Analysis of bending failure behavior of polyetheretherketone thin-walled tubes with different geometric and loading conditions

Abstract This study investigated the effects of geometric and loading conditions on the bending mechanical response and failure modes of polyetheretherketone thin-walled tubes. The tubes with wall thicknesses of 1, 2, and 3 mm were subjected to three-point bending experiments and numerical simulations under different bending spans. Experimental results showed that for the 1 mm-thick tubes, increasing the span from 80 mm to 140 mm led to a 41.62% reduction in the fracture load. Under a bending span of 80 mm, reducing the wall thickness from 3 mm to 1 mm resulted in an 89.22% decrease in fracture load and a 70.51% reduction in the specific energy absorption. These findings indicated that both the fracture load and energy absorption capacity of polyetheretherketone tubes increased with wall thickness but decreased with bending span. Two concurrent deformation modes were observed in polyetheretherketone tubes during three-point bending: localized compressive indentation at the midspan and global bending. The deformation behavior is primarily dominated by wall thickness, indenter shape and diameter, as well as bending span. Specifically, the 1 mm-thick tubes exhibited a typical localized indentation-dominated mode, while the tubes with 2 mm and 3 mm thicknesses underwent a transition from localized indentation to global bending deformation. This study elucidated the bending mechanical response and failure mechanism of polyetheretherketone thin-walled tubes, thereby providing practical support for the lightweight structural design in the transportation industry.