Hill Engineering Blog

Fatigue Analysis

by Adrian DeWald

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

by Adrian DeWald

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

by Adrian DeWald

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

by Adrian DeWald

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

by Adrian DeWald

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

by Camille Fowler

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

Failure analysis of high strength nuts

by Robert Pilarczyk

Fracture and fatigue are important material performance issues that Hill Engineering examines on a regular basis. Hill Engineering recently contributed to a publication titled “Investigating and interpreting failure analysis of high strength nuts made from nickel-base superalloy.” The publication includes a detailed review of work performed to understand the failure of these fracture critical nuts. The abstract text is copied below. A temporary link to download a pdf of the publication is provided at the bottom. Continue reading Failure analysis of high strength nuts