Patent Abstract:
A coupon fabrication with defined distortion in the form of marceled fibers and test protocol is employed to determine the shape of the failure probability density curve to improve the analyses of the risk of fiber distortion anomalies in composite structures. This protocol provides a method to determine the probability of and the severity of the various distorted fiber conditions that might exist on composite structure in fabrication and in service. A distortion characterization matrix is established for determining test shapes and providing defect characterization based on the results of tests on the selected shapes. Coupons for test are created using resin pool.

Full Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to the field of testing for failure criteria determination in composite matrices and more particularly to a protocol including a method for coupon fabrication and testing to determine failure characteristics in multi-ply composite systems with templates for distortion comparison and disposition. 
   2. Description of the Related Art 
   Composite fabrication aircraft and helicopter structural systems requires high reliability for safety of flight elements. Testing for various voids or distortions in the plies of composite materials such as glass reinforced fiber composites and related determinations of engineering quality dispositions for anomalies that are located requires repeatable techniques for development of a database for use in such review. As an example, fiber distortions occur in helicopter rotor blade spar straps near critical root end stations. This area is critical because it is a force concentration area during the operation of the rotor blade. Any degradation of strength in that area is of concern. 
   The fiber distortion anomalies are detectable through various testing techniques such as X-ray. However, since no repair is possible upon detection of distorted fibers in the root end as in many other critical structural components in aircraft and helicopters, the disposition can only be “use as is” or “scrap” depending on the severity of the distorted fibered composite. In the specific example this is particularly true if it occurs in the critical blade root end. Current procedures have allowed a number of the blades to be dispositioned “use as is” following careful case-by-case evaluation. 
   Current fatigue and crack propagation models and statistical analysis methods employed in analyzing composite anomalies use the Miners Rule or the later fatigue model by Birnbaum-Saunders. Both are models for crack propagation in metal. No current models for glass reinforced composite materials are available. Some limited experimentation has been performed at the University of Akron, Cambridge University and numerous papers are available on the development of finite element models, for example Pratt, W. F. and Allen, M. S.  Patterned Fiber Composites, Inc. Characterization and finite element model correlation of wavy composites ; Caiazzo, A. and Orlet, M., McShane, H., Strait, L., and Rachau, C.  The effects of marcel defects on composite structural properties . Little has been done in the development of empirical data for the determination of the shape of the failure curve for glass reinforced composite with marceled conditions. 
   It is therefore desirable to provide consistent and repeatable data for characterization of marceled conditions and their impact on the life of rotor blades and other crack-prone parts made from the same or similar material. Such information is desirable to catalog the physical properties for use in engineering disposition of comparable anomalies identified in production components and to validate the current inspection routines in the composite shop and also to calculate the risk to fielded rotorcraft and/or determine the impact on the manufacturing processes creating rotor blade root ends. 
   SUMMARY OF THE INVENTION 
   The embodiments disclosed herein for the present invention provide a coupon fabrication technique with defined distortion in the form of marceled fibers and test protocol to determine the shape of the failure probability density curve to improve the analyses of the risk of fiber distortion anomalies in composite structures. This protocol provides a method to determine the probability of and the severity of the various distorted fiber conditions that might exist on the rotor blades for the exemplary application in the future and those that are currently in fabrication and in service. 
   The response variable data and analyses information provided by the invention enables operations and quality personnel to make better informed decisions during production operations and at inspection points during the production and at final buy off of composite structural components using comparative standards derived from the distortion shapes employed in the coupon testing protocol. 
   The determination of the failure characteristics instigated by distorted fibers in the material also enables improvements to the design of future composite structures. The data provided by the invention and associated finite element analyses which can be conducted based on the test protocol enhances engineering decision-making ability and add to the knowledge of composite materials engineering, stress engineering, quality engineering and composite testing and quality verifications. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
       FIG. 1   a  is side view of a test coupon defined according to the protocol of the present invention; 
       FIG. 1   b  is a front view of the test coupon of  FIG. 1   a;    
       FIG. 1   c  is a front view of an exemplary test coupon with added gripping pads; 
       FIG. 1   d  is a side view of an exemplary test coupon with the added gripping pads. 
       FIG. 2  shows distortion curve shapes defined for selecting a test set according to the protocol of the invention and comparative standard templates for uncontoured regions; 
       FIG. 3  is a pictorial view of a resin pool distortion shape, as machined, during insertion into the layup; 
       FIGS. 4   a - 4   i  show comparative standard templates for determination of distortion sizing; 
       FIG. 5  shows comparative standard templates for pin regions with positive curvature; and, 
       FIG. 6  shows comparative standard templates for pin regions with negative curvature. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The protocol of the present invention defines the impact of fiber distortion defects on the tensile strength property of composite lay-ups. A coupon  100 , shown in  FIG. 1   c  employs the same materials and simulates the wave-like characteristics found in marceled distortions present in production fiber composite layups. For an exemplary composite system of BMS 08-196 Unidirectional coupons are built using a multi-ply layup incorporating a resign pool distortion shape selected from a distortion curve set as will be described in greater detail subsequently. For example coupons described herein the layup comprises 40 layers. The coupons are then sliced perpendicular to the layup with a thickness of approximately 0.050 inch. Tapes of varying width are created depending on the number of layers with 1.5 inch to 2.0 inch tapes  102 , shown in  FIG. 1   a  (exaggerated in the thickness dimension in the figure for clarity) and  1   b  showing a 0.050 slice of the test element resin pool distortion shape  104  included at a predetermined position as described above. The cure cycle replicates the production cure for the material being tested. Gripping pads  106  are added at the top and bottom of the coupon for engagement in a tensile testing machine. 
   To replicate potential defect locations, sample coupons are prepared with the defect present in the surface layer, two layers from the surface and at the middle of the layers in the coupon. For the exemplary coupons discussed herein a 40 ply layup is employed. 
     FIG. 2  shows exemplary curves  1  to  60  representative of half shapes for idealized cases of the marceled distortions found in composites studied. Curves  1 - 10  have a height of 0.0625 inch with total length (cord) varying from 0.188 inch to 1.5 inches. Similarly, curves  11 - 20  have a height of 0.125 inch with cord varying from 0.188 to 1.5 inches. Curves  21 - 30  have a height of 0.1875, curves  31 - 40  a height of 0.25 inch, curves  41 - 50  a height of 0.3125, curves  51 - 60  a height of 0.375 inch, curves  61 - 70  a height of 0.5 inch. Selected ones of the curves, as will be defined subsequently, have distortion shapes machined from resin pools comprised of the same resin as the composite under test. 
   As shown in  FIG. 3 , a resin pool is cured and machined to provide a distortion shape  104  which is inserted between composite layup layers  108  at the location predetermined as previously described. The middle layer location is shown in  FIG. 3  as exemplary. Slicing of the layup to create the test coupons is accomplished as represented by line  1   a - 1   a.    
   A distortion category is created by establishing a figure of merit based on the amplitude of the distortion and its length. For the exemplary embodiment, the figure of merit is proportional to h 2  and L and is specifically defined by first determining the aspect ratio, h/L, based on the distortion amplitude and length for each of the shapes defined in  FIG. 2 . A determination of a figure of merit is then accomplished by multiplying the distortion amplitude by the aspect ratio multiplied by a percentage of fiber involvement. This function for the embodiment disclosed herein is equal to the percentage for lugs with less than 80% distortion and grows to 160% for completely involved lugs. A defined distortion category is then determined based on the figure of merit by value assignment where if the figure of merit (FOM) is less than or equal to 0.125 then the distortion category is defined as 1. If 0.125&lt;FOM&lt;=0.25 the distortion category is defined as 1.5. If 0.25&lt;FOM&lt;=0.85 the distortion category is defined as 2. If 0.85&lt;FOM&lt;=1.75 the distortion category is defined as 2.5. If 1.75&lt;FOM&lt;=3.1 the distortion category is defined as 3. If 3.1&lt;FOM&lt;=4.8 the distortion category is defined as 3.5. If 4.8&lt;FOM&lt;=6.8 the distortion category is defined as 4. If 6.8&lt;FOM&lt;=9.3 the distortion category is 4.5. While if the FOM&gt;9.3 the distortion category is defined as 5. Table 1 shows the resulting aspect ratio and calculated FOM for the distortion shapes of  FIG. 2 . Table 2 provides the resulting distortion category with values over 5 being ignored. 
   
     
       
             
             
             
             
             
             
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
             
             
             
             
           
         
             
               TABLE 1 
             
             
                 
             
             
                 
                 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
                 
             
             
               h 
               L 
               0.100 
               0.200 
               0.300 
               0.400 
               0.500 
               0.600 
               0.700 
               0.800 
               1.100 
               1.600 
               h/L 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               0.063 
               0.188 
               0.208 
               0.417 
               0.625 
               0.833 
               1.042 
               1.250 
               1.458 
               1.667 
               2.292 
               3.333 
               3.0 
             
             
               0.063 
               0.25 
               0.156 
               0.313 
               0.469 
               0.625 
               0.781 
               0.938 
               1.094 
               1.250 
               1.719 
               2.500 
               4.0 
             
             
               0.063 
               0.375 
               0.104 
               0.208 
               0.313 
               0.417 
               0.521 
               0.625 
               0.729 
               0.833 
               1.146 
               1.667 
               6.0 
             
             
               0.063 
               0.5 
               0.078 
               0.156 
               0.234 
               0.313 
               0.391 
               0.469 
               0.547 
               0.625 
               0.859 
               1.250 
               8.0 
             
             
               0.063 
               0.625 
               0.063 
               0.125 
               0.188 
               0.250 
               0.313 
               0.375 
               0.438 
               0.500 
               0.688 
               1.000 
               10.0 
             
             
               0.063 
               0.75 
               0.052 
               0.104 
               0.156 
               0.208 
               0.260 
               0.313 
               0.365 
               0.417 
               0.573 
               0.833 
               12.0 
             
             
               0.063 
               0.875 
               0.045 
               0.089 
               0.134 
               0.179 
               0.223 
               0.268 
               0.313 
               0.357 
               0.491 
               0.714 
               14.0 
             
             
               0.063 
               1 
               0.039 
               0.078 
               0.117 
               0.156 
               0.195 
               0.234 
               0.273 
               0.313 
               0.430 
               0.625 
               16.0 
             
             
               0.063 
               1.25 
               0.031 
               0.063 
               0.094 
               0.125 
               0.156 
               0.188 
               0.219 
               0.250 
               0.344 
               0.500 
               20.0 
             
             
               0.063 
               1.5 
               0.026 
               0.052 
               0.078 
               0.104 
               0.130 
               0.156 
               0.182 
               0.208 
               0.286 
               0.417 
               24.0 
             
             
               0.125 
               0.188 
               0.833 
               1.667 
               2.500 
               3.333 
               4.167 
               5.000 
               5.833 
               6.667 
               9.167 
               13.333 
               1.5 
             
             
               0.125 
               0.25 
               0.625 
               1.250 
               1.875 
               2.500 
               3.125 
               3.750 
               4.375 
               5.000 
               6.875 
               10.000 
               2.0 
             
             
               0.125 
               0.375 
               0.417 
               0.833 
               1.250 
               1.667 
               2.083 
               2.500 
               2.917 
               3.333 
               4.583 
               6.667 
               3.0 
             
             
               0.125 
               0.5 
               0.313 
               0.625 
               0.938 
               1.250 
               1.563 
               1.875 
               2.188 
               2.500 
               3.438 
               5.000 
               4.0 
             
             
               0.125 
               0.625 
               0.250 
               0.500 
               0.750 
               1.000 
               1.250 
               1.500 
               1.750 
               2.000 
               2.750 
               4.000 
               5.0 
             
             
               0.125 
               0.75 
               0.208 
               0.417 
               0.625 
               0.833 
               1.042 
               1.250 
               1.458 
               1.667 
               2.292 
               3.333 
               6.0 
             
             
               0.125 
               0.875 
               0.179 
               0.357 
               0.536 
               0.714 
               0.893 
               1.071 
               1.250 
               1.429 
               1.964 
               2.857 
               7.0 
             
             
               0.125 
               1 
               0.156 
               0.313 
               0.469 
               0.625 
               0.781 
               0.938 
               1.094 
               1.250 
               1.719 
               2.500 
               8.0 
             
             
               0.125 
               1.25 
               0.125 
               0.250 
               0.375 
               0.500 
               0.625 
               0.750 
               0.875 
               1.000 
               1.375 
               2.000 
               10.0 
             
             
               0.125 
               1.5 
               0.104 
               0.208 
               0.313 
               0.417 
               0.521 
               0.625 
               0.729 
               0.833 
               1.146 
               1.667 
               12.0 
             
             
               0.188 
               0.188 
               1.875 
               3.750 
               5.625 
               7.500 
               9.375 
               11.250 
               13.125 
               15.000 
               20.625 
               30.000 
               1.0 
             
             
               0.188 
               0.25 
               1.406 
               2.813 
               4.219 
               5.625 
               7.031 
               8.438 
               9.844 
               11.250 
               15.469 
               22.500 
               1.3 
             
             
               0.188 
               0.375 
               0.938 
               1.875 
               2.813 
               3.750 
               4.688 
               5.625 
               6.563 
               7.500 
               10.313 
               15.000 
               2.0 
             
             
               0.188 
               0.5 
               0.703 
               1.406 
               2.109 
               2.813 
               3.516 
               4.219 
               4.922 
               5.625 
               7.734 
               11.250 
               2.7 
             
             
               0.188 
               0.625 
               0.563 
               1.125 
               1.688 
               2.250 
               2.813 
               3.375 
               3.938 
               4.500 
               6.188 
               9.000 
               3.3 
             
             
               0.188 
               0.75 
               0.469 
               0.938 
               1.406 
               1.875 
               2.344 
               2.813 
               3.281 
               3.750 
               5.156 
               7.500 
               4.0 
             
             
               0.188 
               0.875 
               0.402 
               0.804 
               1.205 
               1.607 
               2.009 
               2.411 
               2.813 
               3.214 
               4.420 
               6.429 
               4.7 
             
             
               0.188 
               1 
               0.352 
               0.703 
               1.055 
               1.406 
               1.758 
               2.109 
               2.461 
               2.813 
               3.867 
               5.625 
               5.3 
             
             
               0.188 
               1.25 
               0.281 
               0.563 
               0.844 
               1.125 
               1.406 
               1.688 
               1.969 
               2.250 
               3.094 
               4.500 
               6.7 
             
             
               0.188 
               1.5 
               0.234 
               0.469 
               0.703 
               0.938 
               1.172 
               1.406 
               1.641 
               1.875 
               2.578 
               3.750 
               8.0 
             
             
               0.25 
               0.1875 
               3.333 
               6.667 
               10.000 
               13.333 
               16.667 
               20.000 
               23.333 
               26.667 
               36.667 
               53.333 
               0.8 
             
             
               0.25 
               0.25 
               2.500 
               5.000 
               7.500 
               10.000 
               12.500 
               15.000 
               17.500 
               20.000 
               27.500 
               40.000 
               1.0 
             
             
               0.25 
               0.375 
               1.667 
               3.333 
               5.000 
               6.667 
               8.333 
               10.000 
               11.667 
               13.333 
               18.333 
               26.667 
               1.5 
             
             
               0.25 
               0.5 
               1.250 
               2.500 
               3.750 
               5.000 
               6.250 
               7.500 
               8.750 
               10.000 
               13.750 
               20.000 
               2.0 
             
             
               0.25 
               0.625 
               1.000 
               2.000 
               3.000 
               4.000 
               5.000 
               6.000 
               7.000 
               8.000 
               11.000 
               16.000 
               2.5 
             
             
               0.25 
               0.75 
               0.833 
               1.667 
               2.500 
               3.333 
               4.167 
               5.000 
               5.833 
               6.667 
               9.167 
               13.333 
               3.0 
             
             
               0.25 
               0.875 
               0.714 
               1.429 
               2.143 
               2.857 
               3.571 
               4.286 
               5.000 
               5.714 
               7.857 
               11.429 
               3.5 
             
             
               0.25 
               1 
               0.625 
               1.250 
               1.875 
               2.500 
               3.125 
               3.750 
               4.375 
               5.000 
               6.875 
               10.000 
               4.0 
             
             
               0.25 
               1.25 
               0.500 
               1.000 
               1.500 
               2.000 
               2.500 
               3.000 
               3.500 
               4.000 
               5.500 
               8.000 
               5.0 
             
             
               0.25 
               1.5 
               0.417 
               0.833 
               1.250 
               1.667 
               2.083 
               2.500 
               2.917 
               3.333 
               4.583 
               6.667 
               6.0 
             
             
               0.3125 
               0.1875 
               5.208 
               10.417 
               15.625 
               20.833 
               26.042 
               31.250 
               36.458 
               41.667 
               57.292 
               83.333 
               0.6 
             
             
               0.3125 
               0.25 
               3.906 
               7.813 
               11.719 
               15.625 
               19.531 
               23.438 
               27.344 
               31.250 
               42.969 
               62.500 
               0.8 
             
             
               0.3125 
               0.375 
               2.604 
               5.208 
               7.813 
               10.417 
               13.021 
               15.625 
               18.229 
               20.833 
               28.646 
               41.667 
               1.2 
             
             
               0.3125 
               0.5 
               1.953 
               3.906 
               5.859 
               7.813 
               9.766 
               11.719 
               13.672 
               15.625 
               21.484 
               31.250 
               1.6 
             
             
               0.3125 
               0.625 
               1.563 
               3.125 
               4.688 
               6.250 
               7.813 
               9.375 
               10.938 
               12.500 
               17.188 
               25.000 
               2.0 
             
             
               0.3125 
               0.75 
               1.302 
               2.604 
               3.906 
               5.208 
               6.510 
               7.813 
               9.115 
               10.417 
               14.323 
               20.833 
               2.4 
             
             
               0.3125 
               0.875 
               1.116 
               2.232 
               3.348 
               4.464 
               5.580 
               6.696 
               7.813 
               8.929 
               12.277 
               17.857 
               2.8 
             
             
               0.3125 
               1 
               0.977 
               1.953 
               2.930 
               3.906 
               4.883 
               5.859 
               6.836 
               7.813 
               10.742 
               15.625 
               3.2 
             
             
               0.3125 
               1.25 
               0.781 
               1.563 
               2.344 
               3.125 
               3.906 
               4.688 
               5.469 
               6.250 
               8.594 
               12.500 
               4.0 
             
             
               0.3125 
               1.5 
               0.651 
               1.302 
               1.953 
               2.604 
               3.255 
               3.906 
               4.557 
               5.208 
               7.161 
               10.417 
               4.8 
             
             
               0.375 
               0.1875 
               7.500 
               15.000 
               22.500 
               30.000 
               37.500 
               45.000 
               52.500 
               60.000 
               82.500 
               120.000 
               0.5 
             
             
               0.375 
               0.25 
               5.625 
               11.250 
               16.875 
               22.500 
               28.125 
               33.750 
               39.375 
               45.000 
               61.875 
               90.000 
               0.7 
             
             
               0.375 
               0.375 
               3.750 
               7.500 
               11.250 
               15.000 
               18.750 
               22.500 
               26.250 
               30.000 
               41.250 
               60.000 
               1.0 
             
             
               0.375 
               0.5 
               2.813 
               5.625 
               8.438 
               11.250 
               14.063 
               16.875 
               19.688 
               22.500 
               30.938 
               45.000 
               1.3 
             
             
               0.375 
               0.625 
               2.250 
               4.500 
               6.750 
               9.000 
               11.250 
               13.500 
               15.750 
               18.000 
               24.750 
               36.000 
               1.7 
             
             
               0.375 
               0.75 
               1.875 
               3.750 
               5.625 
               7.500 
               9.375 
               11.250 
               13.125 
               15.000 
               20.625 
               30.000 
               2.0 
             
             
               0.375 
               0.875 
               1.607 
               3.214 
               4.821 
               6.429 
               8.036 
               9.643 
               11.250 
               12.857 
               17.679 
               25.714 
               2.3 
             
             
               0.375 
               1 
               1.406 
               2.813 
               4.219 
               5.625 
               7.031 
               8.438 
               9.844 
               11.250 
               15.469 
               22.500 
               2.7 
             
             
               0.375 
               1.25 
               1.125 
               2.250 
               3.375 
               4.500 
               5.625 
               6.750 
               7.875 
               9.000 
               12.375 
               18.000 
               3.3 
             
             
               0.375 
               1.5 
               0.938 
               1.875 
               2.813 
               3.750 
               4.688 
               5.625 
               6.563 
               7.500 
               10.313 
               15.000 
               4.0 
             
             
               0.5 
               0.1875 
               13.333 
               26.667 
               40.000 
               53.333 
               66.667 
               80.000 
               93.333 
               106.667 
               146.667 
               213.333 
               0.4 
             
             
               0.5 
               0.25 
               10.000 
               20.000 
               30.000 
               40.000 
               50.000 
               60.000 
               70.000 
               80.000 
               110.000 
               160.000 
               0.5 
             
             
               0.5 
               0.375 
               6.667 
               13.333 
               20.000 
               26.667 
               33.333 
               40.000 
               46.667 
               53.333 
               73.333 
               106.667 
               0.8 
             
             
               0.5 
               0.5 
               5.000 
               10.000 
               15.000 
               20.000 
               25.000 
               30.000 
               35.000 
               40.000 
               55.000 
               80.000 
               1.0 
             
             
               0.5 
               0.625 
               4.000 
               8.000 
               12.000 
               16.000 
               20.000 
               24.000 
               28.000 
               32.000 
               44.000 
               64.000 
               1.3 
             
             
               0.5 
               0.75 
               3.333 
               6.667 
               10.000 
               13.333 
               16.667 
               20.000 
               23.333 
               26.667 
               36.667 
               53.333 
               1.5 
             
             
               0.5 
               0.875 
               2.857 
               5.714 
               8.571 
               11.429 
               14.286 
               17.143 
               20.000 
               22.857 
               31.429 
               45.714 
               1.8 
             
             
               0.5 
               1 
               2.500 
               5.000 
               7.500 
               10.000 
               12.500 
               15.000 
               17.500 
               20.000 
               27.500 
               40.000 
               2.0 
             
             
               0.5 
               1.25 
               2.000 
               4.000 
               6.000 
               8.000 
               10.000 
               12.000 
               14.000 
               16.000 
               22.000 
               32.000 
               2.5 
             
             
               0.5 
               1.5 
               1.667 
               3.333 
               5.000 
               6.667 
               8.333 
               10.000 
               11.667 
               13.333 
               18.333 
               26.667 
               3.0 
             
             
                 
             
           
        
       
     
   
   
     
       
             
             
             
             
             
             
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
             
             
             
             
             
             
           
         
             
                 
               TABLE 2 
             
             
                 
                 
             
             
                 
                 
                 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
               % 
             
             
                 
               h 
               L 
               10% 
               20% 
               30% 
               40% 
               50% 
               60% 
               70% 
               80% 
               90% 
               100% 
             
             
                 
                 
             
           
           
             
                 
             
           
        
         
             
               1 
               0.063 
               0.188 
               1.5 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               2.5 
               3.0 
               3.5 
             
             
               2 
               0.063 
               0.25 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               2.5 
               3.0 
             
             
               3 
               0.063 
               0.375 
               1.0 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
             
             
               4 
               0.063 
               0.5 
               1.0 
               1.5 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
             
             
               5 
               0.063 
               0.625 
               1.0 
               1.5 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
             
             
               6 
               0.063 
               0.75 
               1.0 
               1.0 
               1.5 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
             
             
               7 
               0.063 
               0.875 
               1.0 
               1.0 
               1.5 
               1.5 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
             
             
               8 
               0.063 
               1 
               1.0 
               1.0 
               1.0 
               1.5 
               1.5 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
             
             
               9 
               0.063 
               1.25 
               1.0 
               1.0 
               1.0 
               1.5 
               1.5 
               1.5 
               1.5 
               2.0 
               2.0 
               2.0 
             
             
               10 
               0.063 
               1.5 
               1.0 
               1.0 
               1.0 
               1.0 
               1.5 
               1.5 
               1.5 
               1.5 
               2.0 
               2.0 
             
             
               11 
               0.125 
               0.188 
               2.0 
               2.5 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.0 
               4.5 
               5.0 
             
             
               12 
               0.125 
               0.25 
               2.0 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               3.5 
               4.0 
               4.5 
               5.0 
             
             
               13 
               0.125 
               0.375 
               2.0 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
             
             
               14 
               0.125 
               0.5 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
               4.0 
             
             
               15 
               0.125 
               0.625 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
             
             
               16 
               0.125 
               0.75 
               1.5 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               2.5 
               3.0 
               3.5 
             
             
               17 
               0.125 
               0.875 
               1.5 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               2.5 
               3.0 
               3.0 
             
             
               18 
               0.125 
               1 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               2.5 
               3.0 
             
             
               19 
               0.125 
               1.25 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               3.0 
             
             
               20 
               0.125 
               1.5 
               1.0 
               1.5 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
             
             
               21 
               0.188 
               0.188 
               3.0 
               3.5 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               22 
               0.188 
               0.25 
               2.5 
               3.0 
               3.5 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               23 
               0.188 
               0.375 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               24 
               0.188 
               0.5 
               2.0 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
             
             
               25 
               0.188 
               0.625 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               3.5 
               4.0 
               4.5 
             
             
               26 
               0.188 
               0.75 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
               4.5 
             
             
               27 
               0.188 
               0.875 
               2.0 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
             
             
               28 
               0.188 
               1 
               2.0 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.0 
               3.5 
               4.0 
             
             
               29 
               0.188 
               1.25 
               2.0 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
             
             
               30 
               0.188 
               1.5 
               1.5 
               2.0 
               2.0 
               2.5 
               2.5 
               2.5 
               2.5 
               3.0 
               3.0 
               3.5 
             
             
               31 
               0.25 
               0.188 
               3.5 
               4.0 
               5.0 
               5.0 
             
             
               32 
               0.25 
               0.25 
               3.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               33 
               0.25 
               0.375 
               2.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               34 
               0.25 
               0.5 
               2.5 
               3.0 
               3.5 
               4.0 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               35 
               0.25 
               0.625 
               2.5 
               3.0 
               3.0 
               3.5 
               4.0 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               36 
               0.25 
               0.75 
               2.0 
               2.5 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.0 
               4.5 
               5.0 
             
             
               37 
               0.25 
               0.875 
               2.0 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
             
             
               38 
               0.25 
               1 
               2.0 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               3.5 
               4.0 
               4.5 
               5.0 
             
             
               39 
               0.25 
               1.25 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
               4.5 
             
             
               40 
               0.25 
               1.5 
               2.0 
               2.0 
               2.5 
               2.5 
               3.0 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
             
             
               41 
               0.313 
               0.188 
               4.0 
               5.0 
             
             
               42 
               0.313 
               0.25 
               3.5 
               4.5 
               5.0 
               5.0 
             
             
               43 
               0.313 
               0.375 
               3.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               44 
               0.313 
               0.5 
               3.0 
               3.5 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               45 
               0.313 
               0.625 
               2.5 
               3.5 
               3.5 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               46 
               0.313 
               0.75 
               2.5 
               3.0 
               3.5 
               4.0 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               47 
               0.313 
               0.875 
               2.5 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               48 
               0.313 
               1 
               2.5 
               3.0 
               3.0 
               3.5 
               4.0 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               49 
               0.313 
               1.25 
               2.0 
               2.5 
               3.0 
               3.5 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
             
             
               50 
               0.313 
               1.5 
               2.0 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               3.5 
               4.0 
               4.5 
               5.0 
             
             
               51 
               0.375 
               0.188 
               4.5 
               5.0 
             
             
               52 
               0.375 
               0.25 
               4.0 
               5.0 
               5.0 
             
             
               53 
               0.375 
               0.375 
               3.5 
               4.5 
               5.0 
               5.0 
             
             
               54 
               0.375 
               0.5 
               3.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               55 
               0.375 
               0.625 
               3.0 
               3.5 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               56 
               0.375 
               0.75 
               3.0 
               3.5 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               57 
               0.375 
               0.875 
               2.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               58 
               0.375 
               1 
               2.5 
               3.0 
               3.5 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               59 
               0.375 
               1.25 
               2.5 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               4.5 
               5.0 
               5.0 
             
             
               60 
               0.375 
               1.5 
               2.5 
               3.0 
               3.0 
               3.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               61 
               0.500 
               0.188 
               5.0 
             
             
               62 
               0.500 
               0.25 
               5.0 
             
             
               63 
               0.500 
               0.375 
               4.0 
               5.0 
             
             
               64 
               0.500 
               0.5 
               4.0 
               5.0 
             
             
               65 
               0.500 
               0.625 
               3.5 
               4.5 
               5.0 
             
             
               66 
               0.500 
               0.75 
               3.5 
               4.0 
               5.0 
               5.0 
             
             
               67 
               0.500 
               0.875 
               3.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               68 
               0.500 
               1 
               3.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               69 
               0.500 
               1.25 
               3.0 
               3.5 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
               70 
               0.500 
               1.5 
               2.5 
               3.5 
               4.0 
               4.0 
               4.5 
               5.0 
               5.0 
             
             
                 
             
           
        
       
     
   
   The testing protocol provides for the preparation of coupons as described previously with 2 category  2  curves, 2 category  3  and 2 category  4  to simulate the changes in both amplitude and wavelength that categorize a typical fiber distortion wave as a 2, 3, or 4. The shape factor and the amplitude are controlled by the inserts that created by selecting a curve from the inspection standard that is a score of 2, 3, or 4. One that has a high (tall) amplitude and one that has a low (short) amplitude. These 6 inserts provide the standard shapes for the resin pocket around which the fiber distortion is created. The location of the insert will either be at the edge, 2 plies in, or at the middle of the coupon, 20 plies in. 
   The resulting test design is shown in Table 3 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
         
             
               TABLE 3 
             
             
                 
             
             
                 
                 
                 
               Wave 
                 
             
             
               StdOrder 
               RunOrder 
               Amplitude 
               Shape 
               location 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               17 
               1 
               short 
               3 
               edge 
             
             
               14 
               2 
               short 
               1 
               middle 
             
             
               3 
               3 
               short 
               2 
               edge 
             
             
               18 
               4 
               short 
               3 
               middle 
             
             
               12 
               5 
               tall 
               3 
               middle 
             
             
               22 
               6 
               tall 
               2 
               middle 
             
             
               34 
               7 
               tall 
               2 
               middle 
             
             
               13 
               8 
               short 
               1 
               edge 
             
             
               9 
               9 
               tall 
               2 
               edge 
             
             
               35 
               10 
               tall 
               3 
               edge 
             
             
               6 
               11 
               short 
               3 
               middle 
             
             
               19 
               12 
               tall 
               1 
               edge 
             
             
               26 
               13 
               short 
               1 
               middle 
             
             
               29 
               14 
               short 
               3 
               edge 
             
             
               27 
               15 
               short 
               2 
               edge 
             
             
               16 
               16 
               short 
               2 
               middle 
             
             
               24 
               17 
               tall 
               3 
               middle 
             
             
               15 
               18 
               short 
               2 
               edge 
             
             
               30 
               19 
               short 
               3 
               middle 
             
             
               36 
               20 
               tall 
               3 
               middle 
             
             
               7 
               21 
               tall 
               1 
               edge 
             
             
               25 
               22 
               short 
               1 
               edge 
             
             
               5 
               23 
               short 
               3 
               edge 
             
             
               1 
               24 
               short 
               1 
               edge 
             
             
               2 
               25 
               short 
               1 
               middle 
             
             
               33 
               26 
               tall 
               2 
               edge 
             
             
               23 
               27 
               tall 
               3 
               edge 
             
             
               4 
               28 
               short 
               2 
               middle 
             
             
               32 
               29 
               tall 
               1 
               middle 
             
             
               20 
               30 
               tall 
               1 
               middle 
             
             
               31 
               31 
               tall 
               1 
               edge 
             
             
               21 
               32 
               tall 
               2 
               edge 
             
             
               10 
               33 
               tall 
               2 
               middle 
             
             
               11 
               34 
               tall 
               3 
               edge 
             
             
               8 
               35 
               tall 
               1 
               middle 
             
             
               28 
               36 
               short 
               2 
               middle 
             
             
                 
             
           
        
       
     
   
   The test protocol is repeated as required to determine initial failure using a load line parallel to or normal to the axis of the marcel with a force testing machine at varying head speeds. Repetition of the protocol for varying temperature and moisture or other operationally specific environmental conditions provides additional data to establish acceptance criteria. The stress levels for fatigue testing will vary by material and category of distortion. 
   The data provided by the test protocol is then applied to the distortion characteristics defined in Table 2 to provide a definitive means for determining whether the associated defect as characterized by the table has engineering structural properties sufficient for a “use as is” determination or whether the structural properties warrant a “scrap” disposition. 
   The curves of  FIG. 2  provide templates for determination of approximate shape of a distortion in a production composite identifiable using the tracer fibers present in the layup. Tracer fibers are doped prior to composite creation to allow visualization of fiber placement and distortion. 
   The templates of  FIGS. 4   a - 4   i  are employed in inspection to determine the number of plies affected by a distortion for the composite embodiments defined herein.  FIG. 4   a  provides a boundary for a distortion involving 10 plies or less,  FIG. 4   b  a boundary for a distortion involving 20 plies or less  FIG. 4   c  30 plies or less,  FIG. 4   d  40 plies or less,  FIG. 4   e  50 plies or less,  FIG. 4   f  60 plies or less,  FIG. 4   g  70 plies or less,  FIG. 4   h  80 plies or less and  FIG. 4   i  90 plies or less. 
     FIGS. 5 and 6  provide templates for determination of approximate shape of a distortion in a production composite identifiable using the tracer fibers where the distortion is present in a region surrounding a pin in the layup.  FIG. 5  with shapes  1 A- 60 A provide the positive curvature while  FIG. 6  with shapes  1 B- 60 B demonstrate a negative curvature. 
   The determined shape and number of plies involved in a distortion are then applied to define the distortion category for determining the appropriate disposition of the defect. 
   Having now described the invention in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present invention as defined in the following claims.

Technology Classification (CPC): 1