Evaluation of Forging Process Induced Residual Stress in Aluminum Die Forgings

2021 ◽  
Author(s):  
Michael R. DeWald ◽  
William D. Musinski ◽  
Dale L. Ball ◽  
Mark A. James ◽  
Thomas J. Spradlin
Keyword(s):  
Residual Stress ◽  
Cold Work ◽  
Negative Consequences ◽  
Forging Process ◽  
Work Related ◽  
Rapid Quench ◽  
Aerospace Alloys ◽  
Stress Relieving ◽  
Wide Range ◽  
Crack Initiation Life

Abstract Aircraft 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 bulk 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 summarize recent work related to quantifying and accounting for residual stress in aluminum die forgings. Key residual stress engineering concepts will be described. Since the artifacts studied are associated with an aircraft supply chain (multiple parts and multiple lots), the results are relevant to the aerospace community. Overall, the results show that forging residual stress is a repeatable phenomenon with approximate repeatability less than 5% of A-basis yield strength.

Work-Related Negative Experience

2010 ◽  
Vol 15 (2) ◽  
pp. 109-120 ◽  
Author(s):  
Antonio Duro Martín
Keyword(s):  
Well Being ◽  
Cross Sectional Study ◽  
Personal Factors ◽  
Negative Consequences ◽  
Cross Sectional ◽  
Negative Experience ◽  
Work Related ◽  
Wide Range ◽  
Substance Consumption ◽  
Organizational Distance

This cross-sectional study examines the relationship between poor employee well-being (PEWB) and work-related mental ill-health and substance consumption (MIH). It is proposed as a unification model that links both work-related negative consequences on the basis of the experiences of threat, loss, and frustration at work. PEWB contains the following elements: emotional discomfort, bodily uneasiness, organizational distance, task impairment, and dragging workday; and MIH includes work-related anxiety, depression, irritability, cigarette smoking, alcohol and drug consumption, and physical illness. Six hundred ninety-seven participants, working in a wide range of jobs and occupations, completed the survey. Results indicated that PEWB and MIH are significantly associated, after controlling for demographic and personal factors. Sense sharing between PEWB-MIH and PEWB element combination explained the relationships between both constructs. These findings could be helpful for organizations interested in preserving and improving worker mental health.

scholarly journals Healthcare Providers’ Perceptions of Challenges with Frequent Users of Emergency Department Care in Switzerland: A Qualitative Study

2021 ◽  
Vol 58 ◽  
pp. 004695802110281
Author(s):  
Patrick Bodenmann ◽  
Miriam Kasztura ◽  
Madison Graells ◽  
Elodie Schmutz ◽  
Oriane Chastonay ◽  
...  
Keyword(s):  
Online Survey ◽  
Emergency Services ◽  
Healthcare Providers ◽  
Negative Consequences ◽  
Emergency Department Care ◽  
Frequent Users ◽  
Complex Needs ◽  
Wide Range ◽  
Ed Overcrowding ◽  
Ed Visits

Frequent users of emergency departments (FUED; ≥ 5 ED visits/year) commonly cumulate medical, social, and substance use problems requiring complex and sustained care coordination often unavailable in ED. This study aimed to explore ED healthcare providers’ challenges related to FUED care to gain insight into the support and resources required to address FUED complex needs. An online survey was sent to all general adult emergency services within Switzerland (N = 106). Participants were asked to indicate the extent to which they perceived that FUED represented a problem and to describe the main challenges encountered. In total, 208 physicians and nurses from 75 EDs (70.7%) completed the survey. Among the 208 participants, 134 (64%) reported that FUED represented a challenge and 133 described 1 to 5 challenges encountered. A conventional content analysis yielded 4 main categories of perceived challenges. Negative consequences in the ED secondary to FUED’s presence (eg, ED overcrowding, staff helplessness, and fatigue) was the most frequently reported challenge, followed by challenges related to FUEDs’ characteristics (eg, mental health and social problems) leading to healthcare complexity. The third most frequently encountered challenge was related to the ED inappropriateness and inefficiency to address FUEDs’ needs. Finally, challenges related to the lack of FUED healthcare network were the least often mentioned. ED healthcare providers experience a wide range of challenges related to FUED care. These findings suggest that currently EDs nor their staff are equipped to address FUEDs’ complex needs.

Measurement of Residual Stresses in Linear Friction Welded In-Service Inconel 718 Superalloy

2016 ◽  
Vol 879 ◽  
pp. 1800-1806 ◽  
Author(s):  
M. Smith ◽  
L. Bichler ◽  
D. Sediako
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Material ◽  
Peak Stress ◽  
Weld Interface ◽  
Aerospace Alloys ◽  
Aero Engine ◽  
Linear Friction ◽  
Inconel 718 Superalloy ◽  
Residual Strains

Measurement of residual strains by neutron diffraction of linear friction welded Inconel® 718 (IN 718) superalloy acquired from a mid-service aero-engine disk was undertaken in this study. Residual strain and stress throughout the various weld regions including the heat affected zone (HAZ), thermomechanical affected zone (TMAZ) and dynamically recrystallized zone (DRX) were characterized. The residual stresses were observed to increase from the base material to the weld interface, with a peak stress at the weld interface in all orthogonal directions. The trends for residual stress across the weld are in agreement with other work published in literature for solid state welding of aerospace alloys, where high residual stresses were commonly reported at the weld interface.

Third Order Elastic Constants and Rayleigh Wave Dispersion of Shot Peened Aero-Engine Materials

2013 ◽  
Vol 768-769 ◽  
pp. 201-208 ◽  
Author(s):  
Marek Rjelka ◽  
Martin Barth ◽  
Sven Reinert ◽  
Bernd Koehler ◽  
Joachim Bamberg ◽  
...  
Keyword(s):  
Residual Stress ◽  
Rayleigh Wave ◽  
Elastic Constants ◽  
Cold Work ◽  
High Strength ◽  
Wave Dispersion ◽  
Third Order ◽  
Third Order Elastic Constants ◽  
Aero Engine ◽  
Rayleigh Wave Dispersion

Aero-engine components exposed to high mechanical stresses are made of high-strength alloys and additionally, they are surface treated by shot peening. This process introduces compressive residual stress into the material making it less sensitive to stress corrosion cracking and fatigue and therefore benefits the components performance and lifetime. Moreover cold work is induced in an amount depending on the peening parameters. To approximate the remaining lifetime, a quantitative, non-destructive method for stress assessment is required. It was shown that surface treatment of such alloys can be characterized by broadband Rayleigh wave dispersion measurements. However, the relative contributions of residual stress and cold work, respectively, remained an open point. This paper presents the determination of third order elastic constants (TOEC) for IN718 and Ti6246, providing, together with a model for the inversion of dispersion data, a quantitative access to the acoustoelastic effect. Finally, some measurements of differently treated samples are given.

scholarly journals Prediction of Residual Stress Relaxation of Shot Peened 2024-T351 Aluminum Alloy: Part 1

2011 ◽  
Vol 462-463 ◽  
pp. 1355-1360
Author(s):  
Omar Suliman Zaroog ◽  
Aidy Ali ◽  
Sahari B. Barkawi
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Shot Peening ◽  
Applied Load ◽  
Cold Work ◽  
Cyclic Tests ◽  
Initial State ◽  
Loading Cycle ◽  
Residual Stress Relaxation ◽  
Alloy Part

It is important to account for residual stress relaxation phenomenon in the design of the component. Specimens of 2024-T351 aluminium alloy were used in this study. The specimens were shot peened under three different shot peening intensities. Cyclic tests for two load magnitudes were performed for 1, 2, 10, 1000 and 10000 cycles. Residual stresses, microhardness and the cold work percentage were measured at initial state and after each loading cycle for the three shot peening intensities and for the two loads. The study revealed that most of the drop in the residual stress, microhardness and cold work happened in the first cycle are dependent on the applied load.

Evaluation of Blister Behavior for U10Mo Mini Fuel Plates With Cold Rolled Foils

2012 ◽  
Author(s):  
Hakan Ozaltun ◽  
Samuel J. Miller
Keyword(s):  
Cold Rolling ◽  
Thermal Cycling ◽  
Cold Work ◽  
Rolling Process ◽  
Foil Thickness ◽  
Rolled Plate ◽  
Stress Profile ◽  
Wide Range ◽  
Threshold Temperatures ◽  
Cold Rolled

This article aims to provide possible mechanical causes for the lowered blister temperatures of RERTR-12 and AFIP-4 fuel plates. Recent experimental investigations to determine the blister threshold temperatures have indicated lower thresholds for similar plates with comparable burn-up histories. Measured blister temperatures of roughly 100 °C lower compared to the previously tested plates may not be satisfactory for some plates. The primary differences between recent experiments and previous tests are: (1) An aggressive cold work process involving large thickness reduction ratios without normalization or full annealing (2) Subjecting the plates to a thermal cycling process prior to irradiation, and finally (3) A primarily frontal neutron flux as opposed to a transverse flux profile. It is believed that the stress field has implications to blister behavior. To investigate this claim, the stress-strain states for the fabrication procedure were evaluated. First, the residual stress profile caused by the cold rolling process was calculated. Modeling of the cold rolling process has shown confirmation of residual stresses of considerable magnitude and the existence of stress gradients with respect to foil thickness prior to the HIP process. Once calculated, these stress profiles were used as an initial condition for the fabrication process. Due to the variation in stress fields depending on location at which a foil is cut from the cold rolled plate, three representative regions were selected and implemented in the HIP simulation. Variation in stresses, depending on location of the cold rolled plate as well and variation in the through-thickness, results in a wide range of mechanical stress states. This suggests that inhomogeneous irradiation and thermal cycling behavior will result from the use of cold rolled foils. Additionally, these results suggest that there will be fundamental differences in fuel plate behavior observed between plates fabricated with cold rolled foils versus hot rolled and fully annealed foils.

Discriminatory Aspects of Pre-employment Screening: Low-Back X-ray Examinations in the Railroad Industry

1979 ◽  
Vol 5 (3) ◽  
pp. 197-214
Author(s):  
Paul H. Rockey ◽  
Jane Fantel ◽  
Gilbert S. Omenn
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Screening Program ◽  
Job Applicants ◽  
Radiation Hazard ◽  
Low Back ◽  
Negative Consequences ◽  
X Ray ◽  
Work Related ◽  
Increased Risk

AbstractIn screening the majority of job applicants, most of this nation's railroads administer a low-back X-ray examination in an attempt to ascertain the likelihood that the applicant will sustain future work-related low-back pain or injury. Many applicants are rejected for employment on the basis of the X-ray findings. The railroads apparently perceive this screening program as a cost-effective means (1) of decreasing the incidence of compensation claims for work-related injuries, brought against the rail-roads under the Federal Employers' Liability Act (FELA), (2) of reducing the number of lost workdays resulting from low-back pain or injury, and (3) of protecting particularly susceptible workers from job-related hazards.The authors of this Article submit that low-back X-ray examinations are poor predictors of future low-back pain or injury. They assert that the railroads' use of such examinations misclassifies a substantial number of job applicants as being at increased risk for such pain or injury, and, in consequence, unfairly denies them employment. Furthermore, the authors claim, the screening program has other negative consequences. For example, applicants rejected for railroad employment on the basis of X-ray findings may as a result have difficulty finding jobs in other industries. In addition, they state, there is a potential radiation hazard to examinees. Moreover, both the railroads and those applicants accepted for employment may inappropriately be reassured by normal findings.On balance, the authors conclude, the screening program has a negative social value. The authors suggest that the program, in effect, erroneously labels many applicants as handicapped, and then denies them employment. Such persons might have legal recourse under federal and state statutes prohibiting employment discrimination against the handicapped.

Prevention of Alcohol Misuse: A Review of Health Promotion Efforts among American Indians

1995 ◽  
Vol 9 (4) ◽  
pp. 288-299 ◽  
Author(s):  
Philip A. May ◽  
James R. Moran
Keyword(s):  
Health Promotion ◽  
Native American ◽  
American Indian ◽  
American Indians ◽  
Local Community ◽  
Alcohol Misuse ◽  
Heavy Drinking ◽  
Community Empowerment ◽  
Negative Consequences ◽  
Wide Range

Purpose. The purpose of this review is to provide an overview of a wide range of potentially useful strategies to address the prevention of alcohol misuse among American Indians. This broad approach to the review is useful because the extreme heterogeneity of the American Indian population requires that health promotion professionals explore many options and tailor their activities to specific communities. Search Method. A literature search was initiated through MEDLINE using the following key words: prevention, alcohol, substance abuse, American Indian, and Native American. The search yielded 29 articles from the years 1982 through 1994. These articles, along with 45 previously identified in three overview articles, form the basis of the review and discussion in this paper. Summary of findings. As a group, American Indians experience many health problems that are related to alcohol misuse. Comparison of Indians to non-Indians shows that the age of first involvement with alcohol is younger, the frequency and amount of drinking is greater, and negative consequences are more common. Health promotion programs that address these issues must take into account American Indian heterogeneity and should use a comprehensive approach that addresses both heavy drinking and the sequelae of problems related to alcohol misuse. Major Conclusions. Important concepts for providing health promotion services to this population are: cultural relevance must be carefully planned and monitored; individuals in the local community must be involved; the drunken Indian stereotype must be addressed; and community empowerment should be an important goal.

scholarly journals Analytical solution for residual stress and strain preserved in anisotropic inclusion entrapped in an isotropic host

Solid Earth ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 817-833
Author(s):  
Xin Zhong ◽  
Marcin Dabrowski ◽  
Bjørn Jamtveit
Keyword(s):  
Residual Stress ◽  
Aspect Ratio ◽  
Analytical Solution ◽  
Strain State ◽  
Spherical Inclusion ◽  
Raman Shift ◽  
Stress And Strain ◽  
Wide Range ◽  
Inclusion Shape ◽  
Diamond Inclusions

Abstract. Raman elastic thermobarometry has recently been applied in many petrological studies to recover the pressure and temperature (P–T) conditions of mineral inclusion entrapment. Existing modelling methods in petrology either adopt an assumption of a spherical, isotropic inclusion embedded in an isotropic, infinite host or use numerical techniques such as the finite-element method to simulate the residual stress and strain state preserved in the non-spherical anisotropic inclusions. Here, we use the Eshelby solution to develop an analytical framework for calculating the residual stress and strain state of an elastically anisotropic, ellipsoidal inclusion in an infinite, isotropic host. The analytical solution is applicable to any class of inclusion symmetry and an arbitrary inclusion aspect ratio. Explicit expressions are derived for some symmetry classes, including tetragonal, hexagonal, and trigonal. The effect of changing the aspect ratio on residual stress is investigated, including quartz, zircon, rutile, apatite, and diamond inclusions in garnet host. Quartz is demonstrated to be the least affected, while rutile is the most affected. For prolate quartz inclusion (c axis longer than a axis), the effect of varying the aspect ratio on Raman shift is demonstrated to be insignificant. When c/a=5, only ca. 0.3 cm−1 wavenumber variation is induced as compared to the spherical inclusion shape. For oblate quartz inclusions, the effect is more significant, when c/a=0.5, ca. 0.8 cm−1 wavenumber variation for the 464 cm−1 band is induced compared to the reference spherical inclusion case. We also show that it is possible to fit an effective ellipsoid to obtain a proxy for the averaged residual stress or strain within a faceted inclusion. The difference between the volumetrically averaged stress of a faceted inclusion and the analytically calculated stress from the best-fitted effective ellipsoid is calculated to obtain the root-mean-square deviation (RMSD) for quartz, zircon, rutile, apatite, and diamond inclusions in garnet host. Based on the results of 500 randomly generated (a wide range of aspect ratio and random crystallographic orientation) faceted inclusions, we show that the volumetrically averaged stress serves as an excellent stress measure and the associated RMSD is less than 2 %, except for diamond, which has a systematically higher RMSD (ca. 8 %). This expands the applicability of the analytical solution for any arbitrary inclusion shape in practical Raman measurements.

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