FAQ
What units does BJSFM use?
All inputs are in US customary units: moduli in Msi, thicknesses in inches, running loads in lb/in, and strain allowables in microstrain (με).
Can I analyze metallic joints?
BJSFM is primarily designed for composite laminates. However, you can model an isotropic material by setting E1 = E2, using the appropriate shear modulus (G = E / 2(1+ν)), and defining a single ply at 0° with the full plate thickness. The anisotropic solution reduces to the isotropic solution in this case.
What is the difference between single-shear and double-shear?
In a double-shear joint, the fastener is loaded in two shear planes (e.g., a center panel sandwiched between two outer panels). The bearing load is distributed more uniformly through the laminate thickness. In a single-shear joint, there is only one shear plane, which can cause secondary bending and non-uniform bearing pressure through the thickness.
How are countersink effects handled?
When a countersink depth is specified, the effective bearing area is reduced because the countersunk portion of the hole does not carry bearing load. This increases the bearing stress concentration. The analysis accounts for this by adjusting the effective thickness for bearing load distribution.
Why are my margins clamped at ±10?
To keep the margin plots readable, values are capped at ±10.0. A margin of +10 or greater simply means the structure has substantial positive margin at that location and ply angle. The exact numeric value is available in the underlying data.
Can I save my laminate configuration?
Currently, laminate configurations are session-local and reset when you reload the page. A persistent save/load feature is planned for a future release.