II.4.7.5 Other ply results

Several methods of the ClaLam class allow to estimate values from the stored ply stresses and strains. Three such methods return the values calculated for several plies:

• “getDerived” returns an equivalent stress or strain corresponding to the components stored in the laminate. For example, a Tresca or Von Mises equivalent stress.
• “getFailureIndices” is devoted to the calculation of failure indices like the Tsai-Hill or Tsai-Wu. This method differs from the previous one by the fact that failure indices are calculated from the stored results and corresponding allowables.
• “getReserveFactors” calculates reserve factors.
• “getStrengthRatios” calculates strength ratios.

“getDerived” and “getFailureIndices” have the same parameters:

• A ClaDb object that provides the definition of materials used in the laminate, and of the corresponding allowables. If this first parameter is omitted, then the allowables stored in ClaLam object are used instead of material allowables.
• An Array of Strings containing a list of criteria for the calculations.
• Then follows an arbitrary number of arguments. Each argument corresponds to an identifier of the layer and location at which the layered components are recovered. (Same principle as methods returning plies strains and strains in section II.4.7.3.) If none of these arguments identifier is provided, the calculation is done for all layers.

So for example, “getFailureIndices” method may be called as follows:

Note that several criteria can be calculated by a single call.

Methods “getReserveFactors” and “getStrengthRatios” have one additional parameter: the factor of safety. This parameters is a Real value provided after the list of criteria and before the optional layer identifiers. For example

Each of the four methods described above returns an Array containing two elements:

1.

The first element is an Array of Strings containing the list of criteria that have been calculated. Indeed, the criteria are calculated only if the criterion is available. This Array has X elements.

2.

The second element contains the new layered results. Each element of this Array contains 2+X elements:

• The two first elements of the sub-array identify the layer to which the calculated results correspond.
• The X elements 3 to 2+X of the sub-array contain the Real calculated values. These X elements correspond to the X Strings referred to above in the list of criteria returned by the method.

The four methods “getDerived”, “getFailureIndices”, “getReserveFactors” and “getStrengthRatios” have “Min” and “Max” variants. This makes six additional methods: “getMinDerived”, “getMinFailureIndices”, “getMinReserveFactors”, “getMinStrengthRatios”, “getMaxDerived”, “getMaxFailureIndices”, “getMaxReserveFactors” and “getMaxStrengthRatios”. These methods have the same parameters as their basic corresponding methods and are used to return values associated to the most critical ply. (The ply leading to maximum or minimum calculated criterion.) The returned Array, however, is different. The returned value is an Array of which each element is an Array of four elements:

1.

The calculated criterion (String).

2.

Two elements identifying the critical layer (an integer and string value).

3.

A Real object corresponding to the critical value.

The criteria presently available are summarized in Table II.1.2.