The module "Laminates" with the option STRESSES calculation, for a given generalized mechanical load and a given hygrothermal load, makes possible to determine

• Stresses and strains in the layers (calculated in the global coordinates system and in the local coordinates system) caused by the thermal load
• Stresses and strains in the layers (calculated in the global coordinates system and in the local coordinates system) caused by the hygroscopic load
• Stresses and strains in the layers (calculated in the global coordinates system and in the local coordinates system) caused by the hygrothermal load
• Stresses and strains in the layers (calculated in the global coordinates system and in the local coordinates system) caused by the mechanical load
• Stresses and strains in the layers (calculated in the global coordinates system and in the local coordinates system) caused by all of the loads
• Average stresses on the multi-layered material thickness deduced from the generalized stresses and moments.
  

Calculations are based on the classical laminates theory [1] . For the mechanical loads, we do not consider the out-of plane loads so that strains and stresses are in the plane (x, y).

Let's discuss in a more detailed way how to operate MAC LAM in order to obtain the previous values:

• First of all, the multi-layered material has to be defined
• after that, the loads have to be defined
• then, the calculation and report options have to be selected
• after that, click on <<Analyze>> in the main window (see Figure 1)

Figure 1. Launching STRESSES calculations.

• Now a graphical window appears (see Figure 2). By clicking on the buttons in the upper part of the window you may visualize the stresses or strains in the layers.

Figure 2. Selection of stresses/strains to be plotted.

• If you visualize stresses (strains) and want to visualize strains (stresses), you have to click on the button <<Chart properties>> in the lower part of the window (see Figure 2). Similarly, if you want to visualize stresses or strains in another coordinates system (local or global), you have to click on this last button. After having clicked on the button <<Chart properties>> a new window appears (see Figure 3). This window makes possible to select quickly the fields to be plotted, the line colors and the scales.

Figure 3. Chart properties.

• If you want all the stresses values to appear in the graph, click on the button <<Stress values>> in the window which contains the graph (see Figure 4). In the same way, if you want to save the results in a file to plot them in Excel or ORIGIN or other software, you have to click on the button <<Save the results in a file>> and follow the instructions (see Figure 4).

Figure 4. Stresses values in the graph and saving the results in a file.

• If you want to create a graphic report to print it later, click the button <<Create a graphic report>> (see Figure 5). Similarly, in order to create or print a textual report with the results, click on the button <<Create a text report>> (see Figure 5).

Figure 5. Creation of graphic and text reports.

Loads

For the STRESSES calculation type, the user has to define the mechanical, thermal and hygroscopic loads. To do this, it is necessary to click on the button <<Mechanical loads, temperature and moisture variations>> of the main window (see Figure 6).

Figure 6. Enter loads type and values.

Then the window in Figure 7 appears. You have to decide if generalized forces (moments) or strains (curvatures) are imposed (see Figure 7). Then you have to enter the loads value (units appear on the right side of the blanks). Finally, if you chose to take into account temperature and humidity variations (in the window Calculation and report options) you have to give the temperature variation DT and the relative moisture variation DH (see Figure 7).

Figure 7. Selection of mechanical and hygrothermal loads.

Calculation and report options

For the STRESSES calculation type, there are options to which you may access by clicking on "Options" in the menu bar in the main window (see Figure 8).

Figure 8. Calculation and report options of STRESSES calculation type.

Then the window in Figure 9 appears. You have to specify

• if you want to take into account a thermal load or not. If this is the case, you have to give the temperature variation value in the loads window.
• if you want to take into account hygroscopic strains or not. If this is the case, you have to give the relative moisture variation in the loads window.
• everything you want to appear in the text report.

Figure 9. Calculation and report options of STRESSES calculation type.

References

[1] R.M. Jones, "Mechanics of composite materials", second edition, Taylor & Francis, United States, 1999.