Initial Stress and Eigenstrain Computation via Inverse Elastic Analysis
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Solution Overview
Problem
Current methods for estimating initial stresses and eigenstrains in materials caused by manufacturing processes are inefficient, requiring substantial measurements and struggling to distinguish linear elastic responses from pre-existing residual stresses, especially for surface processes.
Innovation Solution
A system and method that uses measured geometric data from a scanner to calculate linear elastic strains and reactions in a coupon, estimating initial stresses and eigenstrains, and predicting deformation, fatigue life, or buckling in materials by combining residual stress and linear elastic reaction data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to estimate initial stresses and eigenstrains, then measurement accuracy may be maintained, but measurement effort and time increase substantially
Solution Approach 1:
The patent segments the measurement process into two distinct phases: (1) measuring only surface geometric data and residual stresses at limited locations, and (2) using inverse elastic analysis to compute the full initial stress and eigenstrain fields. This segmentation allows obtaining complete stress information without performing exhaustive measurements throughout the entire material domain, thereby reducing measurement time while maintaining accuracy.
Solution Approach 2:
The patent replaces direct mechanical measurement methods (which would require substantial physical measurements) with an inverse elastic analysis computational approach. By substituting mechanical measurement systems with computational mechanics based on linear elasticity theory, the method achieves accurate stress estimation from minimal measurements, significantly reducing measurement effort.
2Measurement precision
If comprehensive residual stress measurements are performed throughout the material domain, then initial stress estimation accuracy is improved, but measurement complexity and cost increase
Solution Approach 1:
The patent extracts only the essential measurement data needed for accurate initial stress estimation—specifically, surface geometric data and residual stresses at limited locations—rather than performing comprehensive measurements throughout the entire material domain. The inverse elastic analysis then computes the complete stress field from these extracted measurements, reducing measurement complexity while maintaining estimation accuracy.
Solution Approach 2:
The patent creates a computational model (copy) of the material's elastic behavior and uses inverse analysis to reconstruct the full initial stress and eigenstrain fields from limited measurements. This computational copying approach allows obtaining complete stress information without physically measuring every point in the material, thereby reducing measurement complexity.
3Reliability
If pre-existing residual stresses are present, then distinguishing linear elastic response becomes difficult, but the patent enables accurate distinction through inverse elastic analysis
Solution Approach 1:
The patent employs inverse elastic analysis that uses feedback from measured surface geometric data and residual stresses to iteratively compute and distinguish the linear elastic response from pre-existing residual stresses. The computational model adjusts its predictions based on the measured data, enabling accurate separation of stress components even when they are coupled in the physical system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for efficient calculation of initial stresses and eigenstrains, enabling the estimation of distortion and residual stresses in complex shapes, improving fatigue life assessment and structural integrity evaluation with minimal measurements.
Implementation Method 1
receiving measured geometric data from a scanner configured to scan a coupon of the material before and after the application of the manufacturing process
Implementation Method 2
calculating linear elastic strains in respective opposing sides of the coupon caused by application of the manufacturing process, the linear elastic strains being calculated based at least in part on the measured geometric data
Implementation Method 3
calculating an estimated initial stress in the material as a sum of the residual stress in the coupon and the linear elastic reaction of the material
Data Source
AI summary
A system and method are provided for estimating initial stresses in and eigenstrains of a material. The system may receive measured geometric data including measurements of a material before and after the application of a manufacturing process thereto. The measurements may indicate a residual stress in a coupon after application of the manufacturing process. Estimated linear elastic strains may be calculated in respective opposing sides of the coupon based on the measured geometric data. A linear elastic reaction of the material to the manufacturing process may be calculated based at least in part on the estimated linear elastic strains. The system may then calculate an estimated initial stress in the material as a sum of the residual stress in the coupon and the linear elastic reaction of the material, and calculate an estimated eigenstrain of the material based at least in part on the estimated initial stress in the material.