Nonlinear Effects on the Stiffness of Bolted Joints
Axisymmetric finite element modeling of bolted joints was performed to show the effects of the magnitude and position of the external load, member thickness, and member material on the bolt and member stiffnesses. The member stiffness of the bolted joint was found to decrease 10 to 42 percent for the 20-mm to 8-mm bolts, respectively, as the magnitude of the external load was increased. Member stiffness appears to be independent of the radial location of the external load and increases as the member thickness decreases. Member stiffness decreased by a factor of 2.5 to 3 with a change in the member material from steel to aluminum. The cast iron members had a decrease in member stiffness of a factor of 1.7 to 1.9. The aluminum over cast iron combination had a member stiffness between the aluminum and cast iron alone. Bolt stiffnesses varied by less than two percent for changes in the magnitude of the external load for all bolt sizes and member materials, except for the 8-mm bolt where stiffness increased by approximately 11 percent. Changes in radial position of the external load had no effect on the bolt stiffness. A 3 to 13-percent decrease in the bolt stiffness was found when changing from steel to aluminum members. A 2 to 3-percent bolt stiffness decrease resulted when the member material was changed from steel to cast iron and similarly from steel to the aluminum over cast iron combination
T. F. Lehnhoff and W. E. Wistehuff, "Nonlinear Effects on the Stiffness of Bolted Joints," Journal of Pressure Vessel Technology, American Society of Mechanical Engineers (ASME), Jan 1996.
The definitive version is available at http://dx.doi.org/10.1115/1.2842162
Mechanical and Aerospace Engineering
Keywords and Phrases
Bolted Joints; Stiffness; Aluminum; Cast Iron; Stress; Steel; Thickness; Finite Element Analysis; Modeling
Article - Journal
© 1996 American Society of Mechanical Engineers (ASME), All rights reserved.