Abstract:
A method of defining a rib structure within an iso-grid composite component according to an exemplary aspect of the present disclosure includes, among other things, defining a first rib at least partially with a uni-tape ply bundle at a first level, the uni-tape ply bundle including uni-tape plies and a first spacer ply, and defining a second rib transverse to the first rib at least partially with a spacer at the first level, the spacer including a second, different spacer ply, the spacer transverse to the uni-tape ply bundle such that the spacer is interrupted by the uni-tape ply bundle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 12/892,014, filed Sep. 28, 2010. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    This disclosure was made with Government support under N00019-02-C-3003 awarded by The United States Air Force. The Government has certain rights in this invention. 
     
    
     BACKGROUND 
       [0003]    The present disclosure relates to an iso-grid composite component and more particularly to gas turbine engines having convergent/divergent nozzles with iso-grid composite components. 
         [0004]    A variable area exhaust nozzle optimizes the thrust produced within a gas turbine engine. In augmented gas turbine engines, convergent/divergent (C/D) nozzles provide a multitude of nozzle positions. The term “convergent-divergent” describes an exhaust nozzle having a convergent section upstream of a divergent section. Exhaust gases exiting the turbine section pass through the decreasing diameter convergent section before passing through the increasing diameter divergent section. 
         [0005]    The convergent section is pivotally connected to an exhaust duct structure and to the divergent section. The divergent section is pivotally connected to the convergent section and to an external fairing positioned radially outboard of the divergent section. The upstream end of the external fairing is pivotally attached to an outer static structure to provide an outer aerodynamic surface for the C/D. The convergent, divergent, and external fairing sections generally include flaps and seals to accommodate changes in the nozzle variable orifice area and axis skew (if the nozzle is vectorable) by sliding relative to and overlapping each other as the orifice area decreases or increases. 
         [0006]    The flaps and seals are often manufactured of carbon fiber composites which incorporate either monocoque constructions (consistent thickness part) or hollow rib reinforcements. Although effective, these techniques may require significant weight or design space. 
       SUMMARY 
       [0007]    An iso-grid composite component according to an exemplary aspect of the present disclosure includes a spacer transverse to a uni-tape ply bundle, the spacer interrupted by the uni-tape ply bundle. 
         [0008]    An iso-grid composite component according to an exemplary aspect of the present disclosure includes a multiple of uni-tape ply bundles, each of the multiple of uni-tape ply bundles at different levels within a rib pattern such that each uni-tape ply bundle within a level of a first rib of the rib pattern is uninterrupted by a spacer which at least partially defines a second rib of the rib pattern transverse to the first rib at the respective level. 
         [0009]    A method of defining a rib structure within an iso-grid composite component according to an exemplary aspect of the present disclosure includes defining a first rib at least partially with a uni-tape ply bundle at a first level and defining a second rib transverse to the first rib at least partially with a spacer at the first level, the spacer interrupted by the uni-tape ply bundle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0011]      FIG. 1  is a general perspective view of a variable geometry C/D exhaust nozzle of the present invention with the nozzle shown in a minimum dilated position; 
           [0012]      FIG. 2  is a general partial sectional side view of a variable geometry C/D exhaust nozzle of the present invention with the nozzle shown in a minimum dilated position which corresponds with  FIG. 1 ; 
           [0013]      FIG. 3  is an outer perspective view of an external flap manufactured of composite materials in an iso-grid construction according to the present disclosure; 
           [0014]      FIG. 4  is an inner perspective view of the external flap of  FIG. 3  manufactured of composite materials in an iso-grid construction according to the present disclosure; 
           [0015]      FIG. 5  is an inner perspective view of the external flap illustrating a multiple of lateral ribs and longitudinal ribs formed from a multiple of uni-tape ply bundles and spacers in which only the spacers are interrupted, the iso-grid construction shown without interstitial ply layer between each level of the multiple of uni-tape ply bundles and spacers; 
           [0016]      FIG. 6  is an exploded view of the layup which provides a multiple of uni-tape ply bundles and spacer levels which define the ribs and the interstitial ply layers which separate the multiple of uni-tape ply bundles and spacer levels; and 
           [0017]      FIG. 7  is an exploded view of a single uni-tape ply bundle. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1  schematically illustrates a convergent/divergent (C/D) nozzle system  20  for a gas turbine engine. The nozzle system  20  is movable between a minimal dilated position ( FIG. 1 ), which is typical during non-afterburning operation and a maximum dilated position (not shown), which is typical during afterburning operation. 
         [0019]    The nozzle system  20  generally includes a plurality of circumferentially distributed convergent flaps  22 , each pivotably connected to a nozzle static structure  24 . A plurality of circumferentially distributed divergent flaps  28  are pivotably connected through a joint structure  30  to adjust an aft end section of each convergent flap  22 . A plurality of convergent seals  32  are each pivotally connected to a respective divergent seal  34  which are respectively distributed circumferentially between each divergent flap  28  and convergent flap  28  sets. Each convergent seal  32  is pivotably connected to the static structure  24  with each divergent seal  34  pivotably connected through a joint structure  36  adjacent an aft end section of each convergent seal  32 . The convergent and divergent flaps  22 ,  28  and the convergent and divergent seals  32 ,  34 , taken collectively, define the radial outer boundary of a combustion gas path F to define a convergent section  38  and a divergent section  40  with a throat area  42  defined therebetween ( FIG. 2 ). 
         [0020]    With reference to  FIG. 2 , an outer aerodynamic surface of the nozzle system  20  is defined by a plurality of external flaps  50  ( FIGS. 3 and 4 ). Each of the plurality of external flaps  50  pivot relative a respective divergent flap  28  about a pivot axis  52  defined by an external flap hinge  54  ( FIG. 4 ). Each of the plurality of external flaps  50  also slide relative the nozzle static structure  24  through track arms  56  ( FIG. 4 ). The plurality of external flaps  50 , taken collectively, define an outer aerodynamic surface of the nozzle system  20  and accommodate movement between the maximum dilated position and the minimal dilated position through sliding movement relative the static structure  24  and overlapping movement between adjacent external flaps  50 . 
         [0021]    With reference to  FIG. 5 , each external flap  50  includes an iso-grid construction ( FIG. 6 ) that alternatively interrupts the internal load paths within a multiple of lateral ribs  60  and longitudinal ribs  62  so as to prevent an internal thermal fight which would heretofor cause internal dissolution of the component. In one non-limiting embodiment, the external flap  50  includes four longitudinal ribs  62 - 1 - 62 - 4  and five lateral ribs  60 - 1 - 60 - 5 . It should be understood that the particular rib arrangement is related to the desired shape of the component such as the external flap  50 . Although the iso-grid construction is illustrated herein with regards to an external flap  50  in accords with one non-limiting embodiment, it should be realized that any composite iso-grid structure will benefit herefrom. It should also be understood that although relatively rectilinear iso-grid geometry is illustrated, other geometries are usable herewith. 
         [0022]    With reference to  FIG. 6 , the multiple of lateral ribs  60  and longitudinal ribs  62  of the iso-grid construction are formed from a multiple of uni-tape ply bundles  70  and spacers  72  in which only the spacers  72  are interrupted. In one non-limiting embodiment, each uni-tape ply bundle  70  is a buildup of four (4) uni-tape plies  74 - 1 ;  74 - 2 ; 74 - 3 ;  74 - 4  and one spacer ply  76  such that the spacer ply  76  separates two (2) uni-tape plies  74 - 1 ;  74 - 2  from two (2) uni-tape plies  74 - 3 ;  74 - 4  ( FIG. 7 ). Two (2) uni-tape plies  74  are generally of an equivalent height to one spacer ply  76  such that one (1) uni-tape ply bundle  70  is of an approximate equivalent height to three (3) spacer plies  76  within each of the ribs  60 ,  62 . Generally, no more than 4 uni-tape plies are located adjacent to each other and the middle spacer ply  76  of the uni-tape ply bundle  70  may be oriented at a 45° direction to the associated uni-tape ply  74  direction. 
         [0023]    The iso-grid composite component construction makes use of the higher strength uni-tape plies  74  to build up strong and low weight internal ribs  60 ,  62 . Internal thermal fights between transverse uni-tape plies  74  are avoided by selectively alternating each uni-tape ply bundle  70  at different heights within the rib pattern such that when one un-interrupted uni-tape ply bundle  70  is within one level of the longitudinal rib  62 , the lateral rib  60  transverse thereto is defined by a spacer  72  which is interrupted at that level. At an adjacent level, the uni-tape ply bundle  70  runs un-interrupted within the lateral rib  60  while the longitudinal rib  62  at the same level includes the interrupted spacer  72 . That is, each uni-tape ply bundle  70  runs un- interrupted regardless of the level or direction for that particular uni-tape ply bundle  70 . It should be understood that any number of levels may be provided to build up the particular iso-grid component such as the disclosed external flap  50 . 
         [0024]    In addition, each level of uni-tape ply bundles  70  and spacers  72  which form the multiple of lateral ribs  60  and longitudinal ribs  62  may be separated by an interstitial ply layer  80 . Each interstitial ply layer  80  may itself be a layup of any number of spacer plies such as fabric plies which are arranged at particular relative angular orientations. It should be understood that any number of such plies may be so utilized between the multiple of lateral ribs  60  and longitudinal ribs  62 . 
         [0025]    The uni-tape ply bundles  70  are uninterrupted and the spacers  72  are utilized to equalize height such that the uni-tape ply bundles  70  within the lateral ribs  60  and longitudinal ribs  62  do not directly overlap to form uni-tape ply “bumps” at intersections between the lateral ribs  60  and longitudinal ribs  62 . That is, transverse uni-tape ply bundles  70  are separated and spaced by the spacers  72  so that a constant height is maintained as Applicant has determined that such “bumps” may result in delamination regions since uni-tape has an inherent difference in thermal growth along the fiber direction as compared to across the fiber direction. Typical differences in this thermal growth approach 20 times such that the thermal expansion at a “bump” in conventional rib layups in which uni-tape directly overlaps and forms a “bump” may often result in delaminating and potential internally generated destruction of the layup. Moreover, Applicant has determined that the spacers  72  cushion and accommodate the thermal expansion which results in a robust but relatively light weight component. 
         [0026]    The iso-grid construction is lighter than monocoque constructions as uni-tape fibers can be placed to selectively follow the load paths. The iso-grid construction is also considerably more compact in the thickness direction than top hat hollow rib construction which facilitates usage in confined regions such as C/D nozzles as well as various other components. 
         [0027]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
         [0028]    Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0029]    The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.