Category "Dassault Systemes"

In the years to come, fuel efficiency and reduced emissions will be key factors in determining success within the transportation & mobility industry. Fuel economy is often directly associated with the overall weight of the vehicle. Composite materials have been widely used in the aerospace industry for many years to achieve the objectives of light weight and better performance at the same time.

The transportation & mobility industry has been following the same trends, and it is not uncommon to see the application of composites in this industry sector nowadays; however, unlike the aerospace industry, wide application of composites instead of metals is not feasible in the automotive industry. Hence, apart from material replacement, other novice methods to design and manufacture lightweight structures without compromise in performance will find greater utilization in this segment. In this blog post, I will discuss the application of TOSCA, a finite element based optimization technology.

The lightweight design optimization using virtual product development approach is a two-step process: concept design followed by improved design.

Design concept: The product development costs are mainly determined in the early concept phase. The automatic generation of optimized design proposals will reduce the number of product development cycles and the number of physical prototypes; quality is increased and development costs are significantly reduced. All you need is the definition of the maximum allowed design space – Tosca helps you to find the lightest design that fits and considers all system requirements. The technology associated with the concept design phase is called topology optimization that considers all design variables and functional constraints in optimization cycle while chasing the minimum weight objective function. The technique is iterative that often converges to a best optimal design.

HOW IT WORKS

The user starts with an initial design by defining design space, design responses, and objective function. Design space is the region from where material removal is allowed in incremental steps and objective function is often the overall weight of the component that has to be optimized. With each incremental removal of material, the performance of the component changes. Hence each increment of Tosca is followed by a finite element analysis to check existing performance against target performance. If target performance criteria is satisfied, the updated design increment is acceptable and TOSCA proceeds to the next increment. This process of incremental material removal is continued until the objective function is satisfied or no further design improvement is feasible. The image below depicts a complete CAD to CAD process flow in Tosca. The intermediate processes include TOSCA pre-processing, TOSCA and a finite element code based co-simulation and TOSCA post processing.

Tosca workflow

During the material removal process, TOSCA may be asked to perform the optimization that provides a feasible solution not only from a design perspective but from a manufacturing perspective as well. For example, TOSCA may be asked to recommend only those design variations that can be manufactured using casting and stamping processes. This is possible by defining one or more of manufacturing constraints available in TOSCA constraints library.

manufacturing constraints

While the topology optimization is applicable only on solid structures, it does not mean TOSCA cannot perform optimization on sheet metal parts. The sizing optimization module of TOSCA allows users to define thickness of sheet metal parts as design variables with a lower bound and an upper bound. […]

In this blog post, we will look into the basics of surface development and gain an understanding of what continuity is. Years ago when I used to teach full time I would tell my students that I called it “continue-ity,” the reason being that you are essentially describing how one surface continues or flows into another surface. Technically, you could describe curves and how they flow with one another as well. So let’s get started.

G0 or Point Continuity is simply when one surface or curve touches another and they share the same boundary.  In the examples below, you can see what this could look like on both curves and surfaces.

G0 Continuity

G0 Continuity

 

G0 Curve Continuity

G0 Curve Continuity

As we progress up the numbers on continuity, keep in mind that the previous number(s) before must exist in order for it to be true. In other words, you cant have G1 continuity unless you at least have G0 continuity. In a sense, it’s a prerequisite.  G1 or Tangent continuity or Angular continuity implies that two faces/surfaces meet along a common edge and that the tangent plane, at each point along the edge, is equal for both faces/surfaces. They share a common angle; the best example of this is a fillet, or a blend with Tangent Continuity or in some cases a Conic.  In the examples below, you can see what this could look like on both curves and surfaces. […]

It’s time to share more specials for the month of December! Check out these offers from Dassault Systèmes and Tata Technologies, which expire December 30th.  It truly is the best time of year to purchase software for all of your manufacturing and design needs!

Dassault Systèmes Promotions

  • Deals on CATIA End Soon!Grow with CATIA: Save up to 35% on all CATIA V5 products and select 3D EXPERIENCE solutions, including configurations such as MD2, CAT, or MDHX, as well as, add-ons and shareables like FPE, MCE, or ASD.
  • CATIA Machining Deal: Save up to 50% on all CATIA Machining portfolios and discover the value of integrated design and manufacturing. CATIA Machining can reduce your programming time and increase your competitiveness.

Terms and conditions apply. Please contact us here or email me at carol.hansen@tatatechnologies.com to inquire about an offer.

 

Tata Technologies SpecialsDassault Systemes Training

Space: the final frontier!

…at least that is how I am beginning to feel as design software and its features evolve. In this post, I want to talk about the basics – specifically the basics of component design.

The age-old question will arise at times: do I begin the design at 0,0,0 or do I design the component in its assembly position? Does it matter? Well, yes and no. With most CAD software packages, you have the ability to constrain or mate the feature to the component it is mating to. So technically, almost every component can be designed at 0,0,0 and then just assembled when you are done, as long as you have a mating condition to work with. This method is typically referred to as Bottom Up design. You see this most often in design of off-the-shelf items you would basically plug and play as needed, e.g. Fasteners, Tubing, Brackets, etc.

Fasteners

Fasteners

The alternative to this type of design is when you have a group of components that don’t necessarily mate together but need to come into the correct assembly position every time they are inserted. This method is typically referred to as Top Down design.  In the Automotive realm of design, all of the body panels are designed using a top down method.  Generally you will hear the term “designed in body position,” which indicates it is a top down design.

The key to working on a top down design is that every component is designed using a common axis system, aka common 0,0,0 location. The major systems in a vehicle that are used in other vehicles as well will be developed using a common axis system that won’t be the vehicle axis system.  For example, an engine would maybe have an axis system built at the rear face of the block and the centerline of the crank. […]

Laws are very useful when it comes to wanting to control something that has a known variance in it.  For example, if I were a designer and needed a linear surface that begins at one angle at one end of the guide curve and ends with a different angle. Without the ability to do this, you would have to create two surfaces and do some sort of transition surface in between them. In this video below, I will run a linear surface using a simple law on the angle value to take it from 15 degrees and one end to 45 degrees at the other end.

In this case I used a linear style law, and as you see, when I looked at the surface from a plan view (from above) the angle direction was linear from the 15 deg to the 45 deg.  Below, I will show what would have happened if I had done it as an “S Type” law by modifying the law.

In the image below you can see them if they are overlayed over each other. The surface highlighted is the S Type law and as you can see it definitely has an “S” shape for the transition in between the 2 knows angles.

Both Law Types

Both Law Types

You’re probably thinking, “What if I wanted a specific angle somewhere in the middle of the transition?” This gets a little trickier. In that case you would use an Advanced Law.

In order to used the advanced type law, you have to first develop it.  The easiest way I have found to do this is with a sketch.  In the example below, I am showing what the sketch would look like for the original linear law. […]

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. […]

MANIPULATE DIALOGI often hear customers designing mechanical components say something like “I have assembly design constraints and don’t think I need Kinematics.” The truth is, you may not need them – if you design items that do not move. Kinematics is the study of motion, and even with the standard CATIA V5 Assembly Design constraints, you are limited to a single movement based on a given set of constraints by holding down the right mouse button when using the compass to move an item (holding down the right mouse button respects constraints already applied) or you have the option to check the button in the Manipulate dialog With respect to constraints. 

Below is an example of what can be done with simple assembly constraints and the manipulator and where its limitations are.

 

What if you needed more than one movement to happen at the same time? That is where Kinematics will help. With CATIA V5 Kinematics, you have many, many options for setting up motion.  Each grouping of given movements would be called a mechanism, and within the mechanism you would have joints. CATIA V5 offers every kind of joint I can think of and I have yet to run across anything else I would need.

joints

The joints are groupings of your constraints that can then be controlled by commands; they are very simple to set up. The freedom to have anything move at any given time!  In fact, if you already have constraints defined in your assembly, it has a slick converter option to re-use the work you already have done and add your constraints to joints! Below is just a simple mechanism with multiple joints defined being played to show how the toy excavator product works.

 

Although this is a simple mechanism, the Kinematics package has the ability to do so much more….like analyze the travel of a particular joint and check if the limits have been reached.  If you combine the Kinematics package with the CATIA V5 Space Analysis license you will have the ability to check for clash and clearance between moving parts – which is exactly what most customers need to do! Add in a CATIA V5 DMU Navigator license and you can animate your sections – how cool is that?!

Bottom line: if you need motion and need to know how your motion affects other parts in your assembly, contact us and we will get you moving in the right direction!

 

 

In today’s engineering environment, there are a plethora of design tools available. One question I often hear is “Why CATIA?” It’s a question that seems simple enough, but the answer is much more complex. CATIA generally involved a greater initial investment, but in terms of overall design cost, you may be surprised to learn that a CATIA license can be a real bargain.

Ask: “What are we trying to accomplish?”

What type of design work are you doing? Do you require the ability to create complex surfaces? Are you going to create a small number of models and small assemblies or will there be a large number of models and large assemblies? Are you sharing the models with customers or vendors? Do you start every design from scratch or reuse as much data as possible?

The list of questions above is certainly not complete, but you can see by the number of questions already posited, the answer is multifaceted.

Complex Surfacing

Let’s look at the creation of complex surfaces. Many CAD systems can create surfaces of some level, but what if your company needs to create complex shapes? Look at how many CAD systems can create complex surfaces, and the list gets shorter – much shorter. Next, how many systems can modify complex surfaces? One example of this is the actual morphing of a complex surface. One might use this ability to compensate for springback in a metal stamping or counteract warpage in a plastic part. Now the list is much shorter. CATIA can easily handle these operations.

RSO

Large Assemblies

Next let’s look at large assemblies – something on the order of 500-1,000+ models. While virtually all systems can create assemblies, what happens when these assemblies get very large? Can the system handle them? How are you going to manage these assemblies? Is the system still able to operate or has its performance degraded to the point that it is virtually unusable? CATIA can handle very large assemblies, entire automobiles, aircraft, ships, etc. With CATIA V6 the management of these models is OOTB. Again the list is short at this point.

Data Reuse

Lastly, let’s look at data reuse. […]

When I think of the countless customers I have consulted with over the years, it amazes me how many don’t use parameters to control the design and capture design intent! What is a parameter, you ask?  A parameter can be thought of in two ways when it comes to CATIA V5. Parameters are built the moment you start a new part – as you can see in the image below, we already have parameters for the Part Number, Nomenclature, Revision, Product Description, and Definition created automatically. Parameters are being created each time you build any feature.  These types of parameters are known as system parameters.

new_part_parameters

You can and should build your own parameters to define your design intent. It’s every bit as important during the initial stages of a design to define your intent this way as it is to make sure sketches are constrained properly. In fact, it helps you in your sketch constraints (every constraint is a feature that has parameters associated to it). In this simple example of a piece of standard rectangular tubing shown below, there are constraints defining the height, width, wall thickness, and radii. Even though this is very easy to create, if I am a designer I would want to design it in such a way that I never have to waste any time designing a piece of rectangular tubing again. If I am a design leader, I feel the same and don’t want any of my designers doing this again in any design that involves any piece of rectangular tubing. The use of parameters will get us there!

RECTANGLUAR TUBING SKETCH

 

The parameters I am talking about are user defined parameters. Simple to create but very, very powerful in their functionality.  The simplest way to create a user defined parameter in CATIA V5 is through the fx icon found on the Knowledge toolbar.

knowledge_toolbar

You might be thinking, where have I seen that icon before? Oh yeah, in Excel when I need to create a formula for my cell. That is the point we are making here! In Excel, I use this function to compute things for me and make it easy to come up with a desired result.  In CATIA, we will create some parameters and then, when necessary, assign formulas to them to come up with our desired result.  When you click on the icon, you get the Formulas dialog and when you click on the drop down list next to the New Parameter of Type button, you can see you have many, many options.

new_parameters_types

[…]

There is a phrase among finite element analyst user community. Those who have been in the industry since a while must have heard of it at some point in their career.

     GARBAGE IN….GARBAGE OUT

It means that if the data being fed into the input deck is not correct or appropriate, the solver is very likely to give incorrect results, and that’s if it does not fail with errors. Many of us believe that getting some sort of result is better than getting fatal errors, which is not correct. Fatal errors give clear diagnostic messages to the user that allow him to correct the input deck. However, getting erroneous results sometimes makes a user feel that the simulation has been successful even though the results may be far from reality. Such situations are hard to predict and correct, as the underlying cause is not clearly visible.

One such situation arises when the user inadvertently chooses an element type that is not capable of capturing the actual physical behavior of the part or assembly with which the element is associated. The incompatibility may lie with respect to element material, element topology, element dimension, or the type of output associated with the element. The objective of this post is to highlight the capabilities and limitations of some lesser known element types available in the Abaqus element library to promote their proper usage.

Planar elements

These elements are further classified as either plane stress (CPS) or plane strain elements (CPE). The plane stress elements are used to model thin structures such as composite plate. These elements must be defined and can deform only in X-Y plane. For these types of elements:

szz = t xz = t yz = 0

Image1

The plane strain elements are used to model thick structures such as rubber gaskets. These types of elements must be defined and can deform only in X-Y plane. For these types of elements:

ezz = gxz = gyz = 0

Image2

Generalized plane strain elements

[…]

© Tata Technologies 2009-2015. All rights reserved.