A method of joining a first and a second object with the aid of a joining element, the method comprising the steps of: - Providing the first object; - Providing the joining element, the joining element extending between a distal end and a proximal end and comprising a thermoplastic material; - Positioning the joining element relative to the first object; - Using a tool to press the joining element towards distally relative to the first object while energy is coupled into the first object and/or the joining element, until a first portion of the thermoplastic material belonging to a distal portion of the joining element, the distal portion comprising the distal end, is made flowable and is caused to flow into a structure of the first object to yield, after re-solidification, an anchoring of the distal portion of the joining element in the first object; wherein during the step of coupling of the energy into the first object and/or the joining element, a pressing face of the tool abuts against an abutment face of the joining element, which abutment face is distally of the proximal end; - Providing the second object; - After causing the first portion of the thermoplastic material to flow into a structure of the first object, placing the second object relative to the first object; - and - pressing the first and second objects against each other while mechanical vibration energy is coupled into at least one of the first and second objects (1, 2), until a second portion of the thermoplastic material belonging to a proximal portion of the joining element, the proximal portion comprising the proximal end, is made flowable and is caused to flow into a structure of the second object to yield, after re-solidification, a fixation between the joining element and the second object - characterized in that the second object has a second opening being a blind hole, in that in the step of placing the second object relative to the first object, the second object is placed so that the protruding proximal portion of the joining element is inserted into the second opening and in that the step of pressing the first and second objects against each other causes the proximal end of the joining element to be pressed against a bottom face of the second opening. - Providing the first object; - Providing the joining element, the joining element extending between a distal end and a proximal end and comprising a thermoplastic material; - Positioning the joining element relative to the first object; - Using a tool to press the joining element towards distally relative to the first object while energy is coupled into the first object and/or the joining element, until a first portion of the thermoplastic material belonging to a distal portion of the joining element, the distal portion comprising the distal end, is made flowable and is caused to flow into a structure of the first object to yield, after re-solidification, an anchoring of the distal portion of the joining element in the first object; wherein during the step of coupling of the energy into the first object and/or the joining element, a pressing face of the tool abuts against an abutment face of the joining element, which abutment face is distally of the proximal end; - Providing the second object; - After causing the first portion of the thermoplastic material to flow into a structure of the first object, placing the second object relative to the first object; - and - pressing the first and second objects against each other while mechanical vibration energy is coupled into at least one of the first and second objects (1, 2), until a second portion of the thermoplastic material belonging to a proximal portion of the joining element, the proximal portion comprising the proximal end, is made flowable and is caused to flow into a structure of the second object to yield, after re-solidification, a fixation between the joining element and the second object - characterized in that the second object has a second opening being a blind hole, in that in the step of placing the second object relative to the first object, the second object is placed so that the protruding proximal portion of the joining element is inserted into the second opening and in that the step of pressing the first and second objects against each other causes the proximal end of the joining element to be pressed against a bottom face of the second opening.