Mating Linear and Spherical Components

I was recently contacted by a customer who designs and manufactures a range of optical and crystal monitoring and control systems. Included in their design work is the requirement to position lens components with a high level of precision. This often includes using a spacer component to ensure that an energy source is a specified distance from the lens surface.

The customer wanted advice on how to accurately mate the spacer to the domed surface of the lens as automatic mates would not give him the result that he wanted. The following post has been written to assist users with similar issues.

The projection of a linear dimension onto a spherical surface produces an irrational number and you will therefore be unable to mate the surfaces directly together. However there is a way of working around this by creating sketches within the individual parts and mating these together instead as explained below.



For this example, a spherically domed lens is required to mate with a cylindrical tube spacer to be used within the prism assembly shown above. The transparency has been changed in the parts to make the images clearer.

If attempts are made to mate surfaces or edges together on the parts, the following results may be given.

If you attempt to mate the domed face and the related face on the spacer, the option of a Tangent mate is the only one available. This will position the face of the spacer on the tangent of the extent of the dome.

By selecting the domed face and the internal circular edge of the spacer, the required calculations to produce a coincident mate create irrational numbers and the geometry cannot be mated.

By selecting the circular face of the spacer part and the circular edge of the domed face of the lens part, the mate produced will pull the spacer part through the domed surface.

 

Solution for the problem

Open the Lens part and start a new sketch on a plane that dissects the domed face of the lens.

Select the silhouetted edge of the dome and use the convert entities function. This will create a 2D sketch profile of the dome. Ensure the sketch is left visible and save the part.

Open the Spacer component.  This example was constructed using a Boss-extrude followed by a cut extrude.

Open the sketch that defines the profile of the hole through the spacer. Use the sketch point tool and add a point that is coincident with the profile of the sketch that defines the hole.

Show the sketch that defines the profile of the hole so that it will be visible when you view the part in an assembly.

Now that the sketches in the part files have been created, they can be used to mate the parts together.

In an assembly that contains the lens and spacer parts, you can now mate the point that you created on the sketch for the profile of the hole in the spacer, with the silhouette sketch on the lens part.

 

This will ensure that the point will be coincident to the silhouette sketch

 

Make the temporary axes visible to be able to mate to the central axis of the lens. In this case the spacer’s axis will be mated to the axis of the lens.

The sketch point on the profile of the hole sketch is coincident with the silhouette edge of the domed surface of the lens, and will keep this relation when the parts axes are mated.

 

By mating the sketch geometry created together, the required result of the spacer connecting with the lens at their extents can be achieved

Simulating The Repair Of Sports Injuries

We're all used to hearing about footballers and other professional athletes damaging their cruciate ligament or suffering some other tendon injury.  I remember being told once that they can repair this by cutting away more of the damaged tendon and it seemed like a crazy statement.  How can removing material make something stronger?

Time to do a little bit of medical Simulation!

I fired up SolidWorks and modelled a simple strip with two small tears on each side.  Keeping things symmetrical helped with the setup.  

Close up of the tear



A quick simulation was set up

And here's the results

Maximum stress here was just over 1GPa, almost double the yield limit of the material.

Clearly we are failing here so now for the repair!

All I did here was increase the angle of the cut from 10 to 170 degrees.  This removes 13% of the original bar.

So what did this do to the stress?  Let's take a look:

Wow!  The maximum stress has fallen by 800MPa, a 79% drop in peak stresses.  We can live to run another day!

But why does this happen?  How can removing material increase the strength of the part?

It's all to do with how the stress can spread through the part.  With the narrow/sharp tear the stresses can only act at the root because there are no stresses at the top of the tear openings, but by smoothing out the damage, stress can spread across the entire width of the part allowing more material to take up the strain.

Once again I was able to use SolidWorks Simulation to illustrate what seems to be a paradox, and get the truth.

New SolidWorks Support Resources

Some of you may have already noticed an addition to our Support page.  The SolidWorks Knowledge Base makes it easy for you to search for solutions to common issues though the Customer Portal.  Browse through the topics or enter a keyword in the search to be directed to the relevant section.

We have also added the Customer Forums section which gives you access to direct questions being asked by SolidWorks users.  Often these questions address a specific task within SolidWorks pertaining to a users job function.  Head over to our support page and see what questions are being asked right now.

The SolidWorks forums can be viewed by anyone but the Knowledge Base is only available to customers with a current subscription.

From the deepest depths to the highest heights.

James Cameron is in the news this morning, not for another box office smash, this time he has hit rock bottom...of the Mariana Trench!  He is the third person to venture to the bottom of the trench following the historic dive by US Navy Lt Don Walsh and Swiss oceanographer Jacques Piccard more than 50 years ago.

James Cameron on his return (courtesy of National Geographic)

SolidWorks posted a study last year on the design of submersible vehicles within SolidWorks and Simulation.  You can read about it and see the video here.


From the deepest depths of the ocean, to the outer limits of the atmosphere where Felix Baumgartner is working on the worlds highest skydiving altitude record.  This is another feat of exploration that hasn't been attempted in more than half a century.  The SolidWorks Simulation team have also done a study to see what forces Felix will be exposed to and if he will reach supersonic speeds during his attempt.  Check it out here.

So, the next time you are planning some extreme record breaking attempt, see if SolidWorks can help.

SolidWorks 2012 Tips & New Features (part 1)

Part Reviewer
Ever wondered how a model has been created?

Now you can use the Part Reviewer to find out how parts have been modelled feature-by-feature.

Part Reviewer can help you learn best practices for creating various types of parts.

 You can also create your own parts and add your own comments.

To access Part Reviewer, click Tools > Add-Ins. Under SolidWorks Add-ins, select

SolidWorks Part Reviewer.

The Part Reviewer tab appears in the Task Pane.

Large Design Review
Don't like waiting for large assemblies to open just to check something simple?

Try using Large Design Review which lets you open very large assemblies quickly, while still retaining

capabilities that are useful when conducting design reviews of assemblies.

When you open an assembly in Large Design Review mode, you can:

• Navigate the FeatureManager design tree

• Measure distances

• Create cross sections

• Hide and show components

• Create, edit, and play back walk-throughs

To open an assembly in Large Design Review mode, click Open (Standard toolbar)

or File > Open. In the dialog box, select the assembly you want to open, and then, in

Mode, select Large Design Review.

Assembly and Component Information

Information about the assembly and its components is limited in Large Design Review.

FeatureManager Design Tree

The FeatureManager design tree displays information about the assembly components

and hierarchy.

Information displayed in the tree includes:

• Component names

• Assembly and subassembly hierarchy

An eye overlay appears on the icons of all components when the assembly is opened in

Large Design Review mode.

Align Balloons With Magnetic Lines
Spending a long time tidying up how your GA drawings look?

You can use magnetic lines to align balloons. You attach balloons to magnetic lines, choose

to space the balloons equally or not, and move the lines freely at any angle. The balloons

maintain their alignment when the magnetic lines are not visible. You can insert magnetic

lines automatically when you use the Auto Balloon command. You can also insert balloons

before or after inserting magnetic lines

Search Commands
Do you forget where that really useful command is, the one you used last month?

Using Search Commands lets you find and run commands from SolidWorks Search or locate

a command in the user interface.

These features make it easy to find and run any SolidWorks command:

• Results are filtered as you type and typically find the command you need within a few

keystrokes.

• When you run a command from the results list for a query, Search Commands

remembers that command and places it at the top of the results list when you type the

same query again.

• Search shortcuts let you assign simple and familiar keystroke sequences to commands

you use regularly.