Patent Document

BACKGROUND 
       [0001]    This disclosure relates generally to inspecting and, more particularly, to controlling a beam from a curved transducer array. 
         [0002]    Phased array inspection tools are well-known. One of the tools is a phased array probe. Phased array probes typically consist of an array of transducer elements. Each of the individual transducer elements can be pulsed (excited) separately. The pulses cause transducer elements to generate sound waves that combine to form a sound beam that propagates through a component. Potential defects in the component reveal themselves by reflecting the sound beam back to the transducer. 
         [0003]    Typical phased array systems include flat (non-curved) arrays of transducer elements. These arrays of transducer elements constitute a flat (non-curved) surface of a probe. The timing of pulsing (or exciting) individual transducer elements is phased or varied. The phasing changes how the sound waves from transducer elements combine with each other. The phasing steers and shapes the sound beam. Flat probes, however, are not well-suited for inspecting many components, especially components having relatively complex geometries. 
       SUMMARY 
       [0004]    An example component inspection method includes directing a wave from a curved array of transducer elements toward a component. The method forms the wave using focal law calculator software. 
         [0005]    An example component inspection method includes directing a wave from a transducer array toward a component. The transducer array is curved. The method uses focal law calculator software to determine the phasing of the elements in order to focus the wave, stretch the wave, steer the wave, or some combination of these. 
         [0006]    An example phased array inspection system includes a curved array of transducer elements. A computer uses a focal law calculator to calculate focal law files. A controller controls a wave generated by a curved array of transducer elements based on the focal law files. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0007]    The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: 
           [0008]      FIG. 1  shows a highly schematic view of an example phased array inspection system incorporating a curved probe. 
           [0009]      FIG. 2A  shows a front view of an example curved probe for use in the  FIG. 1  phased array inspection system. 
           [0010]      FIG. 2B  shows a side view of the  FIG. 2A  curved probe in a second plane perpendicular to the first plane. 
           [0011]      FIG. 3A  shows a schematic of a focused beam formation. 
           [0012]      FIG. 3B  shows a schematic for a beam with a positive stretch. 
           [0013]      FIG. 3C  shows a schematic for a beam with a negative stretch. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIGS. 1 to 2B , an example phased array inspection system  10  includes a probe  14  coupled to a controller  18 . An outer surface of the probe  14  includes a curved transducer array  22 . The probe  14  is considered a curved probe because of the curved transducer array  22 . 
         [0015]    The curved transducer array  22  includes multiple individual transducer elements  28 . Each of the transducer elements  28  can be pulsed (excited) to generate a sound wave. Sound waves generated by the transducer elements  28  combine to form a sound beam  32  that propagates from the curved transducer array  22 . 
         [0016]    During an inspection procedure, the beam  32  is directed toward the component  34 . In one example, the probe  14  and the component  34  are both submerged within a tank of water. The water facilitates transmission of the beam  32 . 
         [0017]    Portions of the beam  32  are reflected toward the curved transducer array  22  after encountering a defect, inclusion, void, etc. within the component  34 . The curved transducer array  22  receives the reflected portions of the beam  32 , which are analyzed in a known way to reveal the defect, inclusion, void, etc. 
         [0018]    In this example, component  34  is a new or used component, such as a turbine disk in a high pressure turbine section of a turbomachine. Other examples may be used with other types of turbomachine components and components other than turbomachine components. The system  10  could be used with any component or material that will be further processed to produce a component needing an inspection. 
         [0019]    The example curved transducer array  22  is particularly useful for inspecting the component  34  because the curvature of the curved transducer is designed to facilitate formation of an appropriate sound beam inside component  34 . Flat (non-curved) arrays of transducers often cannot generate an appropriate sound beam in (typically curved) turbomachine components. 
         [0020]    The example curved transducer array  22  is curved in three directions. That is, the curved transducer array  22  is curved relative to axes X, Y, and Z. (In  FIG. 2A , axis X extends outward from the page.) Other example probes are curved in at least two directions. 
         [0021]    The curved transducer array  22  includes transducer elements  28 C near the center of the probe  14  (relative to the axis X) and transducers elements  28 P that are near the radial perimeter of the probe  14 . In this example, focal law calculator software utilizes coordinates of the transducer elements  28 C and  28 P to form a beam propagating from the curved transducer array  22 . 
         [0022]    The example controller  18  is a stand-alone electronic device that is controlled by an external control software  44  running on a stand-alone personal computer  20 . The control software  44  uses internally or externally generated focal laws that define how and when individual elements of an array are excited and how data received by individual array elements is processed. 
         [0023]    A focal law software  46  generates focal laws that are used by the control software  44 . The focal law software  46  is considered a focal law calculator in this example. 
         [0024]    The example personal computer  20  includes a memory portion  40  and a processor  42 . The focal law software  46  produces focal law files. The control software  44  uses focal law files and produces phasing commands that are stored in the memory portion  40  and are sent by the processor  42  to the controller  18 . The controller  18  executes phasing commands and thus controls how the sound beam  32  is formed by controlling how and when the transducer elements  28  generate pulses. 
         [0025]    The example focal law software  46  is a focal law calculator that generates focal law files. The control software  44  uses the focal law files and sends appropriate commands to the controller  18  that excite elements of the curved transducer array  22  to form the sound beam  32 . Examples of beam forming include stretching the sound beam  32 , steering the sound beam  32 , and focusing the sound beam  32 . 
         [0026]    In this example, the sound beam  32  is stretched during the transmission or generation of a sound beam. Dynamic Depth Focusing (DDF) occurs upon reception of the reflected sound beam. DDF involves combining reflected waves. In the prior art, standard ‘off-the-shelf’ focal law calculators do not have capability to form focused or stretched beams for a generally curved phased array probe. They also cannot program DDF for generally curved probes. 
         [0027]    In this example, stretching the sound beam  32  may involve a positive stretch or a negative stretch. Positive and negative are determined with reference to a nominal focus distance and whether central elements are focused closer or father than ‘outer rim’ elements. 
         [0028]    For example, referring to  FIGS. 3A to 3C  with continuing reference to  FIGS. 1 to 2B , a nominal focus distance F is this distance between the transducer array  22  and a point P when the transducer elements  28  are focused on the point P. 
         [0029]    The individual transducer elements  28  of the array  22  produce rays that combine to form the beam  32 . In the  FIGS. 3A-3C , the size of the beam  32  relative to the array  22  has been increased for clarity.  FIG. 3A  shows the beam focused on the point P. A positive stretch of the beam  32  is achieved when the transducer elements  28 C are refocused at a distance less than the nominal focus distance F, and the transducer elements  28 P refocused at a distance greater than the nominal focus distance F. Thus, when the beam  32  is positively stretched, waves from the transducer elements  28 C intersect an axis A of the beam  32  closer to the probe  14  than the waves from the transducer elements  28 P.  FIG. 3B  shows a positive stretch of the beam  32 . 
         [0030]    A negative stretch of the beam  32  is achieved when the transducer elements  28 C are refocused at a distance greater than the nominal focus distance F, and the transducer elements  28 P—at a distance less than the nominal focus distance F. Thus, when the beam  32  is negatively stretched, waves from the transducer elements  28 C intersect an axis A of the beam  32  further from the probe  14  than the waves from the transducer elements  28 P.  FIG. 3C  shows a negative stretch of the beam  32 . 
         [0031]    In this example, focal law calculator software  46  executes the stretching F n  according to the algorithm ( 1 ). 
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         [0032]    In algorithm ( 1 ), F is the nominal focus distance, D str  is a desired amount of stretch, n is a number of the transducer element rings  28  within the curved transducer array  22 , and N is a total number of element rings within the curved transducer array  22 . In this example, the algorithm ( 1 ) is utilized with annular arrays of transducer elements such as the array  22 . 
         [0033]    In this example, the focal law software  46  includes a portion executing the algorithm ( 1 ) to stretch the beam  32 . 
         [0034]    Another way the focal law software  46  may stretch the beam  32  is by controlling the distribution of focal points of the waves from the transducers elements  28  within the curved transducer array  22 . The focal law software  46  may use the algorithm ( 2 ) to control the focal points. 
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         [0035]    In the algorithm ( 2 ), ξ corresponds to stretch uniformity. When ξ=1, focusing distribution is uniform ( FIG. 3A ). When Ξ=2, distribution is denser near the far end of the range ( FIG. 3B ), when ξ=0 focusing is denser near the near end of the range. 
         [0036]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.

Technology Category: 3