Abstract:
A method for working a component to reduce a propensity for advanced dynamic change analyzes affects of a StressWave process on at least one location on a size and shape of the component. The component is also analyzed as to the affects of adding at least one feature on a size and shape of the component. A beginning shape of the component is then extrapolated.

Description:
BACKGROUND 
       [0001]    Embodiments of this disclosure relates generally to extending a length of service of component parts, and more particularly, to method of extending a length of service of component parts so if a shape of the component changes during the process, the shape and size of the component still remains within a specified tolerance envelope to be used in final assembly. 
         [0002]    In many aircraft, structural components may experience advanced dynamic changes. These advanced dynamic changes generally occur in features of the component such as in and around indentations, slots, holes, other types of openings, discontinuities or transition areas (hereinafter features). Advanced dynamic changes in these or other areas of the component may result in operating restrictions, and/or grounding of the aircraft. 
         [0003]    Presently, there are several different methods to extend the length of service of structural components that may experience advanced dynamic changes. Coldworking is a process of expanding metal at a temperature below its annealing point in order to increase its hardness and tensile strength. Several methods of coldworking can be used. One method pushes a shaft having an enlarged diameter portion (commonly referred to as a mandrel) through an opening from one direction to radially expand the opening and compress the surrounding region to achieve a desired strain hardening. Another method involves lining the opening with a sleeve and pulling a mandrel through the sleeve to expand and thereby coldwork the opening. A further method includes inserting a collapsible mandrel (also known as a split mandrel) in collapsed form through the opening, expanding the mandrel, and then pulling the mandrel back through the opening to coldwork the opening. All of these methods require the feature to be present prior to coldworking. These methods may be difficult to automate. 
         [0004]    Another method to extend the length of service of structural components that may experience advanced dynamic change is called StressWaving. StressWaving is a form of coldworking wherein compressive residual stresses are applied around areas of the component which may experience advanced dynamic changes. An indentation device is used to create the residual stresses around the areas of the component which may experience advanced dynamic changes. StressWave coldworking allows the coldworking process to be automated. Stresswaving imparts beneficial residual stress into a location prior to addition of a feature. The residual stresses applied increases the hardness and tensile strength of the area. After the StressWaving process, different features may be fabricated in to the component. 
         [0005]    The coldworking process and adding the features may cause the component to change from its original shape and size. This is especially true when the component has a complex shape, a large number of areas of a component that need to be coldworked and/or when features formed in a component have a complex shape. Attempts to change the component back to its original shape and size may require the component going back through a stress relieve process that may eliminate the coldworked zone put into the component or may result in a non-beneficial high residual stress in the component. 
         [0006]    Therefore, it would be desirable to provide a method of extending a length of service of component parts so that even if a shape of the component changes during the process, the size and shape of the component will remain within a specified tolerance envelope to be used in final assembly without high residual stress. 
       SUMMARY 
       [0007]    A method for working a component to reduce a propensity for advanced dynamic change is disclosed. The method analyzes affects of a StressWave process on at least one location on a size and shape of the component. The component is also analyzed as to the affects of adding at least one feature on a size and shape of the component. A beginning shape of the component is then extrapolated. 
         [0008]    The features, functions, and advantages can be achieved independently in various embodiments of the disclosure or may be combined in yet other embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Embodiments of the disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0010]      FIG. 1  shows one method for extending a length of service of structural components that may experience advanced dynamic change so that a final shape of the component is within a specified tolerance envelope to be used in final assembly; 
           [0011]      FIG. 2  shows another method for extending a length of service of structural components that may experience advanced dynamic change so that a final shape of the component is within a specified tolerance envelope to be used in final assembly; 
           [0012]      FIG. 3  shows another method for extending a length of service of structural components that may experience advanced dynamic change so that a final shape of the component is within a specified tolerance envelope to be used in final assembly; 
           [0013]      FIG. 4  is a perspective view of a component part being coldworked and formations added; 
           [0014]      FIG. 5  shows another method for extending a length of service of structural components that may experience advanced dynamic change so that a final shape of the component is within a specified tolerance envelope to be used in final assembly; 
           [0015]      FIG. 6  is a perspective view of a pre-shape model formed in accordance with the method of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    With reference now to the  FIGS. 1-3 , different flowcharts are shown that disclose methods of extending a length of service of structural components that may experience advanced dynamic change. The methods allows, for example without limitation, fabricating a component with a large number of features and coldworking some or all of the feature locations prior to feature addition so that if a size and shape of the component is altered during this process, the final shape and size of the component will remain within a specified tolerance envelope. Fabrication of the component may involve, but is not limited to, molding, forging, forming, machining, or milling. Features may be added to the component for example, without limitation, during milling, drilling, or other machining. This processing allows the component to be used in final assembly. The methods below will be discussed in regards to StressWaving. However, other coldworking processes may be used. The component may be an aircraft or aerospace vehicle component or may be for a vehicle, such as without limitation, an aircraft, a spacecraft, or the like. 
         [0017]    The term “dynamic changes,” as used in the appropriate context throughout this disclosure, refers to the difference between one or more measured characteristics of a structure under inspection (and potentially effected by repeated exposure to factor(s) including, but not limited to, thermal load(s), structural load(s), oxidation, lightning, or electrical arcing) with expected values for the same characteristics of an analogous structure unaffected by repeated exposure to those factors. Advanced dynamic changes are a highly developed state of dynamic changes. 
         [0018]    A determination of the pre-shape model is made by simulating a shape change of the component due to a coldworking process  12 . The pre-shaped model will account for how coldworking affects the size and shape of the component. A coldworking process such as StressWaving, will apply compressive residual stresses at specific locations and/or areas of the component which may experience advanced dynamic changes. The individual or cumulative application of compressive residual stresses may alter the size and shape of the component. 
         [0019]    In accordance with one embodiment, a pre-shaped model of the component is determined using existing software programs  12 A. Different programs using finite element analysis may be used to extrapolate a pre-shaped model taking into consideration, for example and without limitation, the size and shape of the component, the material of the component, method of component fabrication, method or means of feature addition, the different areas of the component part where the residual stresses will be applied, and the like. 
         [0020]    Alternatively, one or more prototypes may be fabricated  12 B. The fabricated prototype component may be built, for example without limitation, using the same dimensions, method of fabrication, and materials as the actual item. The fabricated prototypes are put through the StressWave process. After the model has gone through the StressWave process, the model will be analyzed to see how the StressWave process affects the model. Actual measurements may be taken of the prototypes to see how the process altered the final size and shape of the prototype. One can extrapolate a starting shape of the component by using finite element analyses. 
         [0021]    In accordance with one embodiment, a computer generated pre-shaped model is created  13 A. A computer generated pre-shaped model may allow one to get a multidimensional view of the pre-shaped model without having to actually fabricate the part. The computer generated pre-shaped model will also save both time and money since an actual prototype of the pre-shaped model does not have to be built. Alternatively, one or more prototypes of the pre-shaped component may be fabricated  13 B. 
         [0022]    Once the pre-shaped model is created, either via a computer generated model and/or an actual physical prototype, the pre-shaped model is put through the StressWaving process. Different finite element methods may be used to simulate the StressWaving process  14 A. Alternatively, the one or more prototypes of the pre-shaped component that were fabricated could be subjected to the StressWave process  14 B. Each area of the pre-shaped component which may experience advanced dynamic changes may be StressWaved. The pre-shaped model that has been StressWaved will then be analyzed to determine if it is within design tolerances. 
         [0023]    Once the pre-shaped model has been StressWaved, features may be added in the pre-shaped model  15 . Features may be added in the computer generated model  15 A or the pre-shape components that were fabricated  15 B. The addition of the features may alter the shape of the pre-shaped model. Thus, the pre-shaped model that has been StressWaved and features added, needs to be compared to the engineering model to determine if the component is still within tolerance. 
         [0024]    If the pre-shaped model is created via a software program, different finite element methods may be used  16 A. Finite element analysis may be used to see how the StressWaving and feature forming process altered the final size and shape of the pre-shaped model. In a like manner, if one or more prototypes are built, and put through the StressWaving and feature forming process, actual measurements may be taken of the prototypes to determine whether the component is within tolerances  16 B. 
         [0025]    By using finite element analyses, one can extrapolate a final pre-shape model  17  including the location of the StressWave compressive zones of the component. The final pre-shape model needs to be one such that after applying the StressWave process to the final pre-shaped model in a specified method and locations, and adding the features in the desired locations and order, the final pre-shaped model will meet a pre-defined shape and be within a specified tolerance envelope  18  to be used in final assembly  19  without having to be scrapped or reworked. 
         [0026]    A confirmation of the final pre-shape model of the component may be performed  20 . The above analysis/steps are reapplied to the final pre-shaped model. Thus the analysis/steps to add features and StressWave may be reapplied to see if the final pre-shaped model which has been processed will meet the pre-defined shape and be within the specified tolerance envelope to be used in final assembly without having to be scrapped or reworked. Once the final pre-shape model of the component is confirmed, the component part may be formed with the dimensions of the final pre-shaped model  21 . The component part may then be StressWaved in the locations that may experience advanced dynamic changes. StressWaving in different manners can affect the size and shape of the component part. Thus, to control the location of the StressWave for later feature addition, one needs to control the changes in relation to the StressWaved locations. Each location or feature of the component part to be StressWaved should be StressWaved in a specific location on the component and in a specific order as determined by the computer analysis  22 A or the pre-shaped models that were formed  22 B. 
         [0027]    Features may be added to the StressWaved component in an order suitable to maintain the final component within tolerance  23 . For instance, and without limitation, each feature may be drilled in the component according to a particular order or no order. StressWaving may be done in a particular order or no order. For instance, without limitation, a location may be StressWaved and a feature added in that location prior to the next location being stressWaved. 
         [0028]    Referring now to  FIG. 4 , in order to control the locations  62  of the StressWave for later feature  64  additions, one needs to control the changes in relation to the StressWaved locations  62 . Each location  62  of the component part  60  to be StressWaved should be StressWaved in a specific location  62  on the component  60  and in a specific order as determined by the computer analysis or the pre-shaped models that were formed. An indentation device  66  is used to create residual stresses around the locations  62  of the component  60  which may experience advanced dynamic changes. After the StressWaving process, features  64  may be added. Features  64  are added by machine  68 . During the forming of the features  64 , one may need to allow the component  60  to grow in one or more axis (X-Y-Z) or the component  60  may need to be constrain in one or more of the component part axis (X-Y-Z) from twisting or other changes to ensure the proper locations of each feature  64  formed. Different tools  70  may be used to prevent the component  60  from twisting. Alternatively, a user may manually, by hand, prevent the component  60  from twisting. Other methods may be used to prevent the component  60  from twisting. 
         [0029]    In accordance with another embodiment, as shown in  FIGS. 5 and 6 , finite element analyses may be used to extrapolate a rough pre-shape model  100  taking into consideration, the size and shape of the component, the material of the component, the different areas of the component part where coldworking will be applied, and the like. As shown in the  FIG. 5 , a determination  32  of a rough pre-shape model is made by simulating a shape change of the component due to a coldworking process  30 . The rough pre-shaped model  100  is then fabricated  34 . The rough pre-shaped model  100  is formed thicker than the final component part  110  since the StressWave process will generate compressive zones in the areas of the component which may experience advanced dynamic changes. The StressWaving process may result in changes to the size and shape of the rough pre-shaped model. After StressWaving  36  each area of the rough pre-shaped model  100 , the rough pre-shaped model  100  is then then refixtured and final fabrication  38  to form the component part  110 . In this embodiment, finite element analyses may be used to establish a minimum size of the rough pre-shaped model  100  to allow the rough pre-shaped model  100  to be StressWaved and final machined to be used in final assembly. 
         [0030]    By using the methods discussed above, one can extrapolate the dimension and/or a shape of a component that needs to be created. The desired shape of the component to be created takes into consideration addition of features and application of the StressWave process to specified features and possibly adding features that do not require StressWaving after the StressWave process. The component formed will meet a pre-defined shape so that the component is within a specified tolerance envelope so that it may allow finalizing of component fabrication prior to final assembly and eliminate final assembly drilling, coldworking, deburring and clean-up. Coldworking, drilling, deburring and clean-up may be completed prior to final assembly. 
         [0031]    The ability to StressWave complex shapes further has the benefit of eliminating the need to remove the component after the formation process and/or during assembly to coldwork and/or add features and/or clean and debur. This can be a major reduction in manufacturing costs and/or part weight. The flexibility of StressWaving allows it to be used upstream of final assembly providing further cost reductions when compared to other coldworking processes. 
         [0032]    While embodiments of the disclosure have been described in terms of various specific embodiments, those skilled in the art will recognize that the embodiments of the disclosure can be practiced with modifications within the spirit and scope of the claims.