Posts Tagged ‘Robert Warren’

Nominal Wall Thickness Inside Plastics Simulation

Thursday, July 16th, 2015

Wall Thickness – a major concern when designing a plastic part.

During the injection of the mold the melted plastic flow front will always move in the direction of least resistance. You can think of this similar to water flowing through a pipe.  The larger the pipe the easier the volume of water will flow.  If the wall is too thick in comparison to other sections of the part the plastic flow will “Race Track” or move ahead of the rest of the flow front.  This causes issues such as air traps, weld/knit lines, and possible cosmetic problems.  If the walls are too thin this can cause issues such as “Short Shot”. Short shots occur when the flow front becomes to hard to push by the machine (typically reaching the maximum injection pressure), or the flow front cools too fast due to the lack of volume.  Short shots do not fully fill the cavity and create an incomplete plastic part.  Ideally a part will have a uniform wall thickness.  In real life this is hard to accomplish but being able to predict areas that may be a problem before running an injection analysis helps an engineer find a good balance.

SolidWorks has always had the ability to check the thickness of a part through the evaluate tab of the command manager.  The command is “Thickness Analysis” and it has been the go to command to determine different thickness within a part.

Thickness Analysis

Nominal Wall Thickness Command

Now SolidWorks offers a “Nominal Wall Thickness” tool under the Advisor category of the Plastics Tree.  The “Nominal Wall Thickness” command allows a user to compare thickness in the model based on a value or percentage.  This addition gives the user a quick thickness analysis right inside the Plastics Interface.

Nominal Wall Thickness

 

Property Manager

The results are a quick and easy to understand plot that facilitates the reduction in sink, short shot, and warping.

 

 

Nominal Wall

 

 

Have you used this command before? want to learn about a different command in SOLIDWORKS? Let me know in the comment section below!

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

ABS Snap Fit Non-Linear Static Study

Monday, June 22nd, 2015

I recently acquired a dehumidifying rod from a family member and it was missing the mounting components.  After looking everywhere in my family members basement we could not locate the missing items.  So what is some one who has access to SOLIDWORKS and a 3D Printer to do?  That’s right lets make our own.

A dehumidifying rod is an electric heater that facilitates natural convection in enclosed areas like safes, vehicles, small rooms etc.  The first place to start is thermal side of things and material selection.  The Uprint Plus uses an ABS like material for the printer with a melting temperature of 600 degrees F.  The rod runs at a constant 100 degrees F with a maximum of 125 degrees F.  The wide temperature factor of safety lead me to proceed with a 3D printed design.

The dehumidifying rod mounts had two requirements.  One that they could be screwed down to secure the rod, and that the rod can be easily removed for maintenance if needed.  This lead to a snap fit design.  The original design was stout and bulky and left me wondering if it was overkill.  This is where SOLIDWORKS Simulation is introduced into the design phase.  I wanted to verify that the rod could be removed and “snapped” back into place easily. Because the material is an ABS and the snap fit is a sliding contact this requires a Non-Linear analysis.


DriRod

The Simulation  setup was straight forward.  The rod will remain stationary and the the Clip will be moved a prescribed displacement until it “snaps” onto the rod.  To simplify the model and speed up the run time the analysis will be completed using symmetry.  A no penetration contact was specified on the contacting faces of the rod and the clip.  A mesh control was specified in these contact areas as well.

Steel was the material choice for the rod and an modified default ABS was used for the clip.  The ABS was copied to a custom material folder and changed to be a Plasticity- von Mises material model.  The true Stress-Strain curve of the ABS material was unknown so a representation of the curve known as a Bilinear stress-strain curve was used.  This curve uses the Tangent modulus roughly 1/10th of the Elastic modulus, as the second portion of the curve beyond yield.

Material Properties ABS

 

DRiRod2

 

The results from the first design did indeed show that it was too stout and required a large force to push the clip onto the rod.  The contact plot clearly shows a force requirement of 45 lbs. to spread the clip at the widest point.  This force value lead to a redesign of the clips upper arm.

Design 1 Stress

Contact 1

 

Design Two narrowed the upper arm and reduced the force required by 30 lbs.  The force however was still too high and required another design change.

Design 2 Stress

Contact 2

 

The Third and final design change reduced the arm thickness as well as changed the lower fillet size.  The changes reduced the force required to “snap” the rod in place to a reasonable 3.5 lbs.

Design 3 Stress

Contact 3

 

SOLIDWORKS Simulation Premium Non-Lienar analysis allowed me to design a mounting clip that holds the dehumidifying rod firm and in place without over design.  Quickly and easily I was able to walk through multiple design iterations and Simulations verifying a reasonable “snap” force.  I am happy to report the dehumidifying rod is in place and has been working for a couple of weeks without issue. Have you used a Non-Linear analysis before or have questions? Let me know in the comment section below!

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Pack and Go Now Available for Flow Results

Wednesday, June 3rd, 2015

Pack and Go Now Available in SolidWorks Flow Simulation

Pack and Go has been a staple in SolidWorks functionality for years. It allows a SolidWorks user to package SolidWorks  files such as Assemblies, Parts, and Drawings into a new folder location, or a Zipped file.  Pack and Go can keep the current file structure of folders and sub folders, or flatten to one folder.  This allows a user to make back ups of their work, or transfer files to others easily.  You can rename the new saved files individually or globally with a suffix or prefix creating a new file set.  The user does not loose custom appearances decals or scenes saving time and work when copying the files.  Toolbox components can also be included in the Pack and Go.

SolidWorks Simulation files have always been able to be included with the Pack and Go, However New for 2015 SolidWorks Flow Simulation can now add results files (.fld) to a Pack and Go.  This added functionality allows a user to quickly roundup all the important files needed to transfer, or store their design.  Simply select the Pack and Go option from the file menu. Choose the “Include Simulation Results” check box, and proceed like normal.  Please note that with the Flow Results included the Pack and Go .zip file will be large in size.

Pack and Go

Pack and Go has always made it easy to accumulate all the important files to transfer or store.  Now in 2015 Flow results are added to this great functionality. Lets us know through the blog comments how this functionality has helped you in your daily engineering tasks.  Pack and Go will continue to improve and add functionality as it matures.  Users like you help shape how the product behaves and what new functionality is added.  keep up the good work.  It has been requested for a while and we finally have Flow Results included with Pack and Go.

 

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Plastics Symmetry Analysis Saves Time

Monday, May 11th, 2015

SolidWorks Plastics has joined the other Solidworks Simulation Products (Simulation, and Flow)in offering a Symmetry Option.   What is Symmetry you ask?

According to Merriam- Webster Symmetry noun sym·me·try \?si-m?-tr?\ is: the quality of something that has two sides or halves that are the same or very close in size, shape, and position : the quality of having symmetrical parts.

With regards to analysis not only does the geometry need to be symmetric but the analysis boundary conditions need to be as well.

For SolidWorks Plastics Symmetry two rules need to apply.

  1. The model needs to be symmetric about a plane, two planes, or an axis.
  2. The injection location is also split by the symmetry condition.  This allows a user to take a fraction of a cavity and analyze it better, faster, and smarter.

Plastics Symmetry

 

 

Symmetry is accessed through the mesh settings with a solid mesh type.

Symmetry

 

Symmetry is an excellent option to save processing time.  The results are fast, efficient, and reliable getting the user answers like never before.

 

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Material Models for Simulation Premium

Friday, March 20th, 2015

What Material Model should be used for a specific

Non-Linear Study?

A commonly asked question is what material model should be used for a specific Non-Linear Study?  The answer is divided into three parts.

1. What is the material in the design(Steel, Rubber, Plastic, etc.)?

2. What is happening to the material(remain elastic, plastically deform etc.)?

3. What material property data is available for the material?

Material Choice in Design

Lets discuss material choice first.  Typically metals are characterized as a linear material and act as such.  Linear materials are simplified to behave predictably under specific loading criteria.  For Linear materials the Elastic Modulus, Poisons Ratio, and Yield Strength are all assumed to be constants.  Rubber, Plastics and Composites are accepted as Non-Linear materials and immediately require more than fixed material values.  As a rule of thumb the fore mentioned grouping holds true as long as the loading conditions dictate as such.

What is Happening to the Material?

What happens to the material under load?  What happens to the material during loading is as much a factor as the original material choice when specifying a material model.  Metals typically operate with a portion of the stress strain curve known as the elastic region.  The elastic region is typically from zero stress/strain to the yield point.  The slope of this line is the Elastic Modulus. When a load is applied and then removed the geometry will return to a zero state of stress and strain.  However what happens when the model moves beyond yield.  The once Linear Material is now Non-Linear and requires a defined Stress Strain Curve.  The Stress Strain Curve dictates how the material behaves under load beyond yield. Plastics, Rubbers, and composites are already Non-Linear and require a Stress Strain curve for their definition as the linear region of their curves either does not exist or is very small.

Stress Strain

The information assumed about the material helps determine what material model can be utilized within simulation.  For some materials a simple stress strain curve is not enough and one or more of the simple tension, bi-axial tension and shear test curves is required.

 What material property data is available for the material?

SOLIDWORKS Simulation Premium contains several different material mathematical models to choose from, and covers a wide range of options to best suite the analysis being ran. Please consult the Simulation technical reference guide and help file for more information on the models and their uses.

Simulation Material Choices

A general list of materials models and its use is below.

Elastic Models: Geometry Returns To It’s Original Position After Loading

Linear Elastic Isotropic –        Linear Material with properties the same in all directions x,y,and z

Linear Elastic Orthotropic-   Linear Material with properties different in the x,y, and z directions

Non-Linear Elastic-                Non-Linear Material with elastic properties (require a stress/strain curve)

Elasto- Plastic Models: Geometry Can Plasticity Deform When Loaded and Unloaded

Plasticity von Mises-              Studies von Mises Stress values, Goes Beyond Yield

Plasticity Tresca-                    Uses Shear Criteria and more conservative than von Mises formalization

Plasticty Drucker Prager-      Approximates Granular soil

Hyper Elastic Elastomers: Large Capacity To Take Strain With Relatively Low Stress Require a combination of the three curves mentioned above.

Mooney-Rivlin(M-R)-            In-compressible Strain up to 150% derived from 3 curves

Ogden(OHE)-                          In-compressible Strain up to 500-600%

Blatz-Ko-                                   Compressible Poisson’s Ratio is assumed to be 0.25

Simulation Premium also offers a Nitinol Model and a Viscoelastic for specific applications.

The above is meant to be a general guide as to what material model to choose for specific applications.  Three main factors are involved when choosing a material model, the material itself, loading conditions/application, and the material properties.

Click Here to learn more about SOLIDWORKS Simulation Premium. 

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Rotating Mesh Region SOLIDWORKS FLOW SIMULATION

Friday, January 30th, 2015

The SOLIDWORKS Flow Simulation team has added powerful new functionality to their arsenal,  Rotating Mesh Regions.  Rotating mesh regions or “sliding mesh regions” allow the user to rotate geometry in the model and drive the fluid of the system.  If you are designing any device that utilizes, impellers, propellers, or other rotational apparatus Flow Simulation can provide results such as flow rate, pressure drop, velocity, and many more, all based on the rotation of the geometry.  A transient or time based study is required to use the Rotating Mesh Region.

Application of Rotating Mesh

Application of Rotating Mesh

 

Rotating Mesh Region

Rotating Mesh Region

 

If you have SOLIDWORKS Flow Simulation 2015 already loaded you can find the rotating mesh region under the rotation type “Local regions(s) (Sliding mesh).  Utilize the rotating region boundary condition as usual in the Flow Simulation Design Tree.

Analysis Settings

Analysis Settings

 

For a look at the Rotating Mesh Region please see the following link.

 

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

2015 Flow Simulation Compare Tool Improvements

Monday, November 24th, 2014

Every new release of Flow Simulation adds more functionality, faster solution times, and customer requested enhancements.  One of the 2015 enhancements is the Study Compare Tool overhaul.  In 2014 a user could compare any active plot and goals between projects in the same model.  This is very useful functionality when comparing between different design options under the same flow conditions.  Only being able to compare active plots lead to some drawbacks and some fumbling for what you actually wanted to see.  The goal plots gave the engineer only a table view of the reported values.  Great for a quick numerical comparison, but this left the user manipulating the data in Excel to get nice visual graphs.

 

This is where 2015 Flow Simulation Compare Tool comes in.  2015 Compare improvements allow the user to directly compare all the generated plots in the project, not just the active one.  If they do not want all the plots they can pick and choose which ones they want to see though a check box interface.  The comparison does not end there, we now can compare XY plots, Tabular Data, and other enhanced chart options.  New to the goal plot is a series of enhanced display options allowing the user to display the goal plot data in bar chart, scatter plot, and over/under displays.

Compare Interface

 

 

Pressure Chart

Bar Chart

 

To access the Flow Simulation Compare Tool, go to Tools>Flow Simulation>Results>Compare, or choose the compare Icon on the Flow Command manager.

Compare Results

Compare Results

 

2015 Flow Simulation Compare Tool enhancements, improve the direct outputs from Flow Simulation,  greatly decrease the time to get to the important data, give the engineer better knowledge of the Project results.  Flow Simulation in 2015 is helping make the user, Better, Faster, and Smarter.

Globe Valve Flow

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Duplicate SolidWorks Plastics Project

Tuesday, June 24th, 2014

SolidWorks Simulation allows a user to ‘Duplicate’ a study, and SolidWorks Flow Simulation allows a user to ‘Clone’ a project.  Why not SolidWorks Plastics?  SolidWorks plastics is an injection molding software that allows a user to understand the manufacturability of a plastic part.  Because this is a fully integrated SolidWorks Simulation product different Projects are related to configurations in the part.  To re-use the setup from project to project please follow the instructions in the link below.

Duplicate Plastics Project

This functionality allows a user to quickly duplicate a project to change different parameters and re-run.  If you are currently using SolidWorks Plastics this information will speed up your work flow and Simulation setup times.

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Multiple Flow Result Plots in E-Drawings for 2014

Tuesday, April 22nd, 2014

New for 2014, The ability to save multiple result plots in one E-Drawings file.  Previously the result plots needed to be saved in individual E-Drawings files. This caused more files to be generated and shared than need be.

To generate multiple result file plots in one E-Drawings file follow this procedure.

  • Show all plots desired to be included in the E-Drawings file
  • Right Mouse Button on the Results Folder and Select Save Image
EDrawings Save Image

E-Drawings Save Image

  • Choose the E-Drawings File Format
EDrawings Pull Down

E-Drawings Pull Down

Once in E-Drawings you can turn on or off the individual plots as needed to convey the content you wish to show.

Multiple Flow Plots E-Drawings

Multiple Flow Plots E-Drawings

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

Flow Simulation ‘Replicate Condition’

Thursday, March 20th, 2014

New for 2014 a user has the ability to apply a single Boundary Condition to multiple instances of the same part.  This is a great time saving tip.  No more manually adding the same Boundary Condition to instances of the a part.

With your setup you can assign Boundary Conditions such as an “Inlet”, “Outlet”, and “Heat Source” to  “Part1 “(face/volume) for example.

Simply Right Mouse Button the Boundary Condition and select “Copy to Component Instance”.

The Boundary Condition auto populates on all “Part 1s” in the model.

You can deselect the instance(s) you do not want included.

Note: the “Part 1″ needs to be a part in an assembly for the transfer to work.

For the full pdf instructions please see the link below:

Replicate Condition Flow

Robert Warren

Elite Application Engineer CAE Technical Specialist 3DVision Technologies

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