Fabrication method for making a trim element by welding of a structural element and a functional element

An assembly method for assembling a lining element comprising at least one structural element and one functional element made of plastic material constituted of a first functional element part and a second functional element part, wherein the method includes the following steps:

• bringing into contact the first functional element part, the second functional element part and the structural element in at least one assembly zone, the first functional element part being in contact with the second functional element part, and the first functional element part and the second functional element part in addition being respectively in contact with the structural element in the assembly zone,
• welding of the first and the second functional element parts on to the structural element in the assembly zone in a single welding pass in a manner so as to simultaneously attach the first and the second functional element parts to the structural element,
• wherein the first and the second functional element parts each comprise at least one rib extending in the assembly zone, said ribs being brought into contact with the structural element in the assembly zone and being welded to the structural element during the welding step,
• wherein the first and the second functional element parts are welded to each other during the welding of the first and second functional element parts to the structural element, and
• wherein the ribs are welded together at least in certain zones during the welding step.