Plastic lever with fatigue fracture

The lever of a wine bottle opener broke after about 20 years. The stereomicroscopic images of the fracture surface indicate a fatigue fracture with separate incipient cracks from three corners, where the 90° angle is only mitigated by a small radius. The actual residual overload fracture ratio is unclear. In the SEM, at high magnification, dimple fracture is seen everywhere; in the area of the clear fatigue incipient cracks, the dimples are only flatter and more finely formed.