Hill Engineering Blog

Hole Drilling Method for Measuring Residual Stresses

by Adrian DeWald

We’d like to share with our loyal followers a new book: Hole Drilling Method for Measuring Residual Stresses, written by Gary S. Schajer and Philip S. Whitehead. As you all know, Hole Drilling measures near-surface residual stress. The Hole Drilling method can be applied to quantify the average residual stress over the depth of a drilled hole (typically 1.0 mm depth). It can also be applied to determine the distribution of residual stress versus depth from the surface to a depth of half the hole diameter. Hole Drilling is portable and is a common method for residual stress measurement that can be applied under a variety of circumstances, including in the field. Continue reading Hole Drilling Method for Measuring Residual Stresses

Thermal Processing in Motion 2018 – recap

by Adrian DeWald

Hill Engineering recently attended the 2018 Thermal Processing in Motion Conference in Spartanburg, South Carolina. This conference brings together international experts from around the globe to present the latest innovations and research in thermal processing including: additive manufacturing; phase transformations; microstructure/property relationships; quenching and quenchants; thermomechanical thermal processing; and surface hardening. The second day of the conference included a Residual Stress Workshop. Continue reading Thermal Processing in Motion 2018 – recap

Thermal Processing in Motion 2018

by Adrian DeWald

Hill Engineering is delivering a keynote address titled Overview of Residual Stress Measurement in Industry Applications at the upcoming 2018 Thermal Processing in Motion Conference in Spartanburg, South Carolina. The mission of this conference is to bring together international experts from around the globe to present the latest innovations and research in thermal processing including: additive manufacturing; phase transformations; microstructure/property relationships; quenching and quenchants; thermomechanical thermal processing; and surface hardening. Hill Engineering’s presentation will include a summary of recent work related to residual stress measurement in support of production quality control. Continue reading Thermal Processing in Motion 2018

A Closer Look at Fatigue Surfaces

by Camille Fowler

We’ve previously talked about fracture surfaces created as a result of material fatigue. Through fatigue tests, we are able to create a typical loading cycle on a test specimen to see how the number and magnitude of cycles affects the growth of cracks on the surface. After the test, we can perform fatigue analysis to see how the crack grew over time using a microscope. Continue reading A Closer Look at Fatigue Surfaces

Case Study: Contour Method Repeatability

by Robert Pires

Recently, Hill Engineering posted a new case study detailing our research into contour method repeatability. In the case study, we performed contour method measurements on multiple similar specimens belonging to six different specimen types: aluminum T-section, stainless steel plate with dissimilar metal slot-filled weld, stainless steel forging, titanium plate with electron beam slot-filled weld, nickel disk forging, and aluminum plate. Continue reading Case Study: Contour Method Repeatability

AeroMat 2018: Residual stress production quality control

by Adrian DeWald

Hill Engineering is presenting about residual stress production quality control at the upcoming 2018 AeroMat Conference in Orlando, FL. The AeroMat Conference focuses on innovative aerospace materials, fabrication and manufacturing methods that improve performance, durability and sustainability of aerospace structures and engines with reduced life-cycle costs. Hill Engineering’s presentation will include an overview of ongoing work related to quality control processes for residual stress in manufacturing. The abstract text is presented below. Continue reading AeroMat 2018: Residual stress production quality control

Aircraft Airworthiness & Sustainment 2018

by Adrian DeWald

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

by Robert Pires

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

by Adrian DeWald

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

by Adrian DeWald

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