Category "Dassault Systemes"

The Dassault Systèmes SIMULIA portfolio releases new versions of its software products every year, and this year is no different. The first release of Abaqus 2017 is now available for download at the media download portal. SIMULIA has developed and broadcast 2017 release webinars to make users aware of new features available in the 2017 release, but those webinars are long recordings ranging from one to two hours each, which can be daunting. This blog post will provide a brief highlight of materials and explicit updates in Abaqus solver 2017. A more detailed explanation of any mentioned update, or answers to further questions, can be obtained either by listening to the webinar recordings at the SIMULIA 3DExperience user community portal, leaving a comment on this post, or contacting us.

SPH boundary conditions improvements

SPH particles located on opposite sides of a surface cannot interact with each other in the absence of boundary condition. This was not the case in previous releases; in Abaqus 2017, this is the default boundary condition setting. There are further improvements in tensile instability control to prevent instability among particles subjected to local tensile stresses. Below is an example in which there are SPH particles in two different chambers; the lower chamber particles are subjected to displacement BC while upper chamber particles are not subjected to any BC.

DEM improvements

  1. The series and parallel search algorithms for contact are unified to improve the DEM performance. The search cells are created only once.
  2. It is now possible to run DEM jobs with particle generators in parallel mode. This means more than one particle generator can be active while a DEM job is running.
  3. In previous releases, only fixed time increment scheme was available and it was difficult for the user to predict the appropriate time increment. In the 2017 release, an automatic time increment scheme has been introduced.
  4. Adhesive particle mixing is now supported. The algorithm used is called JKR adhesive inter particle contact. Both Hertz contact and friction are supported.

Material Enhancements

  1. There is some good news for users in the health care industry who design and manufacture cardiovascular stents: Super-elasticity, which was previously a part of user subroutines, is now available in the Abaqus 2017 material library. The motivation is Nitinol, a nickel titanium alloy used in cardiovascular stents because of super elasticity, shape memory effect, biocompatibility, and fatigue. The Nitinol model exhibits linear elastic Austensite behavior at lower stresses. On further loading, transformation from Austensite to Martensite occurs but behavior is still linear elastic. Beyond full transformation, Martensite exhibits elastic plastic behavior. A similar phenomenon is observed in compression loading. It is supported in Abaqus CAE.

 

 

 

 

 

 

 

 

 

 

2. A multilinear kinematic hardening model is now available in Abaqus 2017. In previous releases, this model was available as a user subroutine material called ABQ_MULTILIN_KINHARD.  Plasticity follows an array of perfectly plastic subvolumes that follow Von-Mises criteria, each with a unique yield strength. This model offers more flexibility than the linear kinematic hardening model. It is available only in Abaqus standard and intended for thermo-mechanical fatigue of metals. It is supported in Abaqus CAE.

3. The definition of damage initiation and damage evolution of cohesive elements with traction separation response has been enhanced to include rate dependent cohesive behavior. It is available only in Abaqus explicit. Non-linear damage initiation of ductile metals is now supported in Abaqus 2017. This model provides more flexibility to predict damage under arbitrary loading paths. It is available both in Abaqus standard as well as in explicit for ductile, shear and Johnson Cook material models.

 

4. Non-linear damage initiation of ductile metals is now supported in Abaqus 2017. This model provides more flexibility to predict damage under arbitrary loading paths. It is available both in Abaqus standard and explicit for ductile, shear and Johnson Cook material models.

5. The parallel rheological framework model now supports plane stress elements as well, in both standard as well as in explicit.

6. A new subroutine for user defined thermal expansion coefficients has been introduced. It is called VUEXPAN. This routine can be used in explicit to define thermal strain increments as a function of temperature, time, element number, state, or field variable. It is available only with Mises plasticity, Hill Plasticity and Johnson Cook model.

Usability Enhancements

1.Enhancements in distortion control: In Abaqus explicit, it is possible to convert highly compressed solid elements to linear kinematic formulation. Once that happens, the analysis does not stop even if the elements get inverted. It is activated by default when solid elements are used with crushable foam material.

2. Larger stable time increments in Abaqus explicit: In Abaqus 2017, there is an improved estimate method of element characteristic length to get larger stable time increments. It is defined in explicit step as follows:

*Dynamic, Explicit, improved DT method=YES (by default) or NO

It is further possible to invoke this method selectively in individual sets instead of global model as follows

*section control, improved DT method = YES or NO

 

The Dassault Systèmes SIMULIA portfolio releases new versions of its software products every year, and this year is no different. The first release of Abaqus 2017 is now available for download at the media download portal. SIMULIA has developed and broadcast 2017 release webinars to make users aware of new features available in the 2017 release, but those webinars are long recordings ranging from one to two hours each, which can be daunting. This blog post will provide a brief highlight of standard and explicit updates in the Abaqus 2017 Solver. A more detailed explanation of any mentioned update, or answers to further questions, can be obtained either by listening to the webinar recordings at the SIMULIA 3DExperience user community portal, leaving a comment on this post, or contacting us.

Updates in Abaqus Standard

Abaqus Standard 2017 has been substantially improved with respect to contact formulations. Mentioned below are the key highlights of various contact functionalities improvements.

  • Edge to surface contact has been enhanced with beams as master definition. This new approach facilitates the phenomenon of twist in beams during frictional contact.
  • Cohesive behavior in general contact.

General contact has always been useful in situations where either it becomes cumbersome to visualize and define large number of contact pairs, even by using contact wizard, or it’s not possible to predict contact interactions based on initial configuration. The general contact support now includes cohesive behavior, thereby making it possible to define contact in situations shown in figure below.Image1

 

Cohesive contact does not constrain rotational degree of freedoms. These DOFs should be constrained separately to avoid pivot ratio errors.

There have been few other changes in cohesive contact interactions. In the 2016 release, only first time cohesive contact was allowed by default, i.e. either a closed cohesive behavior at initial contact or an open initial contact that could convert to a close cohesive contact only once. In the 2017 release, only a closed initial contact could maintain a cohesive behavior by default settings. Any open contact cannot be converted to cohesive contact later. However, it is possible to change the default settings.

Image1

 

  • Linear complementary problem

A new step feature has been defined to remove some limitations of perturbation step. In earlier releases, it was not possible to define a contact in perturbation step that changes its status from open to close or vice versa. In 2017 release, an LCP type technique has been introduced in perturbation step to define frictionless, small sliding contact that could change its contact status. No other forms of non-linearity can be supported in perturbation steps.  LCP is available only for static problems. Any dynamic step is not supported.

Image1

Updates in Abaqus XFEM (crack modeling) […]

The Dassault Systèmes SIMULIA portfolio releases new versions of its software products every year, and this year is no different. The first release of Abaqus 2017 is now available for download at the media download portal. In this blog post, I provide a brief highlight of updates in Abaqus CAE 2017. A more detailed explanation of any mentioned update, or answers to further questions, can be obtained either by listening to the webinar recordings at SIMULIA 3D Experience user community portal, leaving a comment on this post, or contacting us.

  • Consistency check for missing sections

Abaqus CAE users would probably agree that this mistake happens quite often, even though the parts with defined section assignments are displayed in a separate color. In previous releases, this check was not included in data check runs, so it was not possible to detect this error unless a full run was executed. In the 2017 release, missing regions can be identified in a data check run, thus saving time by eliminating fatal error runs.

image1

 

  • New set and surface queries in query toolset

The sets and surfaces can be created at part as well as assembly level. In earlier releases, it was not possible to see the content of a set or surface in the form of text, though it was possible to visualize the content in the viewport. In the 2017 release, query toolbox includes set and surface definition options. In case of sets, information about geometry, nodes, and elements can be obtained with respect to label, type, connectivity and association with part or instance, whichever is applicable. In case of surfaces, name, type, and association with instances, constraints, or interactions can be obtained.

image1

 

  • Geometry face normal query

In the 2017 release, it is possible to visualize the normal of the face or surface by picking it in the viewport. In case of planar faces, normal is displayed instantly. In case of curved faces, CAE prompts the user to pick a point location on the face by various options.

image1

[…]

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!

 

 

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