GE Aviation’s GEnx Engine Made Better With Braid

Powering Boeing’s 787-8, -9, -10 and Boeing’s 747-8, the GEnx is the most fuel efficient, quiet, and low-emissions jet engine that GEAE has ever introduced for large jet aircraft.

One of the reasons for the GEnx engine’s efficiency is its braided jet engine fan case by A&P Technology.

Like metal, a braid with an isotropic architecture provides properties that are the same in all directions. These isotropic layers of braid provide better impact and better fatigue properties than other materials while greatly reducing manufacture times.

In a typical woven tape lay-up, layers are stacked one on top of another to tailor the properties of the laminate to best withstand the loads to which it will be subjected. This mismatch of individual ply stiffness results in a variance in layer stress and strain that causes the laminate to fail in such a way that post-impact load-carrying ability is greatly reduced.

With braid, however, this mismatch between plies does not occur. The interwoven 0°, +/-60° fibers within each layer of braid, which distribute load evenly, along with the isotropic architecture offered within each individual ply, provide braid with a unique resistance to crack propagation. Since each ply is isotropic within itself and identical to each neighboring ply, any interlaminar stresses are minimized during response to an impact event and the crack growth is contained to an area substantially smaller than those found upon impact of a much-heavier aluminum case.

These containment properties have been proven with the GEnx engine fan case by GE Aviation. In this case, the use of braid provides 30% better containment properties along with a weight savings of 350 pounds per engine, or 700 pounds in the case of a twin-engine aircraft. With braid, the weight of the twin-engine installation and retention features can be further reduced by as much as 100 pounds.

This increase in performance, combined with substantial weight savings, is the reason braided composites are playing an increasingly significant role in the manufacture of primary and impact critical aircraft structures. These structures include airplane fuselage frames, fuselage skins, stringers, flaps, and ailerons.

Sheet Molding Compound Made Better with Braid

IDI Composites offers Fortium SMC and QISO in a chemically matched prepreg for use in high stress areas with complex geometries. By inserting layers of 0°, +/-60° QISO, useage of SMC can be decreased – increasing strength, and reducing mass, cost and waste.

Fortium™ is discontinuous fiber-reinforced composite with field proven resilience to UV radiation and chemicals. QISO^®is a 0°, +/-60° fabric providing increased strength, impact resistance, and ease of manufacture. QISO is balanced and symmetric in a single layer so cutting is not a concern and nesting is optimized. Co-molding Fortium™ and QISO^®optimizes part performance and minimizes waste.

The Combination

Fortium SMC and Fortium QISO have the same fiber loading by weight simplifying design parameters, ie. for high stress areas one layer of QISO can be used to replace one layer of SMC until mechanical requirements are met.

Fortium QISO cuts as easily as SMC, lays in the tool the same way and cures the same – simplifying manufacture of parts. QISO’s quasi-isotropic architecture has the same properties in every direction, so nesting is improved further minimizing waste.

Fortium QISO enables the production of lighter, higher performing parts and can be molded in both simple and complex geometries. In the example below, key stress areas of a truck bed typically manufactured using only SMC were produced using Fortium QISO.

Two QISO charges were laid over SMC on the B side of a deep draw tool. Even though the SMC was laid down first, the QISO stayed in place allowing the SMC to fully flow around it.

Preliminary trials of Fortium QISO were also conducted in larger scale tooling further demonstrating its moldability to create rib structures and its ability to conform to complex structures.

Property	Fortium F250-UV (SMC)	Fortium QISO
Glass Fiber	48-52%	48-52%
Specific Gravity	1.7 – 1.8	1.7 – 1.8
Sheet Weight	5.4 kg/m²	2 kg/m²

Impact Testing shows major improvement using Fortium + QISO

Performance

Impact Testing of an SMC baseline panel and a 20% thinner SMC panel reinforced with QISO shows major improvement with Fortium QISO:

Same Tensile Strength
25% Higher Flex Strength
Improved Impact Resistance

Fortium QISO Improves Part Performance, Reduces Part Thickness and Conforms to Complex Geometries

For more detailed information about this case study, visit https://www.youtube.com/@aptechnologyinc

Honeywell Jet Engine Guide Vanes made BETTER WITH BRAID

A good example of braided preforms created to support high volume applications are the braided stator vane preforms produced for Honeywell jet engine exit guide vanes. A&P produces over 30,000 stator vane preforms a year, closing in on the production of a million total.

net shape braided preform — Braided Preform

net shape molded braided part — Molded Stator Vane

Fan exit guide vanes on turbojet engines are stationary; however, they must endure the pounding of adjacent rotating fan blades while remaining resistant to foreign object damage (FOD). Therefore, precise airfoil shape and high fatigue strength are primary factors in designing and producing stator vanes.

Vanes molded using braided carbon fiber exceed the fatigue and other performance requirements of vanes made with unidirectional carbon prepreg while dramatically reducing part cost. Best of all, braided vanes can be perfectly tailored to the shape of the mold, significantly increasing throughput at the molder.

A&P Technology specially braids the preforms by braiding an aramid preform to shape and then over-braiding the aramid with a carbon fiber shaped sleeve. Braiding angles are precisely controlled to allow for thickness variations in the airfoil shapes. The resulting sleeve, thick in the center portion and thin at the edges, is trimmed to length at A&P Technology. Then, the molder places the preforms in a multi-cavity RTM tool. Once the mold is closed, epoxy resin is injected and cured. The resulting vane is ready for use with only minor trim and deflash operations.

Inflatables Made BETTER WITH BRAID

HDT Global, Inc utilizes A&P’s braid for AirBeam® structures used for framing aircraft maintenance hangars for the U.S. Air Force. Traditionally, metal frames requiring a lot of time and labor to build are used to construct the shelters. HDT Global’s high-pressure AirBeam® structures offer a more cost-effective, more efficient, safer alternative to metal frames.

HDT Global’s AirBeam® structures are based on innovative manufacturing technology that exploits the unique properties of braid by creating a layer of highly oriented fiber reinforcement that is, in effect, a flexible composite structure. Multiple fiber angles are used to create a completely determinant structure giving the beam extremely high strength, high bending stiffness, and high inflation pressure.

HDT Global’s AirBeams® frames are highly structural and damage tolerant with benign failure modes. They are also extremely overload tolerant. When loads exceed the shelter design’s load the beams deflect, but no permanent damage is incurred; when the load is removed, the beams return to their original shape with full load capability. The AirBeam® frames also have large inflation margins, the amount by which the beam can be over-inflated without damage. All AirBeam® structure designs are tested to 300% of their working pressure. If punctured by sharp objects or small firearms, the beams will not decompress explosively. Instead, they fail gracefully, allowing for easy repair.

Tough, flexible, and easily repaired, A&P braid helps make HDT Global’s AirBeams® the perfect choice for the U.S. Air Force.