Our Work

Development of the Contour Method

The contour method uses careful sectioning and precision inspection techniques to develop a two-dimensional map of residual stress on a plane through a part. The contour method was invented circa 2000 by Dr. Mike Prime of Los Alamos National Laboratory.

Hill Engineering staff were instrumental in commercialization of the contour method, working in close collaboration with  Dr. Prime as early as 2000, and licensing the technology in 2006 from Los Alamos under US Patent 6,470,756 B1.

The first commercial applications of the contour method were related to the development of laser shock peening and improving manufacturing processes like welding and forging. Investments from the federal Small Business Innovative Research (SBIR) program have allowed us to demonstrate the usefulness of the contour method, and to enhance the quality, precision, and capability of the measurements we perform.

The contour method provides a unique capability to reveal the two-dimensional distribution of residual stress on a plane cut through a part, referred to as a residual stress map. After more than a decade of research and development, Hill Engineering is the industry leader in providing contour method stress mapping services for industry.

Further information on the contour method is provided elsewhere on our site, and other case studies illustrate its use.

Illustration of the contour method principle

Residual stress measured in a Ti-6Al-4V weld using the contour method superimposed on top of a photograph of the specimen

Case studies

Residual Stress Field Team TrueSlot® – near surface residual stress measurement ExpressRS® – expedited residual stress results Strain Gaging Services Residual Stress DART – automated residual stress measurement Mechanical stress relief of aluminum alloys Rapid Forge Design Aluminum forging quench modeling Machining distortion modeling with multi-step models including residual stress

Technical Publications

Measurement-driven, model-based estimation of residual stress and its effect on fatigue crack growth. Part 2: fatigue crack growth testing and modeling Measurement-driven, model-based estimation of residual stress and its effects on fatigue crack growth. Part 1: validation of an eigenstrain model Near Surface Residual Stress Measurement Using Slotting Measurement Layout for Residual Stress Mapping Using Slitting Precision of Hole-Drilling Residual Stress Depth Profile Measurements and an Updated Uncertainty Estimator An Uncertainty Estimator for Slitting Method Residual Stress Measurements Including the Influence of Regularization Validation of a Contour Method Single-Measurement Uncertainty Estimator Repeatability of Contour Method Residual Stress Measurements for a Range of Materials, Processes, and Geometries PSR Biaxial Residual Stress Mapping Validation The Contour Method (book chapter)