The disclosure relates generally to inspection and repair of adhesive-bonded joints using ultrasonic pulses. In many industries, adhesive bonding is employed for bonding many different types of materials. For example, adhesive bonding is used to bond polymeric composites, which are lightweight, conformable and durable. The adhesive employed may have missing portions over time. A method of inspection to determine the state of an adhesive-bonded joint is desirable, including subsequent repair of a discrepant joint.
A method of inspection and repair of a joint in an assembly. The joint is formed by a first work piece and a second work piece. An adhesive placed between the first and second work pieces to define the joint. The assembly includes an ultrasonic welding device including an ultrasonic horn configured to deliver ultrasonic energy to the joint. A controller is operatively connected to the ultrasonic welding device. The controller includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of inspecting and repairing the adhesive-bonded joint. The controller is programmed to deliver a first ultrasonic pulse (P1) to the joint, via the ultrasonic welding device, and determine an adhesive coverage (AC) based at least partially on the first ultrasonic pulse (P1).
The first work piece and the second work piece may be composed of identical materials. The first work piece and the second work piece may be composed of dissimilar materials. At least one sensor may be operatively connected to the controller and configured to measure a depth of displacement of the ultrasonic horn in the joint. Determining an adhesive coverage (AC) includes determining if the adhesive is cured. If the adhesive is not cured, the controller is programmed to obtain a depth of displacement of the ultrasonic horn in the joint after delivery of the first ultrasonic pulse (P1), via the at least one sensor. If the adhesive is not cured, the controller is programmed to obtain the adhesive coverage (AC) for the joint based at least partially on the depth of displacement and a first look-up table. If the adhesive is cured, determining an adhesive coverage (AC) includes obtaining an energy delivered to the joint by the first ultrasonic pulse (P1) and obtaining the adhesive coverage (AC) based at least partially on the energy delivered by the joint and a second look-up table.
The controller may be further programmed to determine if the adhesive coverage (AC) is at or below a predefined threshold coverage (TC). If the adhesive coverage (AC) is at or below the threshold coverage (TC), the controller is programmed to determine the energy of a second ultrasonic pulse (P2) based at least in part on the adhesive coverage (AC) and a third look-up table.
If the adhesive coverage (AC) is at or below the threshold coverage (TC), the controller is programmed to deliver the second ultrasonic pulse (P2), via the ultrasonic welding device, to the joint under a compressive force to form a weld at the joint, thereby repairing the joint. The predefined threshold coverage (TC) may be selected such that a joint strength (SU,TC) of an un-repaired bonded joint at the threshold coverage is less than or equal to a joint strength (SR,TC) of a repaired welded joint at the threshold coverage [SU,TC≦SR,TC]. The predefined threshold coverage may be 50%.
The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to like components,
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The controller 40 of
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Method 100 may begin with block 102. In block 102, the controller 40 is programmed to deliver a first ultrasonic pulse (P1) to the joint 20, via the ultrasonic welding device 24. As shown in
In block 104, the controller 40 is programmed to determine an adhesive coverage (AC) of the joint 20 based at least partially on the first ultrasonic pulse (P1). Block 104 includes sub-blocks 106, 108, 110, 112 and 114, described below. In sub-block 106, the controller 40 is programmed to determine if the adhesive 18 is cured. Curing is defined as a process, such as a chemical reaction or physical action, which results in a tougher or stronger adhesive bond. An adhesive bond may be cured via a baking step where the adhesive 18 is subject to an elevated temperature for a predetermined amount of time. The controller 40 may determine if the adhesive 18 is cured or not by a method available to those skilled in the art. For example, a user can determine this from visual inspection or knowledge of the history of the joint 20, and convey the information to the controller 40 via a user interface 52 (see
If the adhesive 18 is not cured, the method 100 proceeds from sub-block 106 to sub-block 108, where the controller 40 is programmed to obtain the depth of displacement D of the ultrasonic horn 26 in the joint 20 after delivery of the first ultrasonic pulse (P1). The measurement of the depth of displacement D may be made via the depth sensor 34. As mentioned above the measurement of displacement depth (D in
The method 100 then proceeds to sub-block 110, where the controller 40 is programmed to obtain the adhesive coverage (AC) for the joint 20 based at least partially on the depth of displacement D (from block 108) and a first look-up table. The values of the first look-up table (and second and third look-up tables described below) may be obtained via calibration or in a test cell or laboratory. The first, second and third look-up tables may be a type of data repository or storage medium. Interpolation may be employed to determine values in between the data points in the respective look-up tables. A non-limiting example of a first look-up table is shown below in Table 1:
If the adhesive 18 is cured, the method 100 proceeds from sub-block 106 to sub-block 112, the controller 40 is programmed to obtain an energy delivered (ED) to the joint 20 by the first ultrasonic pulse (P1). The energy delivered (ED) to the joint 20 may be obtained based at least partially on the power delivered to the joint 20, e.g., via integration of power delivered over time. The power source 32 may be rated by the peak power it can deliver, which may vary from a few hundred watts to several kilowatts. Based on a constant power output, a 0.5-second pulse from a 1.5-kW ultrasonic welding device would deliver 750 joules of energy. The assembly 10 may include a voltage sensor 48 and a current sensor 50 to assess the voltage and current, respectively, delivered to the ultrasonic welding device 24. The assembly 10 may include other sensors or employ other methods or models available to those skilled in the art to obtain the energy delivered (ED) to the joint 20 by the first ultrasonic pulse (P1).
The method 100 proceeds to sub-block 114, where the controller 40 is programmed to obtain the adhesive coverage (AC) based at least partially on the energy delivered (ED) to the joint 20 and a second look-up table. The values of the second look-up table may be obtained via calibration or in a test cell or laboratory. An example of a second look-up table is shown below in Table 2:
In block 116, the controller 40 is programmed to determine if the adhesive coverage (AC) is at or below a predefined threshold coverage (TC). The predefined threshold coverage (TC) may be selected for the application at hand. The predefined threshold coverage (TC) may be selected such that a joint strength (SU,TC) of an un-repaired bonded joint at the threshold coverage is less than or equal to a joint strength (SR,TC) of a repaired welded joint at the threshold coverage [SU,TC≦SR,TC],
If the adhesive coverage (AC) is above the threshold coverage (TC), the method is ended. If the adhesive coverage (AC) is at or below the threshold coverage (TC), the method proceeds to block 118, where the controller 40 is programmed to determine the energy of a second ultrasonic pulse (P2) based at least in part on the adhesive coverage (AC) and a third look-up table. The energy of the second ultrasonic pulse (P2) is required to be of sufficient intensity to form a weld 38 at the joint 20. An example of a third look-up table is shown below in Table 3:
In block 118, the controller 40 is programmed to deliver the second ultrasonic pulse (P2), via the ultrasonic welding device 24, to the joint 20 under a compressive force F. The application of the second ultrasonic pulse (P2) fuses the locations at the faying interfaces between the first and second work pieces 12, 14 and the adhesive 18 to form a weld 38, thereby repairing the joint 20 to a desired joint strength.
The controller 40 of
Look-up tables, databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each such data store may be included within a computing device employing a computer operating system such as one of those mentioned above, and may be accessed via a network in one or more of a variety of manners. A file system may be accessible from a computer operating system, and may include files stored in various formats. An RDBMS may employ the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above.
The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment can be combined with one or more desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.
This application claims the benefit of U.S. Provisional Patent Application No. 62/347,371 filed on Jun. 8, 2016, the disclosure of which is hereby incorporated by reference.
Number | Date | Country | |
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62347371 | Jun 2016 | US |