and over. 3D Experience uses tokens in a very similar fashion as does standalone Abaqus. The token consumption with respect to number of cores is the same for Abaqus as for 3D Experience platform. On the contrary credits are a non-renewable form of compute power. It means that credits, just like the talk time over phone, can be consumed only once.

               Why credits at all!!!

In general credits is an expensive preposition for customer but there are exceptions. Credits are utilized to meet unexpected and rare increase in peak usage. This is somewhat more common in engineering consulting firms that can face high demand of simulation capacity due to influx of many short duration simulation projects at any time. To meet this sudden spike in demand, one-time credit bundle offering makes more sense than increase in perpetual tokens. Once peak demand is over and credits are consumed, simulation capacity is returned to normal levels.

On premise vs. on cloud

Design engineer as well as analyst roles are available in on premise as well as on cloud formats. There are three ways of utilizing cloud resources: store the models on cloud, stores the results on cloud and solve on cloud. The first two offerings require only cloud storage and are available at no additional charge with cloud based license. However, the third offering requires cloud compute resources that consumes compute credits in addition to cloud based license.

Need to know more about SIMULIA 3D Experience platform compute capacity! Please approach us and we are ready to help.

 

Organizations invest huge sums of money in simulation software to avoid expensive and disruptive physical testing processes. But how long it really takes to make this transformation happen! One thing is sure; it does not happen in a day. The flow chart below explains the reason pictorially. The last two blocks “compare and improve model” and “compare and improve theory” make this transformation a longer process than expected.

 

Let’s explore the reasons behind it. Comparison is needed to make sure that simulation results mimic the physical testing results before latter can be discarded, partially or fully. The difference in results can be due to three main factors: lack of user competency, limitation of software used, lack of sufficient input data.

Lack of user competency: FEA analysts are not born in a day. The subject is complex to learn and so are the software associated with it. The ramp up time really depends on analyst background along with complexity of problem being simulated. Organizations usually make a choice between hiring expert and expensive analysts who can deliver the results right away or producing analysts of its own through class room and hands on trainings. First option saves time while the second saves money. CAE software development companies are also making big stories these days by introducing CAD embedded simulation tools that require nominal user competency. Nevertheless, the competency builds up over time.

Limitation of software used: Initial investment in simulation domain is usually small. It means two things: either number of users are less or software functionality is limited. With time, complexity of problems goes up but the software remains the same. A common example I have seen is of a customer starting with simple linear simulation workbench in CATIA and over period trying to simulate finite sliding contact problems with frictional interfaces in the same workbench. Users don’t realize that their problem complexity has exceeded the software capacity to handle and it’s time to upgrade. It’s always recommended that analysts get in touch with their software vendors whenever they anticipate an increase in simulation software capacity or functionality. A certified simulation software vendor is a trusted advisor who can really help.

Lack of sufficient input data: “Garbage in – Garbage out” is a very common phrase in simulation world. However, at times it is very difficult to get the right input for software in use. The complexity of input data can arise either from complex material behavior or from complex loading conditions. Example of complex material may be hyper-elasticity or visco-elasticity observed in elastomeric materials. Examples of complex loading may be real time multi block road load data to estimate fatigue life. Sometimes simple metallic structures exhibit complex behavior due to complex loading. Examples are high speed impact or creep loading. With time many material testing labs have come into existence that can perform in house testing to provide right input data for simulation.

Conclusion: You will come out of the vicious loop of physical and simulation results comparison after couple of iterations if you have three things in place: right people, right software product and right input data. If you need help in any of the three aspects, we are always available.

“What you buy makes a difference but from whom you buy makes a bigger difference”

Most often, I talk about greatness of our product offerings in my blog articles. Such kind of blogs assist prospective customers in choosing the right product. But the same product can be procured in multiple ways, either directly from the developer or through a value-added reseller also called as VAR. In this blog article, I would emphasize on how prospective customer should select the right VAR while purchasing a Dassault Systemes or Siemens simulation product.

The first thing a customer needs to verify is whether VAR is supplying just the product or the complete solution. The difference between the two is the “value added services” associated with product usage.

Without value added services, it’s not possible for a reseller to become a value-added reseller.” Please identify if you are doing business with just a reseller or a value-added reseller. Remember, simulation tools are not easy to use. There is a learning curve associated with these tools that can greatly impact the ROI and break-even timeline. The productivity of the user can be substantially enhanced if he is associated with a reseller who can provide whole bunch of services to shorten the learning curve and achieve break-even faster. Now let’s look at what type of services makes a difference in simulation space.

We are talking about software sales as well as consulting, training and support. Our software partners, Dassault Systemes, Siemens and Autodesk offer a bunch of certifications around these four components to distinguish between just “resellers” and “value added resellers.” Being certified means reseller has enough resources and knowledge to execute a given task of sales or service. Let’s talk about each component with respect to Simulation:

Software: To sell any DS SIMULIA product, the associated VAR should have “SIMULIA V6 design sight” certification as a minimum. There are further brand certifications available such as Mid-Market Articulate for product highlight and Mid-Market Demonstrate for product technical demonstration. To sell FEMAP product from Siemens, the VAR must have “FEMAP technical certification” as a minimum. All these certifications are associated with timed examinations.

Training: Training should be an integral part of simulation software sales. It gives users enough knowledge to use the software product in production environment. To offer technical training on any SIMULIA product, the VAR should have “finite element analysis with Abaqus specialist” certification as a minimum.

Support: Once users are in production environment, technical support is required on continuous basis. While many answers related to product usage are in documentation, it’s not a full source of information. Many queries are model specific that require attention of a dedicated support engineer. To offer technical support on any SIMULIA product, the VAR should have at-least one engineer who has “SIMULIA technical support specialist” certification.  This certification should be renewed every two years. It is associated with a lengthy and “hard to pass” support certification examination across all products of SIMULIA brand.

Consulting: Consulting service plays a big role when customer either does not have enough time or resources to execute projects in house in-spite of having software product. It happens during certain burst phases of demand. While there are no certification criteria for VAR’s related to consulting in simulation space, a dedicated consulting and delivery team is needed to offer the service when demand arises.

The above information should help you in ranking your VAR. Do you need to know our rank? Please contact us.

 

Perhaps one of the biggest surprises for Abaqus user community in 2018 is that the two most popular licensing schemes of Abaqus would gradually go away for new customers. These schemes are Abaqus analysis pack and Abaqus portfolio pack. It’s worth mentioning that many of our Abaqus customers are still using either of these two licensing schemes. While our current customers who have perpetual or lease licenses may be able to continue with these schemes, our future customers will have to migrate to something that is available as a replacement. Instead of putting this news as a surprise to each customer individually, I thought a common piece of information well in advance through a blog article would keep the anxiety under control.

THE MIGRATION PATH

The migration path eventually leads to a token configuration that has been available since couple of years now. It is called the extended tokens configuration. While many of our customers have already migrated to this licensing scheme by choice, others are still using one of the traditional licensing schemes. Let’s look at the logic behind this high-level decision. If we look at the history of acquisitions that Dassault Systemes has made in past few years, it looks like this:

 

The inception of extended tokens is related to acquisition of three companies in above chart: FE-Design, Safe Tech and Engineous. The product offerings from these companies, if coupled with Abaqus can greatly enhance its simulation portfolio. Following acquisition, these products were offered as point tools for a long time with their individual licensing and pricing schemes. As a result, existing Abaqus customers who wished to use either one or more of these products had to go through a complicated purchase and IT process. Dassault Systemes has been looking for a consolidated licensing scheme that would enable users to procure these products along with Abaqus in a single license file that works on a single token scheme and on a single license server. This token scheme is now called the extended tokens. At this point of time Dassault Syetemes believes it makes sense to migrate all existing Abaqus users to extended tokens through a migration path that would enhance the simulation portfolio of users in a cost-effective way.

           COMPARISON BETWEEN DIFFERENT TOKEN SCHEMES

MESHING CAPABILITIES IN ABAQUS CAE

It is a well-known fact in the CAE community that the efficiency and accuracy of finite element models are directly dependent on the quality of the underlying meshes in the model. The various quality parameters associated with elements are element size, aspect ratio, skew angle, jacobian, warp, and many more. Yet another parameter of concern is element topology, which means triangular/quadrilateral elements in case of shell meshes and tetrahedral/hexahedral elements in case of solid meshes. Each of these element topologies has its own advantages and disadvantages; for example, tetrahedral elements are easy to create on complex geometries but they have slower convergence, while hexahedral elements are very much desired in computational expensive simulations such as crash due to better convergence and accuracy but cannot be created easily.

Due to specific meshing requirements arising from the increasing complexity of part geometries, meshing techniques are becoming more important across all industry verticals. Transportation & mobility is primarily concerned with hexahedral meshes of pre-defined quality for very complex geometries. This industry has more focus on using Hypermesh and Ansa as a dedicated meshing tools. However these tools are primarily known for good meshing capabilities only. When there is a need to create input decks for advanced non-linear simulations such as with Nastran solution sequences 600/700 or for Abaqus multiphysics or acoustics, many of the solver features are not supported by Hypermesh or Ansa and have to be entered manually into the deck. Aerospace industry has almost always a requirement for composites modeling. They prefer a user interface that can either create or import composite plies and layups. The need for high quality meshes on complex geometries is rather rare. Due to these reasons Aerospace industry has been relying on MSC Patran since many years due to its composites modeling capabilities. However industry is now looking at alternate tools as Patran is losing its competitive edge on CAD import, CAD repair as well as meshing techniques. The CAD repair features are very minimal, there is no CAD associative interface to propagate design changes on FE side and meshing techniques offered are still at very basic level as well.

The objective of this blog is to highlight the meshing techniques in Abaqus CAE that makes CAE a tool of choice in situations where a decent quality mesh, tight integration with multiple CAD platforms as well as tight integration with Abaqus solver are topics of concern for the analyst. It’s worth mentioning for Aerospace industry audience that Abaqus CAE has basic composite modeling capabilities. For advanced composite modeling and visualization capabilities, there is an add on module called composite modeler for Abaqus CAE and there is tight integration between CATIA composites workbench and Abaqus CAE for transfer of FE meshes as well as ply layup information.

THE MESHING TECHNIQUES

 There are primarily four meshing techniques available in Abaqus CAE, both for solid meshes as well as for shell meshes.

Free meshing: This is the easiest of all the techniques as it almost always works with a single click. It primarily generates quadrilateral or triangular elements on surfaces and tetrahedral elements on solids, even on very complex geometries. The downside is that user has very minimal control on elements quality except controlling the mesh density using global and local seeding options.

Sweep meshing: This technique is useful when hexahedral elements are needed on solids with minimal geometry editing though this technique is applicable on surfaces as well. The meshing algorithm automatically identifies a source side and a target side on the geometry, it creates a quadrilateral shell mesh on the source side and sweeps those elements to the target side thereby converting them to hexahedral or bricks. The underlying shell mesh is automatically deleted. The downside is some geometry restrictions with respect to source and target side.

Structured meshing: This meshing techniques is useful when high quality hexahedral or near to perfect shell elements are required on solids or surfaces. This technique offers a better mesh control to the user compared to sweep meshing technique. It works by partitioning the complex solids into smaller six or eight sided parametric solids that can be brick meshed. The nodes at the boundaries are automatically fused to ensure connectivity.

Bottom’s up meshing: This is the last approach when all the other meshing techniques fails. It works on the concept of divide and rule. To some extent it resembles sweep meshing but the underlying geometry restrictions are removed.

THE COLOR CODING FEATURE

This is one feature that sets Abaqus CAE apart from other meshing tools available in the market. While doing meshing, user can see either entire part or regions associated with part (in case of partitions) in pre-defined colors. These colors helps in determining which region of the part would be meshed with which meshing technique if the mesh algorithm is executed. The color cold is as follows:

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The process is quite interactive. The orange color is most undesirable as these regions are non-meshable and require further partitions. Once the region is correctly partitioned and subdivided regions become meshable, the color code is updated instantly. What the user needs to see is the combination of greens, yellows and pinks with peach at certain times before executing meshing operation. During meshing, user has option to either mesh one region at a time or the entire part having multiple regions. In case of interfaces having different element topologies on each side such as green with pink or yellow with pink, tie constraints are automatically created at the boundary to ensure mesh connectivity.

Below is an example of a part that has been partitioned to create certain sweep meshable yellow regions where brick elements are needed. The other region is pink with tetrahedral elements associated to it.

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EFFECTIVE PARTITIONING

Transition of orange region to either yellow, green or peach requires intelligent partitioning of surfaces or solids. While there are many such partitioning tools available, achieving desired results with minimum partitions requires some practice in using these tools. Let’s highlight few of these partitioning methods:

Solid partitions:  Six options are available.

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VIRTUAL TOPOLOGY

This is an optional process that may be needed before partitioning and prior to meshing. This is a way to fix bad CAD data. Many times CAD data has more details than needed by the meshing algorithm. This includes very short edges and very small surfaces. Virtual topology offers certain tools to combine such small faces and edges. There is also an option to suppress these small features so that meshing algorithm does not recognize them.

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The Abaqus user community knows that computational fluid dynamics module was deprecated in 2017 release of Abaqus CAE. It means that within Abaqus CAE or through standalone Abaqus, it is not possible to perform CFD simulations beyond 2016 release. This has been a subject of criticism among few users. However, its worth mentioning that CFD is still available in Abaqus through 3D Experience platform fluid mechanics analyst (FLA) role. Dassault Systemes has decided to migrate the functionality from standalone products to the platform but it is still in existence. The FLA role is available both on premise as well as on cloud. So what are the value adds of performing CFD through 3DExperience platform!!

No need to create fluid domain 😊

This is a BIG BONANZA because every analyst knows how tough it is to create fluid domain for complex 3D Models. The 3DExperience platform offers a technique called hybrid meshing that has two main advantages. Firstly, it does not require a fluid CAD. The user needs to provide minimum information in terms of geometric features such as faces, planes, face normal etc. so that application can well predict fluid location and boundaries in given part of assembly geometry. Once it is will predicted, it gets well meshed also. Take a simple example: flow between two intersecting pipes. User just need to provide surface normal to two pipes in correct direction as well as three planes for inlet and outlet. With this information FLA user interface can create a bounded region internally on its own. The fluid domain tool helps in selecting respective geometries for parts, regions, openings and boundaries. Just this much information is good enough to proceed with the meshing operation.

 

Good quality hexahedral meshes with perfect boundary layer control 😉

FLA offers hex dominant meshing technique that operates on fluid domain created above. It has two outstanding offerings. First it gives maximum number of hexahedral elements. Yes, hexahedral elements and that too without any partitioning. Second, it is possible to define (and achieve) boundary layer as per user specified criteria. User can define number of layers as well as thickness of layers. Even in transition regions such as location where pipes intersect and geometry abruptly changes, the boundary layer specification is well respected.

 

Lastly, FLA role is the center of attraction of SIMULIA R&D for further enhancements. Dassault Systemes recently acquired two CFD companies named XFlow and Exa. The CFD solver offerings from these two companies work on Lattice Boltzmann principles while the traditional Abaqus CFD solver in 3DExperience work on Navier-Stokes principles. The Lattice Boltzmann based solver is suitable for external and unbounded, high speed transient and compressible flows that has many applications in aerodynamic computations in T&M and A&D industry verticals. These solvers will be integrated in future releases of FLA role or will be available as a new role in 3DExperience platform.

Users of Dassault Systemes must have seen the following image multiple times in last few years. In this article, I am talking about what this image means from simulation perspective.

 

The image above is the brand logo of Dassault Systemes next generation innovation called 3D Experience platform. This image is called 3D Compass and its four quadrants symbolizes four major offerings  available in an integrated fashion with the platform. The north quadrant symbolizes collaboration, the east quadrant symbolizes 6W Tags, the west quadrant symbolizes designer applications and the south quadrant symbolizes our favorite simulation applications. The idea behind its introduction is very clear from simulation environment.

“BREAK THE SILOS”

The word silos may seem unpleasant to hear at times but that’s exactly how FEA or MBD simulation community has been since many years. These are small departments of very specialized people in large organizations that mostly work in isolation. The reason of working in isolation has been simple and justified till now. The complexity of products these specialists use has been an overwhelming task for other departments such as design, production, marketing, procurement, IT etc. that are a part of overall product lifecycle management. Moreover simulation forms a process of product lifecycle only when a new concept design is launched that has to be virtually tested either to save cost, reduce time or meet certain requirements imposed by regulatory boards such as NHTSA, FAA, FDA etc. This is not always the case.

The 3D Experience platform integrates and brings together all the departments involved in product lifecycle including simulation experts. The integration happens at base level by a data management and collaboration server called ENOVIA that allows users with different roles to create, modify, share, manage or propagate data from one person to other without using share drives, emails or any sort of data migration. In terms of T&M and A&D companies these roles might be product designers, design engineers, manufacturing engineers, FEA specialists, material experts, method developers etc. The platform offers roles for users. Each role is a collection of apps just like we see in our mobile phones. However, in case of 3D Experience platform, these roles are divided in four different categories based on four corners of the 3D Compass. These are 3D Modeling apps, Social and Collaborative apps, information intelligence apps and simulation apps. Few of these apps serve as pre-requisites to any user who wish to be a part of platform. But others such as simulation apps are assigned only to those users who wish to perform simulation.

 

With the 3D Experience platform, a simulation expert works on the same data that is created by a designer to perform simulation without any manual data transfer. No more specialized product formats such as Abaqus CAE, Tosca, fe-safe that have their own file architecture not compatible with designer products such as CATIA, Creo, Solidworks etc. Once the simulation is complete, results are stored in the same database that can be instantly viewed by engineering managers, product designers, R&D head or any user who is not actively using simulation. So no more specialized output file formats such as odb, conf, ldf, stlx etc. A simulation role armored with simulation apps allows a specialist to get into the platform, access the data created by designer, create simulation model in same environment, perform the analysis on user machine or on cluster and publish and share the results. Simple it is! Once the silos are broken, there is yet another aspect of 3D Experience platform that makes it unique in the way it works.

“ELIMINATE FILE BASED FOLDERS FROM THE SYSTEM”

Everything created or imported in the platform is saved within the ENOVIA collaboration server. The data can reside either on-premise or on-cloud based on chosen architecture. The user can search or access the data using advanced 6W Tags search criteria based on questions such as who, what, when, where, which etc. In case of cloud based architecture, this data can be assessed and modified from anywhere using devices such as smart phones or ipads. Can your smart phone read Abaqus odb files! The answer is perhaps no but yet it is possible to access Abaqus output data on smart phones using 3D experience platform.

Any complete FEA solution has at-least three mandatory components: Pre-Processor, solver and post-processor. If you compare it with an automobile, solver is the engine that has all the steps/solution sequences to solve the discretized model. It can be regarded as the main power source of a CAE system. The pre-processor is a graphical user interface that allows user to define all the inputs into the model such as geometry, material, loads and boundary scenarios etc. In our automobile analogy, pre-processor can be regarded as the ignition key without which it is not possible to utilize the engine (solver) efficiently. The post-processor is a visualization tool to make certain conclusion from requested output: either text or binary. A good CAE workflow is regarded as one that offers closed loop CAD to CAD data transfer.

The above workflow is not closed so there is no scope of model update. Any changes in design requires all the rework. This has been the traditional workflow in organizations that have completely disconnected design and analysis departments. Designers send the CAD data to analysts who perform FEA in specialized tools and submit the product virtual performance report back to designers. If a change is mandatory, FEA is performed manually all over again. Let’s look at a better workflow.

In this workflow, if the initial design does not meet the design requirements, it is updated and sent to the solver, not to the pre-processor. It means that all the pre-processing steps are mapped from old design to new design without any manual intervention. This is an effort to bridge the gap between design and analysis departments that has been embraced by the industry so far. The extent to which the GAP can be bridged depends on the chosen workflow but to some extent, almost every CAE company has taken an initiative to introduce products that bridge this GAP. Let’s discuss in context of Dassault Systemes and Siemens.

Dassault Systemes: After acquiring Abaqus Inc in 2005, Dassault Systemes rebranded it as SIMULIA with the objective of giving users access to simulation capabilities without requiring the steep learning curve of disparate, traditional simulation tools. They have been introducing new tools to meet this objective.

  • The first one in series was Associative interfaces for CATIA, Pro-E and Solidworks which is a plug-in to Abaqus CAE. With this plug-in it is possible to automatically transfer the updated data from above mentioned CAD platforms to Abaqus CAE with a single click. All the CAE parameters in Abaqus CAE are mapped from old design to updated design. It’s a nice way to reduce re-work but design and simulation teams are still separate in this workflow.
  • Next initiative was SIMULIA V5 in which Abaqus was introduced in CATIA V5 as a separate workbench. This workbench includes additional toolbars to define Abaqus model and generate Abaqus input file from within CATIA. Introduce Knowledge ware, and user has all the nice features to perform DOE’s and parametric studies. This approach brings designers and analysts with CATIA experience under one roof.
  • Next Dassault Systemes introduced SIMULIA on 3D Experience platform allowing analysts to utilize data management, process management and collaboration tools with Abaqus in the form of simulation apps and roles. The solution is now in a mature stage with incorporation of process optimization, light weight optimization, durability and advanced CFD tools. By merging SIMULIA with BIOVIA we are also talking about multi scale simulation from system to molecular level. It is further possible to perform the simulation and store the data on public or private cloud.

Siemens PLM solutions: Siemens traditional CAE tools include FEMAP user interface and NX Nastran solver. Both have been specialized tools primarily meant for analysts with little or no connectivity to CAD. More specialized and domain specific tools were added with the acquisition of LMS and Mentor Graphics.

  • In 2016 Siemens introduced its new Simulation solutions portfolio called as Simcenter that includes all Siemens simulation capabilities that can be integrated with NX environment. The popular pre-processor in Simcenter series is NX CAE that has bi-directional associativity with NX CAD. Though meant for specialists, NX CAE offers a closed loop workflow between NX CAD and NX Nastran thus making easier to evaluate re-designs and perform DOE’s.
  • Siemens also offers NX CAE add-on environments for Abaqus and Ansys thereby allowing analysis to efficiently incorporate these solvers in their NX design environment.
  • It is further possible to use Simcenter solutions with Siemens well known PLM solution Teamcenter for enterprise wide deployment of Siemens simulation tools.

This shift in approach is not limited to Dassault Systemes and Siemens. Every organization in this space be it Ansys, Autodesk or Altair are introducing such closed form solutions. One reason may be the recent acquisition of many CAE companies by bigger organizations such as Dassault, Siemens and Autodesk. Nevertheless, the change has been triggered and it will continue.

 

 

In the FEA solver world, users come across multiple numerical schemes to solve the formulated stiffness matrix of the problem. The most popular ones among all are the implicit and explicit solvers. In Abaqus terminology they are called a standard solver and explicit solver respectively. Each of these schemes has its own merits and demerits and this blog post compares these two schemes based on several parameters.

For ease of understanding, I am avoiding the use of long and complicated mathematical equations in this post. 😉

        Implicit Scheme

From an application perspective, this scheme is primarily used for static problems that do not exhibit severe discontinuities. Let’s take an example of the simplest problem: Linear static in which any physical situation can be mathematically formulated as:

[K]{x}={F}

Here K is the stiffness matrix, x is the displacement vector and F is the load vector. The size of the matrix and vectors can vary depending on the dimensionality of the problem. For example, K can be a 6×6 matrix for a 3D continuum problem or a 3×3 matrix for a 2D structural problem. The composition of K is primarily governed by material properties. F primarily includes forces and moments at each node of the mesh. Now, to solve the above equation for x, matrix K should be inverted or inversed. After inversion, we get a displacement solution used to compute other variables, such as strains, stresses, and reaction forces.

[M]d2{x}/dt2+[C]d{x}/dt+[K]{x}={F}

The Implicit scheme is applicable to dynamic problems as well. In the above equation, M is mass matrix, C is damping matrix and the rest are as usual. This equation is defined in real time. Backward Euler time integration is used to discretize this equation in which the state of a system at a given time increment depends on the state of the system at later time increment. K matrix inversion takes place in a dynamic scenario as well because the objective is still to solve for x. Abaqus standard solver uses three different approaches to solve implicit dynamic problems: quasi static, moderate dissipation or transient fidelity. Each method is recommended for specific types of non-linear dynamic behavior. For example, the quasi static method works well in problems with severe damping.

Merits of this scheme

  • For linear problems, in which K is a constant, implicit scheme provides solution in a single increment.
  • For non-linear problems, in which K is a function of x, thereby making it necessary to solve problem in multiple increments for sake of accuracy, size of each increment can be considerably large as this scheme is unconditionally stable.

Due to these reasons, implicit scheme is preferred to simulate linear/non-linear static problems that are slow or moderate in nature with respect to time.

Demerits of this scheme […]

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