Friction stir welding method and assembly
A friction stir welded structure includes first and second members. The first member has a base defining opposed first and second surfaces, and spaced first and second walls extending outwardly from the second surface of the base to define a receptacle therebetween. The second member includes an elongate rib extending from a root portion to a first tip portion, the root portion having a uniform root portion thickness and the first tip portion having a first tip portion thickness not greater than the root portion thickness. The first tip portion is sized for insertion into the receptacle and shaped conformally with the receptacle so that the first tip portion engages a closed end of the receptacle. A friction stir weld joint extends through the base and at least portions of the first and second walls of the first member and into the first tip portion of the second member, thereby to join the first and second members.
1. A method of joining first and second members together, the method comprising:
providing the first member with a base defining opposed first and second surfaces, and spaced first and second walls extending outwardly from the second surface of the base to define a receptacle therebetween;
providing the second member as an elongate rib extending from a root portion to a first tip portion, the root portion having a uniform root portion thickness and the first tip portion having a first tip portion thickness not greater than the root portion thickness, the first tip portion being sized for insertion into the receptacle and shaped conformally with the receptacle;
positioning the first and second members so that the first tip portion of the second member is inserted into the receptacle of the first member with the first tip portion engaging a closed end of the receptacle; and
friction stir welding the first tip portion and first and second walls to form a welded joint between the first and second members;
wherein each of the first and second walls of the first member has a uniform wall thickness that is approximately half of the root portion thickness of the second member.
2. The method of claim 1 , in which the first tip portion has a radiused cross-sectional profile.
3. The method of claim 1 , in which the closed end of the receptacle is substantially aligned with the second surface of the base.
4. The method of claim 1 , in which:
each of the first and second walls includes a distal end disposed at an end distance from the first surface of the base, and
the friction stir welding is performed by inserting a pin of a friction stir welding tool through the base of the first member and into the second member to a pin depth that is not greater than the end distance.
5. The method of claim 4 , in which the pin of the friction stir welding tool has a pin diameter that is greater than the root portion thickness of the second member.
6. The method of claim 5 , in which each of the first and second walls has a wall exterior surface, the wall exterior surfaces are spaced by an outer wall distance, and the pin diameter is less than the outer wall distance.
7. The method of claim 1 , in which an interface region is formed between the first and second members, the interface region including first and second longitudinal legs spaced by a lateral distance, and in which each of the first and second longitudinal legs has a length that is greater than the lateral distance.
8. The method of claim 1 , further comprising:
providing a third member with a base defining opposed first and second surfaces, and spaced first and second walls extending outwardly from the second surface of the base to define a second receptacle therebetween;
further providing the second member with a second tip portion opposite the first tip portion, and the second tip portion having a second tip portion thickness not greater than the root portion thickness of the second member, the second tip portion being sized for insertion into the second receptacle and shaped conformally with the second receptacle;
positioning the second and third members so that the second tip portion of the second member is inserted into the second receptacle of the third member with the second tip portion engaging the closed end of the second receptacle; and
friction stir welding the second tip portion and the first and second walls of the third member to form a second welded joint between the second and third members.
9. A structure comprising:
a first member having a base defining opposed first and second surfaces, and spaced first and second walls extending outwardly from the second surface of the base to define a receptacle therebetween;
a second member including an elongate rib extending from a root portion to a first tip portion, the root portion having a uniform root portion thickness and the first tip portion having a first tip portion thickness not greater than the root portion thickness, the first tip portion being sized for insertion into the receptacle and shaped conformally with the receptacle so that the first tip portion engages a closed end of the receptacle; and
a friction stir weld joint that extends through the base and at least portions of the first and second walls of the first member and into the first tip portion of the second member;
wherein each of the first and second walls of the first member has a uniform wall thickness that is approximately half of the root portion thickness of the second member.
10. The structure of claim 9 , in which the first tip portion has a radiused cross-sectional profile.
11. The structure of claim 9 , in which the closed end of the receptacle is substantially aligned with the second surface of the base.
12. The structure of claim 9 , in which an interface region is formed between the first and second members, the interface region including first and second longitudinal legs spaced by a lateral distance, and in which each of the first and second longitudinal legs has a length that is greater than the lateral distance.
13. The structure of claim 9 , in which the second member further includes a second tip portion opposite the first tip portion, the second tip portion having a second tip portion thickness not greater than the root portion thickness of the second member.
14. The structure of claim 13 , further comprising a third member with a base defining opposed first and second surfaces, and spaced first and second walls extending outwardly from the second surface of the base to define a second receptacle therebetween, wherein the second tip portion of the second member is sized for insertion into the second receptacle and shaped conformally with the second receptacle so that the second tip portion engages a closed end of the second receptacle.
15. The structure of claim 14 , further comprising a second friction stir weld joint that extends through the base and at least portions of the first and second walls of the third member and into the second tip portion of the second member.
16. A structure comprising:
a first member having a base defining an interior surface, and spaced first and second walls extending outwardly from the interior surface of the base of the first member to define a first receptacle;
a second member including an elongate rib having a root portion and first and second tip portions, the root portion having a uniform root portion thickness and each of the first and second tip portions having a tip portion thickness not greater than the root portion thickness;
a third member having a base defining an interior surface, and spaced first and second walls extending outwardly from the interior surface of the base of the third member to define a second receptacle;
the first tip portion being sized for insertion into the first receptacle and shaped conformally with the first receptacle so that the first tip portion engages a closed end of the first receptacle;
the second tip portion being sized for insertion into the second receptacle and shaped conformally with the second receptacle so that the second tip portion engages a closed end of the second receptacle;
a first friction stir weld joint extending through the base and at least portions of the first and second walls of the first member and into the first tip portion of the second member; and
a second friction stir weld joint extending through the base and at least portions of the first and second walls of the third member and into the second tip portion of the second member;
wherein the first and second walls of both the first member and the third member have a uniform wall thickness that is approximately half of the root portion thickness of the second member.
17. The structure of claim 16 , in which a first interface region is formed between the first and second members and a second interface region is formed between the second and third members, each of the first and second interface regions including first and second longitudinal legs spaced by a lateral distance and having lengths greater than the lateral distance.
18. The structure of claim 16 , in which the each of the first and second tip portions has a radiused cross-sectional profile.
19. The structure of claim 16 , in which the base of the first member further defines an exterior surface opposite the interior surface of the base of the first member, and in which the closed end of the first receptacle is substantially aligned with the exterior surface of the base of the first member.
20. The structure of claim 16 , in which an interface region is formed between the first and second members, the interface region including first and second longitudinal legs spaced by a lateral distance, and in which each of the first and second longitudinal legs has a length that is greater than the lateral distance.