“HoneycombAirbusSR” criterion

X.D.1.2 “HoneycombAirbusSR” criterion

This criterion is used to calculate honeycomb core margin of safety according to the so-called “Airbus” core failure criterion than combines the two components of out-of-plane stress tensor. The margin of safety is calculated according to the following expression:

MoS = \frac{1}{FoS \sqrt{{(\frac{τ_{L}}{σ_{L}})}^{2} + {(\frac{τ_{W}}{σ_{W}})}^{2}}} - 1,

in which $τ_{L}$ and $τ_{L}$ are the honeycomb longitudinal and transversal shear components of Cauchy stress tensor and $σ_{L}$ and $σ_{W}$ the corresponding allowables. Actually, one calculates a strength ratio instead of a margin of safety. The relation between strength ratio, reserve factor and margin of safety is as follows:

S R = \frac{1}{R F} = \frac{1}{M o S + 1} .

This leads to the following expression for the strength ratio:

SR = FoS \sqrt{{(\frac{τ_{L}}{σ_{L}})}^{2} + {(\frac{τ_{W}}{σ_{W}})}^{2}},

(The display of strength ratios instead of margins of safety allows usually a better identification of critical areas. This is true,for example, when results are saved in GMSH format.)

The arguments of the criterion are given in Table X.D.3. Compared to the “HoneycombAirbusMoS” discussed in section X.D.1.1, two new parameters are defined: “strL” and “strW” String arguments. These arguments, allow to specify the Cauchy Stress Tensor components that should be considered for $τ_{L}$ and $τ_{W}$ respectively. Possible values are “XZ”, “ZX”, “YZ”, “ZY”, “XY” and “YX”. (This capability has been added to allow the post-processing of stress when the usual convention for honeycomb core material definition have not been followed.

The method returns an Array of 8 elements according to Table X.D.4:

The four first elements correspond to the Result key on which the minimum margin of safety is calculated.
Then, the two components of the out-of-plane shear stress at critical location is given.
Then, one gives the critical (maximum) strength ratio.
The last element of the Array is a Result object that contains the strength ratio element-per-element, node-per-node...

Table X.D.3: Arguments of the “HoneycombAirbusSR” predefined criterion


Pos.	Name	Type	meaning	can be modified?


1	dB	DataBase	DataBase (or derived)	NO

2	fos	Real	factor of safety	NO

3	allL	Real	shear allowable in L-direction	NO

4	allW	Real	shear allowable in L-direction	NO

5	strL	String	shear allowable in L-direction	NO

6	strW	String	shear allowable in L-direction	NO

7	stressRes	Result	Cauchy Stress Tensor	NO

Table X.D.4: Outputs of the “HoneycombAirbusSR” predefined criterion


Pos.	Name	Type	meaning


1	ElemId	Integer	Critical Element ID

2	NodeId	Integer	Critical Node ID

3	LayerId	Integer	Critical Layer ID

4	SubLayerId	Integer	Critical Sub-Layer ID

5	sigLmax	Real	L OOP shear component of stress tensor at critical location

6	sigWmax	Real	W OOP shear component of stress tensor at critical location

7	srMax	Real	Critical strength ratio

8	srRes	Result	All the strength ratios that have been calculated

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