RTM-Worx User Manual - Getting Started

1.4 Getting Started

1.4.1  Step by step checklist
1.4.2  Built-in assistance and online help
1.4.3  The RTM-Worx filing system
1.4.4  Integration with MS-Windows

This section provides some information you will need if you use RTM-Worx, and possibly MS-Windows™ for the first time. The first paragraph contains a checklist which lists the steps to follow from the start of a new project to running the simulation and viewing the results. RTM-Worx uses several techniques to assist you, varying from hints you might need for commands that are seldom used to online help. Paragraph 1.4.2 explains how to access this information. The third paragraph contains some basic information about managing the size and position of the window and how to access display and sound settings. RTM-Worx is tightly integrated with the document-centered Windows™ environment, which makes it possible to start RTM-Worx and load projects in several ways as described in paragraph 1.4.4. Finally, in paragraph 1.4.5, the RTM-Worx filing system is explained because it differs in several ways from the standard single document interface that is implemented in most applications' File menu.

1.4.1 Step by step checklist

RTM-Worx doesn't force you to work in a specific sequence of steps. This is nice once you know how to use the program, but it can be difficult to find out where to start if you use it for the first time. Therefore, we outline the strategy to follow in general briefly here:

Define the geometry of the part.
Start with a simplified geometry, don't add all the details yet. Build the model by repeating the following steps (selecting keypoints and curves with the mouse is easier if you display them as 3D symbols, adjust the symbol size if necessary):
- Enter keypoints in the Keypoint editor.
- Define curves in the Curve editor by connecting keypoints.
- Add surfaces in the Surface editor by selecting closed loops of curves.
Add and verify runner and surface properties
- Select curves in the Curve editor, choose runner type and assign properties. You only need to do this for curves that are used to model runners.
- Select surfaces in the Surface editor, choose shell type and assign properties. All surfaces need at least a thickness, otherwise they will be impermeable and ignored in the calculation.
- Use shaded contour plots of properties like thickness, porosity and average permeability and vector plots of the permeability to verify the correctness of your model.
Define injection and venting ports
- Select keypoints, choose type (injection or venting port) and define properties. For the injection pressure or flow rate, an educated guess is good enough at this stage.
Optimize the mesh
- Go to the Mesh generator and adjust mesh parameters until the part geometry is reasonably approximated and the number of elements is about 1000 to 2000.
Enter resin viscosity and calculation parameters
- Go to the simulator and enter the viscosity, and the increment between the time steps that must be saved to the database for post-processing: an increment of 5% or 10% is recommended for the first calculation, use the default value for the numerical tolerance (0.1%).
Run the simulation
- Go to the Simulator and choose the Go command to start the calculation or hit F9 (fast, but you must be sure that viscosity and calculation parameters are correct).
View results
- Go to the Plot Selector and select shaded contour plots, line contour plots and vector plots in any combination to view filling time (flow-front locations in time), pressures and velocities, optionally in combination with the properties like thickness or permeability.
- Use the arrow buttons to animate the filling (only filled parts of runners and surfaces are plotted once you have simulation results) and ensure that all geometry objects are properly connected.
Repeat: change something and rerun simulation.
- Go to the Keypoint/Curve/Surface editor to change properties (for example location of injection and venting ports) or geometry of the part (add details)
- Run the simulation again (use F9).
- View results (see step 7).
Recalculate most promising alternatives with refined mesh to asses numerical accuracy
- Refine the mesh in the Mesh Generator and repeat the calculation. Compare the results (especially pressures and filling times) to get an idea of the numerical error. If the difference between the coarse and fine meshes are large, you might need to repeat more calculations.
Document your work, repeat some calculations if necessary.
- Often neglected but very important because you need to remember what your conclusions were and how you reached them at the time you need to evaluate results obtained from experiments or production of the part.

Step 8 is where you test your ideas, correct or refine the model and you should not move on to step 9 until you developed a feeling for the process, parameters that have the largest influence on the filling pattern and the pro's and con's of different alternative injection strategies. Don't worry too much about documenting your actions during this step, but follow your ideas quickly. The worst that can happen is that you need to repeat some calculations afterwards if you're writing the documentation. However, if you don't make any notes when you finished this step, you might need to repeat a lot of calculations later!
Use the archive facility in RTM-Worx to save the milestones of your work. At the end of each step and during step 8 use archives to save promising alternatives. Clean up before you do something else because you can easily generate a large number of files which take up a lot of disk space. Make short notes of what's in the archives while you work or you may have to inspect them one by one afterwards.
When your model is large, the calculation times may become too long to work interactively. It helps to repeatedly stop the calculation, view intermediate results and restart the calculation again. You will stay concentrated on the problem and may decide to try something different as soon as you see that your changes don't have the desired effect.

1.4.2 Built-in assistance and online help

Few people will use RTM-Worx on a daily basis, but the majority of the RTM-Worx have an engineering background and are experienced computer users. Therefore, most of the assistance you get from RTM-Worx is in the form of hints and pointers that stay out of your way if you don't need them. Here is a short list of the functionality designed to assist you and the help facilities RTM-Worx offers:

Buttons, selection lists and edit fields display a short description if you move the mouse cursor over them, so-called 'ToolTips'. For numerical edit fields, the ToolTip also contains upper and lower bounds for the value.
Values that are out of range, or have an incorrect format are displayed in red. The ToolTip contains a description of the error. When the value is needed and is not corrected, the default value is used.
All the edit fields where you enter floating point values have a built in calculator. You can type simple arithmetic expressions using addition, subtraction, multiplication and division. The ToolTip will show the result of the expression. Type the equal sign to replace the expression by the evaluated result.
Default values are defined for all parameters and properties. The default value is shown in the ToolTip if no value is entered, and you can explicitly get it by typing the equal sign '=' in a blank field, or replace any value by the default value by typing '5' on the numeric keypad (NumLock should be turned off).
RTM-Worx uses variable units wherever applicable. If you click on the unit text at the right of the edit field (or use the down arrow key when the edit field has the keyboard focus) a menu is displayed from which you can select an alternative unit.
For all menu commands accessible through toolbar buttons, the bitmaps are shown in the menu. You will quickly learn to recognize the toolbar buttons and work faster. When you select a menu command, a one-line description of the command is displayed on the statusbar.
Context-sensitive help is available for all the buttons, edit fields, selection lists and menu commands. Enter context-sensitive help mode with Shift+F1 or the Help/What's This? Menu command. The mouse cursor will turn into an arrow with a question mark. Click on any part of the RTM-Worx window to get a brief description, which is often sufficient, but contains links to the on-line help system for a more extensive explanation and related documentation.
Online-help is available through the RTM-Worx menu (Help/Help Topics) and main toolbar, and separately from RTM-Worx through the Windows Start menu.

1.4.3 The RTM-Worx filing system

RTM-Worx provides a file interface that differs somewhat from the standard File menu. The reason is that the database is too large to fit in memory when you run a simulation, and using separate files for the model and calculation results is a potential source for trouble and makes it harder for you to do your bookkeeping. If you keep the following basic rules in mind, working with RTM-Worx projects will be very easy:

Only one copy of your project exists, there is no difference between the project data currently loaded in memory and the contents of the project file.
When you leave RTM-Worx, or when you load another project, the current project is closed and all changes you made are flushed to disk. RTM-Worx will never ask you if you want to save your changes.
If you want a copy of the current project, you have to create one. You can create a snapshot copy or you can archive your project (e.g. a milestone copy). The difference with the standard 'Save As' file command is that you will continue to work on the current project, not on the copy you made.
If you want to change the name of the current project, simply edit the name. RTM-Worx will automatically rename the project file. The standard file menu offers no equivalent command.
You can move the current project database to another location (on the same disk, another disk or in a location on the network) and rename the database using the Project|Rename menu command.

In addition, RTM-Worx supports a hierarchical archiving system. Archives created from your project are sequentially numbered. If you open the archive, a project file is automatically created that inherits the archive number (your original project file will not be overwritten), and if you archive this project again, a new level of version numbering is added. This hierarchical project and archive numbering scheme reflects the relations between the files and makes it much easier to organize your simulation work.

1.4.4 Integration with MS-Windows

With Windows 95™ the document-oriented shell was introduced which is also available on it's successors Windows 98, ME and on Windows NT 4.0, 2000 and XP. RTM-Worx is a native Win32 application and is designed to supports the following functions:

Loading projects, and starting RTM-Worx when it is not already running by double-clicking on files with a WRX or ARX extension (or alternatively, selecting a file followed by pressing Return).
If you click the right mouse button in Windows Explorer and select New from the context menu that pops up, you will see the entry 'New RTM-Worx project'. This will create an empty database in the current folder. You can start RTM-Worx by double-clicking the new file.
Projects loaded in RTM-Worx are added to the Windows Start|Documents menu, where you can select those projects to load them in RTM-Worx (and launch RTM-Worx if necessary).
RTM-Worx uses sound events which can be customized through the Sounds Control Panel applet.
If you want to remove RTM-Worx from your computer, you can uninstall RTM-Worx by running the Add/Remove Programs applet in the Control Panel. You will find RTM-Worx in the list of applications.