Inventor – Mathcad User Guide

IntroductionThis integration provides users with an opportunity to combine both products, allowing Inventor dimensions to drive Mathcad calculations. The results of those calculations can then be sent back to Inventor to optimize the design.

This utility is a non-supported example of how Mathcad and Inventor can be used in conjunction, based upon each product’s supported API.

This integration is built for Intel-32 XP computers.

DescriptionThe integration is offered as a VB.NET DLL which implements the Inventor AddIn Class. This DLL uses both the Inventor API and the Mathcad API to pass data values and units between the 2 products.

Use Case Scenarios1.) An engineer has design a model in Inventor and wishes to do a quick analysis to

see if this design will buckle under a certain pressure. Mathcad is not an FEA tool like Cosmos, but given height, width and length, Mathcad can do a scratchpad analysis to allow the designer to quickly understand if he has derailed his design.

In this case the designer can send height, width and length dimensions to a pre-built Mathcad worksheet. This worksheet will use the parameters to calculate the allowable pressure and then perform a simple comparison to see if this allowable pressure meets design criteria.

2.) This same designer would like to minimize the size of his/her model while staying within the limits of buckling. The earlier Mathcad worksheet can be extended to include constraint based optimization. The results of this optimization would be a new height, width and length. These new dimension values can be sent back to Inventor to update the model.

3.) Many ad-hoc calculations are done throughout the course of a design. Mathcad is the ultimate tool for documenting those calculations and even tying the results of those calculations to the model in Inventor. This documentation can be submitted with the Inventor model to whatever Document Management/PLM system the user has installed.

How to install 1.) Register the Mathcad DLL using the regasm utility.

a. Open a command window.b.

c. Change the directory to your Microsoft.Net Framework version directory,:

C:\windows\microsoft.net\framework\v1.1.4322

d. At the command prompt, type the following command:

regasm /codebase C:\mystuff\bin\ MathcadInvAddIn.dll

where c:\mystuff\bin represents the directory where your MathcadInvAddIn.dll file is located.

2.) Attach the Add-In to the Inventor Interface through the Tools menu.

e. Using the Inventor Tools Add-Ins menu, check the box to select MathcadAddIn

f. Select “OK”.

How to prepare your Mathcad worksheet for use in the integration The first step is to decide what model in Inventor you want to tie to Mathcad calculations.

Once this is done, you need to think about what calculations you want to drive the model you have in mind. Many pre-built calculations exist in Mathcad Libraries and Extension Packs. Of course Mathcad allows you to build your own equations in natural math notation with units on the terms or systems of linear and non-linear equations, or optimization calculation and more.

OK, assume now we have our CAD model and we have our calculations in Mathcad.

Looking at the Mathcad worksheet, decide which variables you want to have driven by the Inventor model. Also decide which Mathcad variables you want to send to Inventor to modify the CAD model.

The variables you want to have driven by Inventor need to be tagged as INV2MC”. To do this simply right mouse click on the region, select properties. In the TAG text box type (in capitols) INV2MC.

The variables you want to send to Inventor from Mathcad need to be tagged as”MC2INV”. To do this simply right mouse click on the region, select properties. In the TAG text box type (in capitols) MC2INV.

Now your worksheet is prepped and the integration is ready to go.

How to use the integrationTo use the Inventor-Mathcad integration, load an Inventor model into Inventor. Select the Load Mathcad Worksheet and use the file dialog to find a pre-treated Mathcad worksheet.

Use the drop downs on the left to map values to the selected values in the drop down on the right.

Use the 2 submit buttons to transfer from Inventor to Mathcad or vice-versa.

With the example Mathcad worksheet and Inventor CAD part provided try the following mapping

The results going from Mathcad back to Inventor must be represented in Mathcad as evaluations using Inventor database units. This means the return values must be displayed in Mathcad with the equal sign and have units of Centimeters, Kilograms, Seconds, Radians or Kelvin.

Map : Inventor Mathcad D1 lug_diameter D3 inner_diameter D4 wheel_width

Map : Mathcad Inventor new_lug_diam D1 new_inner_diam D3 new_wheel_width D4

Caveats:

A button to make the integration visible is still not working. Therefore the integration shows up when you start Inventor. I am working with Autodesk to figure out what happens to the Mathcad button.