An in-situ fiber-optic temperature field measurement is disclosed that can allow process monitoring and diagnosis for thermoplastic composite welding and other applications. A distributed fiber-optic sensor can be permanently embedded in a thermoplastic welded structure when it is welded and left there to perform lifelong monitoring and inspection. The fiber optic sensor can include a dissolvable coating, or a coating matched to the composite material to be welded. Other applications include in-situ fiber-optic temperature field measurement on thermoset composite curing (autoclave), for thermoplastic and thermoset composites during compression molding, and for fiber-optic field measurements on freeze/thaw of large items of public health interest, such as stored or transported foodstuffs.

A method and installation for joining a cover layer to an object in a continuous process. Joining is effected with the aid of a joining material having thermoplastic properties, wherein the joining material is arranged between the cover layer and the object and is liquefied using ultrasonic vibration energy. Before application of the ultrasonic vibration energy, the joining material is preheated in a contactless manner with the aid of electromagnetic induction in the region of the glass transition temperature of the joining material or above this glass transition temperature. The object is in particular a chip board and the cover layer an edge strip to be joined to an edge of the chip board.

An installation for welding a stack of parts made of thermoplastic composite materials (20) in a local welding plane (P), this installation including an electromagnetic induction head (8), pairs of elements for guiding and pressing the workpiece stack (20) in this local plane (P), and, on each side of the induction head (8), at least one pair of guide elements, each pair of guide elements having a lower guide element (14) and an upper guide element (10) that are superposed, receiving between one another the stack of parts (20) by guiding it in the direction perpendicular to the local welding plane (P).

A dynamic induction welding installation for welding first and second workpieces in a weld zone (S), the second workpiece being placed between a lightning protection system and the first workpiece, the workpieces including a composite material, the installation having an induction heating device placed on one side of the first workpiece facing away from the second workpiece and configured to create a magnetic field (Bi) so as to form the weld in the weld zone (S), and a medium placed in contact with the lightning protection system on a side opposite to the second workpiece, the medium being configured so as to be capable of generating a reaction magnetic field (B.sub.2) at least partially opposing the magnetic field (B.sub.1) in at least a part of the lightning protection system.

A fiber-reinforced composite laminate for use in electromagnetic welding of molded parts of said laminates. The laminate has a plurality of structural layers, each formed of electrically conductive fibers embedded in a thermoplastic matrix. Eddy currents may be induced in the electrically conductive fibers by an electrical conductor that generates an electromagnetic field. The structural layers include a first, a second and, optionally, a third pair of two adjacently positioned structural layers. The first pair has an intermediate layer which allows eddy currents to flow between the two structural layers of the first pair. The second pair has an intermediate layer which prevents eddy currents from flowing between the two structural layers of the second pair. The optional third pair does not have an intermediate layer. The laminate shows efficient heating by an electromagnetic field.

Composite joints and methods of forming composite joints are presented. A composite joint comprising: a first composite component formed of one of a thermoset material or a first thermoplastic material; a second composite component formed of a thermoset material or a third thermoplastic material; a thermoplastic joining film formed of a second thermoplastic material between the first composite component and the second composite component, the second thermoplastic material different from the thermoset material, first thermoplastic material, and third thermoplastic material; and a carbon conductive layer in the thermoplastic joining film.

A method and apparatus for welding a thermoplastic structure. The apparatus comprises a base, a cover, and a channel. The base is formed of a material that is magnetically opaque to a frequency in a range of 30 KHz to 350 KHz. The cover is formed of the material. The channel extends between the base and the cover.

A joint between dissimilar thermoplastic materials comprising a first thermoplastic material layer; a second thermoplastic material layer having a melting point temperature different from a melting point temperature of the first thermoplastic material layer; and an interface layer coupled between the first thermoplastic material layer and the second thermoplastic material layer; wherein the interface layer is configured to join the first thermoplastic material layer and the second thermoplastic material layer together to form the joint, wherein the interface layer comprises a melting point temperature having a value selected from the group consisting of between the melting point temperature of the first thermoplastic material layer and the melting point temperature of the second thermoplastic material layer; or lower than the melting point temperature of the first thermoplastic material layer and the melting point temperature of the second thermoplastic material layer.

A method of connecting surfaces of first and second molded parts by electromagnetic welding. The first molded part includes a first lightning strike protection (LSP) material at an outer surface thereof. The method includes providing the first and second molded parts to comprise a heat meltable coupling and an induction-sensitive component; bringing together the surfaces to be connected and pressurizing the surfaces by providing a pressurizing body against the molded parts; generating an electromagnetic field in the surfaces to be connected of the molded parts by means of an inductor, thereby heat melting the coupling means by heating the induction-sensitive component; cooling the outer surface of the first molded part by providing a heat sink in contact with the outer surface; and coupling the molded parts under pressure by the molten heat meltable coupling means. A second lightning strike protection (LSP) material is provided at the surfaces to be connected.

A composite fibrous susceptor for use in induction welding is described, along with methods of its construction and use. The composite fibrous susceptor can include a magnetically susceptible continuous fiber in conjunction with a thermoplastic polymer. The composite fibrous susceptor can be deposited according to an additive manufacturing process on a surface to be bonded according to an induction welding process.