Every buckle has a wavelength and in the derivation of buckling allowable values the value λ , the buckle half wave length is an important value. λ is also used later in this section for the calculation of the panel rotational edge fixity.

The value of λ varies depending on the type of loading.

**15.2.2.1. Shear Buckle Wavelength**

(NACA-TN-2536, 1951) provides some basic data on half wavelengths/panel width for a range of buckling situations. Note that this reference is concerned with the combination of transverse and not axial shear. Therefore, the cases where k_{s} has a non-zero and k_{b} and k_{c} are zero are pure shear.

*Note that the half wavelength is measured in the panel axial direction and NOT perpendicular to the 45-degree buckle.*

From this reference, a first approximation for the *λ /b *ratio can be assumed to be **1.2** for all states of panel rotational edge fixity.

**15.2.2.2. Compression Buckle Wavelength**

(ARC-RM-2652, 1953) gives a range of good experimental data for compression buckle wavelength:

It is noted that the *λ /b* ratio varies between **0.6** and **1.0**.

The wavelength decreases with increasing panel edge rotational fixity.

**15.2.2.3. Bending Buckle Wavelength**

Using the reference for the shear buckle wavelength (NACA-TN-2536, 1951) the wavelength for the bending buckle can be found from the case where k_{s} and k_{c} are equal to zero:

For a simply supported panel the *λ /b* ratio can be assumed to equal **0.70**, and for a panel with clamped edges **0.50**.

As with the compression buckle the wavelength decreases with increasing panel edge rotational fixity.

These compression, bending and shear buckling wavelengths can be estimated using the following spreadsheet: