Hill Engineering Blog

Aircraft Airworthiness & Sustainment 2017

Hill Engineering is presenting about residual stress engineering to support fleet management and life extensions of legacy fleets at the upcoming 2017 Aircraft Airworthiness & Sustainment Conference (AA&S) in Phoenix, AZ. 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 use of residual stress engineering tools to support design and sustainment. The abstract text is presented below. Continue reading Aircraft Airworthiness & Sustainment 2017

Welcome Josh Hodges

We would like to welcome Josh Hodges to Hill Engineering. Josh has worked in the United States Air Force T-38 ASIP office (Hill Air Force Base) for the past 8+ years as a Structural Integrity Analyst. During his time in the T-38 ASIP office, Josh filled many roles including: developer of the Broad Application for Modeling Failure software and manager of the T-38 Damage Database, while also serving as a subject matter expert on the effects of residual stress on fracture and fatigue. Continue reading Welcome Josh Hodges

Fatigue Analysis

Fatigue is a material failure mechanism whereby repeated sub-critical loads nucleate and grow cracks that can ultimately lead to failure of a structure. Hill Engineering routinely performs fatigue analysis to quantify and predict fatigue performance of materials. State-of-the-art fatigue analysis is subdivided into categories, including durability (crack initiation) or damage tolerance (crack growth). The appropriate fatigue analysis for a given design depends on the application. Continue reading Fatigue Analysis

Come see us at AeroMat 2017

Hill Engineering is presenting about advanced manufacturing methods and their effects on residual stress at the upcoming 2017 AeroMat Conference in Charleston, SC. The event is organized by ASM International and is hosted by Arconic. Hill Engineering’s presentation will include a summary of recent programs where we evaluated the residual stress from a variety of advanced manufacturing methods. The abstract text is presented below. Continue reading Come see us at AeroMat 2017

Building a Quality System

As was previously discussed, Hill Engineering was recently awarded ISO17025:2005 accreditation for our Quality System. Developing a Quality System that is compliant with ISO is a significant effort, and at Hill Engineering we took it as an opportunity to improve the quality and documentation of our laboratory residual stress measurement services. Here’s a look back on some of the highlights in the development of our Quality System. Continue reading Building a Quality System

Cold expansion

Fatigue is one important failure mode that guides the design and engineering of aircraft structure. As we have discussed previously aircraft are often manufactured using rivets and fasteners, which require drilling many holes in the structure during assembly. The holes act as stress concentrations, which tend to be locations where fatigue cracks are found. Compressive residual stresses act to hold cracks shut and result in improved fatigue performance. This residual compressive stress can provide substantial benefits in terms of performance, safety, cost, and inspection requirements. To take advantage of the benefits of compressive residual stress, cold expansion is often applied to aircraft fastener holes. Continue reading Cold expansion

The Prime Room

Hill Engineering recently moved into a new facility in Rancho Cordova, CA. The new facility features a combination of laboratory, research and development, and office space; all of which are important as we work tenaciously to meet the needs of our current projects, while at the same time keeping an eye towards innovation and new opportunities. We have proudly named the primary conference room in our new facility the Prime Room, a fitting tribute to a special Hill Engineering collaborator, the inventor of the contour method, and inspirational figure, Mike Prime. Continue reading The Prime Room

Fracture surfaces evaluation

Aircraft undergo complex loading during their operation and lifecycle. For example, take off, landing, turbulence, and flight/ground maneuvers are all instances where significant loading occurs. The cyclic loading and unloading activates a failure mechanism called fatigue, which is most prevalent at the highest stressed regions. Continue reading Fracture surfaces evaluation