Overview
ISO 16130:2015 - Aerospace series - Dynamic testing of the locking behaviour of bolted connections under transverse loading conditions (vibration test) specifies a method for evaluating the self-loosening (locking) behaviour of aerospace fasteners under controlled transverse vibration. The standard is intended primarily for development and comparative evaluation of locking elements (nuts, washers, prevailing torque devices, etc.), not for making absolute statements about in-service performance, because test rigs and stiffness distributions vary.
Key topics and technical requirements
- Test principle: Fasteners are tightened to a defined initial clamp force and exposed to transverse vibration; clamp force is recorded versus number of load cycles.
- Comparative objective: The test is designed to compare locking elements under defined conditions (reference and verification tests), not to predict exact in-service loosening.
- Apparatus: Vibration test machine with stationary base and floating glider plate, clamp-force sensor, displacement sensor and data acquisition. Optional transverse-force sensor.
- Critical settings and tolerances:
- Transverse displacement adjustable up to ±1.5 mm (thread diameters ≤ 25.4 mm); typical test displacements t = ±0.5 mm (≤ M12) and t = ±0.8 mm (> M12).
- Testing frequency range 10–15 Hz (commonly 12.5 Hz); frequency accuracy ±3%.
- Clamp-force measurement uncertainty within ±2%; displacement uncertainty within ±3%.
- Concentricity and guidance tolerances: concentricity ±0.1 mm, lateral guidance ±0.10 mm; gap at fastener position 1.00 mm ± 0.05 mm under load.
- Procedure: Perform reference tests on unsecured joints to determine displacement that causes full loss of preload within 300 ± 100 cycles; verification tests use same conditions. Tests end on fracture, stabilization, or complete loss of clamp force.
- Clamp force settings: Example tables use 75% of calculated ultimate clamp force (Fu) as target clamp force; use recommended formulas or referenced tables for other sizes/strengths.
Applications and users
ISO 16130:2015 is useful for:
- Aerospace fastener manufacturers evaluating locking devices (prevailing torque nuts, lock washers).
- Design and R&D teams comparing self-loosening resistance of fastening solutions.
- Accredited test laboratories performing vibration loosening tests for product development.
- Engineers assessing relative performance for selection of fasteners in airframe assemblies where transverse vibration is a concern.
Keywords: ISO 16130:2015, vibration test, bolted connections, locking behaviour, self-loosening, clamp force, transverse displacement, aerospace fasteners.
Related standards
- ISO 16047 - Fasteners - Torque/clamp force testing (normative reference)
- ISO 5858, ISO 5408, ISO 3161 - referenced for terms, thread geometry and strength calculations
This standard provides reproducible, comparative test methods to inform fastener selection and development for aerospace applications where vibration-induced loosening is critical.