Selectively Tuning Frequency Modes Of A Structure

Abstract

Selectively tuning frequency modes of a structure, including: identifying, by a finite element analysis module, a plurality of frequency modes of the structure; and selectively altering, by the finite element analysis module, a target frequency mode a greater amount than the other frequency modes of the structure, including modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure.

1 - 6 . (canceled) 
     
     
         7 . An apparatus for selectively tuning frequency modes of a structure, the apparatus comprising a computer processor, a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer program instructions that, when executed by the computer processor, cause the apparatus to carry out the steps of:
 identifying, by a finite element analysis module, a plurality of frequency modes of the structure; and   selectively altering, by the finite element analysis module, a target frequency mode a greater amount than the other frequency modes of the structure, including modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure.   
     
     
         8 . The apparatus of  claim 7  wherein modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure further comprises:
 receiving, from a user, an identification of the target frequency mode; 
 identifying a current frequency of the target frequency mode; 
 receiving, from the user, an identification of a preferred frequency of the target frequency mode; 
 calculating a modal ratio as the quotient of the preferred frequency divided by the current frequency; 
 iteratively, until a modal ratio falls within a predefined range of acceptable values:
 calculating an amount of mass to change in dependence upon the modal ratio; 
 providing, to a geometry modification module, the calculated amount of mass to change; 
 identifying one or more locations of the structure to change the mass the calculated amount, including identifying locations at which deflection is greater than a predefined threshold when operating at the target frequency mode; 
 providing, to the geometry modification module, the identified locations of the structure to change the mass the calculated amount; 
 changing, by the geometry modification module, mass by the calculated amount at the identified locations; 
 identifying again the frequency modes of the structure, including identifying a shifted frequency of the target frequency mode; and 
 recalculating the modal ratio as the quotient of the target frequency divided by the shifted frequency. 
 
 
     
     
         9 . The apparatus of  claim 7  wherein modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure further comprises:
 receiving, from a user, an identification of the target frequency mode; 
 identifying a current frequency of the target frequency mode; 
 receiving, from the user, an identification of a preferred frequency of the target frequency mode; 
 calculating a modal ratio as the quotient of the preferred frequency divided by the current frequency; 
 iteratively, until a modal ratio falls within a predefined range of acceptable values:
 calculating an amount of stiffness to change in dependence upon the modal ratio; 
 providing, to a geometry modification module, the calculated amount of stiffness to change; 
 identifying one or more locations of the structure to change the stiffness the calculated amount, including identifying locations at which strain is greater than a predefined threshold when operating at the target frequency mode; 
 providing, to the geometry modification module, the identified locations of the structure to change the stiffness the calculated amount; 
 changing, by the geometry modification module, stiffness by the calculated amount at the identified locations; 
 identifying again the frequency modes of the structure, including identifying a shifted frequency of the target frequency mode; and 
 recalculating the modal ratio as the quotient of the target frequency divided by the shifted frequency. 
 
 
     
     
         10 . The apparatus of  claim 7  wherein:
 the structure comprises one part of an apparatus comprising at least a second structure; and 
 selectively altering a target frequency mode a greater amount than the other frequency modes of the structure further comprises selectively altering the target frequency mode a greater amount than any frequency mode of the second structure. 
 
     
     
         11 . The apparatus of  claim 7  wherein the finite element analysis module comprising a finite element analysis application. 
     
     
         12 . The apparatus of  claim 7  wherein the finite element analysis module comprising a plug-in to a finite element analysis application. 
     
     
         13 . A computer program product for selectively tuning frequency modes of a structure, the computer program product disposed upon a computer readable medium, the computer program product comprising computer program instructions that, when executed, cause a computer to carry out the steps of:
 identifying, by a finite element analysis module, a plurality of frequency modes of the structure; and   selectively altering, by the finite element analysis module, a target frequency mode a greater amount than the other frequency modes of the structure, including modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure.   
     
     
         14 . The computer program product of  claim 13  wherein modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure further comprises:
 receiving, from a user, an identification of the target frequency mode; 
 identifying a current frequency of the target frequency mode; 
 receiving, from the user, an identification of a preferred frequency of the target frequency mode; 
 calculating a modal ratio as the quotient of the preferred frequency divided by the current frequency; 
 iteratively, until a modal ratio falls within a predefined range of acceptable values:
 calculating an amount of mass to change in dependence upon the modal ratio; 
 providing, to a geometry modification module, the calculated amount of mass to change; 
 identifying one or more locations of the structure to change the mass the calculated amount, including identifying locations at which deflection is greater than a predefined threshold when operating at the target frequency mode; 
 providing, to the geometry modification module, the identified locations of the structure to change the mass the calculated amount; 
 changing, by the geometry modification module, mass by the calculated amount at the identified locations; 
 identifying again the frequency modes of the structure, including identifying a shifted frequency of the target frequency mode; and 
 recalculating the modal ratio as the quotient of the target frequency divided by the shifted frequency. 
 
 
     
     
         15 . The computer program product of  claim 13  wherein modifying a local attribute of a portion of the structure associated with the target frequency mode without modifying the attribute over the entire structure further comprises:
 receiving, from a user, an identification of the target frequency mode; 
 identifying a current frequency of the target frequency mode; 
 receiving, from the user, an identification of a preferred frequency of the target frequency mode; 
 calculating a modal ratio as the quotient of the preferred frequency divided by the current frequency; 
 iteratively, until a modal ratio falls within a predefined range of acceptable values:
 calculating an amount of stiffness to change in dependence upon the modal ratio; 
 providing, to a geometry modification module, the calculated amount of stiffness to change; 
 identifying one or more locations of the structure to change the stiffness the calculated amount, including identifying locations at which strain is greater than a predefined threshold when operating at the target frequency mode; 
 providing, to the geometry modification module, the identified locations of the structure to change the stiffness the calculated amount; 
 changing, by the geometry modification module, stiffness by the calculated amount at the identified locations; 
 identifying again the frequency modes of the structure, including identifying a shifted frequency of the target frequency mode; and 
 recalculating the modal ratio as the quotient of the target frequency divided by the shifted frequency. 
 
 
     
     
         16 . The computer program product of  claim 13  wherein:
 the structure comprises one part of an apparatus comprising at least a second structure; and 
 selectively altering a target frequency mode a greater amount than the other frequency modes of the structure further comprises selectively altering the target frequency mode a greater amount than any frequency mode of the second structure. 
 
     
     
         17 . The computer program product of  claim 13  wherein the finite element analysis module comprising a finite element analysis application. 
     
     
         18 . The computer program product of  claim 13  wherein the finite element analysis module comprising a plug-in to a finite element analysis application. 
     
     
         19 . The computer program product of  claim 13  wherein the computer readable medium comprises a signal medium. 
     
     
         20 . The computer program product of  claim 13  wherein the computer readable medium comprises a storage medium.