A catheter including a core wire, a sonic connector at a proximal terminus of the core wire, and a tip member at a distal terminus of the core wire. The core wire can be at least partially disposed within a lumen of an elongate body. The sonic connector can be configured to couple to an ultrasound-producing mechanism. The tip member can be welded to the core wire at one or more weld locations between the tip member and the core wire, and the tip member can flare from the core wire at one or more weld-free locations between the tip member and the core wire. The manner in which the tip member can flare from the core wire at the one or more weld-free locations is characteristic of ultrasonic activation of the tip member.
