A method for welding thermoplastic composite components is provided that includes: providing a first thermoplastic composite component having a first weld region surface; providing a second thermoplastic composite component having a second weld region surface; disposing the first and second weld region surfaces in stationary contact with one another; ultrasonically welding the first and second thermoplastic composite components using a ultrasonic welding device having a sonotrode that linearly reciprocates, the welding including contacting an engagement surface of the first or second thermoplastic composite component with the sonotrode and reciprocating the sonotrode along a travel axis that is parallel to the first and second weld region surfaces until at least one of the first or second thermoplastic material reaches a melt temperature; and then maintaining the first and second weld region surfaces stationary until cooled.