Are Junker Tests fundamentally flawed for testing the integrity of bolted joints?

Are the Junker Test and standards based on it, DIN 65151, DIN 25201 and ISO 16130 fundamentally flawed for validating the integrity of bolted joints?

Traditionally, fastener engineers have used DIN 65151, DIN 25201 and ISO 16130 to test the self-loosening behaviour of fastener locking elements. Although valuable, these standards don’t replicate real-world bolted joint conditions or rubber stamp a bolted joint as safe.

The arrival of a powerful new methodology for validating bolted joint integrity is set to change this…

Instead of standards focussing on full displacement amplitude from the beginning of the test, we can now subject a bolted joint to a controlled transverse shear force that first triggers limited microslip. This leads to an increased displacement amplitude only when the clamp force reduces because of rotational self-loosening or joint embedding and relaxation increase.

Never before has a validation test mirrored real life conditions to allow transverse shear force – one of the first inputs needed to perform a bolted joint calculation according to VDI 2230 – to be the lead parameter rather than displacement amplitude.

Read more about the new methodology to validate bolted joint integrity.