Bearing Friction Torque in Bolted Joints
Abstract
In this paper, formulas are developed for the calculation of the effective radius of the bearing friction forces on the rotating contact surface in threaded fasteners. These formulas provide a more accurate estimation of the underhead bearing friction torque component in threaded fastener applications. This enhances the reliability, safety, and the quality of bolted assemblies, especially in critical applications. It is well known that the torque-tension correlation in threaded fasteners, and the resulting joint clamping force, is highly sensitive to friction torque components: under the turning head and between threads. This analysis focuses on the bearing friction torque component under the turning head of a threaded fastener. Further, it analyzes the error contained in the current practice when an approximate value, equal to the mean contact surface radius, is used instead of the actual bearing radius. The new formulas for the bearing friction radius are developed for a mathematical model of a bolted joint using four different scenarios of the contact pressure distribution under the rotating fastener head or nut. The effect of the radially varying sliding speed over the rotating contact surface is analyzed and compared with a constant friction coefficient scenario. Numerical results and error analysis are presented in terms of a single non-dimensional variable; namely, the radii ratio between the outside and the inside bearing area.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 12, 2004
- Accession Number
- ADA421463
Entities
People
- Dajun Zuo
- G. C. Barber
- Sayed A. Nassar
Organizations
- Oakland University