Real-time resonant inspection for additive manufacturing

Abstract

A method of additive manufacturing comprises determining a first resonant frequency of an unflawed reference workpiece at a first partial stage of completion, fabricating a production workpiece to the first partial stage of completion via additive manufacture, sensing a second resonant frequency of the production workpiece in-situ at the first partial stage of completion, during the fabrication, analyzing the workpiece for flaws based on comparison of the first and second resonant frequencies, and providing an output indicative of production workpiece condition, based on the analysis. An additive manufacturing system comprises an additive manufacturing tool, a sensor, and a controller. The additive manufacturing tool is disposed to construct a workpiece via iterative layer deposition. The sensor is disposed to determine a resonant frequency of the workpiece in-situ at the additive manufacturing tool, during fabrication. The controller is configured to terminate manufacture of the workpiece if the resonant frequency differs substantially from a reference frequency.

1 . A method of additive manufacturing comprises:
 determining a first resonant frequency of an unflawed reference workpiece at a first partial stage of completion;   fabricating a production workpiece to the first partial stage of completion via additive manufacture;   sensing a second resonant frequency of the production workpiece in-situ at the first partial stage of completion, during the fabricating;   analyzing the workpiece for flaws based on comparison of the first and second resonant frequencies; and   providing an output indicative of production workpiece condition, based on the analysis.   
     
     
         2 . The method of  claim 1 , further comprising:
 prematurely terminating fabrication of the production in response to substantial deviation of the second resonant frequency from the first resonant frequency.   
     
     
         3 . The method of  claim 2 , wherein the first resonant frequency differs substantially from the second resonant frequency if the first and second resonant frequencies differ by 10% or more. 
     
     
         4 . The method of  claim 1 , wherein determining the first resonant frequency comprises sensing the resonant frequency of a workpiece independently verified as unflawed, at the first partial stage of completion 
     
     
         5 . The method of  claim 1 , wherein determining the first resonant frequency comprises:
 completely fabricating the unflawed reference workpiece;   machining away material from the unflawed reference workpiece until the unflawed reference workpiece is reduced to the first partial stage of completion; and   acoustically sensing a resonant frequency of the unflawed reference workpiece.   
     
     
         6 . The method of  claim 1 , wherein determining the first resonant frequency comprises simulating the unflawed reference workpiece, and computing a resonant frequency of the simulated unflawed reference workpiece. 
     
     
         7 . The method of  claim 1 , further comprising:
 determining at least a third resonant frequency of the unflawed reference workpiece at a second partial stage of completion distinct from the first stage of completion;   sensing at least a fourth resonant frequency of the production workpiece in-situ at the second partial stage of completion; and   analyzing the workpiece for flaws based on comparison of at least the third and fourth resonant frequencies.   
     
     
         8 . An additive manufacturing system comprises:
 an additive manufacturing tool disposed to construct a workpiece via iterative layer deposition;   a sensor disposed to determine a resonant frequency of the workpiece in-situ at the additive manufacturing tool, during fabrication; and   a controller configured to terminate manufacture of the workpiece if the resonant frequency differs substantially from a reference frequency.   
     
     
         9 . The additive manufacturing system of  claim 8 , wherein the additive manufacturing tool comprises an electron beam machining apparatus 
     
     
         10 . The additive manufacturing system of  claim 8 , wherein the additive manufacturing tool comprises a direct metal laser sintering apparatus. 
     
     
         11 . The additive manufacturing system of  claim 8 , wherein the sensor is disposed to periodically determine the resonant frequency at multiple stages of completion of the workpiece, and the controller is configured to terminate manufacture of the workpiece if at any time the resonant frequency differs substantially from a corresponding reference frequency. 
     
     
         12 . The additive manufacturing system of  claim 8 , wherein the controller comprises a processor and a database containing a plurality of reference frequencies. 
     
     
         13 . The additive manufacturing system of  claim 8 , wherein the sensor is an active sensor disposed to both induce and sense vibration in the workpiece.