METHOD FOR JOINING FIBER COMPOSITE PARTS BY ULTRASONIC WELDING

Abstract

To improve a method for ultrasonic welding of parts for vehicles and/or aircraft, a method in which an energy director made of non-woven fiber material is arranged between a first fiber composite part and a second fiber composite part to be joined together. A sonotrode is used to join/weld the parts together by pressing on the parts. The energy director is compliant such that a uniform even contact is generated between the first and second fiber composite parts during the welding process.

Claims

1. A method for joining a first fiber composite part to a second fiber composite part, the method comprising: a) arranging the first fiber composite part and the second fiber composite part to form a joint portion to be joined; b) arranging within the joint portion and between the first fiber composite part and the second fiber composite part an energy director that is suitable for influencing propagation of acoustic energy; and c) arranging a sonotrode on the first fiber composite part and energizing the sonotrode such that acoustic energy is transferred to the joint portion and finally a joint between the first fiber composite part and the second fiber composite part is formed.

2. The method according to claim 1, wherein the first fiber composite part and/or the second fiber composite part is a fuselage part for an aircraft fuselage or a body part for a vehicle body.

3. The method according to claim 1, wherein the first fiber composite part or the second fiber composite part is a fuselage part for an aircraft fuselage or a body part for a vehicle body and the second fiber composite part or the first fiber composite part is a stiffener part configured for stiffening the fuselage part or the body part when joined to the part.

4. The method according to claim 1, wherein the energy director includes a compliant fiber material.

5. The method according to claim 4, wherein the fiber material is a non-woven material.

6. The method according to claim 4, wherein the fiber material includes fibers having a maximum length of 10 mm.

7. The method according to claim 1, wherein the first fiber composite part and/or the second fiber composite part includes a matrix material, and the energy director is made of a different material as the matrix material.

8. The method according to claim 7, wherein the matrix material is is selected from a group consisting of polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), and polyamide (PA).

9. The method according to claim 7, wherein the energy director is made of a polyetherimide (PEI) material.

10. The method according to claim 1, wherein step c) includes pressing of the sonotrode onto the first fiber composite part and/or the second fiber composite part.

11. The method according to claim 1, wherein the joint portion extends in a longitudinal direction and step c) includes moving the sonotrode along the longitudinal direction such that a weld seam is formed as the joint.

12. The method according to claim 10, wherein the sonotrode is pressed onto the first fiber composite part and/or the second fiber composite part in a sliding manner for a duration the sonotrode is energized to form the weld seam.

13. The method according to claim 1, wherein step b) includes adhesively fixing the energy director to the first fiber composite part and/or the second fiber composite part.

14. The method according to claim 1, wherein step a) includes arranging the first fiber composite part and the second fiber composite part such that they form a partial overlap as the joint portion.

15. The method according to claim 1, wherein step c) includes energizing the sonotrode until the first fiber composite part, the second fiber composite part and the energy director melt at least partially such that subsequent to de-energizing or moving the sonotrode a joint is formed between the first fiber composite part and the second fiber composite part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the disclosure herein are described in more detail making reference to the accompanying drawings wherein FIGS. 1A-1D depict an embodiment and a method for joining fiber composite parts.

DETAILED DESCRIPTION

[0028] Initially as depicted in FIG. 1A, a first fiber composite part 10 is provided that is to be joined to a second fiber composite part 12. The first fiber composite part 10 may be an aircraft fuselage part, such as a structural panel for an aircraft, and the second fiber composite part 12 may be a stiffener part for the structural panel. It is also possible that the first and second fiber composite parts 10, 12 are structural panels or skins for an aircraft to be joined together.

[0029] As shown in FIG. 1B, an energy director 14 is arranged on the first fiber composite part 10 at a joint portion 16. The energy director 14 is a piece of non-woven material that is preferably made from PEI or high performance polymer, such as any of the usual PAEKs.

[0030] As illustrated in FIG. 1C, the second fiber composite part 12 is arranged on the energy director 14 so as to overlap with the first fiber composite part 10 at the joint portion 16. The energy director 14 is a compliant member that is able to ensure a uniform even contact between the first and second fiber composite parts 10, 12, when pressed.

[0031] Subsequently as illustrated in FIG. 1 D, a sonotrode 18 is pressed onto the second fiber composite part 12 and energized so as to melt a matrix material of the first and second fiber composite parts 10, 12 as well as the energy director 14. As a result, both the first and second fiber composite parts 10, 12 are fused together. The sonotrode 18 may be moved along the joint portion 16 (i.e. into or out of the drawing plane) in order to form a continuous weld seam. The sonotrode 18 may also be repeatedly energized and deenergized in order to form a series of weld points. It is also possible that the sonotrode 18 extends along the joint portion 16 in order to join the first and second fiber composite parts 10, 12 in one go.

[0032] It should be noted that, while the method was illustrated with reference to an arrangement of the first and second fiber composite parts 10, 12 being joined with their two large sides, other arrangements are possible. For example, both small sides may be joined together or a small and a large side.

[0033] In order to improve a method for ultrasonic welding of parts for vehicles and/or aircraft, the disclosure herein proposes a method in which an energy director (14) made of non-woven fiber material is arranged between a first fiber composite part (10) and a second fiber composite part (12) to be joined together. A sonotrode (18) is used to join/weld the parts (10, 12) together by pressing on the parts (10, 12). The energy director (14) is compliant such that a uniform even contact is generated between the first and second fiber composite parts (10, 12) during the welding process.

[0034] While at least one example embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the example embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF REFERENCE SIGNS

[0035] 10 first fiber composite part [0036] 12 second fiber composite part [0037] 14 energy director [0038] 16 joint portion [0039] 18 sonotrode