Hill Engineering Blog

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

A Feast of Fall Festivities

by Robert Pires

The Hill Engineering employees took a quick break from all the residual stress analysis to partake in a few fall-themed festivities this season. We recognize that enjoying quality time together is an important way to strengthen our resolve as a team. What better way to do that than through everybody’s favorite activities: pumpkin carving and food! Continue reading A Feast of Fall Festivities

Hill Engineering achieves ISO 17025 certification

by Adrian DeWald

We are excited to announce that Hill Engineering was recently awarded ISO17025:2005 accreditation!

ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories is the primary ISO standard used by testing and calibration laboratories. Hill Engineering was accredited by the American Association for Laboratory Accreditation (A2LA). Compliance with the ISO/IEC 17025:2005 standard provides an internationally recognized basis for laboratory accreditation. The standard is used to govern Hill Engineering’s Quality System and entails adherence to rigorous technical requirements. Continue reading Hill Engineering achieves ISO 17025 certification

Residual stress in linear frictions welds

by Adrian DeWald

In a previous blog post we discussed, in general, issues related to residual stress in welding. In this post, we’ll follow up with a more detailed look at a specific welding application – linear friction welding of titanium alloys.

Titanium alloys are widely used in aerospace applications for their high strength to weight ratio, good corrosion resistance, and metallurgical stability. New joining methods are being implemented that allow for more efficient manufacture of titanium components. Linear friction welding (LFW) is a solid phase bonding process, which is particularly appropriate for titanium alloys. Due to the titanium’s great affinity for oxygen, nitrogen, and hydrogen, protective atmospheres must be used to prevent contamination of the welded material. LFW avoids the formation of a liquid phase during the welding process, and can therefore be carried out in air. Likewise, the typical defects caused by melting and solidification during traditional welding process such as pores, pinholes, shrinkage cracks and grain coarsening are avoided. However, as with all welding and deformation processes, understanding the weld residual stress is important. Continue reading Residual stress in linear frictions welds

ASIP Conference

by Adrian DeWald

Hill Engineering is presenting about fatigue analysis methods for cold expanded aircraft fastener holes at the upcoming 2016 Aircraft Structural Integrity Program (ASIP) Conference in San Antonio, TX. Cold hole expansion is a method commonly used to induce compressive residual stress around the perimeter of fastener holes, which are common in aircraft structure. The compressive residual stress has significant benefits related to fracture and fatigue of the structure. Hill Engineering’s presentation will include a summary of current analysis methods and a plan for how these methods can evolve to allow for improvements in aircraft design and sustainment. The abstract text is presented below. Continue reading ASIP Conference

Residual stress analysis

by Adrian DeWald

Material fabrication processes like forging, rolling, extrusion, quenching, additive manufacturing, machining, and welding lock spatially varying residual stress fields into structural materials. These residual stresses can influence the way that materials perform (e.g., fatigue, fracture, distortion, and corrosion). Hill Engineering has developed expertise to support many different types of residual stress analysis, which we apply to help our customers manage residual stresses effectively in design. The following are some examples of residual stress analysis. Continue reading Residual stress analysis