Category "Dassault Systemes"

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.

 

 

There is an interesting news regarding CATIA to be shared by composites user community. While almost all the composites related functionalities such as composites design by zones/plies, ply drop offs, core sampling, ply producibility, ply flattening, ply cut outs, lay-up export etc. have been existing as native CATIA offerings in composites workbenches, one valuable piece has been missing. That piece is called Laser Projection, a tool that can assist manufacturing guys in placing cut plies at right location on the tool. Earlier this functionality was offered through one of Dassault Systemes software partner called Majestic. However, Majestic got acquired by Autodesk a while ago so Dassault Systemes decided to develop a similar functionality in-house.

Laser Projection functionality was introduced in V5-6R 2016 release of CATIA, both in classic as well as in Express configurations and has been refined in service packs such as V5-6R 2016 SP2 and SP3. In classic configuration license is named as CLA and in express configuration license is named as LPX. Either CATIA composites design or manufacturing workbenches are a pre-requisite in either of these configurations. This technology is most suitable for most hand-layup parts such as panels, hulls, wind blades etc.

Within the application, it is possible to define any number of lasers by coordinates and assign properties to them such as its dimensions and range in terms of distance, horizontal and vertical angles. It is also possible to optimize the resource allocation. The reach envelope can be visualized to make sure largest ply in the model can be displayed with given number of lasers in the model. If not, more lasers can be defined or their positions can be changed.

The Laser Projection module is compatible with most commercial available vendor machines such as Virtek, LAP, LPT etc. The core thickness as well as plies thickness is automatically taken into account during projection. It is also possible to change display properties such as laser color, length of normal vectors etc. It is further possible to include additional geometry or text as a part of the display from predefined CATIA sets.

For any further information regarding licensing or functionality of this module, including a demonstration, please approach us and we are ready to help. It is also possible to import the laser projection files such as .py and .cal extensions to review the laser projections data in CATIA laser projection.

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 […]

In the simulation community, when it’s time to learn applications of software tools in real-life product development, one of the best ways to do it is to approach other users. The regional user meetings organized by SIMULIA once every year have a similar objective: bring together the user community. These meetings gather users to share their knowledge and experience in advancing methods and technology for finite element analysis, multi-physics, process automation, design optimization, and simulation management. There is also an opportunity to present a white paper, listen to keynote speakers about the value simulation brings in virtual product development, get updates on new releases from the SIMULIA product management team, and  contribute to this success by being a sponsor of the event. As SIMULIA is not so much a product but a portfolio that offers multiple products, SIMULIA regional user meetings are often a conglomeration of various product specific events: Abaqus, Tosca, ISight, Fesafe, Simpack, Simpoe, and the 3DEXPERIENCE platform.

Initially this event was called the SIMULIA community conference, with a single location at the North American Headquarters in Rhode Island. As its popularity grew, the size of the event grew as well, so there was a need to offer it in multiple locations, making it more accessible to regional users. The new series of events was named the SIMULIA regional user meetings, which are now held at different locations every year: Great Lakes, Houston, California, Toronto, Sao Paulo (Brazil).

How big this event could be in terms of public gathering! We try to never miss it because of its size and value; a snapshot below from the 2014 event held at Providence, RI speaks for itself.

The 2017 Regional User Meetings are coming up!

For all the information regarding dates, venue, agenda and registrations, please click below.

Registrations

ENOVIA PLM Essentials, on the 3DEXPERIENCE platform, is a package of essential PLM capabilities for mid-sized manufacturers using CATIA V5, SOLIDWORKS, and/or 3rd-partry CAD systems. Capabilities include CAD and doc management, BOM management, Change Management and Project Management, plus social collaboration; these capabilities help increase revenues, improve product quality, shorten time to market, drive innovation, and achieve a competitive advantage.

Innovation is the only way to stay competitive and profitable, and even to survive. When non-productive tasks can be removed, engineering teams get more time back to focus on innovation and produce more alternatives to decide on the best solution.

We are hosting a live seminar with Dassault Systèmes on September 7th, 2017 at our Novi, MI headquarters. We’ll be covering all of the essentials topics discussed above and showing the value you can get by adopting the 3DEXPERIENCE platform.

Register to join us for a half day of education, networking, and lunch! If you want a closer look, stay after and chat one-on-one with our team. A full agenda is available to peruse on the registration page as well.

Many of our Abaqus customers don’t know that the Computational Fluid Dynamics approach (CFD) is not the only method of modeling fluids in Abaqus. There are many other possibilities and the right approach depends on the physics of the problem. This blog post discusses the multi physics methods of modeling fluids in Abaqus.

  • CFD method: This is the well-known and traditional method for fluids modeling. It’s based on Eulerian formulation, in which material flows through the mesh and can be accessed through the Abaqus/CFD solver. Application example: Flow through exhaust systems.
  • CEL method: This is a coupled Eulerian Lagrangian method primarily used in problems involving unbounded fluids where fluids free surface visualization is required. It’s also possible to simulate interaction between multiple materials, either fluids or solids. This method is accessible through Abaqus/explicit solver. Application example: Fluid motion in washing machine.
  • SPH method: This is a smooth particle hydrodynamics approach primarily used to model unbounded fluids that undergo severe deformation or disintegrate into individual particles. This method uses a Lagrangain approach in which material moves with the nodes or particles and can be accessed through the Abaqus/explicit solver. This method can be used for fluids as well as for solids. Application example: bird strike on an aero structure.

We can compare these three methods against multiple parameters such as materials, contact, computation speed, etc. to understand their applications and limitations:

  • Material considerations:

SPH method is most versatile in terms of material support. SPH supports fluids, isotropic solids as well as anisotropic solids.

CFD is the only technique that can model fluid turbulence

CFD is the only technique to model porous media

CFD and CEL allows material flow through the mesh: Eulerian

  • Contact considerations:

[…]

In today’s post, I would like to focus on Functional Modeling.

Plastic Part

I’ve always wondered why this workbench never really caught on. Speaking purely from an FM1 trigram standpoint, it comes with the MCE add-on that most people who have PLM Express have added on to their CAC (CAC+MCE).

CAC+MCE

FM1 gets you the Functional Modeling Part Workbench.

Functional Modeling Part Workbench

First let’s talk about what it was created for, which is plastic parts or parts with draft, because it could also be used for core-cavity type parts like castings. This workbench is very unique in that you do not necessarily model in a particular sequence order like you would in the Part Design workbench. Modeling in the Part Design workbench is what we would call traditional feature modeling, i.e. create a sketch then make a pad, then add some dress up features like draft, fillets, then shell it out, etc.

Feature Based Modeling

There is nothing at all wrong with modeling this way – in fact, it is how most of this work is done today! Now let’s look at what we call Functional modeling which looks at a shape and incorporates a behavior for a specific requirement. […]

Abaqus has always been first choice of analysts for modeling any form of non-linearity in the model: geometric non-linearity, material non-linearity, or boundary condition non-linearity which is large sliding contact. Within material non-linearity, the most popular model is piecewise linear plasticity used to model plastic deformations in alloys or metals beyond their yield point. This blog post primarily discusses another powerful but somewhat less known non-linear material model of Abaqus used to model elastomers or rubbers.

Before getting into Abaqus’ functionalities for rubbers, let’s see what types of rubbers primarily exist, along with their mechanical characteristics:

Solid Rubbers

They exist almost everywhere: tires, weather seals, oil seals, civil engineering equipment, etc. Their main mechanical characteristics are

  • Nearly incompressible: While it is easy to stretch these materials, it is very difficult to compress them volumetrically. It’s a common observation that a rubber band can be stretched easily but a piece of pencil eraser cannot be compressed so easily. This behavior is particularly important in elastomer modeling.
  • Progressive loading and unloading cycles show hysteresis as well as damage. As cycles continue, damage progresses.

Thermoplastics

They are a physical combination of rubber materials and thermal plastics. They can be easily molded or extruded. They are not physically as strong as solid rubbers, neither resistant to heat and chemicals. They are more prone to creep and permanent set.

Elastomeric foams

Commercially, they are referred to as porous rubbers or just foams.

  • They can undergo very large strain, as large as 500% that is still recoverable. Their counterparts, crushable foams, can exhibit inelastic strains.
  • They exhibit cellular structure that may be open or closed type. Typical examples are cushions, paddings, etc.
  • The compressive stress strain curve is as follows:

Foams exhibit a linear behavior in a compressive strain range of 0% to 5%. Subsequently, there is a plateau of severe deformation at almost constant stress. In this region, the walls and plates of cells buckle under compression thereby forming a denser structure. Post buckling, the cellular walls and plates start interacting with each other, causing a gradual increase in compressive stress.

  • Due to high porosity, foams exhibit very large axial compressive strain without any lateral strain. Due to this, the Poisson’s ratio of foams is nearly zero. This behavior is critical for material modeling of foams in Abaqus.

Material models in Abaqus for rubbers

Abaqus uses the “hyperelastic materials” terminology for its material libraries that support rubbers. This is primarily because rubbers are elastic in nature even at very high strains. The basic assumptions in modeling solid rubbers are: elastic, isotropic and nearly incompressible. Foam material libraries in Abaqus are referred as “hyperfoam” and are highly incompressible. None of the rubber material models can be represented by a single coefficient such as modulus. It rather requires a strain energy density function that can have an infinite number of terms. Therefore, in Abaqus, strain energy functions have specific forms with certain numbers of parameters to be determined. Each of these function is associated with a separate material model, as shown below. […]

Today we will continue our series on the hidden intelligence of CATIA V5.  It is important to note that I am using a standard Classic HD2 license for this series In my last post, we discussed building a catalog of parts based on a single part that has a spreadsheet that drives the parameters with part numbers.  What about features?  If CATIA V5 is powerful enough to generate entire parts based on parameters, shouldn’t it also be able to be able to generate repetitive features? For instance, take a boss feature that appears on the B-Side of a plastic part. As a leader, I would not be interested in paying my designer his rates to keep repeatedly modeling a feature that may only change slightly throughout the backside! Model smarter: make once, use many times.

To do this successfully, you must address a few things – the first being how it may change. Of course you may not anticipate all changes, but a good rule of thumb is to try to model with maximum flexibility (big slabs for surfaces, overbuild everything, pay close attention to design intent) and do not use B-reps for your design. Avoid creating and building off of features CATIA builds, meaning whenever possible build your own and pick only from the tree to link to them.  The second issue to address is – what are going to be the parametric numerical inputs to drive the design? See my first post in this series on how to set these up.  i.e. Draft Angle, Wall thickness, Outer Diameter, etc.

Finally, what are going to be the geometric inputs to drive the design?  i.e. Location point, Pull Line, Slide Line, Mating Surface, etc.  A good rule of thumb here is to limit these features to as few as possible that are needed to get the job done. Sometimes it may be beneficial to sketch all this out on paper before you build it; I suggest gathering input from all the possible parties to help you in your definition.

In the example below, I have constructed a boss. Let’s review what I did. […]

Additive manufacturing is not a new technology – it was introduced in the manufacturing industry in late 80s for very niche applications. Stereolithography, a variant of additive manufacturing, was introduced in 1986 for rapid prototyping applications; however, its true potential remained hidden for a long time. Additive manufacturing primarily refers to methods of creating a part or a tool using a layered approach. As a still-evolving technology, it now covers a family of processes such as material extrusion, material jetting, direct energy deposition, power bed fusion, and more.

Additive manufacturing expands design possibilities by eliminating many manufacturing constraints. Contrary to rapid prototyping and 3D printing, there has been a shift of focus to functional requirements in additive manufacturing; however, these functional requirements may deviate from what is expected due to many factors typical of an additive manufacturing process.

  • Change in material properties: Mechanical and thermal properties of a manufactured part differ from raw material properties. This happens due to material phase change which is typical to most additive manufacturing applications.
  • Cracking and failure: The process itself generates lots of heat that produces residual stresses due to thermal expansion. These stresses can cause cracks in material during manufacturing.
  • Distortion: Thermal stresses can lead to distortion that can make the part unusable.

The additive manufacturing process is not certifiable yet, which is a major barrier in widespread adoption of these processes commercially. The ASTM F42 committee is working on defining AM standards with respect to materials, machines, and process variables.

The role of Simulation in additive manufacturing

  • Functional design: The first objective is to generate a suitable design that meets functional requirements, then subsequently improve the design through optimization methodologies that work in parallel with simulation.
  • Generate a lattice structure: Many of the parts manufactured through AM have a lattice structure instead of a full continuum. One objective of simulation in AM is to generate a lattice structure and optimize it using sizing optimization.
  • Calibrate material: As mentioned before, the material properties of a final part can differ substantially from that of the raw material. The next objective is to capture the phase transformation process through multi-scale material modeling.
  • Optimize the AM process: Unwanted residual stresses and distortions can develop in the process. It is necessary to accurately capture these physical changes to minimize the gap between the as-designed and as-manufactured part specs.
  • In service performance: Evaluate how the manufactured part will perform under real life service loads with respect to stiffness, fatigue, etc.

 

Now let’s discuss each of these objectives in more detail, with respect to SIMULIA. […]

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