Hill Engineering Blog

A Feast of Fall Festivities

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

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

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

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

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

Axes & Alloys mix metal with music!

Who says engineers don’t know how to have fun?

Axes & Alloys is a band comprised of six of Hill Engineering’s employees. Formed out of a shared love for all things rock n’ roll (or maybe pop, country, and some rock), the Axes got our start around three years ago, with original members Teresa (lead vocals), Adrian (guitar), and Brett (guitar). Their casual rehearsal format eventually welcomed Camille as the keyboardist, Robby as a second singer and keyboardist, and Justin as drummer. Continue reading Axes & Alloys mix metal with music!

Residual stress in welding

Welding is a very common manufacturing process that is used to join materials together to form assemblies and systems. In many cases the welded joints are large, have reduced material properties (e.g., stress corrosion cracking resistance, fracture toughness), and contain defects. The welded joints tend to be critical locations in terms of design and sustainment. For this reason, residual stress in welding is a primary concern. Hill Engineering has extensive experience with residual stress measurements and welding residual stress. Continue reading Residual stress in welding

AFGROW User Workshop

Hill Engineering is presenting about fatigue analysis as part of the AFGROW User Workshop 2016 in Layton, UT. The objective of the workshop is to provide a forum for AFGROW users to exchange information and ideas related to fracture and fatigue. Hill Engineering’s presentation will include a summary of recent work on the formulation and solving of benchmarking problems in the field of fatigue crack growth analysis. The abstract text is presented below. Continue reading AFGROW User Workshop