Rancho Cordova, CA, United States
Rancho Cordova, CA, United States

Time filter

Source Type

Hayes N.,Hill Engineering, LLC | Jokar A.,ThermoFluids Technology | Ayub Z.H.,Isotherm Inc.
International Journal of Heat and Mass Transfer | Year: 2011

The experimental investigation of carbon dioxide condensation in brazed plate heat exchangers is the main objective of this study. The current level of concern for the environment is at an all time high, therefore, it is important to look into methods and resources that lead to a cleaner and healthier future for the planet. This study details one such effort to reach this goal, focusing on condensation of carbon dioxide as a natural refrigerant in refrigeration systems. Three brazed plate heat exchangers with different geometry, each consisting of three channels, are tested. This paper focuses on the two-phase analysis, where carbon dioxide was the working fluid, flowing through the middle channel, and dynalene brine, the cooling fluid, flowed through the side channels of each geometry. Condensation of carbon dioxide occurred at saturation temperatures ranging from -17.8 °C to -34.4 °C and heat fluxes spanning 2.5-15.7 kW/m2. An in-depth dimensional analysis was completed on the two-phase data yielding heat transfer correlations. Relationships of the two-phase heat transfer characteristics are presented, the data are compared with related studies, and conclusions are made from the two-phase data. © 2010 Elsevier Ltd. All rights reserved.


Wagner J.T.,Hill Engineering, LLC
SAE Technical Papers | Year: 2013

Link-X Stability System ("Link-X") is a control arm geometry that forces the control arms to both locate the tire and control the orientation of the chassis. This is achieved via crossing the control arms in the elevation view without having the control arms touch one another. Link-X inverts the overturning moment at each tire and applies the inverted moments to the chassis. In terms of traditional suspension analysis, this geometry creates a high yet completely stable roll center. Changing the vertical distances between the attachment points on the chassis or the spindle changes the amount of anti-roll generated. Anti-pitch is created by shifting the line of intersection of the control arm planes toward the vehicle's center of gravity. Copyright © 2003 SAE International and Copyright © 2003 Society of Automotive Engineers of Japan, Inc.


Trademark
Hill Engineering, LLC | Date: 2016-04-15

Computer-controlled apparatus for testing and measuring residual stress.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.97K | Year: 2013

ABSTRACT: 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. While bulk residual stresses are often accounted for with simple approximations that ensure safety, improved understanding of bulk residual stress fields would enable higher quality design and analysis methods. This could lead to overall higher performing structure. The proposed work plan will develop improved technology for the measurement of bulk residual stress and will demonstrate the effectiveness of this approach under representative conditions. BENEFIT: The proposed residual stress measurement technology is a significant improvement that would fill a critical gap in capability for bulk residual stress measurement, enabling high-quality measurements in aerospace materials. This technology is important to the aerospace community, but is applicable to many other industries as well. For example, pressure vessels, turbines, industrial facilities, and heavy equipment all contain critical structure with significant amounts of residual stress. As design and analysis techniques evolve to incorporate residual stress effects, it is important to have residual stress measurement techniques capable of providing the necessary supporting data. The proposed technology expands residual stress measurement capability to support these important challenges.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2013

ABSTRACT: It is widely recognized that near surface residual stresses play a significant role in fatigue performance. Tensile residual stresses are of concern because they accelerate fatigue crack initiation and fatigue crack growth relative to what would occur in the absence of residual stress. Compressive residual stresses, on the other hand, have the opposite effect and can be used to improve fatigue performance. To effectively understand and predict residual stress effects on fatigue durability or crack initiation, which accounts for the majority of the total component life under high-cycle applications, accurate and reliable residual stress data are required in the near-surface region. The proposed work plan will develop improvements to a novel near-surface residual stress measurement technique, will demonstrate the effectiveness of this measurement technique under representative conditions, and will develop technology to implement the measurement. BENEFIT: The proposed residual stress measurement method is a significant improvement to existing residual stress measurement technology and will fill a critical gap in capability for near-surface residual stress measurement, enabling high-quality measurements in the near-surface regime under conditions typical of the aerospace industry. This technology is important to many industries (e.g., aerospace, transportation, utilities, etc). Current design methods are evolving to include residual stress effects and these methods benefit from high quality residual stress data.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 749.51K | Year: 2013

ABSTRACT: Aircraft engine and structural components are being produced from forgings with increasingly complex geometries in a range of aerospace alloys. The forging process involves a number of steps required to attain favorable material properties (e.g., heat treatment, rapid quench, and cold work stress relieving). These processing steps, however, also result in the introduction of residual stress. Excessive bulk residual stresses can have negative consequences including: part distortion, reduced crack initiation life, and increased crack growth rates. While bulk residual stresses are often accounted for with simple approximations that ensure safety, there is an opportunity to improve the understanding of the bulk residual stress fields in forged parts and to monitor them as a routine part of quality assurance, which would reduce design uncertainty associated with residual stresses and would allow for higher performing structure. The proposed program will develop an approach for quality management of residual stresses in aerospace forgings, will develop technology to support quality system implementation, and will demonstrate the quality system in a production environment. The proposed quality system will combine advanced computational process modeling and residual stress measurement technology to establish a robust system of production control. BENEFIT: The proposed program offers a logical next-step in the continued improvement of structural engineering methods. Advances in residual stress technology over the past decade (or more) have resulted in improved tools for the analysis of residual stress effects on material performance. Technology is available, for example, to predict fatigue crack growth accounting for residual stress effects. By specifically accounting for residual stress effects in these calculations, designs can become more efficient and require lower safety margins. This leads to higher, more aggressive performance. One significant missing ingredient inhibiting the full accounting of residual stress in design is the fact that residual stress levels are typically not certified in the material supply chain. The development of a quality management system for residual stresses in forged aerospace components will enable material suppliers to certify the level of residual stress in their forged product, which will enable end users to specifically account for residual stress effects in design (and will result in significant positive benefit).


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2012

ABSTRACT: It is widely recognized that near surface residual stresses play a significant role in fatigue performance. Tensile residual stresses are of concern because they accelerate fatigue crack initiation and fatigue crack growth relative to what would occur in the absence of residual stress. Compressive residual stresses, on the other hand, have the opposite effect and can be used to improve fatigue performance. To effectively understand and predict residual stress effects on fatigue durability or crack initiation, which accounts for the majority of the total component life under high-cycle applications, accurate and reliable residual stress data are required in the near-surface region. The proposed work plan will develop improvements to a novel near-surface residual stress measurement technique and will demonstrate the effectiveness of this measurement technique under representative conditions. Phase I evaluation will include an assessment of measurement repeatability and accuracy. The measurement technique will also be validated during Phase I using independent measurement technologies. BENEFIT: The proposed residual stress measurement technique development is a significant improvement to existing residual stress measurement technology that would fill a critical gap in capability for near-surface residual stress measurement, enabling high-quality measurements in the near-surface regime under conditions typical of the aerospace industry. This technology is important to many industries as methods advance for assessment of fatigue performance in the presence of residual stress.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.97K | Year: 2012

ABSTRACT: Hill Engineering is committed to developing and expanding residual stress engineering technology. The proposed program will develop an approach for quality management of residual stresses in aerospace forgings and will demonstrate important elements of this approach on a representative forged component. The proposed quality management system will combine advanced computational process modeling and residual stress measurement technology to establish a robust system of production control. During Phase I, Hill Engineering will demonstrate the concepts of the quality system using an aerospace forging. The quality system will be evaluated for consistency and reliability and will be validated using independent techniques. BENEFIT: The proposed program offers a logical next-step in the continued improvement of structural engineering methods. Advances in residual stress technology over the past decade (or more) have resulted in improved tools for the analysis of residual stress effects on material performance. Technology is available, for example, to enable engineers to predict fatigue crack growth accounting for residual stress effects. By specifically accounting for residual stress effects in engineering analyses, designs can become more accurate and require lower safety margins. This leads to higher, more aggressive performance. One significant missing ingredient inhibiting the full accounting of residual stress in design is the fact that residual stress levels are typically not certified in the material supply chain. The development of a quality management system for residual stresses in forged aerospace components will enable material suppliers to certify the level of residual stress in their forged product, which will enable end users to specifically account for residual stress effects in design (and will result in significant positive benefit).


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 749.96K | Year: 2014

ABSTRACT: 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. While bulk residual stresses are often accounted for with simple approximations that ensure safety, improved understanding of bulk residual stress fields would enable higher quality design and analysis methods. This could lead to overall higher performing structure. The proposed work plan will develop improved technology for the measurement of bulk residual stress and will demonstrate the effectiveness of this approach under representative conditions. BENEFIT: The proposed residual stress measurement technology is a significant improvement that would fill a critical gap in capability for bulk residual stress measurement, enabling high-quality measurements in aerospace materials. This technology is important to the aerospace community, and is applicable to many other industries as well. For example, pressure vessels, turbines, industrial facilities, ships, and heavy equipment all contain critical structure with significant amounts of residual stress. As design and analysis techniques evolve to incorporate residual stress effects, it is important to have residual stress measurement techniques capable of providing the necessary supporting data with a high degree of accuracy. The proposed technology expands residual stress measurement capability to support these important challenges.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.94K | Year: 2014

ABSTRACT: Due to their excellent strength-to-weight characteristics, integral components (i.e., thin-walled components machined from a single piece of material, which typically consist of a series of pockets, ribs, and stiffeners, have become commonplace on modern aircraft structure. The fabrication of integral components is a machining-intensive process that employs non-conventional machining at high material removal rates. One of the biggest limitations of high speed milling of integral structures is distortion, which results from changes in the residual stress state within the machined component. Excessive distortion can lead to the introduction of excessive fit-up stresses during assembly, can result in improper joints/connections, and can result in parts being scrapped. In certain instances, shops are allowed to use mechanical means (e.g., plastic bending over a fixture) to rectify some of the distortion. This can be effective, but is limited to use on simple geometry and this approach is lacking in quality and traceability. The proposed work plan will develop improved technology for correcting distortion (i.e., reshaping back within drawing tolerance) in complex aerospace parts. BENEFIT: The proposed shape correction technology would provide significant improvements to the efficiency of high speed machining processes. Currently, significant losses result from machined parts that are scrapped due to excessive distortion. Generally, significant machining has been performed on these parts prior to scrapping so the scrapped parts have considerable value. A process to efficiently and effectively correct the shape of these distorted parts and return them into the production supply offers the potential for significant cost savings relative to the current approach (scrapping these distorted parts). This technology is important to the aerospace community and is applicable to many other industries as well. For example, ships and space vehicles use similar integral components that have distortion related issues. Large welded structures like pressure vessels and industrial facilities are often adversely affected by distortion due to residual stresses from welding. As this technology becomes more mature there is an opportunity to apply it for benefit in other industries.

Loading Hill Engineering, LLC collaborators
Loading Hill Engineering, LLC collaborators