Bonding objects together

A method of bonding a first object and a second object together by a connector, the method comprising the steps of:

• providing the first object with a first opening, the first opening being a through opening;
• providing the second object with a second opening, the second opening being a through opening
• providing a connector comprising a thermoplastic material and a core element of a material that is not liquefiable or liquefiable only at substantially higher temperatures than the thermoplastic material;
• arranging the first object, the second object and the connector relative to one another so that the first and second openings are aligned with each other and the connector reaches from a proximal side through the first opening and the second opening;
• using a source of mechanical vibrations to generate vibrations, and applying the vibrations and mechanical pressure to the connector until, under the effect of the vibrations and the pressure, a flow portion of the thermoplastic material is liquefied and caused to flow;
• and
• removing the source of the vibrations and causing the liquefied thermoplastic material to re-solidify;
• wherein the core element has on a surface at least one locking feature;
• wherein after the step of removing, the connector comprises a foot portion, a head portion, and a shaft portion between the foot portion and the head portion, the shaft portion extending along an axis through the first and the second opening;
• wherein the flow portion forms at least a part of the foot portion or the head portion or both, the foot portion and the head portion;
• and
• wherein after the step of removing, the core element is secured to the thermoplastic material by a positive fit connection caused by the locking feature, the locking feature being arranged laterally with respect to the axis.