Additive Manufacturing Benchmark Publication

Hill Engineering recently contributed to a publication related to residual stress measurement in additive manufacturing (AM) test specimens titled, Elastic Residual Strain and Stress Measurements and Corresponding Part Deflections of 3D Additive Manufacturing Builds of IN625 AM‑Bench Artifacts Using Neutron Diffraction, Synchrotron X‑Ray Diffraction, and Contour Method. The work was performed under the NIST AM-Bench program in collaboration with researchers from NIST, Los Alamos National Laboratory, University of California Davis, and Cornell High Energy Synchrotron Source. The abstract text is available here along with a link to the publication. Continue reading Additive Manufacturing Benchmark Publication

ASIP Conference 2019

Hill Engineering is presenting about residual stress aerospace forgings at the upcoming 2019 United States Air Force Structural Integrity Program Conference (ASIP) in San Antonio, TX. The 2019 ASIP Conference is specifically designed to bring together the world leaders in the area of aircraft structural integrity and to disseminate information on state-of-the-art technologies for aircraft structures in both the military and civilian fleets. Hill Engineering’s presentation will include a summary of recent work to quantify the residual stress variability in aerospace forgings. The abstract text is presented below. Continue reading ASIP Conference 2019

Welcome Dallen Andrew

We would like to welcome Dallen Andrew to Hill Engineering. Dallen has 10 years of experience as a mechanical engineer supporting aircraft structural integrity programs. He received a BS degree in Mechanical Engineering from Utah State University in 2009, and a MS degree in Mechanical Engineering from the University of Utah in 2011.

During his career, Dallen has gained experience in many aspects of aircraft structural integrity, with specialization in the fatigue and fracture of metals. He has worked on many projects requiring him to utilize his capabilities in  fatigue crack growth analysis, fracture mechanics, durability and damage tolerance analysis (DADTA), fatigue testing, continuing damage, residual stress, finite element analysis (FEA), and non-destructive inspection.

Dallen is an organizer of the Engineered Residual Stress Implementation (ERSI) working group developing the analytical framework to allow the benefits from deep engineered residual stresses to be applied to aircraft inspection intervals for the United States Air Force. Dallen has significant experience supporting the A-10 and T-38 aircraft fleets. He also has significant expertise in the use of AFGROW and NASGRO fracture mechanics and damage tolerance software packages.

Please contact us today for additional information about Hill Engineering and the services we offer.

Hill Engineering announces agreement with VEQTER for Deep-Hole Drilling technology

Hill Engineering, answering strong demand for its residual stress measurement services, would like to announce our agreement with VEQTER, Ltd to license the Deep-Hole Drilling (DHD) technology. VEQTER, along with the University of Bristol, aided in the development of the DHD technique, and have practiced the technology for over 25 years. With this agreement, VEQTER will provide Hill Engineering with the equipment, technology, and support to deliver state-of-the-art DHD measurements within the North and South American Continents. Continue reading Hill Engineering announces agreement with VEQTER for Deep-Hole Drilling technology

Welcome John Watton

We would like to welcome John Watton to Hill Engineering. John comes with more than 30 years of experience, most recently from Arconic where he worked at the Arconic Technical Center. John obtained an undergraduate degree in mechanical engineering jointly with Acadia University and the Technical University of Nova Scotia, and earned graduate degrees in mechanical engineering at Stanford University (masters, applied mechanics) and Carnegie Mellon University (Ph.D., design and expert systems).

Continue reading Welcome John Watton

Additive Manufacturing Benchmark Test Series

As a follow-up to our previous post about additive manufacturing (AM) we wanted to highlight some other activities in the additive manufacturing space.

One such activity that Hill Engineering has been involved in is the NIST AM-Bench program. AM-Bench is developing a continuing series of controlled benchmark tests with two initial goals: 1) to allow modelers to test their simulations against rigorous, highly controlled additive manufacturing benchmark test data, and 2) to encourage additive manufacturing practitioners to develop novel mitigation strategies for challenging build scenarios. As part of this program, Hill Engineering has been working in collaboration with UC Davis to support residual stress measurement activities using the contour method. Continue reading Additive Manufacturing Benchmark Test Series

2019 SEM Annual Conference and Exposition on Experimental and Applied Mechanics

Hill Engineering will be presenting at the upcoming SEM Annual Conference and Exposition on Experimental and Applied Mechanics in Reno, NV from June 3rd through June 6th. We invite you to come see us. This conference focuses on all areas of research and applications pertaining to experimental mechanics, and has evolved to encompass the latest technologies supporting:

  • optical methods
  • additive & advanced manufacturing
  • dynamic behavior of materials
  • biological systems
  • micro-and nano mechanics
  • fatigue and fracture
  • composite and multifunctional materials
  • residual stress
  • inverse problem methodologies
  • thermomechanics
  • time dependent materials.

Hill Engineering’s presentation will include a summary of recent work related to regularization uncertainty in slitting residual stress measurement. The abstract text is presented below.

This presentation describes the development of an uncertainty estimate for slitting residual stress measurement. The uncertainty estimate includes a newly developed uncertainty estimate related to the smoothing used in the stress calculation procedure called the regularization uncertainty. This work describes the approach to define the regularization uncertainty, shows the usefulness of the uncertainty estimate in a numerical experiment and a repeatability study. The uncertainty estimate is shown to meet an acceptance criterion that compares the calculated (measured) stress ± its uncertainty estimate to the true value for the numerical experiment or the mean stress from the repeatability study. This works shows the regularization uncertainty estimate to be a necessary contributor to the uncertainty in slitting and additionally the uncertainty estimate developed here reasonably predicts the uncertainty present in slitting method residual stress measurements.

If you are planning to attend the conference please stop by to discuss Hill Engineering’s capabilities in fatigue analysis and design and residual stress measurement . Please contact us for more information.

Propulsion Safety & Sustainment Conference 2019

Hill Engineering is presenting at the upcoming Propulsion Safety & Sustainment Conference (PS&S) in Washington, D.C. from April 23rd through April 25th. We invite you to come see us. The mission of this conference is to proactively address or prevent problems with safety, readiness, reliability, and sustainment within the tri-service turbine engine fleet. This is to be accomplished through the transition of existing and emerging technologies. Hill Engineering’s presentation will include a summary of recent work related to residual stress measurement in support of production quality control. The abstract text is presented below. <!–more–>  

Aircraft engine and structural components are being produced from forgings with increasingly complex geometries in a wide range of aerospace alloys. The forging process involves a number of steps required to attain favorable material properties (e.g., heat treatment, rapid quench, cold work stress relieving, and artificial aging). These processing steps, however, also result in the introduction of residual stress. Excessive bulk residual stresses can have negative consequences including: part distortion during machining and/or during service, reduced crack initiation life, increased crack growth rates, and an overall reduction in part life. This presentation will describe an approach for quality management of residual stresses in aerospace forgings. The quality management system relies upon computational process modeling, residual stress measurement, and the integration of these concepts within the framework of a standard production quality system.  

If you are planning to attend the conference, please stop by to discuss Hill Engineering’s capabilities in fatigue analysis and design and residual stress measurement. Please contact us for more information.  



Illustration of residual stress in an aluminum forging before and after cold work residual stress relief