Patent Application
20120183347
The present disclosure generally relates to fabrication of composite items. More particularly, the present disclosure pertains to a configuration for joining a composite tube to an end fitting of a dissimilar material.
Composite materials have been used increasingly in a variety of industries, including the automotive, marine and aerospace industries. In these applications, composites often include strong fibrous materials, such as carbon, aramid, glass or quartz, bonded together with a resin, such as an epoxy. Composite materials generally possess a high strength to weight ratio in comparison to metals and plastics. These attributes enable composite items to be made lighter and/or stronger than conventional metal parts.
However, fabrication of composite items is relatively more complicated than metal fabrication. Generally, composite items are built up, layer upon layer on a mold or the fiber component is placed and then impregnated with resin. Afterward the item is cured and removed from the mold. While some shapes are relatively easy to generate in this manner, others are not. In addition, while composites are quite strong, they are generally not as tough as metals. Conventionally, when dissimilar qualities are to be combined in a single component, two materials are welded, glued, or otherwise joined together. For example, a dense plastic film may be glued to a foamed plastic to form a light, abrasion resistant material. Unfortunately, conventional adhesives and joining methods may not form adequate bonds when joining high strength carbon fiber composites to metals. Furthermore, many safety-critical bonded structures, such as primary aircraft structures, may be required to have redundant load paths which allow the structure to continue performing even if the primary adhesive bond fails.
Accordingly, it is desirable to provide a hybrid composite item that includes dissimilar materials joined together, where this joint is capable of overcoming the disadvantages described herein at least to some extent.
The foregoing needs are met, to a great extent, by embodiments the present disclosure, wherein in one respect a joint and method is provided that in some embodiments facilitates joining dissimilar materials together.
An embodiment relates to a fail-safe torque tube for an aircraft. The torque tube includes a composite body and an end fitting. The composite tube includes a body having a body interior diameter, wall thickness, an end having an edge, and a set of grooves. Each groove of the set of grooves passes through the wall thickness. Each groove of the set of grooves begins at the edge and ends in the body. The end fitting includes a sleeve configured to mate with the body interior diameter and a set of ribs configured to mate with the set of grooves.
Another embodiment pertains to a fail-safe torque tube for an aircraft. The torque tube includes a composite body and an end fitting. The composite tube includes a body having a body interior diameter, wall thickness, an end having an edge, and a set of grooves. Each groove of the set of grooves is disposed through a portion of the wall thickness. Each groove of the set of grooves begins at the edge and ends in the body. The end fitting includes a sleeve configured to mate with the body interior diameter and a set of ribs configured to mate with the set of grooves.
Yet another embodiment relates to a method of providing a fail-safe load path for a torque tube in an aircraft. In this method, a torque tube is provided, a first end of the torque tube is secured to a first aircraft component in a load path and a second end of the torque tube is secured to a second aircraft component in the load path. The torque tube includes a composite body and a pair of end fitting. The composite tube includes a body having a body interior diameter, wall thickness, an end having an edge, and a set of grooves. Each groove of the set of grooves passes through the wall thickness. Each groove of the set of grooves begins at the edge and ends in the body. The end fittings includes a sleeve configured to mate with the body interior diameter and a set of ribs configured to mate with the set of grooves.
There has thus been outlined, rather broadly, certain embodiments of the disclosure in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed device and method is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the various embodiments. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the various embodiments.
The present disclosure provides a device and method for providing a fail-safe torque tube to transmit torque along a load path of an aircraft. The torque tube device includes a composite tube body secured to metal end fittings. The composite tube body is relatively lighter than current metal tube bodies. The metal end fittings provide a durable connection between the torque tube and components attached to the torque tube. To join the composite tube body to the end fitting, an improved joint conformation is utilized. As described herein, an embodiment of this improved joint provides an efficient fail-safe connection between the torque tube and the end fitting. For the purpose of this disclosure, the term, “fail-safe” refers to a device, system, and method having a redundant feature. For example, as used herein, the term “fail-safe torque tube” refers to a torque transmission device with a redundant load path. As such, in the event of a failure in one load path, a second load path is configured to transmit torque.
In an aircraft, a torque tube may be utilized to transmit torque from a motor or other such actuator to a control surface actuator. The control surface actuator modulates the attitude of a control surface on the wing, for example, and is therefore of critical importance to the operation of the aircraft. As such, it is an advantage of embodiments described herein that a primary and secondary load path for the transmission of torque is provided.
The disclosure will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout.
The tube body 12 may include any suitable material. Examples of suitable materials include fiber reinforced plastics, metal foil and/or film reinforced plastics, and the like. Particularly suitable materials include, for example, carbon fiber reinforced plastic. The plastic matrix includes any suitable polymer such as, for example, epoxy and the like. The tube body 12 includes a first end 18 and a second end 20. The ends 18 and 20 include respective sets of grooves 22 and 24. The end fittings 14 and 16 include respective sets of ribs 26 and 28. For the sake of clarity, in the following description, an example will be made with reference to the end fitting 14 and end 18. It is to be noted that the following description of the end fitting 14 and end 18 may pertain to the end fitting 16 and end 20.
It is another advantage of the torque tube 10 that the joint or interface between the set of grooves 22 and the set of ribs 26 may augment the adhesive bond. For example, in the event that a portion of the adhesive bond delaminates, the ribs 26 to either side of the delaminating portion may prevent or reduce the likelihood that the bond delamination may propagate to other portions of the adhesive bond.
The adhesive 30 is configured to bond the end fitting 14 to the tube body 12. As such, in response to torque being applied to the end fitting 14, the resulting load is translated through the adhesive 30 to the tube body 12 and the tube body 12 is urged to rotate as indicated by arrow 32. This adhesive bond may thus be considered the primary load path. In the event the primary load path is compromised, the torque tube 10 includes a secondary load path shown in inset B. As shown in inset B, groove 22a includes bearing surfaces 34a and 34b and the rib 26a includes corresponding bearing surfaces 36a and 36b. The bearing surface 34a is configured to bear upon the bearing surface 36a. Similarly, the bearing surface 34b is configured to bear upon the bearing surface 36b. In this manner, torque may be translated between the tube body 12 and end fitting 14.
Also shown in inset B, the groove 22a may be fabricated slightly larger relative to the rib 26a. For example, to account for machining tolerances, a small gap may be anticipated. This gap may be preferable to binding caused by the groove 22a being relatively smaller than the rib 26a. The small gap between the bearing surfaces 36b and 34b may be filled with the adhesive 30 or any suitable shimming material. Examples of suitable shimming materials include metal and polymer shims, epoxy, epoxy thickened with cut fibers or powders, and the like. The expected loads exerted upon the adhesive 30 and/or shimming material disposed between the bearing surfaces 36b and 34b are compressive loads. As such, with regard to the secondary load path, the adhesive qualities of the adhesive 30 and/or shimming material disposed between the bearing surfaces 36b and 34b are unimportant. That is, failure of the adhesive 30 and/or shimming material disposed between the bearing surfaces 36b and 34b will not affect the integrity of the secondary load path.
Furthermore, the grooves 22a to 22c of
The many features and advantages of the disclosure are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the disclosure which fall within the true spirit and scope of the disclosure. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the disclosure.
This application claims priority to pending U.S. application Ser. No. 11/934,198 entitled JOINT FOR HYBRID COMPOSITE ITEMS and filed on Nov. 2, 2007, the entire contents of which is expressly incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11934198 | Nov 2007 | US |
| Child | 13427877 | US |
