2.2.1 Matrix properties

CADEC lets you place the cursor over any textbox and read the tooltip to find out what property is expected, but this section explains a bit more.

The following properties are entered here:

Name A Name is required for every new object, like a matrix, etc.

$\rho _ m$ is the density of the matrix. You can use the default value if you do not plan to calculate density for higher objects, such as laminas and laminates. If the default is wrong, the results for lamina density and so on will be wrong. But if you do not care about density, you don’t have to spend time right now looking for the density of the matrix. Densities of most matrices are listed in [2, Table 2.1–2].

$E_ m$ is the (Young) modulus of the matrix. All matrices are assumed to be isotropic.

$\nu _ m$ is the Poisson’s ratio of the matrix. All matrices are assumed to be isotropic.

$F_{mt}, F_{mc}, F_{ms}$ are the tensile, compression, and shear strength of the matrix.

These values are empirical parameters for which there is no standard method for testing. A designer usually adjust this values based on his experience with a particular material system.

These values are used to compute the transverse, compression, and shear strengths of the unidirectional lamina. It is not required if you do not plan to compute the strength of the composite. Transverse means perpendicular the fiber direction, but still on the plane of the lamina. The plane of the lamina refer to a 2D surface located halfway through the thickness of the lamina.

$\sigma _ m,D_ m,k_ m$ are the electrical conductivity, mass diffusivity, and thermal conductivity of the matrix. Unless you plan to calculate similar properties for the lamina, etc., you do not have to worry about these properties.

$\alpha _ m$ is the coefficient of thermal expansion of the matrix. This is an important property because it allows you to calculate the CTE of the lamina and the laminate. CTE is an important aspect of design so you should pay attention to this.

If you don’t know all the material properties, and you know you will not be using the properties that you don’t know, you can enter a zero. Don’t enter fake values because later you will forget and think that the properties that you entered for this Matrix are correct, not fake. Better enter zero and live with the consequences (i.e., some derived properties will not calculate or they will be wrong). You will always know what you need for a given calculation because the calculation pages (localed under Chapters) will tell you what properties are being used.

If you change your mind and want to cancel all your edits, simply leave the page. It you do not click on \includegraphics[width=14pt]{./Images/Save.png}, nothing is saved.