Method and apparatus for joining thermoplastic composite components

A method of welding a first thermoplastic composite component to a second thermoplastic composite component, wherein the first thermoplastic composite (FTPC) component has a thickness that extends between an outer surface and an opposite FTPC bonding surface, and the second thermoplastic composite (STPC) component has a STPC bonding surface, wherein an interface layer is disposed between the FTPC bonding surface and the STPC bonding surface, the method comprising:

• applying a normal force to the outer surface of the first thermoplastic composite component without an application of an opposing second normal force to the second thermoplastic component;
• applying an electromagnetic field to at least portions of the first thermoplastic composite component, the second thermoplastic composite component, and the interface layer while the normal force is applied, the applied electromagnetic field configured to create a weld pool;
• determining a first inflection point of the applied normal force, a second inflection point of the applied normal force, wherein the applied normal force decreases between the first inflection point and the second inflection point, and a third inflection point whereafter the applied normal force becomes substantially constant;
• and
• removing the applied electromagnetic field to permit the weld pool to solidify upon determining the third inflection point.

A system for welding a first thermoplastic composite component to a second thermoplastic composite component, wherein the first thermoplastic composite (FTPC) component has a thickness that extends between an outer surface and an opposite FTPC bonding surface, and the second thermoplastic composite (STPC) component has a STPC bonding surface, wherein an interface layer is disposed between the FTPC bonding surface and the STPC bonding surface, the system comprising:

• a force actuator configured to apply a normal force to the outer surface of the first thermoplastic composite component without an application of an opposing second normal force to the second thermoplastic component;
• an electromagnetic inductor configured to selectively produce an electromagnetic field sufficiently to melt at least portions of the first thermoplastic composite component, the second thermoplastic composite component, and the interface layer;
• and
• a system controller in communication with the force actuator, the electromagnetic inductor, and a non-transitory memory storing instructions, which instructions when executed cause the system controller to:
• control the force actuator to apply a normal force to the outer surface of the first thermoplastic composite component without an application of an opposing second normal force to the second thermoplastic component;
• control the electromagnetic inductor to apply an electromagnetic field to at least portions of the first thermoplastic composite component, the second thermoplastic composite component, and the interface layer while the normal force is applied, the applied electromagnetic field configured to create a weld pool;
• determine a first inflection point of the applied normal force, a second inflection point of the applied normal force, wherein the applied normal force decreases between the first inflection point and the second inflection point, and a third inflection point whereafter the applied normal force becomes substantially constant;
• and
• control the electromagnetic conductor to remove the applied electromagnetic field to permit the weld pool to solidify upon determining the third inflection point.