Overview of the Geometric Parameters of a Press-Fit Interlocking Mechanism: Experimental and FEA Analysis of Steel Pipe Joint

摘要

Interlocking pipe joints have been utilized in the trenchless technology industry for over 20 years. This technology allows a pipe segment with a notched male end to be joined to a pipe segment with a notched female end by pressing them together using axial force, eliminating the need for circumferential welding of the segments. Although industry familiarity with these joints is well established, the mechanics of the interlocking process has received little attention in the literature. This paper provides insights into the mechanical behavior of the interlocking, press-fit joints that secure steel pipe casings in auger boring and pipe jacking construction. Four male/female pairs of 914.4 mm outer diameter specimens were assembled to determine engagement forces; these four pairs were then disassembled to determine disengagement forces. The axial forces required to engage the joints ranged from 205 to 320 kN, and the forces to disengage the joints ranged from 254 to 365 kN. The experimental results showed that on average, the disengagement force exceeded the engagement force by 15%. Nonlinear finite element analysis (FEA) of the locking mechanism was implemented resulting in important insights into joint behavior, mechanics, and design. The press-fit geometric parameters (joint thickness, diametral interference, inner and outer diameters, and joint length) along with material and contact properties that define the computational model were studied to gain insights that could consequently lead improved interlocking joint designs.