Posts Tagged "ISight"

I mentioned the process automation concept of ISight in a previous simulation automation blog. ISight is an open source code simulation automation and parametric optimization tool to create workflows that automate the repetitive process of model update and job submission with certain objectives associated with it. The objective could be achievement of an optimal design through any of the available techniques in ISight: Design of experiments, optimization, Monte Carlo simulation or Six Sigma. In this blog post, I will be discussing various value added algorithms in DOE technique; I will discuss other techniques in future blogs.

Why design of experiments

Real life engineering models are associated with multiple design variables and with multiple responses. There are two ways to evaluate the effect of change in design variable on response: Vary one at a time (VOAT) approach or Design of experiments (DOE) approach. The VOAT approach is not viable because:

  • This approach ignores interactions among design variables, averaged and non-linear effects.
  • In models associated with large FE entities, each iteration is very expensive. VOAT does not offer the option of creating high fidelity models with a manageable number of iterations.

With the DOE approach, user can study the design space efficiently, can manage multi dimension design space and can select design points intelligently vs. manual guessing. The objective of any DOE technique is to generate an experimental matrix using formal proven methods. The matrix explores design space and each technique creates a design matrix differently. There are multiple techniques which will be discussed shortly and they are classified into two broad configurations:

  • Configuration 1: User defines the number of levels and their values for each design variable. The chosen technique and number of variables determines number of experiments.
  • Configuration 2: User defines the number of experiments and design variables range.

Box-Behnken Technique

This is a three level factorial design consisting of orthogonal blocks that excludes extreme points. Box-Behnken designs are typically used to estimate the coefficients of a second-degree polynomial. The designs either meet, or approximately meet, the criterion of rotatability. Since Box-Behnken designs do not include any extreme (corner) point, these designs are particularly useful in cases where the corner points are either numerically unstable or infeasible. Box-Behnken designs are available only for three to twenty-one factors.untitled

Central Composite Design Technique […]

For many years, finite element modeling has been the job of a specialist; the tools used to perform even simple finite element analysis have been complex enough to require a subject matter expert. This is primarily due to the complex, difficult to understand graphical user interfaces of these products. The job is made further difficult to perform due to the requirement of advanced engineering subject knowledge by the analyst.

Can a mechanical designer who uses CAD tools to create engineering drawings be trained to perform engineering simulations?

In today’s product availability scenario, the answer is “yes.”

A CAD designer using CATIA can create and execute simple finite element models within the CATIA environment by using CATIA workbenches that have been developed for simulations. This makes it intuitive and easier for designers to ensure that their parts meet their design requirements.

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How the simulation methodology gets simplified using designer level tools

  • No need of an expert level analyst tool to perform simple finite element simulation.
  • No need of manual data transfer between design and analysis departments.
  • No need of geometry clean up tools to fix data translation errors.

There are obvious benefits to adopting this simplified approach that integrates the design and analysis environments. The designer can predict design problem early in design process; subsequently the designer can check various alternatives of design in less time. This is primarily due to the tight integration of designer level tools with knowledge based engineering that allows the designer to deliver better product in less time.

Part Level Simulation

From a geometrical perspective, the simulation model can be generated at part level to begin with. The native integration within CATIA allows users to perform stress, displacement, and vibration analysis at any time in the design process, allowing more accurate sizing of parts and fewer design iterations. Individual parts consisting of solid, surface, and wireframe geometries can be analyzed under a variety of loading conditions. The analysis specifications, such as loads and restraints, are associative, with the design allowing users to perform analyses quickly and easily. These specifications are then automatically incorporated into the underlying finite element model, meaning that users do not have to work directly with the finite element model. “Virtual parts” allow items like forces, moments, and restraints to be easily modeled without having to have a detailed geometric representation.

Standard reports can be automatically generated in HTML format, providing clear and detailed information about the results of the analysis, including images associated with the computations. These reports can be used to document the analyses that have been performed and to communicate the results of the analysis to other stakeholders in the organization. CATIA V5 Analysis users benefit naturally from the overall PLM solution provided by Dassault Systèmes, including ENOVIA V5 for data and product lifecycle management. CATIA V5 Analysis users can store, manage, and version all the data associated with their product’s simulation and share the information within the extended enterprise. This unique capability allows collaboration and provides access to advanced PLM practices such as concurrent engineering and change management.

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     Assembly level simulation

 If the concept of virtual parts does not hold good anymore and the complexities of various parts interacting with each other make assembly level simulation mandatory, it is possible to create analysis models for assemblies as well. The analysis of assemblies, including an accurate representation of the way the parts interact and are connected, allows for more realistic and accurate simulation. The designer does not have to make simplifying assumptions about the loading and restraints acting on an individual part. Instead the part can be analyzed within the environment that it operates with the loading automatically determined based on the way the part is connected to and interacts with surrounding parts.

The various types of connections that can be modeled include bolted connections, welded connections, pressure fitting connections, and many more. To make the job further easier for the designer, these connections can be defined using assembly level constraints that already exist in the CAT Product model. Once the design changes, the associated assembly constraints as well as corresponding FEA connections get updated, thereby creating an updated FEA model that is ready for analysis.

         Concurrent engineering made easier 

The “assembly of analysis” capability enables concurrent engineering. For example, the various parts in an assembly can be modeled and meshed separately by different users. They can either use the CATIA V5 meshing tools or import orphan meshes (meshes that don’t have any geometry associated with them) developed outside of CATIA Analysis using a variety of different modeling tools. The user responsible for analyzing the assembly can consolidate the different meshes, connect the parts, apply the loading specifications, and run the simulation. This can significantly reduce the turnaround time when analyzing large assemblies, particularly since some of the parts may have already been analyzed and therefore, the analysis models would already be available.

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Extended solver capabilities

The basic level FEA solver present in the CATIA designer workbench is called the “Elfini” solver and can model only simpler physical problems such as linear materials, small deformations, small rotations and bonded contacts; real life problems can be much more complex and may necessitate the need of an advanced solver. To address such scenarios it is possible to include the well known non-linear solver Abaqus into the CATIA designer environment; it can model the effects of geometric nonlinearity, such as large displacements, and allows nonlinear materials to be included, such as the yielding of metals and nonlinear elastic materials like rubber. It also offers more advanced contact capabilities including the ability to model large relative sliding of surfaces in contact.

The Abaqus capability enables the effect of multiple steps to be analyzed, where the loading, restraints, contact conditions, etc., vary from one step to the next. This powerful technique allows complex loading sequences to be modeled. For example, a pressure vessel might be subjected to an initial bolt tightening step, followed by internal pressurization, and conclude with thermal loading.

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How many times has the first design iteration submitted to FEA modeling passed the design criteria?

The answer is close to zero, but even if it does happen by stroke of fortune, the design is not the optimal design – which means that although design requirements are met and validated by FEA, there is always scope of improvement either in terms of cost or in terms of performance. In general, it is not unusual to reach the optimal design in 15 to 20 iterations.

An analyst know the pain of creating a detailed finite element simulation model. Most of the steps involved, such as geometry cleaning and meshing, are very time-consuming, and they are primarily driven by geometry. Let’s look at the workflow in more detail:

An analyst in automotive industry often performs finite element modeling work in Hypermesh, stress analysis in Abaqus, optimization in Optistruct, and durability in Fe-Safe or N-code. An analyst in the aerospace industry often performs CAD composites work in CATIA, finite element modeling in Abaqus CAE, stress analysis in Abaqus or Nastran, and durability in Fe-Safe. An analyst working in other industries has his own suite of FEA tools to work with. The entire process requires data flow from one simulation code to the other. This means output from one code serves as an input to the other. Quite often this work is also done manually by the analyst.

This means that in situations where optimal design is obtained in 20 iterations as mentioned above, an analyst has to perform geometry cleaning 20 times, create FE meshes manually 20 times, and also transfer the simulation data from one piece of code to the other 20 times. By the time these design iterations are over, the analyst’s face and computer looks somewhat like this:

Let analysts remain as analysts and let simulation robot do the rest!

The traditional job of finite element analyst is to build robust high fidelity simulation models that gives correct results under real life load applications. The analyst is not an FE robot who can perform repetitive tasks with ease. In situations like one mentioned above, it makes perfect sense to let FE analyst create a robust FE model only once per FE code involved. Subsequently introduce a simulation robot that can capture hidden steps and workflow, create a script and execute that script multiple times. This simulation robot is called ISight. […]

Our SIMULIA user community has been using the conventional analysis and portfolio tokens for a while now. These tokens are primarily used to access the Abaqus CAE pre-processor, Abaqus solver, and the Abaqus viewer. The analysis configuration offers Abaqus solver licenses in the form of tokens, and Abaqus CAE as well as Abaqus viewer as interactive seats. The portfolio configuration offers all three components of Abaqus, i.e. the solver itself, Abaqus CAE as well as Abaqus viewer as tokens.

                                                                                                                                                      IS SIMULIA = only ABAQUS!

The new equation has been EXTENDED

                                                                                                                                   SIMULIA = ABAQUS + ISIGHT + TOSCA + FESAFE

The overall simulation offerings from Dassault Systèmes go way beyond Abaqus finite element simulations. The functionalities now include process automation, parametric optimizations, topology optimization, fatigue estimation, and many more. And starting from Abaqus release 6.13-2, all these additional capabilities are included in a single licensing scheme called extended tokens. Here is an overview of these additional SIMULIA products.extended-products

ISIGHT

ISight is an open desktop solution for creating flexible simulation process flows, consisting of a variety of applications, to automate the exploration of design alternatives, identify optimal performance parameters, and integrate added-value systems. The simulation process flows created from ISight can include multiple third party simulation components such as Ansys, LS-DYNA, Nastran, Mathcad as well as general purpose components such as Matlab, excel, calculator, and many more. It offers advanced parametric optimization, Design of experiments and Six Sigma techniques. Moreover, the vast amount of Simulation output data generated by such techniques can be managed effectively using the post processing runtime gateways of ISight. It’s rightly called a Simulation Robot.

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TOSCA

Tosca is a general purpose optimization solution for designing high performance light weighted structures. As fuel economy continues to be the most important design factor in the transportation and aviation industries, designing lightweighted components and assemblies will remain a top priority, and Tosca can really help to achieve those objectives. […]

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