Acoustic coupling with a fluid retainer

#The present invention is generally related to the examining of the internal structure of materials and, more particularly, is related to a system and method for the non-destructive internal examination of a material.

#If a structure, such as a machine or a part of a product, has a defect, such as a crack, a void, or a recess, there is a risk that the machine or part will become inoperable due to the defect. Thus, it is desired that the part having such a defect is eliminated or replaced by detecting the presence of such a defect in advance of the machine or part becoming inoperable. For example, aircraft skins and other manufactured components are frequently made from laminates, which are layers of material adhered together by layers of adhesive, such as, but not limited to, sealant, epoxy, and glue, interposing the layers of material. Laminates can delaminate when the adhesive layers can no longer adhere the layers of material together. Typically, delamination does not occur spontaneously, but rather, it occurs after voids have formed in the adhesive layers. In addition to concerns about delamination due to voids, laminates can also fail due to cracks. Thus, it is desirable to examine by non-destructive means the internal structure of a laminate to search for voids, cracks, and other internal defects before the laminate fails.

#It is desirable that the examination of an object occurs in situ. In situ examination of a component can typically be done more rapidly and inexpensively than non-in situ because there it requires less disassembly and reassembly of the system. It is also desirable that the apparatus used for examining the component be readily transportable.

#Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

#FIG. 1 is a perspective view of a moveable acoustic scanning system scanning a section of an aircraft.

#FIG. 2A is a perspective view of an acoustic scanning apparatus attached to a section of an aircraft.

#Referring to FIG. 1, a moveable acoustic scanning system (MASS) 10 is used to scan the skin 6 of an aircraft 8. The MASS 10 includes an acoustic scanning assembly (ASA) 14 attached to a positioning apparatus 12. The positioning apparatus 12 includes a base 20 and an extendable arm 18 that extends from base 20. The positioning apparatus includes a control system 16, which is typically a computer, or the like, that is used for, among other things, controlling arm 18. In one preferred embodiment, the base 20 is moveable so that the arm 18 can be readily moved around the aircraft 8 and positioned near subsequent aircraft. Non-limiting examples of a moveable base include but are not limited to trucks, trolleys, carts, scissor-jack, sky-jacks, and hand cars. With the arm 18 positioned proximal to the aircraft 8, the arm 18 is used to position the ASA 14 proximal to selected portions of the aircraft 8. In one preferred embodiment, the arm 18 is adapted to move in three-dimensions so that the ASA 14 can be positioned against the aircraft 8 in orientations ranging from horizontal to vertical. In one preferred embodiment, the arm 18 includes a mechanism such as, but not limited to, hydraulically actuated jaws or clamps (not shown) that grip the ASA 14. After the ASA 14 is attached to the skin 6 of the aircraft 8, the control system 16 releases the ASA 14 so that they are not rigidly coupled together during a scan. The arm 18 releases the ASA 14 so that vibrations are not transmitted from the arm 18 to the ASA 14. In another embodiment, the ASA 14 is manually positioned against selected portions of the aircraft 8.

#In one preferred embodiment, the ASA 14 is used to scan a section of the aircraft 8, and when the scan of that section is completed, the controller 16 repositions the ASA 14 to a new section of the aircraft 8. In this manner, the entire skin 6 of the aircraft 8 may be scanned, or selected sections of the aircraft are scanned. The ASA 14 is adapted to scan sections of the aircraft 8 that range in size of up to approximately one meter in length and up to approximately one meter in width. The ASA 14 can be used to scan a portion of the aircraft 8 that is larger than one meter in length by simply scanning that portion of the aircraft 8 in segments. In other embodiments, the ASA 14 is adapted to scan sections that are either longer or wider or both than one meter.

#Typically, the ASA 14 is positioned on the aircraft 8 by the controller 16 manipulating the arm 18. However, in one embodiment, the operator manually controls the arm 18 using controls (not shown) for positioning the ASA 14 against the aircraft 8. Typically, the ASA 14 is positioned against the aircraft 8 within a tolerance of a couple of inches from the desired location, and the ASA 14 can resolve features in the 1 to 200 micron range. A relatively precise determination of the location of the ASA 14 is determined by comparing the scanned structural features such as rivets with their known locations. Thus, although it is preferable to position the ASA 14 as close as possible to a desired location so as to reduce the amount of unnecessary scanning, it is not necessary to place it in an exact location because a precise position of the ASA 14 is determined from the scanning results. Therefore, it is not necessary for the operator to spend an inordinate amount of time positioning the ASA 14 to an exact location.