Happy 20th birthday to the contour method

Today marks a major milestone in the field of residual stress measurement. The contour method, one of the most useful and advanced residual stress measurement techniques, was first successfully implemented on this date (August 16th) in 1999 by Mike Prime at Los Alamos National Laboratory. The most significant feature of the contour method is its ability to generate detailed two-dimensional residual stress maps like the one shown below. Please join us in wishing the contour method a very happy 20th birthday! Continue reading Happy 20th birthday to the contour method

Residual Stress 101 vlog

Today, we’ve released the newest episode of our vlog: Residual Stress 101. The video is a return to basics, discussing the core of what it is we do here at Hill Engineering.

If you haven’t checked out our YouTube channel, it might be time. Our mission is to post content that helps highlight the capabilities of our organization, so that everyone can see how and why residual stress is important to their manufacturing processes.

Today’s post is a broad overview of what residual stress is, including the several techniques for measuring residual stress found in our lab. Look for future content that delves further into each technique, and contact us if you have any further questions or want to see a video related to something we haven’t discussed.  

New publication – An Uncertainty Estimator for Slitting Method Residual Stress Measurements Including the Influence of Regularization

Hill Engineering recently published new research detailing our efforts to quantify uncertainty for slitting method residual stress measurements. This new approach provides a more accurate estimate of the measurement uncertainty associated with the slitting method, which is very helpful for probabilistic performance assessments. The paper is titled An Uncertainty Estimator for Slitting Method Residual Stress Measurements Including the Influence of Regularization and appears in Experimental Mechanics. The abstract text is available here along with a link to the publication. Continue reading New publication – An Uncertainty Estimator for Slitting Method Residual Stress Measurements Including the Influence of Regularization

Additive Manufacturing Benchmark Publication

Hill Engineering recently contributed to a publication related to residual stress measurement in additive manufacturing (AM) test specimens titled, Elastic Residual Strain and Stress Measurements and Corresponding Part Deflections of 3D Additive Manufacturing Builds of IN625 AM‑Bench Artifacts Using Neutron Diffraction, Synchrotron X‑Ray Diffraction, and Contour Method. The work was performed under the NIST AM-Bench program in collaboration with researchers from NIST, Los Alamos National Laboratory, University of California Davis, and Cornell High Energy Synchrotron Source. The abstract text is available here along with a link to the publication. Continue reading Additive Manufacturing Benchmark Publication

Hill Engineering announces agreement with VEQTER for Deep-Hole Drilling technology

Hill Engineering, answering strong demand for its residual stress measurement services, would like to announce our agreement with VEQTER, Ltd to license the Deep-Hole Drilling (DHD) technology. VEQTER, along with the University of Bristol, aided in the development of the DHD technique, and have practiced the technology for over 25 years. With this agreement, VEQTER will provide Hill Engineering with the equipment, technology, and support to deliver state-of-the-art DHD measurements within the North and South American Continents. Continue reading Hill Engineering announces agreement with VEQTER for Deep-Hole Drilling technology

Engineered Residual Stress Implementation workshop

Hill Engineering is proud to support the USAF and their objective to advance damage tolerance analysis methods through the Engineered Residual Stress Implementation (ERSI) workshop. At this year’s ERSI meeting (September 12-13), Hill Engineering will meet with other stakeholders in the USAF aircraft community to review progress over the past year towards implementation of engineered residual stress in the USAF fleet. Continue reading Engineered Residual Stress Implementation workshop

Additive Manufacturing Benchmark Test Series

As a follow-up to our previous post about additive manufacturing (AM) we wanted to highlight some other activities in the additive manufacturing space.

One such activity that Hill Engineering has been involved in is the NIST AM-Bench program. AM-Bench is developing a continuing series of controlled benchmark tests with two initial goals: 1) to allow modelers to test their simulations against rigorous, highly controlled additive manufacturing benchmark test data, and 2) to encourage additive manufacturing practitioners to develop novel mitigation strategies for challenging build scenarios. As part of this program, Hill Engineering has been working in collaboration with UC Davis to support residual stress measurement activities using the contour method. Continue reading Additive Manufacturing Benchmark Test Series

Residual stress in additive manufacturing

Additive manufacturing (AM) is a manufacturing process that deposits material in a controlled manner to build three-dimensional part geometry (bit by bit). This is in contrast to traditional manufacturing processes where material is cut or removed (i.e., subtracted) from the raw stock to create the intended part shape. The potential for additive manufacturing to significantly improve the economics and performance of manufactured parts for certain applications has made it a popular topic. However, since most additive manufacturing processes are highly thermal (e.g., material is deposited in a melted form and solidifies into the desired shape) significant residual stresses can develop. Hill Engineering has been working with many collaborators to better understand the influence of these processes on residual stress. Continue reading Residual stress in additive manufacturing

Residual stress measurement techniques

Residual stresses exist in most materials and structures. Processes like forging, rolling, extruding, quenching, additive manufacturing, machining, and welding can cause residual stresses to develop. These stresses can influence the way that materials perform (e.g., fatigue, fracture, distortion, and corrosion). There are many different residual stress measurement techniques available to quantify residual stresses. The following are some examples of common measurement techniques. Continue reading Residual stress measurement techniques