Hill Engineering Blog

Aircraft Airworthiness & Sustainment 2018

Hill Engineering is presenting about residual stress evaluation in legacy aircraft cold expanded fastener holes at the upcoming 2018 Aircraft Airworthiness & Sustainment Conference (AA&S) in Jacksonville, FL. The mission of this conference is to identify the challenges and the collaborative work being done within the aerospace community in improving the safety, airworthiness, availability and cost effectiveness of both our military and commercial aircraft fleets. Hill Engineering’s presentation will include a summary of recent work in airframe structures, demonstrating the effect of aircraft service on the residual stress at cold expanded fastener holes. The abstract text is presented below. Continue reading Aircraft Airworthiness & Sustainment 2018

Hill Engineering Vlog: Strain Gaging

Strain gages are key tools when performing residual stress measurements. By tracking the electrical resistance change of the strain gage foil, we can evaluate strain through material deformation. In our vlog presented below, we demonstrate how to apply a strain gage on an aluminum tensile specimen. While the setup described in the video is simple, we are capable of applying strain gages to much more complex geometries to fit the needs of our residual stress tests. For more information or any questions about your residual stress needs, please contact us.

Visiting the Utah office

Last year, Hill Engineering opened a satellite office in Layton, UT with the goal of better connecting with our customers and partners in the local area. Mike and I recently made a trip out to the office to check in and to spend some time working with our excellent team there to better understand and appreciate their outstanding work. Continue reading Visiting the Utah office

Residual stress definition

Residual stress definition – residual stress is defined as the stress that is present in a material in the absence of externally applied loading. Residual stresses often form during manufacturing and are typically an unintentional byproduct of a manufacturing process. As engineers we care about residual stresses because they affect material performance. Continue reading Residual stress definition

Fatigue tests

Fatigue tests are an important part of our work at Hill Engineering. There are many reasons to perform fatigue tests including: 1) qualifying the performance of parts for production, 2) ranking and optimizing different production processes, 3) validating fatigue analysis results and associated models, 4) understanding the performance of parts already in service, and more. The following discussion covers some basic details of typical fatigue tests. Continue reading Fatigue tests

Land of Wolves

This past holiday season, every employee of Hill Engineering was generously gifted a copy of “Land of Wolves: The Return of Lincoln’s Bodyguard.” This book was written by Hill Engineering friend and collaborator, TJ Turner. The historical fiction thriller—set in an alternative historical timeline in which Abraham Lincoln was saved from assassination—is the page-turning sequel to “Lincoln’s Bodyguard,” which was also gifted to the Hill Engineering employees back in 2015. Continue reading Land of Wolves

Residual stress in additive manufacturing

In previous blog posts we have discussed various issues related to residual stress in welding. Here, we’ll follow up with a more detailed look at residual stress in additive manufactured parts, which is a form of welding. Additive manufacturing processes, including powder and wire-fed E-beam and laser, produce residual stress as an undesired consequence. Residual stress in additive manufactured parts results from thermal cycles, temperature gradients, and localized plasticity. Continue reading Residual stress in additive manufacturing

Hill Engineering at Pipeline Pigging & Integrity Management Conference

Hill Engineering gave a presentation about fatigue analysis of pipelines at the 2018 Pipeline Pigging & Integrity Management (PPIM) Conference in Houston, TX. PPIM is the industry’s only forum devoted exclusively to pigging for maintenance and inspection, as well as pipeline integrity evaluation and repair. Hill Engineering’s presentation, titled “Is the Paris Fatigue Crack Growth Relation the Only Model Appropriate for Pressure Cycle Fatigue Analysis of Pipelines,” included an overview of various fatigue analysis models for pipeline fatigue crack growth assessment. The abstract text is presented below. Continue reading Hill Engineering at Pipeline Pigging & Integrity Management Conference

Mike Prime: a history of the contour method

Hill Engineering has proudly named the primary conference room in our new facility the Prime Room, a tribute to special Hill Engineering collaborator and inventor of the contour method, Mike Prime. We were recently honored to have Mike stop by for a ribbon cutting ceremony celebrating the opening of the Prime Room. In addition to the ceremony, Mike also gave a presentation about the history of the contour method and how it almost didn’t happen. Click on the video below to view Mike’s presentation and see how the contour method grew from one man’s curiosity to what it is today. Continue reading Mike Prime: a history of the contour method