Securing second object to first object

According to one aspect of the invention, there is provided a method of mechanically securing a first object (1) to a second object (2), the first object comprising a thermoplastic material in a solid state, the second object having a substantially flat sheet having a perforation (20), the sheet having an edge (21) along the perforation, where the first object is positioned relative to the second object, the rim is in contact with the thermoplastic material, and wherein mechanical vibrations can be coupled into an assembly comprising a first object and a second object, a flow portion of the thermoplastic material becomes flowable due to frictional heat generated between the rim and the thermoplastic material and flows around the rim to at least partially embed the rim within the thermoplastic material. After the mechanical vibration stops, the thermoplastic material is re-cured, whereby the re-cured thermoplastic material at least partially embedded in the rim anchors the first object into the second object.