Embedding loss in a bolted joint occurs due to the plastic deformation of asperities on the contact surfaces, leading to a reduction in bolt preload. This can happen during the tightening process or when the joint experiences an external load.
The formula to calculate the embedding loss is:
Embedding Loss (mm)=Number of Interfaces×Surface Roughness (microns)×0.001
The preload loss can be calculated using the stiffness values:
Preload Loss (N)=Embedding Loss (mm)×(Bolt Stiffness×Joint StiffnessBolt Stiffness+Joint Stiffness)
Consider a bolted joint with the following details:
Using the formula:
Embedding Loss=4×5×0.001=0.02 mm
Preload Loss=0.02×(200×300200+300)=0.02×120=2.4 N
This means the estimated preload loss due to embedding is 2.4 N.