Metal plated additively manufactured plastic rotor shrouds and their method of manufacturing

In one aspect, a rotor shroud for a rotary machine includes a disk portion extending along and oriented about a central axis of the rotary machine, a transition portion extending from the disk portion, and a flared portion extending axially from the transition portion. The disk portion, the transition portion, and the flared portion include a plastic substrate and metal plating disposed on at least apportion of an outer surface of the plastic substrate. The plastic substrate has a matrix material and fibers embedded in the matrix material. The fibers have a first coefficient of thermal expansion. The metal plating has a second coefficient of thermal expansion. The fibers are selected such that a bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating.

BACKGROUND

The present disclosure relates generally to aviation components and, more particularly, to metal-plated plastic rotor shrouds.

Metal-plated plastic aviation components have been developed as a lightweight, high-strength, alternative to metal components. Metal-plated plastic components include a plastic or plastic substrate coated with a metal plating on an outer surface. The metal plating increases the strength and abrasion resistance of the component. Metal-plated plastic components have been particularly attractive for use in gas turbine engine applications, where they can provide overall weight reduction of the engine to improve engine efficiency and provide fuel cost savings.

Limitations in use of metal-plated plastic components are generally due to poor adhesion between the metal plating and the plastic substrate, which reduces long-term component durability. Various methods of manufacture and mechanical locking features have been developed to improve an interfacial bond strength between the metal plating the plastic at variable temperatures, as separation of the metal plating can occur.

SUMMARY

In one aspect, a rotor shroud for a rotary machine includes a disk portion extending along and oriented about a central axis of the rotary machine, a transition portion extending from the disk portion, and a flared portion extending axially from the transition portion. The disk portion, the transition portion, and the flared portion include a plastic substrate and metal plating disposed on at least apportion of an outer surface of the plastic substrate. The plastic substrate has a matrix material and fibers embedded in the matrix material. The fibers have a first coefficient of thermal expansion. The metal plating has a second coefficient of thermal expansion. The fibers are selected such that a bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating.

A method of forming a rotor shroud for a rotary machine includes forming, by an additive manufacturing process, a plastic substrate having an outer surface, impregnating, by the additive manufacturing process, the plastic substrate with fibers having a first coefficient of thermal expansion, and applying a metal plating to the outer surface of the plastic substrate. The metal plating has a second coefficient of thermal expansion and the fibers are selected such that a bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating. The plastic substrate and the metal plating together form the rotor shroud having a disk portion extending along and oriented about a central axis of the rotary machine, a transition portion extending from the disk portion, and a flared portion extending axially from the transition portion.

DETAILED DESCRIPTION

The present disclosure is directed to metal-plated additively manufactured plastic aviation rotating shaft components with controlled thermal expansion behavior to reduce component damage caused by operation in environments of varying temperature or temperature gradients.

FIG.1is a simplified cross-sectional view of a portion of a metal-plated plastic component.FIG.1shows component10, substrate12, matrix14, fibers16, outer surface18, outer region20, inner region22, and metal plating24. Component10can be a rotating shaft component of a turbomachine, including but not limited to a thrust shaft, a compressor and fan shaft, or a turbine shaft. Substrate12has outer surface18, outer region20, and inner region22. Outer region20is adjacent to outer surface18. Inner region22is separated from outer surface18by outer region20. Substrate12includes matrix14and fibers16. Fibers16are embedded in matrix14. Metal plating24is disposed on outer surface18of substrate12.

Substrate12includes matrix14and fibers16. Matrix14is a plastic or polymer material. Matrix14can be a thermoplastic. Matrix14can include but is not limited to acrylonitrile butadiene styrene (ABS), polyetherimide (PEI), thermoplastic polyimide, polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polysulfone, polyamide, polyphenylene sulfide, polyester, polyimide, and combinations thereof. Matrix14can define a shape of substate12. Matrix14can be formed of a plurality of materials with individual materials selectively located in substrate12to provide desired material properties in different regions of component10. In some embodiments, substrate12can include one or more voids or open sections or structures, such as a hollow core or openings formed between internal support structures.

Fibers16are embedded in matrix14. Fibers16are selected and arranged to control a bulk coefficient of thermal expansion (CTE) of substrate12. Fibers16are selected and arranged in substrate12to reduce a CTE mismatch between substrate12and metal plating24. Substrate12with fibers16can be designed to have a bulk CTE substantially matching a CTE of metal plating24to prevent separation of metal plating24from outer surface18during operation of component10in varying temperatures. Fibers16can be selected and arranged to meet additional functional requirements of component10including stress reduction, deflection management, and containment as described further herein.

Matrix14can be formed of a material having a CTE greater than the CTE of metal plating24. Fibers16can be formed of material having a lower CTE than the CTE of matrix14to lower the bulk CTE of substrate12. Fibers16constrain thermal expansion of substrate12. Fibers16can include but are not limited to carbon, metal, para-aramid (e.g., Kevlar® and Twaron®), glass, and combinations thereof. In some embodiments, fibers16can be formed of the same material as metal plating24. In some embodiments, subsets of fibers16can be formed of different materials. Regions of substrate12can include fibers16formed of the same material or different materials. The combinations of materials forming matrix14and fibers16can vary throughout a component to provide desired material properties.

Fibers16can be continuous fibers, discontinuous fibers, or combinations thereof. Fibers16can have a filament diameter and length selected to minimize cracking of substrate12caused by separation at fiber-matrix interfaces. A concentration and arrangement of fibers16can be selected to provide substrate12with a bulk CTE substantially matching the CTE of metal plating24. As shown inFIG.1, fibers16can be substantially uniformly distributed throughout matrix14to provide an entirety of substrate12with a bulk CTE substantially matching the CTE of metal plating24. As discussed further herein, in some embodiments, fiber placement can be tailored to control a bulk CTE of one or more regions of substrate12.

Fibers16can be disposed to extend parallel to outer surface18and metal plating24and/or perpendicular or otherwise angled relative to metal plating24. Fibers16extending perpendicular to otherwise angled relative to metal plating24can extend through outer surface18. Fibers16protruding through outer surface18can improve a bond between metal plating24and substrate12. In some embodiments, a subset of fibers16can be disposed on or at outer surface18. For example, fibers16can form a portion of outer surface18with individual fibers16separated by matrix14. Fibers16disposed at outer surface18or protruding through outer surface18can be formed of a material capable of forming a high-strength bond with metal plating24. Fibers16disposed at outer surface18or protruding through outer surface18can thereby improve a bond between metal plating24and substrate12. For example, fibers16disposed at outer surface18or protruding through outer surface18can be formed of metal. In some embodiments, fibers16and metal plating24can be the same material. In some embodiments, a subset of fibers16formed of metal can be provided to improve bonding of metal plating24, while bulk CTE of substrate12can be controlled primarily by a subset of fibers16formed of another material (e.g., carbon, para-aramid, or glass).

Selection of fiber16material, geometry, orientation relative to metal plating24or outer surface18, and concentration can be made to provide substate12with an expansion rate in outer region20in a plane parallel to metal plating24not exceeding the expansion rate of metal plating24, while also improving a bond between substrate12and metal plating24. While it is particularly important to control CTE mismatch between substrate12and metal plating24at the interface and an adjacent region to prevent separation of metal plating24, it may not be necessary that all regions of substrate12have the same CTE as discussed further herein. In some embodiments, the composition of both fibers16and matrix14can vary from one region to another. The combination of materials can be selected to provide a desired bulk CTE and other material properties optimized for the operation of component10. Metal plating24is disposed on outer surface18. Metal plating can include but is not limited to chromium-nickel alloys or alloys containing at least one of nickel, cobalt, copper, iron, palladium, chromium, and cadmium. Metal plating24can be selected based on the operational environment of component10and performance requirements of component10, including but not limited to operating temperatures, vibrational impacts, environmental contaminants, impact requirements, etc. Metal plating can have a thickness selected to achieve a desired strength of component10while minimizing the amount of weight metal plating24adds to substrate12. Metal plating can have a thickness, for example, in a range of about 0.001 inches (0.0254 mm) to about 0.050 inches (1.27 mm). It may be desirable to provide metal plating24with a thickness outside of these ranges for some applications. Metal plating can be disposed directly on outer surface18of substrate12. Metal plating24can cover all or portions of outer surface18.

FIG.2is a simplified cross-sectional view of a portion of another embodiment of a metal-plated plastic component.FIG.2shows component30, substrate32, matrix34, fibers36, outer surface38, outer region40, inner region42, and metal plating44. Component30can be substantially similar to component10with the exception of the placement of fibers36. Matrix34and metal plating44can be substantially the same as matrix14and metal plating24of component10shown inFIG.1and described with respect thereto. As described further herein, portions of matrix34can be provided with or without fibers36. For example, some regions of substrate32can be formed of matrix34without fibers36.

Fibers36are embedded in matrix34. Fibers36are selected and arranged to control a bulk coefficient of thermal expansion (CTE) of substrate32, particularly in outer region40and outer surface38. Fibers36are selected and arranged in substrate32to reduce a CTE mismatch between substrate32and metal plating44. Substrate32with fibers36can be designed to have a bulk CTE, particularly in outer region40and at outer surface38, substantially matching a CTE of metal plating44to prevent separation of metal plating44from outer surface38during operation of component30in varying temperatures. As further described herein, fibers36can be selected and arranged to meet additional functional requirements of component30including stress reduction, deflection management, and containment as described further herein.

Fibers36can be arranged in a concentration gradient extending from inner region42to outer surface38with inner region42having a lower concentration of fibers36than outer region40. Inner region42can be defined as a region internal to component30and/or separated from outer surface38. Outer region40is disposed between inner region42and outer surface38and extending to outer surface38. In some embodiments, all or a portion of inner region42can be free of fibers36. The arrangement of fibers36in this manner (i.e., concentration gradient) can produce a variation in CTE of substrate12from inner region42through outer region40, however, the variation in CTE can be tailored to minimize an impact at outer surface38or the bond between metal plating44and substrate32.

Fibers36can include but are not limited to carbon, metal, para-aramid (e.g., Kevlar® and Twaron®), glass, and combinations thereof. In some embodiments, fibers36can be formed of the same material as metal plating44. In some embodiments, subsets of fibers36can be formed of different materials. Regions of substrate32can include fibers36formed of the same material or different materials. The combinations of materials forming matrix14and fiber16can vary throughout a component to provide desired material properties.

Fibers36can be continuous fibers, discontinuous fibers, or combinations thereof. Fibers36can have a filament diameter and length selected to minimize cracking of substrate32caused by separation at fiber-matrix interfaces. A concentration and arrangement of fibers36across inner region42and/or outer region40can be selected to provide substrate32with a bulk CTE at and adjacent to outer surface38substantially matching the CTE of metal plating44. As shown inFIG.2, fibers36can be provided in greatest concentration adjacent to outer surface38.

As described with respect toFIG.1, fibers36can be disposed to extend parallel and/or perpendicular or otherwise angled relative to outer surface38and metal plating44. Fibers36extending perpendicular to otherwise angled relative to metal plating44can extend through outer surface38. Fibers36protruding through outer surface38can improve a bond between metal plating44and substrate32. In some embodiments, fibers36can be disposed on or at outer surface38. For example, fibers36can form a portion of outer surface38with individual fibers36separated by matrix34. Fibers36disposed at outer surface38or protruding through outer surface38can be formed of a material capable of forming a high-strength bond with metal plating44. Fibers36disposed at outer surface38or protruding through outer surface38can thereby improve a bond between metal plating44and substrate32. For example, fibers36disposed at outer surface38or protruding through outer surface38can be formed of metal. In some embodiments, fibers36and metal plating44can be the same material. A subset of fibers36formed of metal can be provided to improve bonding of metal plating44, while bulk CTE of substrate32can be controlled primarily by a subset of fibers36formed of another material (e.g., carbon, para-aramid, or glass).

Selection of fiber36material, geometry, orientation relative to metal plating44or outer surface38, and concentration can be made to provide substate32with an expansion rate in outer region40in a plane parallel to metal plating44not exceeding the expansion rate of metal plating44, while also improving a bond between substrate32and metal plating44.

FIG.3is a flowchart of a method forming a metal-plated component according to the present disclosure.FIG.3shows method50. Step52includes forming, by an additive manufacturing process, a plastic substrate (e.g., substrate12or32) having an outer surface. The substrate can be formed by 3D plastic printing by depositing a matrix material, such as matrix materials14and34shown inFIGS.1and2and described with respect thereto.

Step54includes impregnating, by the additive manufacturing process, the substrate with fibers. Fibers can be fibers16and36shown inFIGS.1and2and described with respect thereto. As previously described, the fibers can be selected and arranged to provide desired material properties. Fibers can be co-extruded with the matrix material to form the substrate with fibers embedded in the matrix. The addition of fibers to the matrix material produces a substrate with a bulk CTE less than a CTE of the matrix material.

In some embodiments, fibers can be arranged in concentration and/or material gradients as previously described. Fiber arrangement can be controlled by the 3D printing process. In some embodiments, a dual nozzle can be used to extrude materials of different fiber compositions and/or fiber concentrations and selectively print the different material in different regions of the substrate. For example, step54can include selectively printing the fibers in a concentration gradient extending from an inner region of the plastic substrate to the outer surface of the plastic substrate, such that the concentration of fibers increases from the inner region toward the outer surface of the plastic substrate. In other embodiments, step54can include selectively printing the fibers in a region adjacent to the outer surface of the plastic substrate and/or at an angle relative to the outer surface and/or such that fibers protrude through the outer surface of the plastic substrate to improve bonding with a metal plating applied on the outer surface. In some embodiments, step54can include selectively printing the plastic substrate without the fibers (e.g., matrix material only) in an inner region of the plastic substrate.

Step56includes applying a metal plating to the outer surface of the substrate. Metal plating can be metal plating24and44shown inFIGS.1and2and described with respect thereto. The metal plating can be selectively applied to one or more locations on the outer surface (e.g., locations susceptible to damage by abrasion, etc.). The metal plating has a CTE substantially matching the bulk CTE of the substrate or bulk CTE of the substrate in a region adjacent to the outer surface of the substrate in the location metal plating is to be applied. The metal plating can be applied, for example by electroless plating. In some examples, a printer with a dual nozzle can be used to selectively print a catalyst material layer on all or portions of an outer surface of the substrate. For example, one nozzle can extrude the substrate material (matrix and fiber) and one nozzle can extrude the matrix material loaded with a catalyst. The metal plating can then be formed on the outer surface loaded with the catalyst through a process of electroless plating.

FIG.4is a cross-sectional view of turbomachine110, which can be a cabin air compressor. Alternatively, turbomachine110could be an air cycle machine or other rotary machine. Turbomachine110includes compressor section112, motor section114, tie rod116, compressor inlet housing118, compressor outlet housing120, motor housing122, variable diffuser124, rotor126, and rotor shroud128. Compressor inlet housing118includes inlet130and inlet duct132. Compressor outlet housing120includes outlet duct134and outlet136. Variable diffuser116includes backing plate140, inboard plate142, diffuser vanes144, drive ring146, drive ring bearing148, backup ring150, pinion152, and variable diffuser actuator154. Motor section114includes motor rotor160and motor stator162. Turbomachine110further includes first journal bearing170, first rotating shaft172, second journal bearing174, and second rotating shaft176.FIG.4also shows axis A.

Turbomachine110includes compressor section112and motor section114mounted on tie rod116. Tie rod116is configured to rotate about axis A. Compressor section112includes compressor inlet housing118and compressor outlet housing120that are connected to one another. Motor section114includes motor housing122, which is connected to compressor outlet housing120. Variable diffuser124is positioned between compressor inlet housing118and compressor outlet housing120. Rotor126is positioned between compressor inlet housing118and compressor outlet housing120. Rotor126is mounted on tie rod116, which rotatably connects rotor126and motor section114. Rotor shroud128is positioned radially outward from and partially surrounds compressor rotor126.

Variable diffuser116includes backing plate140, inboard plate142, diffuser vanes144, drive ring146, drive ring bearing148, pinion150, backup ring152, and variable diffuser actuator154. Backing plate140abuts compressor outlet housing120on a first side and inboard plate142on a second side. Inboard plate142abuts backing plate140on a first side and diffuser vanes144on a second side. Diffuser vanes144abut inboard plate142on a first side and rotor shroud128on a second side. Diffuser vanes144are configured to direct the compressed air from rotor126into outlet duct134. Drive ring146is positioned radially outward from rotor shroud128, and drive ring bearing148is positioned between driver ring146and rotor shroud128. Drive ring146abuts rotor shroud128on a first side and backup ring150on a second side. Backup ring150is positioned radially outward of rotor shroud128. Pinion152is connected to variable diffuser actuator154and is coupled to drive ring146. Pinion152permits control of variable diffuser116. Drive ring146is coupled to diffuser vanes144with pins, and as drive ring146is rotated it will drag diffuser vanes144and cause them to rotate.

Motor section114includes motor housing122, motor rotor160, and motor stator162. Motor housing122encases motor rotor160and motor stator162. Motor rotor160is disposed within motor stator162and is configured to rotate about axis A. Motor rotor160is mounted to tie rod116to drive rotation of tie rod116.

Motor rotor160of motor section114drives rotation of tie rod116, first rotating shaft172and second rotating shaft176in turbomachine110. Tie rod116and first rotating shaft172in turn rotate rotor126. The rotation of rotor126draws air into inlet130of compressor inlet housing118. The air flows through inlet duct132to rotor126and will be compressed by rotor126. The compressed air is then routed through variable diffuser116and into outlet duct134of compressor outlet housing120. The air then exits turbomachine110through outlet136of compressor outlet housing120and can be routed to another component of an environmental control system, such as an air cycle machine.

Turbomachine110further includes first journal bearing170, first rotating shaft172, second journal bearing174, and second rotating shaft176. First journal bearing170is positioned in compressor section112and is supported by compressor outlet housing120. First rotating shaft172extends between and rotates with rotor126and motor rotor160. Motor rotor160drives rotation of rotor126with first rotating shaft172. A radially outer surface of first rotating shaft172abuts a radially inner surface of first journal bearing170. Second journal bearing174is positioned in motor section114and is supported by motor housing122. Second rotating shaft176extends from and rotates with motor rotor160. A radially outer surface of second rotating shaft176abuts a radially inner surface of second journal bearing174.

Rotor shroud128includes body200with bore202extending through a center of body200. Body200has first side210and second side212opposite of first side210. InFIG.5, first side210is on a left side and second side212is on a right side. Body200also has radially inner end214and radially outer end216opposite of radially inner end214. Radially inner end214of body200defines bore202extending through body200of rotor shroud128.

Body200includes disk portion218extending from radially outer end216to transition portion220. Disk portion218is a generally flat and radially oriented portion of body200. Transition portion220extends from disk portion218to flared portion222. Transition portion220is curved with a first side connected to disk portion and a second side located radially inward towards radially inner end214and axially towards second side212. Transition portion220has a generally frustoconical shape with a wider portion at the first side that tapers to a narrower portion at the second side. Flared portion222extends from transition portion220axially away from disk portion218. Flared portion222flares radially outward moving axially away from transition portion220. Flared portion222is slightly thicker at second end212than where flared portion222attaches to transition portion220.

Flange224extends from a radially inner end of disk portion218on second side212. Flange224extends axially away from disk portion218towards flared portion222. Flange224includes grooves that are configured to receive O-rings to seal against other components of turbomachine110(as discussed in relation toFIG.6). Bolt holes228include a plurality of holes positioned around disk portion218. Bolt holes228extend through disk portion218from first side210to second side212.

Body200further includes outer surface240and fiber-reinforced plastic structure242. Outer surface240is a solid, continuous surface that surrounds fiber-reinforced plastic structure242in an interior of body200. Outer surface240can include metal plating (for example, metal plating24shown inFIG.1or metal plating44shown inFIG.2). The metal plating can be positioned on the entirety of or portions of outer surface240to help increase strength and reduce degradation of rotor shroud128from abrasives moving through turbomachine110(shown inFIG.4).

Fiber-reinforced plastic structure242can include a matrix (for example, matrix14and matrix34) and a fiber (for example, fiber16and fiber36). Fiber material and arrangement (e.g., orientation and density) can be selected as previously described to control the bulk CTE of fiber-reinforced plastic structure242and, particularly a CTE of fiber-reinforced plastic structure242in locations of rotor shroud128adjacent to locations where metal plating is provided on outer surface240to improve a bond between fiber-reinforced plastic structure242and metal plating. Additionally, fiber density can be increased in regions subject to deflection, increased stress during operation of turbomachine110, or for containing energy during a failure of other components of turbomachine110(for example, rotor126, shown inFIG.4).

Fiber density in fiber-reinforced plastic structure242can vary between regions of rotor shroud128. The embodiment ofFIG.5includes first region250, second region252, third region254, fourth region256, fifth region258, sixth region260, seventh region262, and eighth region264. First region250is a region of fiber-reinforced plastic structure242in disk portion218adjacent radially outer end216. Second region252is a region of fiber-reinforced plastic structure242in disk portion218surrounding bolt holes228. Third region254is a region of fiber-reinforced plastic structure242in disk portion218radially inward of bolt holes228and extending through transition portion220. Fourth region256is a region of fiber-reinforced plastic structure242in flange224extending from disk portion218. Fifth region258is a region of fiber-reinforced plastic structure242in flange224at a second side of flange224. Sixth region260is a region of fiber-reinforced plastic structure242in transition portion220adjacent radially inner end214and first side210of body200. Seventh region262is a region of fiber-reinforced plastic structure242in transition portion220adjacent radially inner end214and near flared portion222. Eighth region264is a region of fiber-reinforced plastic structure242extending from transition portion220and through flared portion222. Fiber content in fiber-reinforced plastic structure242may vary gradually or abruptly between regions. In the embodiment shown inFIG.5, second region252, fourth region256, sixth region260, and seventh region262have a greater density than first region250, third region254, fifth region258, and eighth region264.

Rotor shroud128is a metal-plated plastic component formed according to the present disclosure and including a fiber-reinforced matrix (also referred to as fiber-reinforced plastic structure242) as disclosed inFIGS.1and2and variations thereof. Fibers can be selected and arranged to control thermal expansion of the plastic component relative to the metal plating and a bulk thermal expansion coefficient of rotor shroud128to manage deflection of rotor shroud128during operation of turbomachine110. The metal plating on outer surface240can be disposed on one or more portions of rotor shroud128. In some embodiments, application of the metal plating can be limited to regions susceptible to damage from stress, deflection during operation, or needed for energy absorption (or containment) to reduce the weight of rotor shroud128.

Traditional rotor shrouds for rotary machines have solid cross-sections and are manufactured by casting and/or subtractive manufacturing processes, such as hogout. Additively manufacturing (for example, 3D printing) rotor shroud128allows fiber-reinforced plastic structure242to be used in rotor shroud128. Using fiber-reinforced plastic structure242in rotor shroud128allows rotor shroud128to have a reduced weight compared to traditional rotor shrouds. At the same time, rotor shroud128will have an equivalent strength as traditional rotor shrouds due to the increased strength of fiber-reinforced plastic structure242.

Turbomachine110has the structure and design as described above in reference toFIG.4. Rotor shroud128has the structure and design as described above in reference toFIG.5. Rotor shroud128is positioned radially outward from rotor126and partially surrounds rotor126. First side210of disk portion218of rotor shroud128is positioned adjacent to diffuser vanes144. Second side212of disk portion218of rotor shroud128is positioned adjacent to drive ring146. Bolts extend through backing plate140, inboard plate142, diffuser vanes144, and bolt holes228of rotor shroud128to connect backing plate140, inboard plate142, diffuser vanes144, and rotor shroud128. Bolts extend through drive ring146into rotor shroud128to connect rotor shroud128to drive ring146. Transition portion220of rotor shroud128is adjacent to and curves along blades of rotor126. Flared portion222of rotor shroud128extends into inlet duct132of compressor inlet housing118. Flange224of rotor shroud128has a radially outer surface that abuts drive ring bearing148. Flange224also has grooves to receive O-ring seals that are positioned against compressor inlet housing118.

Rotor shroud128has fourth region256of fiber-reinforced plastic structure242in flange224. Fourth region256is a deflection region of rotor shroud128, which is a region of rotor shroud128that is subject to deflection. As drive ring146rotates against drive ring bearing148, fourth region256of flange224is subject to deflection. Fourth region256of fiber-reinforced plastic structure242is an area of increased fiber density that aids in deflection management of rotor shroud128to reduce and prevent deflection of rotor shroud128, increasing the efficiency of turbomachine110.

Rotor shroud128has seventh region262of fiber-reinforced plastic structure242in transition portion220adjacent radially inner end214and near flared portion222. Seventh region262is a deflection region of rotor shroud128, which is a region of transition portion220of rotor shroud128that is subject to deflection. As rotor126rotates, seventh region262of transition portion220of rotor shroud128can be subject to deflection. Seventh region262of fiber-reinforced plastic structure242is an area of increased fiber density that aids in deflection management of rotor shroud128to reduce and prevent deflection of rotor shroud128, increasing the efficiency of turbomachine110.

Turbomachine110includes clearances between moving components (for example, rotor146) and non-moving components (for example, rotor shroud128). Clearance reduces contact between moving and non-moving components and resultant damage and/or failure of turbomachine110. Clearances account for deflections of both moving and non-moving components during operation of turbomachine110. More deflection and strain in components means larger clearances and reduced efficiency in turbomachine110caused by air leaks through the clearances. Reducing deflection by identifying deflection regions (for example, fourth region256and seventh region262of rotor shroud128) means clearances can be reduced, thereby increasing efficiency of turbomachine110. Reducing deflection can be accomplished by increasing stiffness (by increased density of fiber in fiber-reinforced plastic structure242or adding metal plating to outer surface240) in a region.

Rotor shroud128has second region252of fiber-reinforced plastic structure242in disk portion218surrounding bolt holes228. Second region252is a stress region of rotor shroud128, which is a region of rotor shroud128that is subject to and adapted to withstand high stress during operation of rotor shroud128. The high stress in stress regions of rotor shroud128, such as second region252, is a higher stress than stresses present in other regions of rotor shroud128. During operation of variable diffuser124, second region252will be subject to and adapted to withstand stress that transfers into disk portion218of rotor shroud128from the bolts extending through bolt holes228. Second region252of fiber-reinforced plastic structure242is an area of increased fiber density that aids in stress reduction during operation of turbomachine110to reduce the stress in second region252of rotor shroud128. Stress reduction at critical points of rotor shroud128leads to increased longevity of rotor shroud128.

Fourth region256is also a stress region of rotor shroud128, which is a region of rotor shroud128that is subject to adapted to withstand high stress during operation of rotor shroud128. The high stress in stress regions of rotor shroud128, such as fourth region256, is a higher stress than stresses present in other regions of rotor shroud128. As drive ring146rotates against drive ring bearing148, fourth region256of flange224is subject to adapted to withstand stress. Fourth region256of fiber-reinforced plastic structure242is an area of increased fiber density that aids in stress reduction during operation of turbomachine110to reduce the stress in fourth region256of rotor shroud128. Stress reduction at critical points of rotor shroud128leads to increased longevity of rotor shroud128.

Reducing stress in stress regions of rotor shroud128improves the longevity of rotor shroud128. Reducing the stresses at stress regions can reduce the failure rate of rotor shroud128as well as the failure rate of turbomachine110overall. During operation, these failures can damage components surrounding rotor shroud128and decrease aircraft and passenger safety. Reduced failure rates result in reduced repairs, down time, and operating costs.

Rotor shroud128has sixth region260of fiber-reinforced plastic structure242in transition portion220adjacent radially inner end214and first side210of body200. Sixth region260is an energy containment region of rotor shroud128, which is a region of rotor shroud128that is designed to absorb energy from failed components of turbomachine110. Sixth region260of transition portion220is positioned adjacent to blades on rotor126and needs to be designed to absorb energy from rotor126in the event of a failure of rotor126. Sixth region260of fiber-reinforced plastic structure242is an area of increased fiber density that aids in energy containment during operation of turbomachine110. Energy containment at critical points of rotor shroud128ensures safe operation of turbomachine110.

Increased energy containment is important to the safe operation of turbomachine110. If rotor126fails, rotor shroud128is positioned close to rotor126and designed to absorb the energy from a failed rotor126to protect other components of turbomachine110, portions of aircraft utilizing turbomachine110, and passengers on the aircraft from damage.

Rotor shroud128is one example of a rotor shroud in which variable fiber-reinforced plastic structure242can be used. In alternate embodiments, variable fiber-reinforced plastic structure242can be used in any suitable rotor shroud, for example a rotor shroud for a turbine rotor, having any design. Further, turbomachine110is one example of a turbomachinery or rotary machine in which rotor shroud128or any other rotor shroud with variable fiber-reinforced plastic structure242can be used. In alternate embodiments, rotor shroud128or any other rotor shroud with variable fiber-reinforced plastic structure242can be used in an air cycle machine or any other rotary machine.

The disclosed metal-plated plastic rotor shroud components with controlled thermal expansion behavior have an increased durability in environments of varying temperature or temperature gradients. Additional benefits of the disclosed metal-plated components include reduced weight, reduced costs, and faster design, manufacturing, and testing time. Additionally, plastic parts are not prone to static electric charging.

Any relative terms or terms of degree used herein, such as “substantially”, “essentially”, “generally”, “approximately” and the like, should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations, incidental alignment variations, transient alignment or shape variations induced by thermal, rotational or vibrational operational conditions, and the like. Moreover, any relative terms or terms of degree used herein should be interpreted to encompass a range that expressly includes the designated quality, characteristic, parameter or value, without variation, as if no qualifying relative term or term of degree were utilized in the given disclosure or recitation.

DISCUSSION OF POSSIBLE EMBODIMENTS

In one aspect, a rotor shroud for a rotary machine includes a disk portion extending along and oriented about a central axis of the rotary machine, a transition portion extending from the disk portion, and a flared portion extending axially from the transition portion. The disk portion, the transition portion, and the flared portion include a plastic substrate and metal plating disposed on at least apportion of an outer surface of the plastic substrate. The plastic substrate has a matrix material and fibers embedded in the matrix material. The fibers have a first coefficient of thermal expansion. The metal plating has a second coefficient of thermal expansion. A bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating.

The rotor shroud of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

In an embodiment of the rotor shroud of the preceding paragraph, the fibers are selected such that at least one of a fiber material, a fiber density, or a fiber orientation is selected so the bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating.

In an embodiment of the rotor shroud of the preceding paragraph the matrix material can have a third coefficient of thermal expansion, the third coefficient of thermal expansion greater than the first coefficient of thermal expansion of the fibers.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the first coefficient of thermal expansion of the fibers can be less than the second coefficient of thermal expansion of the metal plating.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the fibers can be selected from the group consisting of carbon, para-aramid, glass, metal, and combinations thereof.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the metal plating and the fibers can be the same material.

In an embodiment of the rotor shroud of any of the preceding paragraphs, a fiber density of the fibers embedded in the matrix material varies within the substrate.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the fiber density gradually transitions between the first region having a reduced fiber density and the one or more second regions having an increased fiber density.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the fiber density abruptly transitions between the first region having a reduced fiber density and the one or more second regions having an increased fiber density.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the regions of varying fiber density can include a first region having a reduced fiber density and one or more second regions having an increased fiber density. The one or more second regions can be a deflection region or a stress region of the rotor shroud. The deflection region is subject to deflections during operation of the rotary machine and the stress region subject to and adapted to withstand higher stress than other regions of the rotor shroud during operation of the rotary machine. The energy containment region is configured to contain energy of failed components of the rotary machine.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the stress region and the deflection region are a flange extending axially outward from the disk portion of the rotor shroud.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the flange extends axially toward the flared portion.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the stress region is a region surrounding a plurality of bolt holes through a radially outer portion of the disk region of the rotor shroud.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the stress is a region of the transition portion adjacent to the flared portion of the rotor shroud.

In an embodiment of the rotor shroud of any of the preceding paragraphs, wherein the energy containment region is a region of the transition portion adjacent a first side and a radially inner end of the rotor shroud.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the energy containment region is a curved region of the transition portion.

In an embodiment of the rotor shroud of any of the preceding paragraphs, an outer region disposed adjacent to the metal coating has an increased fiber density.

In an embodiment of the rotor shroud of any of the preceding paragraphs, the fibers of the outer region protrude through the outer surface of the plastic substrate.

In an embodiment of the rotor shroud of any of the preceding paragraphs, fibers of the plurality of fibers can be angled with respect to the outer surface in the outer region.

A method of forming a rotor shroud for a rotary machine includes forming, by an additive manufacturing process, a plastic substrate having an outer surface, impregnating, by the additive manufacturing process, the plastic substrate with fibers having a first coefficient of thermal expansion, and applying a metal plating to the outer surface of the plastic substrate. The metal plating has a second coefficient of thermal expansion and the fibers are selected such that a bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating. The plastic substrate and the metal plating together form the rotor shroud having a disk portion extending along and oriented about a central axis of the rotary machine, a transition portion extending from the disk portion, and a flared portion extending axially from the transition portion.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, additional components, and/or steps:

In an embodiment of the method of any of the preceding paragraphs, the step of impregnating can include selectively printing the fibers to vary a fiber density in the plastic substrate.

In an embodiment of the method of any of the preceding paragraphs, to form a region of increased fiber density adjacent to the portion of the outer surface of the plastic substrate to which the metal plating is applied.

In an embodiment of the method of any of the preceding paragraphs, the step of impregnating can include selectively printing fibers at an angle relative to the portion of the outer surface to which the metal plating is applied.

In an embodiment of the method of any of the preceding paragraphs, the plastic of the plastic substrate can have a third coefficient of thermal expansion, the third coefficient of thermal expansion greater than the first coefficient of thermal expansion of the fibers.

In an embodiment of the method of any of the preceding paragraphs, the first coefficient of thermal expansion of the fibers can be less than the second coefficient of thermal expansion of the metal plating.

In an embodiment of the method of any of the preceding paragraphs, the fibers can be selected from the group consisting of carbon, para-aramid, glass, metal, and combinations thereof.