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1. US20180045592 - Residual stress estimation method and residual stress estimation device

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Claims

1. A residual stress estimation method based on inherent strain for use in suppressing deformation during plastic processing, the residual stress estimation method comprising steps of:
obtaining a measured value related to residual stress measured from a cut piece collected in a region in which the inherent strain is uniformly distributed in a case where it is assumed that the inherent strain is uniformly distributed in one direction in a structure;
estimating a two-dimensional inherent strain distribution in a direction crossing the one direction in the structure based on the obtained measured value;
estimating a three-dimensional inherent strain distribution in the structure such that the estimated two-dimensional inherent strain distribution continues in the one direction; and
optimizing processing conditions of the structure based on the estimated three-dimensional inherent strain distribution to thereby suppress deformation of the structure resulting from the inherent strain.
2. The residual stress estimation method according to claim 1, wherein in the step of obtaining a measured value, elastic strain or residual stress measured on a cut surface of the cut piece that is cut in the direction crossing the one direction is obtained as the measured value.
3. The residual stress estimation method according to claim 2,
wherein in the step of estimating a three-dimensional inherent strain distribution, in a three-dimensional model of the structure in which a plurality of calculation points are three-dimensionally arranged, the estimated inherent strain value at each calculation point on one surface crossing the one direction is given to each calculation point on the other surface crossing the one direction.
4. The residual stress estimation method according to claim 1,
wherein in the step of estimating a three-dimensional inherent strain distribution, in a three-dimensional model of the structure in which a plurality of calculation points are three-dimensionally arranged, the estimated inherent strain value at each calculation point on one surface crossing the one direction is given to each calculation point on the other surface crossing the one direction.
5. The residual stress estimation method according to claim 4,
wherein in the step of estimating a three-dimensional inherent strain distribution, when a calculation point to which the estimated inherent strain value is not given is present on the other surface, in a case where the one surface is overlapped with the other surface, the inherent strain at the calculation point is compensated based on the inherent strain of the one surface around the calculation point to which the estimated inherent strain value is not given.
6. The residual stress estimation method according to claim 5,
wherein in the step of estimating a three-dimensional inherent strain distribution, a searching region is set around the calculation point, and in a case where the calculation point of the one surface overlapped with the other surface is present in the searching region, the inherent strain at the calculation point to which the inherent strain is not given is compensated based on the estimated inherent strain value at the calculation point of the one surface in the searching region.
7. The residual stress estimation method according to claim 6,
wherein in the step of estimating a three-dimensional inherent strain distribution, in a case where the calculation point of the one surface overlapped with the other surface is not present in the searching region, a searching region larger than the searching region is newly set.
8. A residual stress estimation device for use in suppressing deformation during plastic processing, the residual stress estimation device comprising:
an input unit that receives, in a case where it is assumed that inherent strain is uniformly distributed in one direction in a structure, an input of a measured value related to residual stress measured from a cut piece collected in a region in which the inherent strain is uniformly distributed;
a first estimation unit that estimates a two-dimensional inherent strain distribution in a direction crossing the one direction in the structure based on the measured value received by the input unit;
a second estimation unit that estimates a three-dimensional inherent strain distribution in the structure such that the two-dimensional inherent strain distribution estimated by the first estimation unit continues in the one direction;
a display unit that displays a residual stress estimation result based on the three-dimensional inherent strain distribution estimated by the second estimation unit; and
a processor that optimizes processing conditions of the structure based on the estimated three-dimensional inherent strain distribution to thereby suppress deformation of the structure resulting from the inherent strain.