Analysis method using finite element method, program causing computer to execute same, and system for same

Abstract

An FEM analysis system is provided which is capable of analyzing with high accuracy and within a short time in a drop shock analysis of electronic devices in which a very small mesh size is incorporated. Processing to be performed by an optimal solution selecting and analyzing section includes a step of checking whether an analysis to be performed is a shock analysis, a step of searching for a minimum mesh size when the analysis to be performed is judged to be a shock analysis, a step of creating a simplified analysis model using the minimum mesh size, a step of performing a preliminary analysis on a simplified model by an implicit method and explicit method, and a step of selecting either of the implicit method or explicit method as an optimal analysis method by comparing results from preliminary analysis, results from these analyses and experiments or exact solution.

What is claimed is:  
     
         1 . An analysis method using a finite element method for performing a stress analysis on an analysis model, comprising: 
 a first step of judging whether or not an analysis to be made is a shock analysis;    a second step of performing an analysis using an implicit method when said analysis to be made is judged to be a shock analysis in said first step; and    a third step of performing an analysis using an analysis method selected by an analyzer when said analysis to be made is judged to be not a shock analysis in said first step.    
     
     
         2 . The analysis method using the finite element method according to  claim 1 , wherein a Newmark β method is used as said implicit method.  
     
     
         3 . An analysis method using a finite element method for creating meshes of an analysis model and for making a stress analysis of said analysis model, said analysis method comprising: 
 a first step of judging whether an analysis to be made is a shock analysis;    a second step of searching for a minimum mesh size out of said meshes of said analysis model;    a third step of creating a simplified analysis model using said minimum mesh size;    a fourth step of analyzing said simplified analysis model by using an implicit method and an explicit method;    a fifth step of selecting either of said implicit method or said explicit method as an optimal method, based on a result from an analysis in said fourth step;    a sixth step of having an analyzer select either of said implicit method or said explicit method based on a result from said analysis in said fourth step; and    a seventh step of analyzing said analysis model by using an analysis method selected in said fifth step or said sixth step.    
     
     
         4 . The analysis method using the finite element method according to  claim 3 , wherein a Newmark β method is used as said implicit method.  
     
     
         5 . The analysis method using the finite element method according to  claim 3 , wherein, in said fifth step, when a following expression holds,  
       
         T 
         im 
         <T 
         ex  
       
       where said “T im ” denotes analysis time required for said implicit method and said “T ex ” denotes analysis time required for said explicit method, said implicit method is selected while, when above said expression does not hold, said explicit method is selected.  
     
     
         6 . The analysis method using the finite element method according to  claim 3 , wherein, in said fifth step, when a following expression holds,  
         abs ( E−S   im )< abs ( E−S   ex )  
       where said “abs” denotes an absolute value, said “S im ” denotes an analysis result containing data on displacement, stress, and distortion obtained from said implicit method, said “S ex ” denotes an analysis result containing data on displacement, stress, and distortion obtained from said explicit method, and said “E” denotes a result containing data on displacement, stress, and distortion obtained from said implicit method including an experiment value and an exact solution of a theoretical expression and from a method other than said explicit method, said implicit method is selected while, when above said expression does not hold, said explicit method is selected.  
     
     
         7 . The analysis method using the finite element method according to  claim 3 , wherein, in said sixth step, said analyzer is allowed to select an analysis method based on a relation between analysis time required for said implicit method said “T im ” and analysis time required for said explicit method said “T ex ” and based on a relation among an analysis result said “S im ” containing displacement, stress, and distortion obtained from said implicit method, an analysis result said “S ex ” containing displacement, stress, and distortion obtained from said explicit method, and a result said “E” containing displacement, stress, and distortion obtained from said implicit method including an experiment value and an exact solution of a theoretical expression and from a method other than said explicit method.  
     
     
         8 . A program for having a computer make an analysis using a finite element method used to perform a stress analysis of an analysis model: said program comprising: 
 a first step of judging whether or not an analysis to be made is a shock analysis;    a second step of performing an analysis using an implicit method when said analysis to be made is judged to be a shock analysis in said first step;    a third step of performing an analysis by using an analysis method selected by an analyzer when said analysis to be made is judged to be not a shock analysis in said first step.    
     
     
         9 . The program according to  claim 8 , wherein a Newmark β method is executed by a computer as said implicit method.  
     
     
         10 . A program for having a computer execute an analysis using a finite element method which creates meshes of an analysis model and performs a stress analysis of said analysis model, said program comprising: 
 a first process of judging whether or not an analysis to be performed is a shock analysis;    a second process of searching for a minimum mesh size out of said meshes of said analysis model;    a third process of creating a simplified analysis model using said minimum mesh size;    a fourth process of analyzing said simplified analysis model by using an implicit method and an explicit method;    a fifth process of selecting either of said implicit method or said explicit method as an optimal method, based on a result from said analysis in said fourth process;    a sixth process of having an analyzer select either of said implicit method or said explicit method based on a result from said analysis in said fourth process; and    a seventh process of analyzing said analysis model by using an analysis method selected in said fifth process or said sixth process.    
     
     
         11 . The program according to  claim 10 , wherein a Newmark β method is executed by a computer as said implicit method.  
     
     
         12 . The program according to  claim 10 , wherein, in said fifth process, when a following expression holds,  
       
         T 
         im 
         <T 
         ex  
       
       where said “T im ” denotes analysis time required for said implicit method and said “T ex ” denotes analysis time required for said explicit method, said implicit method is selected while, when above said expression does not hold, said explicit method is selected.  
     
     
         13 . The program according to  claim 10 , wherein, in said fifth process, when a following expression holds,  
         abs ( E−S   im )< abs ( E−S   ex )  
       where said “abs” denotes an absolute value, said “S im ” denotes an analysis result containing data on displacement, stress, and distortion obtained from said implicit method, S ex  said denotes an analysis result containing data on displacement, stress, and distortion obtained from said explicit method, and said “E” denotes a result containing data on displacement, stress, and distortion obtained from said implicit method including an experiment value and an exact solution of a theoretical expression and from a method other than said explicit method, said implicit method is selected while, when above said expression does not hold, said explicit method is selected.  
     
     
         14 . The program according to  claim 10 , wherein, in said sixth process, said analyzer is allowed to select an analysis method based on a relation between said analysis time required for said implicit method said “T im ” and said analysis time required for said explicit method said “T ex ” and based on a relation among an analysis result said “S im ” containing displacement, stress, and distortion obtained from said implicit method, an analysis result said “S ex ” containing displacement, stress, and distortion obtained from said explicit method, and a result said “E” containing displacement, stress, and distortion obtained from said implicit method including an experiment value and an exact solution of a theoretical expression and from a method other than said explicit method.  
     
     
         15 . A finite element method analysis system having a unit for creating meshes of an analysis model and having a unit for making an analysis using a finite element method used to perform a stress analysis on said analysis model using said finite element method, said finite element method analysis system comprising: 
 a first unit to judge whether or not an analysis to be made is a shock analysis;    wherein, when said analysis to be performed by said unit for making said analysis using said finite element method is judged by said first unit to be a shock analysis, an analysis is made by using an implicit method and wherein, when said analysis to be performed by said unit making said analysis using said finite element method is judged by said first unit to be not a shock analysis, said analysis is made by using an analysis method selected by an analyzer.    
     
     
         16 . The finite element method analysis system according to  claim 15 , wherein said unit making said analysis using said finite element method performs a Newmark β method as said implicit method.  
     
     
         17 . A finite element method analysis system having a unit for creating meshes of an analysis model and having a unit for making an analysis using a finite element method used to perform a stress analysis on said analysis model using said finite element method, said finite element method analysis system comprising: 
 a first section to judge whether or not an analysis to be performed is a shock analysis;    a second section to search for a minimum mesh size out of said meshes of said analysis model;    a third section to create a simplified analysis model using said minimum mesh size;    a fourth section to select either of said implicit method or said explicit method as an optimal method, based on a result from a simplified analysis in which said simplified analysis model is analyzed by a unit for making an analysis using a finite element method by using an implicit method and an explicit method;    a fifth section to have an analyzer select either of said implicit method or said explicit method as an analysis method based on a result from said simplified analysis; and    wherein said unit for making an analysis using a finite element method analyzes said analysis model by using said fourth section or said fifth section.    
     
     
         18 . The finite element method analysis system according to  claim 17 , wherein said unit making said analysis using said finite element method performs a Newmark β method as said implicit method.  
     
     
         19 . The finite element method analysis system according to  claim 17 , wherein, said fourth section, when a following expression holds,  
       
         T 
         im 
         <T 
         ex  
       
       where said “T im ” denotes analysis time required for said implicit method and said “T ex ” denotes analysis time required for said explicit method, selects said implicit method while, when above said expression does not hold, selects said explicit method.  
     
     
         20 . The finite element method analysis system according to  claim 17 , wherein, said fourth section, when a following expression holds,  
         abs ( E−S   im )< abs ( E−S   ex )  
       where said “abs” denotes an absolute value, said “S im ” denotes an analysis result containing data on displacement, stress, and distortion obtained from said implicit method, said S ex  denotes an analysis result containing data on displacement, stress, and distortion obtained from said explicit method, and said “E” denotes a result containing data on displacement, stress, and distortion obtained from said implicit method including an experiment value and an exact solution of a theoretical expression and from a method other than said explicit method, selects said implicit method while, when above said expression does not hold, selects said explicit method.  
     
     
         21 . The finite element method analysis system according to  claim 17 , wherein said fifth section has said analyzer select an analysis method based on a relation between analysis time required for said implicit method said “T im ” and analysis time required for said explicit method said “T ex ” and based on a relation among an analysis result said “S im ” containing displacement, stress, and distortion obtained from said implicit method, an analysis result said “S ex ” containing displacement, stress, and distortion obtained from said explicit method, and a result said “E” containing displacement, stress, and distortion obtained from said implicit method including an experiment value and an exact solution of a theoretical expression and from a method other than said explicit method.