OSULaminates Help

Index

The following is an index to OSULaminates help information. Click any topic to read that information. You can use the back arrow key to return to previous location after following a link.

Introduction

OSULaminates does laminated plate theory analysis. You create a laminate using graphic editing tools. For each ply you can either choose ply properties or you can enter a fiber/matrix pair along with a fiber volume fraction. If you enter a fiber and a matrix, OSULaminates will use the Hashin micromechanics model (concentric cylinders assemblage) to calculate the ply properties. You can save laminates for reloading and reanalysis later. OSULaminates comes with many predefined materials (plies, fibers, and matrices), but you can edit those materials; you can change the properties, add you own materials, or delete materials, as desired.

Once a laminate is done you can analyze the structure for stiffness matrices, compliance matrices, or all possible engineering properties. Additionally, you can apply any combination of stress or strain state along with thermal and moisture change and evaluate the stresses and strains on the full laminate and within each ply of the laminate. After stresses and strains are calculated, you can plot the stresses and strains within the laminate. To try out optimization methods, any number of plies can be designed as having a variable angle. For such laminates, you can plot selected engineering properties as a function of that variable angle.

OSULaminates finds mechanical properties, thermal expansion properties, and moisture expansion properties. It does not attempt any failure predictions because, in the author's opinion, laminate failure models based on stresses and strains from laminate plate theory should not be used to predict failure. They are numerous examples where they give poor predictions and some where they make design predictions that are contrary to the optimal design. A potential alternative failure analysis is to use fracture mechanics, but unfortunately, fracture mechanics methods typically require custom analysis for each failure mode and therefore cannot be part of generic laminate software.

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Creating the Laminate

Basic Editing

You can create a laminate with any number of plies and each ply can have any material, angle, and thickness. The basic process is

  1. Decide if you want a symmetric of unsymmetric laminate and choose the "Symmetric" menu command to get it checked for a symmetric laminate or unchecked for an unsymmetric laminate. For symmetric laminates, you enter only the plies in the top half of the laminate (the bottom plies are repeated in reverse order). For an unsymmetric laminate, you enter all the plies. The symbol at the bottom of a laminate indicates a symmetric or unsymmetric laminate
        sym   or    unsym
  2. Decide the total number of plies in the laminate and use the "Set Number of Plies..." menu command to change it if needed. Enter half the total number for symmetric laminates or the total number of plies for unsymmetric laminates.
  3. Select material type for plies. Here you have two options:
  4. Select ply fiber angle by one of the methods below. The angle you choose will remain in effect until you change it.
  5. Select the lamina thickness using the "Set Lamina Thickness..." menu command. The thickness will remain in effect until you change it.
  6. If you are using the Fiber/Matrix mode, also choose the fiber volume fraction using the "Set Lamina Vf..." menu command. The volume fraction will remain in effect until you change it.
  7. Finally, click on plies to set them to have the currently preset properties. To create plies with a new material, angle, thickness, or fiber volume fraction, change those settings (as described above) and then click on new plies. (Hint: to just change the angle to a value not available in a icon, right click (or control click on Macs) on any ply. You can provide the new angle to be used for that and subsequent plies). If you click on a ply that already has a material, it will be replaced with the current material. To make changes to several plies at once or to move plies around, see the next section on selecting and editing plies.

Selecting and Editing Plies

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Click the "Arrow" icon (see above) in the tool bar to enter the "Selection" mode. In this mode you can select plies by clicking on them and they will become hilighted. To select multiple plies, hold the shift key down and click on more plies. Use the "Select All" menu command to select all plies. Once some plies are selected, you can:

Saving Laminates

You can save any laminate you create using the "Save" or "Save As..." commands. These laminates can then be reopened using the "Open..." command the next time you run OSULaminates. Laminates should be saved with the extension ".lam".

A saved laminate will be self-contained file including all material information on its plies. If you edit the material properties in the "Plies" and "Phases" menus and delete or change materials that are in a saved laminate, those materials will be recovered when you reopen the laminate. In other words, when you reopen a laminate, it will look for all materials needed for the laminate in the "Plies" and "Phases" menus and respond as follows if anything has changed:

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Analyzing the Laminate

Once the Laminate is created, you analyze it using the commands in the "Calculations" menu. The calculations output will appear in the bottom half of the window. You can copy and paste text from the window or export the entire text to an RTF file using the "Export Calculations..." menu command (note that RTF stands for rich text format and can be opened by MS Word or other word-processing software and preserve the text styles in the window). To clear the text results at any time, use the "Clear Calculations" menu command.

Laminate Properties

The analysis commands are:

The results will appear in the text results. The current type of matrices and the units for all terms will be included in the output. You can use the Preferences to select the desired output units and to select if you prefer normalized or unnormalized matrices.

Note that many terms and Engineering properties are zero for symmetric laminates. When analyzing symmetric laminates, only the non-zero terms will be output.

Specific Laminate Stress/Strain State

You can calculate the result of any specific applied combination of stresses and strains on the global stresses and strains in the laminate as well as on the stresses and strains in each ply. To do this calculation, choose the "Specific Stress State..." command. You will get a dialog box with the following options:

Also decimal numbers entered above must use the US method of points (.) for the decimal rather than a comma.

After entering all options, click OK to calculate the stress state. After a specific stress state calculation is done, you can plot the ply stresses and strains.

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Plotting Ply Stresses and Strains

After any specific stress state is analyzed, you can plot the ply stresses and strains by choosing the "Plot Ply Stress State..." command. After choosing the command, select any number of quantities to plot from the dialog box:

After clicking OK, all selected quantities will be output in a one or two plot windows (if both stress and strains are selected, they will be output in separate windows). The vertical y axis in each plot will be position in the laminate. The horizontal x axis will be the magnitude of the stress or strain. Plots in laminate coordinates will be solid lines while plots of ply stresses or strains will be dashed lines. Component 1 or x will be black, 2 or y will be blue, and shear 12 or xy will be red. The dotted horizontal lines will indicate breaks between groups of plies with different angles. A dotted green line will be drawn at zero stress or strain.

Once the plot has done, you have many options to change it or save it:


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Plotting Engineering Properties

To try simple design calculations, you can plot the engineering properties as a function of one variable ply angle. The process is

Customizing Material Properties

You can edit material properties right in OSULaminates or you can export material properties, bulk edit them in other software, and then re-import into OSULaminates. Editing in OSULaminates is usually easier. The bulk editing method is only needed for more advanced editing such as rearranging materials, inserting separators in the menu, or backing up your material options. Editing in OSULaminates is described first, followed by bulk editing methods. However you edit material properties, the changes you make are saved in the application preferences and will remain in effect for the next time you run OSULaminates.

Editing an Existing Material

To edit an existing material, select it from the "Plies" or "Phases" menu and then choose "Edit Checked Ply...", "Edit Checked Fiber...", or "Edit Checked Matrix..." as desired. A dialog box will open and you can double click any property on the right to change it. The name can be any text. The properties must be numbers and must use the US method of points (.) for the decimal rather than a comma. Click "OK" to save the changes.

The properties to enter depend on the material type as follows. For ply materials the properties are:

For fiber materials (assumed to be transversely isotropic with axial direction in the fiber direction) the properties are:

For matrix materials (assumed to be isotropic) the properties are:

Adding a New Material

To add a new material choose "Add Ply...", "Add Fiber...", or "Add Matrix..." from the "Settings" menu as desired. A dialog box will open and you can double click any property (as described above) on the right to enter it. Click "OK" to add the material. Note that "Add Ply..." and "Add Fiber..." are the same menu command. The ply option appears when any ply is selected in the "Plies" menu and the fiber option appears when any fiber/matrix pair is selected in the "Phases" menu.

Deleting a Material

To delete an existing material, select it from the "Plies" or "Phases" menu and then choose "Delete Checked Ply...", "Delete Checked Fiber...", or "Delete Checked Matrix..." as desired. You cannot delete a material that is in use by a currently opened laminate (i.e., close the laminate first before deleting it) or if it is the last ply, fiber, or matrix material remaining (i.e., you cannot delete all materials of a particular type). If the deleted material is currently copied in the ply scrap book, that scrap will be emptied. You will have to copy new plies before pasting again.

Bulk Editing Material Data

Alternatively, you can bulk edit all ply and phase properties, delete plies or phases, add more plies and phases, and add menu separators in separate software. This editing process is as follows:

  1. Choose "Export Material Data..." menu command and save using any name with extension ".txt".
  2. Open the file in spreadsheet software (e.g., MS Excel) and edit the material properties (see next section for some editing details).
  3. Save the changed file, but be sure to save as a tab-delimited plain text file and not as an Excel or other spreadsheet software file.
  4. Choose "Import Material Data..." menu command in OSULaminates and select the edited file. The material properties in the edited file will replace all current materials in the "Plies" and "Phases" menus.

Editing the Properties in the Text File

The exported material data file is divided into sections for Plies, Fibers, and Matrices and they must remain as separate sections. You can edit a material in any section by changing the numbers in the columns. You can add new materials by inserting rows and entering all properties. You can insert blank lines within a section to create a dividing line in the corresponding menu in OSULaminates.

The first column for each material type is the name for the material and it must be a unique name to avoid conflicts with other materials. The column headers in each sections explain where to enter each of the required properties. Details on the properties needed for each material type are given above.

Backing Up and Restoring Material Properties

If you mess up material properties, you can restore to the default materials provided with OSULaminates by choosing the "Restore Default Materials" menu command in the "File" menu.

If you make many material changes and might want to restore to those settings, rather than the default settings, you can back up and then later restore for the exported material data file. The process is:

  1. When you have a good material data set, choose "Export Material Data..." menu command and save using any name with extension ".txt".
  2. Whenever you want to restore to those material properties, choose "Import Material Data..." menu command and select the file exported in step 1.

Because the import will replace all current materials in the "Plies" and "Phases" menus, if any of those materials have changes since the last export, you will be asked to confirm if you want to replace them. If you would like to preserve the current properties, you should cancel and export current properties before restoring to the previous set. If you no longer need the current ones, just proceed with the import.

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Preferences

To set preferences for your copy of OSULaminates, choose the "Preferences..." menu command.

Besides the above preference setting, all changes to material properties are also saved in the application preferences (and therefore persistent between runs). See the methods for editing of material properties to set material preferences.


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