BACKGROUND

Field of the Disclosure

The examples described herein relate to apparatus, systems, and methods of stiffened carbon fiber reinforced polymer (CFRP) composite side of body ribs.

Description of the Related Art

Present side of body ribs installed connected to the wing box of an aircraft are typically a monolithic or built-up aluminum rib configuration. One reason for the use of an aluminum side of body rib is to match the thermal expansion of the wing box, which also was typically aluminum. However, aluminum side of body ribs potential present a thermal expansion mismatch for aircraft that utilizes a CFRP wing box. The wing side of body rib of aircraft often experience high fatigue loads, which may result in a side of body rib made of aluminum that is not cost effective due to the added weight required to meet the high fatigue load requirements. The use of an aluminum side of body rib may be inefficient and/or too costly when used in combination with a CFRP wing box. Other disadvantages may exist.

SUMMARY

The present disclosure is directed to apparatus, systems, and methods of stiffened CFRP side of body ribs.

One example of the present disclosure is an apparatus that includes an aft CFRP rib web, a middle CFRP rib web, and a forward CFRP rib web. The apparatus includes a plurality of stiffeners, wherein individual stiffeners of the plurality of stiffeners are connected to the aft CFRP rib web, the middle CFRP rib web, or the forward CFRP rib web. The aft CFRP rib web and the middle CFRP rib web are connected to a first stiffener of the plurality of stiffeners. The middle CFRP rib web and the forward CFRP rib web are connected to a second stiffener of the plurality of stiffeners. The aft CFRP rib web, the middle CFRP rib web, and the forward CFRP rib web form a side of body CFRP rib assembly.

The individual stiffeners of the plurality of stiffeners may be connected to the aft CFRP rib web, the middle CFRP rib web, or the forward CFRP rib web via fasteners or being co-bonded or co-cured with the CFRP rib webs. The first stiffener may be a first aluminum T-shaped stiffener having a first aft flange and a first forward flange. Fasteners may connect the aft CFRP rib web to the first aft flange and fasteners may connect the middle CFRP rib web to the first forward flange. The second stiffener may be a second aluminum T-shaped stiffener having a second aft flange and a second forward flange. Fasteners may connect the middle CFRP rib web to the second aft flange. Fasteners may connect the forward CFRP rib web to the second forward flange.

The fasteners may be interference fit fasteners. An exterior of the interference fit fasteners may include stripes of a coating separated by non-coated stripes. The side of body CFRP rib assembly may have a longitudinal length with each of the plurality of stiffeners being substantially perpendicular to the longitudinal length. The plurality of stiffeners may include stiffeners comprised of a first material and stiffeners comprised of a second material that differs from the first material. The first material may be aluminum and the second material may be a thermoset or a thermoplastic. The aluminum stiffeners may include T-shaped stiffeners and J-shaped stiffeners. The thermoplastic or thermoset stiffeners may comprise Z-shaped stiffeners. The thermoplastic or thermoset stiffeners may comprise L-shaped stiffeners connected to Z-shaped stiffeners. The plurality of stiffeners may include at least a first shape and a second shape. The first shape may be a J-shaped stiffener and the second shape may be a T-shaped stiffener.

One example of the present disclosure is a system that includes a CFRP wing box and a side of body CFRP rib assembly having a longitudinal length connected to the CFRP wing box. The side of body CFRP rib assembly includes an aft CFRP rib web connected to a middle CFRP rib web connected to a forward CFRP rib web. The system includes a plurality of stiffeners connected to the side of body CFRP rib assembly, wherein the individual stiffeners of the plurality of stiffeners are substantially perpendicular to the longitudinal length.

The system may include an upper chord connected to the CFRP wing box, a lower chord connected to the CFRP wing box, a rear spar fitting connected to the CFRP wing box, and a front spar fitting connected to the CFRP wing box. The aft CFRP rib web may be connected to the CFRP wing box via being connected to the upper chord, rear spar fitting and the lower chord. The middle CFRP rib web may be connected to the CFRP wing box via being connected to the upper chord and the lower chord. The forward CFRP rib web may be connected to the CFRP wing box via being connected to the upper chord, the front spar fitting, and the lower chord.

The system may include a plurality of interference fit fasteners having an exterior that has stripes of coating separated by non-coated stripes. A first portion of the plurality of interference fit fasteners may be connected the aft CFRP rib web to the upper chord, rear spar fitting, and lower chord. A second portion of the plurality of interference fir fasteners may connect the middle CFRP rib web to the upper chord and the lower chord. A third portion of the plurality of interference fit fasteners may connected the forward CFRP rib web to the upper chord, the front spar fitting, and the lower chord.

The plurality of stiffeners may include aluminum J-shaped stiffeners connected to the aft CFRP rib web. The plurality of stiffeners may include a first aluminum T-shaped stiffener connected to both the aft CFRP rib web and the middle CFRP rib web. The plurality of stiffeners may include a second aluminum T-shaped stiffer connected to both the middle CFRP rib web and the forward CFRP rib web. The plurality of stiffeners may include thermoplastic stiffeners connected to the middle CFRP rib web. The plurality of stiffeners may include thermoplastic stiffeners connected to the forward CFRP rib web. The thermoplastic stiffeners may be Z-shaped stiffeners or C-channel shaped stiffeners. The thermoplastic stiffeners may be L-shaped stiffeners connected to Z-shaped stiffeners.

One example of the present disclose is method that includes providing an aft carbon fiber reinforced polymer (CFRP) rib web, a middle CFRP rib web, and a forward CFRP rib web. Various process may be used to provide the aft CFRP rib web, the middle CFRP rib web, and the forward CFRP rib web. For example, the method may include forming a side of body CFRP rib web and separating the side of body CFRP rib web into an aft CFRP rib web, a middle CFRP rib web, and a forward CFRP rib web. The method includes connecting stiffeners to the aft CFRP rib web, connecting stiffeners to the middle CFRP rib web, and connecting stiffeners to the forward CFRP rib web. The stiffeners include stiffeners comprised of a first material and stiffeners comprising of a second material that differs from the first material.

The method may include connecting the aft CFRP rib web to a wing box and connecting the forward CFRP rib web to the wing box, wherein an opening is formed between the aft CFRP rib web and the forward CFRP rib web. The method may include connecting the middle CFRP rib web to the wing box. The method may include connecting the middle CFRP rib web to a first T-shaped aluminum stiffener to connect the middle CFRP rib web to the aft CFRP rib web via the first T-shaped aluminum stiffener. The method may include connecting the middle CFRP rib web to a second T-shaped aluminum stiffener to connect the middle CFRP rib web to the forward CFRP rib web via the second T-shaped aluminum stiffener.

