Does your design review process involve others who don’t have NX or Teamcenter yet? Are you dealing with small businesses that don’t have access to NX CAD, or they use a third party CAD software? How do you collaborate with them today? How do you include others in your Model Based Definition and remain in the digital realm?

Siemens has the solution and it’s called XpresReview!

XpresReview is a Siemens freeware for viewing 3D models, 2D drawings, PMI, and other associated documents by combining all of these objects into a single package file. Using XpresReview allows all participants in your review process (workflow) the ability to view all the information they need to collaborate effectively without having NX or Teamcenter installed on their computer.

By selecting Menu + File + Send to Package File, XpresReview creates a lightweight, high-fidelity representation of the parts model and drawings which allows colleagues, suppliers, and others to view, markup, measure, section, and collaborate on the data, and Siemens customers, vendors and suppliers can download the XpresReview viewer free of charge.

This viewer gives selective access to users who do not use Teamcenter or NX so they can exchange data with Teamcenter and NX users.

XpresReview includes easy to use tools for: 

  • Viewing – Navigate 2D drawings and 3D models
  • Measurements – Check dimensions for 2D drawings and 3D models
  • Mark up – Use highlighters to draw attention to specific areas and add text comments
  • Section Views – Create interactive clipping planes to view sections through 3D models and interrogate for clash or clearance.


Tata Technologies is a Siemens Platinum Smart Expert Partner indicating our validated expertise in NX-CAD.

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The Challenge

Often when listening to a CIMdata presentation, their consultant will offer a tongue in cheek remark: “the most widely used PLM tool is Excel”. So, is it true? It is worth examining the issue in more detail.

Before proceeding, a better definition of the title is in order. The more accurate formulation – “Does an Excel spreadsheet contain the master definition of the eBOM during product design in your organization?”

There are two crucial points in this question

  1. Master definition implies that the BOM of record for final design is maintained in a spreadsheet
  2. eBOM is distinct from the mBOM maintained in an ERP system. Organizations generally do not use Excel for this purpose.

The Reality

BOM

So how prevalent is the master Excel BOM? If you are reading this article, you can answer silently for yourself. Aside from that, let us look at two data points:

Tata Technologies has conducted a PLM benchmark assessment at approximately 150 different organizations over the last 4 years. Based on our results, approximately 75% of these organizations use Excel in one form or another to control the eBOM.

Try a Google search on “Bill of Materials” and access the results for “Images”. Count how many of the images show Excel. By my informal count, at least 60% of the images from that search are Excel sheets of one form or another.

So, the prevalence of using Excel for eBOM would seem to be very high. Is that good or bad? Let’s examine that question in following sections.

The Good

Excel is perhaps one of the great inventions of the IT revolution. It is conceptually a simple tool but can be used in sophisticated applications. For generating and specifying a simple eBOM, it has the following merits.

  1. It is flexible and can be formatted in various was to portray an eBOM structure. The inherent layout of rows and columns is convenient for defining a structure
  2. One can add many columns to define and specify the various attributes of Parts in the eBOM
  3. Because Excel can easily perform calculations, the spreadsheet can automatically give aggregate results like total cost, total or sub assembly weights, total selling price, margins etc.
  4. It is a readily available tool across all businesses because of the persuasive nature of MS Office and everybody knows how to use it. Probably most businesses see it as an economical and inexpensive tool; dependent on budgets this may or may not be true
  5. Although it takes a little bit of dedicated formatting, the eBOM can show indented levels and collapsed sub-assemblies
Excel BOM
Excel BOM

The Bad

Of course, Excel may have some strengths, it has some significant weaknesses when it comes to eBOM management:

  1. It is difficult to do a BOM compare in Excel. Such functionality is required when two versions of the BOM need to be compared to see the differences
  2. Change Management in any Product Development environment is always a big challenge. While it may be possible to do revision control on an Excel spreadsheet (e.g. in SharePoint), it is impossible to do change control on individual parts in the eBOM
  3. Excel has no safeguards against anyone inadvertently deleting line items or details out of the eBOM.
  4. Calculations and formulas in Excel must be constantly checked to see they cover the correct ranges as changes will compromise these. Many companies have fallen to the problem of Excel formula mistakes
  5. By their nature, Excel spreadsheets are difficult to control and can proliferate easily, resulting in multiple copies. Which one is then the master?
  6. Excel eBOMs are always entered manually into ERP systems; requiring considerable effort and allowing the possibility of errors

The Ugly

Even if the “Bad” above is manageable, there are some situations where it is impossible to even consider using Excel for eBOM. Here are some of those situations:

  1. Large complex eBOM with part counts in the 200 and above range. No human can reasonably manage this in an Excel worksheet.
  2. Situations were the product has multiple configurations or variants. Because the number of resolved eBOM’s grow exponentially with the number of variants, it becomes impossible very quickly to manage
  3. When multiple downstream users must access the eBOM. This compounds the proliferation problem
  4. When the eBOM changes rapidly – keeping everybody up to date becomes impossible
  5. An eBOM is the very core of Product Development. Why use a half-baked tool?
  6. Excel cannot connect to any digital representation of the Part (3D model, Drawing, Specs etc.). This is a major shortcoming!

The Change

So, are you comfortable driving an automobile knowing that 66% of the eBOM sub-assemblies are managed in Excel?

There is technology that overcomes all the Bad and the Ugly. It exists today and is proven. The change to these systems may be difficult and potentially expensive but given the critical nature of an eBOM to a Product Development organization, it must be embraced!

Watch for the next article.

Tata Technologies is an engineering services company dedicated to engineering a better world. Visit our website at www.tatatechnologies.com

The Problem

Before computers, engineering designs where carried out by armies of draftsmen toiling over drawing boards in vast offices. Some may still express nostalgia for those days, but like all else, change came along. Today sophisticated computer programs allow engineering designs to be created in a full 3D virtual world with great degrees of precision. In the initial phases of the 3D modeling revolution there was a great debate over 2D vs 3D and because software vendors feared rejection over adoption, they included capacity to derive 2D drawings from the 3D model. The CAD programs essentially allowed the production of documents equivalent to what could be produced by a draftsman. But 3D CAD programs have continuing to improve in terms of functionality and capability; so much that all the information (and more) that used to be communicated via a 2D Drawing can be included in the single 3D model. Such an approach is far more efficient.

However, when asked organization after organization will admit to releasing and maintaining 2D Drawings for all sorts of purposes.

So, if technology has moved on beyond the 2D drawing, why are they still widely used in the industry?

The Technology

If you dig into the reasons why 2D Drawings still exist, various technical reasons are commonly offered:

  1. Dimensioning and tolerancing cannot be fully completed on a 3D model
  2. Tabled parts are difficult to create in 3D
  3. Consumers of drawings do not have the capability to view 3D
  4. 3D models cannot be printed out

Current Technology has an answer to all these problems:

  1. CAD software has core modules that can create a fully annotated model in 3D with all information included
  2. Design tables or configurations can achieve this very easily
  3. All major vendors offer viewers for 3D formats; the most basic of these are normally free.
  4. Viewers remove the need for printing; beside printed copies are uncontrolled and can lead to errors

It can easily be demonstrated that any technical objection can be overcome with correct tool deployment.

So, why do 2D drawings still exist?

The Culture

If you dig a bit further, other reasons start emerging from the shadows:

  1. We have always used drawings
  2. It would be difficult to retrain the shop floor
  3. Our suppliers don’t have the capability to use 3D models
  4. It would take years to redesign our processes

Finally, here are the true reasons why 2D drawings still exist and they are all cultural in nature. It is similar to the neighbor who trudges down the driveway in the snow and picks up a hard copy newspaper. Just sit up in bed and pick up a Smartphone!

So, how do you address the cultural issues?

The Change

Here is a high level journey from 2D to 3D

2D to 3D
  1. Technology – Choose the best technology
  2. Best Practices – Figure out how to take information in2D to 3D
  3. Impact – Evaluate impact to downstream processes
  4. Strategy – Design a strategy to replace 2D Drawings
  5. Planning – plan the transition and the OCM (more on that later)
  6. Implement – roll out the transition and goodbye to drawings

Here are some more critical elements of the journey

Best Practices – answer questions like Current information on Drawings? Critical vs Non-Critical? Common standard for GDT information? Company Standards?

Downstream Impact – In a complex organization, there are probably many users of 2D Drawings both within and without the organization. It is important to identify all these users before suddenly removing drawings!

Strategy – the various strategy components that must be considered include how to convert 2D information to 3D; technology purchase; repurpose downstream systems; training courses required; Project Plan; what to do with legacy data

Planning – As noted previously, the biggest obstacle to converting from 2D to 3D is cultural resistance. A well prepared organizational change methodology (OCM) and plan is vital. Considerations include communication, training, support and identifying champions.

Good luck!

Tata Technologies is a global engineering company that helps organizations engineer better products.
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2019 solver has number of enhancements that spans from fracture mechanics to element formulation to material formulation. Let’s start with what’s there on the fracture mechanics side:

Fracture mechanics enhancements

  • Introduction of new linear elastic fatigue crack growth procedure: Allows for change in contact conditions while loading, allows non-linear geometry behavior, mixed mode fatigue loading and viewer improvement. It is currently available for constant amplitude loading only. The input deck for mixed mode behavior looks as follows:
  • Improvements in contour integrals pre-processing and solving time. This applies to both J-integrals as well as K-integrals.
  • XFEM improvement to increase smoothness of 3D non-planar crack front. This is achieved by introducing non-local stress averaging algorithms to predict crack direction. Also limit new crack propagation direction to a certain angle from previous direction.
  • Symmetric cohesive elements have been introduced. Plane of symmetry must be perpendicular to one of the global axis though.
  • Introduction of UDMGINI subroutine to incorporate varied crack initiation criteria for different enrichment zones.

Element technology enhancements

  • Poro-elastic acoustic elements have been introduced to study wave propagation in coupled isotropic poro-elastic medium. It is only available in steady state dynamics analysis.
  • Displacement acoustics pressure elements have been introduced: C3D8A, C3D6A, C3D4A. Primary unknows are structural displacement and pore pressure. Same shape function used for displacement and pressure.
  • Shear panel element SHEAR4 in Abaqus has been introduced to model thin reinforced panels such as in fuselage. Intended to model response of buckled plate. Use is limited to linear elastic only.
  • Variable beam radius element formulation now available in Abaqus that can be well visualized in viewer as well.

Material enhancements

  • Low density foam has been introduced in Abaqus standard in 2019x FD01. This material has already been present in explicit. This material is useful in modeling highly compressible elastomeric foams.
  • Output variable SROCK for rock mechanics effective stress.
  • Enhancements to super-elastic materials to improve convergence and performance of material model. This application would be of interest in healthcare industry. An environment variable should be introduced to activate the model. Available from 2018x FD04.
  • Transverse shear stiffness modulus has been introduced for shell and beam sections. This now obviates the user material model to deal with plates of spatially varying thickness or plates made of composites.
  • Damage in concrete due to plasticity can now be modeled by defining failure criteria and element deletion criteria.
  • Two new outputs introduced in explicit for cohesive elements: equivalent nominal strain NEEQ and equivalent nominal strain rare NEEQR

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Contacts and Constraints

While we introduce new functionalities in Abaqus 2019 in contacts and constraints like we have done for other functionalities in similar blogs, I would retrospect into 2018 and clarify an important point: what’s the difference between FD and FP (hot fix). Believe it or not, they are not the same and the table below clarifies it for 2018 release.

Now let’s look at enhancements

  • One of the biggest enhancement in contact is that 2D and axisymmetric models are now supported in general contact for explicit. This general contact capability was already available in standard. This has been done on many customer requests in the past. Please note that 3DX platform does not support 2D axisymmetric models yet.
  • Another major enhancement is that analytical rigid surfaces are now supported in general contact for standard. This capability was already available in explicit general contact. Most common benefit of analytical rigid surface is precise geometrical data of simple surfaces.
  • Threaded interface approximation has undergone correction to include effects of right handed or left handed threads. This is an enhancement to existing capability in *clearance, bolt keyword entry. The image below shows the effect of thread direction on contact normal.

Further enhancements have been made to differentiate between one way and two-way threads. A two-way thread can resist both tension as well as compression unlike one way thread.

  • Another major enhancement is the introduction of general contact in pure heat transfer as well as coupled thermal-electrical step. Moreover, general contacts defined in any one of these steps can be carried forward and used in subsequent steps such as general static.
  • New Output Variable: CEDGEACTIVE: Dynamic feature edge criteria. It is now possible to visualize active feature edges at any stage of the simulation. This can be of great use in explicit analysis for applications such as air bag deployment.

CSLIPEQ: Relative equivalent tangential slip while in contact. It was present in explicit but now has been introduced in standard as well.

CSLIP_PL: Introduced to quantify plastic slip when shear stress exceeds critical frictional stress.

CICPS: Integral of contact pressure over the surface. It is different from CFN because normal direction is not considered.

Perhaps key differentiator is the situation below in which CFN output is zero due to symmetry but CICPS has a finite value.

  • Moment correction due to shell offset: When shell offset is defined, nodes shift from shell midplane and so does any forces acting on shell edge thereby creating a false moment about the midplane. This affect has been corrected by introducing a counter moment at the nodal force location so that effective location of edge force is at the shell midplane.
  • Deprecate old contact controls: Changes in certain contact controls by user will now result in fatal error by default. These controls are approach, automatic tolerances, Lagrange Multiplier etc. It has been observed that changes in such controls often results in performance degradation. In earlier releases only warning messages were issued that users have tendency to ignore. The default settings can be changed by the user.
  • Initial contact stress: The initial contact stress is now equal to stress of underlying elements instead of being zero. This now obviates the use of penetrations and sliding to generate contact stresses. The feature can be of much use in geotechnical applications.
  • FRIC_COEF enhancement: This subroutine has been enhanced to pass user defined, solution dependent state variables. Now coefficient of friction can be defined as a function of user defined state variable. GETVRC utility routine can be accessed from within FRIC_COEF to access various state variables to define friction coefficient.

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So many welds, so little time… and that’s how long it takes to create them using NX Weld Assistant… very little time.

In addition to the weld types shown in the image above, you have the option to create custom weld types giving you the ability to model any type of weld possible.

One type of custom weld is an extension weld. This type of weld is started and stopped beyond the limits of the parts being welded as seen in the image below.

To create this weld, we will simply create a line weld in the usual way (see image below) and then use synchronous modeling + move face to grab and extend the face that makes up each end of the weld.

Key benefits to modeling welds in Cad include:

  • Provides a key piece of information necessary for a complete Digital Twin.
  • Mass properties inclusion (Weight and Volume).
  • Easy to visualize.
  • Easy to validate for correct location using Weld Advisor.
  • Easy to convey information via a Drawing or PMI
  • Available for inclusion into CAE analysis
  • Available for process planning
  • Available for robot programming
  • Significant time savings compared to manual application of welds
  • Having the ability to create and validate the welds in CAD ensures quality data is being sent to manufacturing thereby reducing the amount of rework.

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There is so much more to this command than welding. Not only is there a full range of weld types, but you can also model beads of adhesives, glue, and mastic as well as fasteners like rivets for example. Basically there are three categories in Weld Assistant for joining parts, they are: discrete welds, line welds, and adhesives. Normally a rivet is a type of fastener, but they are included as a custom weld in Weld Assistant.

In this post, let’s take a look at how to model rivets. We will create a custom spot weld to mimic a rivet. We will start by configuring a custom weld spot under File + Utilities + Customer Defaults.

  • From the Customer Defaults window, select Weld Assistant + Point Locator and then select one of the Custom tabs.
  • Set the Solid Display to Cylinder and give the custom Point Locator a name… Rivet for example.
  • Set the other attributes accordingly, and then select OK to finish the configuration.

Now create a Rivet the same way you would create a Resistance Weld Spot.

  • From the Weld Assistance command select Weld Point Wizard.
  • From the Weld Point Wizard block:
    • Select your Method
    • Set the Type to the new custom Point Locator you just created (i.e. Rivet)
    • Select Next.
  • Select the Face Sets and then select Next
  • Select the points you want to create Rivets at and then select Next.
  • Select Finish to place the Rivets.

If the Rivets don’t show up at first, then select the Solid Weld Point Display option.

Key benefits to modeling welds in Cad include:

  • Provides a key piece of information necessary for a complete Digital Twin.
  • Mass properties inclusion (Weight and Volume).
  • Easy to visualize.
  • Easy to validate for correct location using Weld Advisor.
  • Easy to convey information via a Drawing or PMI
  • Available for inclusion into CAE analysis
  • Available for process planning
  • Available for robot programming
  • Significant time savings compared to manual application of welds
  • Having the ability to create and validate the Rivets in CAD ensures quality data is being sent to manufacturing thereby reducing the amount of rework.

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Product and Manufacturing Information (PMI) consists of non-geometric data, that is attached directly to a 3D CAD model to define geometric dimensioning and tolerancing (GD&T), engineering and manufacturing specifications, dimensions, and text.  PMI is part of Model Based Definition (MBD) and together these two elements are a part of a Digital Twin.

Applying PMI to a 3D model can reduce or eliminate the use of 2D drawings and can be used downstream to perform tolerance analytics and coordinate-measuring machine (CMM) inspection.

PMI is a command within NX that gives you the ability to create/attach dimensions and annotations to define the 3D model, and requires model views similar to the views on a drawing.  These dimensions and annotations are associative to the 3D geometry, and if it is decided that a 2D drawing is required, then the PMI can be inherited from the 3D model and automatically applied to the drawing views.

We think of MBD and PMI as new technologies and 2D drawings as “old school,” but there are valid uses for a 2D drawing.  Given the ability in NX to quickly create 2D drawings with associative dimensions inherited from the 3D PMI… this gives you the best of both worlds.

The image below demonstrates what PMI looks like in a 3D model view, and the next image down demonstrates the inherited PMI in a 2D drawing view:

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NX Realize Shape is a powerful and intuitive subdivision design tool that makes use of primitive shapes to create concept design models.  In the image below you can see a sphere has been chosen, but there are a number of other shapes to select from such as cylinder or block to name a few.

These primitive shapes can be placed over top of background data like sketches or even art work similar to what you see in the image above.  When a primitive shape is created, a cage is automatically created that surrounds the shape.  The shape can be morphed into designs by transforming that cage.  By selecting on, and dragging the cage elements (lines or points), you can mold the shape to fit the background image.

 

As seen in the image above, you can split a face into smaller faces (subdivide) in order to create more cage elements. This gives you greater control of the cage anytime more detail is required in a given area of your design.

By selecting cage elements (lines or points) and dragging them up or down, left or right, the concept designer is able to morph a simple shape into a complex form in a relatively shorter period of time versus having to work with .

Why do we promote the use of Realize shape?

Simple, this model represents the birth of the digital twin.  This digital twin is then used for detailed design, documentation, validation, simulation, and all the way to traditional or additive manufacturing… all within a single unified environment like NX… means you are going to use trusted data from concept to manufacturing… without requiring conversion or translation, and this is going to shorten your innovation lifecycle, getting you from concept to market faster!

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