Quantitative Fracture Mechanics Approach to Fatigue Life Improvement by Shot Peening Application

It is well known that shot peening has a marked benefit on fatigue life for the majority of applications. This effect is attributed mainly due to the compressive residual stress state at the component’s surface due to shot peening. The present paper evaluates the ability of several fatigue life prediction models, commonly used for general analyses, to predict the behaviour of components with compressive residual stress due to shot peening. Advanced elastic-plastic finite element analyses were carried out in order to obtain stress, strain, strain energy and fracture mechanics parameters for cracks within a compressive residual stress field. With these results several total fatigue life prediction models (including critical distance methods) and fracture mechanics based models were applied in order to predict fatigue life. Fatigue life predictions were compared with several experimental fatigue tests carried out on specimens, representative of a critical region of a compressor disc in a gas turbine aero engine. The results obtained showed that total fatigue life methods, even if combined with critical distance methods, give conservative results when shot peening is considered. Fatigue life was successfully predicted using the method proposed by Cameron and Smith, by adding initiation life to crack propagation life. This last method was also successfully applied for the prediction of non-propagating cracks that were observed during the experimental tests.

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Design and Fatigue Analysis of Shot Peened Leaf Spring

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.a3897.119119 ◽

2019 ◽

Vol 9 (1) ◽

pp. 1120-1126

Keyword(s):

Fatigue Life ◽

Shot Peening ◽

High Strength ◽

Load Level ◽

Spring Steel ◽

Leaf Spring ◽

Leaf Springs ◽

Point Test ◽

Life Improvement ◽

The Impact

The paper handles the fatigue and failing analysis of serial shot-peened leaf springs of cumbersome vehicles emphasizing on the impact of shot peening on fatigue life, coping with automotive leaf springs, the shot peening method turns into an important step in production.In the situation of leaf spring suspensions, however, asystematic research of the effect of shot peening about fatigue life isstill required. Experimental stress-life curves are determined with the aid of the usage of investigating clean specimen subjected to shot peening. those test consequences are as compared to corresponding ones identified from cyclic three-point test on shot peened serial leaf springs in order to show the influence of applied heat treatment and shot peening approach on fatigue existence of high-strength used to get leaf spring manufacturing, reliant on the load level. Analyses are performed to explain the effects resulting from shot peening practice on the surface features of the high-strength spring steel under examination. The evaluation of fatigue results shows that almost no life improvement due to production highlighting the importance for mutual variation in parameters of shot peening and thermal treatment so that there is sufficient progress in life

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Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

Volume 3: Turbo Expo 2003 ◽

10.1115/gt2003-38922 ◽

2003 ◽

Cited By ~ 13

Author(s):

Paul S. Preve´y ◽

Ravi A. Ravindranath ◽

Michael Shepard ◽

Timothy Gabb

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Case Studies ◽

Shot Peening ◽

Damage Tolerance ◽

Cold Work ◽

Fatigue Performance ◽

Surface Enhancement ◽

Low Plasticity Burnishing ◽

Life Improvement

Surface enhancement technologies such as shot peening, laser shock peening (LSP), and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design. The x-ray diffraction based background studies of thermal and mechanical stability of surface enhancement techniques are briefly reviewed, demonstrating the importance of minimizing cold work. The LPB process, tooling, and control systems are described. An overview of current research programs conducted for engine OEMs and the military to apply LPB to a variety of engine and aging aircraft components are presented. Fatigue performance and residual stress data developed to date for several case studies are presented including: • The effect of LPB on the fatigue performance of the nickel based super alloy IN718, showing the fatigue benefit of thermal stability at engine temperatures. • An order of magnitude improvement in damage tolerance of LPB processed Ti-6-4 fan blade leading edges. • Elimination of the fretting fatigue debit for Ti-6-4 with prior LPB. • Corrosion fatigue mitigation with LPB in Carpenter 450 steel. • Damage tolerance improvement in 17-4PH steel. Where appropriate, the performance of LPB is compared to conventional shot peening after exposure to engine operating temperatures.

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A Study of the Shot Peening Effect on the Fatigue Life Improvement of Al 7475-T7351 3PB Specimens

Structural Integrity - Mechanical Fatigue of Metals ◽

10.1007/978-3-030-13980-3_43 ◽

2019 ◽

pp. 335-341

Author(s):

N. Ferreira ◽

J. A. M. Ferreira ◽

J. Jesus ◽

C. Capela ◽

J. D. Costa

Keyword(s):

Fatigue Life ◽

Shot Peening ◽

Life Improvement

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Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1807414 ◽

2006 ◽

Vol 128 (4) ◽

pp. 865-872 ◽

Cited By ~ 17

Author(s):

Paul S. Preve´y ◽

Ravi A. Ravindranath ◽

Michael Shepard ◽

Timothy Gabb

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Case Studies ◽

Shot Peening ◽

Damage Tolerance ◽

Cold Work ◽

Fatigue Performance ◽

Surface Enhancement ◽

Low Plasticity Burnishing ◽

Life Improvement

Surface enhancement technologies such as shot peening, laser shock peening, and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design. The x-ray diffraction based background studies of thermal and mechanical stability of surface enhancement techniques are briefly reviewed, demonstrating the importance of minimizing cold work. The LPB process, tooling, and control systems are described. An overview of current research programs conducted for engine OEMs and the military to apply LPB to a variety of engine and aging aircraft components are presented. Fatigue performance and residual stress data developed to date for several case studies are presented including the following. (1) The effect of LPB on the fatigue performance of the nickel based super alloy IN718, showing the fatigue benefit of thermal stability at engine temperatures. (2) An order of magnitude improvement in damage tolerance of LPB processed Ti-6-4 fan blade leading edges. (3) Elimination of the fretting fatigue debit for Ti-6-4 with prior LPB. (4) Corrosion fatigue mitigation with LPB in Carpenter 450 steel. (5) Damage tolerance improvement in 17-4 PH steel. Where appropriate, the performance of LPB is compared to conventional shot peening after exposure to engine operating temperatures.

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Rolling fatigue life improvement effect of zinc thin film formed with shot peening

The Proceedings of the Materials and processing conference ◽

10.1299/jsmemp.2019.27.102 ◽

2019 ◽

Vol 2019.27 (0) ◽

pp. 102

Author(s):

Takumi HASE ◽

Hatsuhiko USAMI

Keyword(s):

Thin Film ◽

Fatigue Life ◽

Shot Peening ◽

Improvement Effect ◽

Life Improvement

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Fatigue Life Improvement of Cracked Aluminum 6061-T6 Plates Repaired by Composite Patches

Materials ◽

10.3390/ma14061421 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1421

Author(s):

Armin Yousefi ◽

Saman Jolaiy ◽

Reza Hedayati ◽

Ahmad Serjouei ◽

Mahdi Bodaghi

Keyword(s):

Fatigue Life ◽

Fatigue Behavior ◽

Weight Ratio ◽

High Strength ◽

Plastic Strain Amplitude ◽

Composite Patch ◽

Life Improvement ◽

Cracked Structures ◽

Aluminum Plates ◽

High Flexibility

Bonded patches are widely used in several industry sectors for repairing damaged plates, cracks in metallic structures, and reinforcement of damaged structures. Composite patches have optimal properties such as high strength-to-weight ratio, easiness in being applied, and high flexibility. Due to recent rapid growth in the aerospace industry, analyses of adhesively bonded patches applicable to repairing cracked structures have become of great significance. In the present study, the fatigue behavior of the aluminum alloy, repaired by a double-sided glass/epoxy composite patch, is studied numerically. More specifically, the effect of applying a double-sided composite patch on the fatigue life improvement of a damaged aluminum 6061-T6 is analyzed. 3D finite element numerical modeling is performed to analyze the fatigue performance of both repaired and unrepaired aluminum plates using the Abaqus package. To determine the fatigue life of the aluminum 6061-T6 plate, first, the hysteresis loop is determined, and afterward, the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted and validated against the available experimental data from the literature. Results reveal that composite patches increase the fatigue life of cracked structures significantly, ranging from 55% to 100% for different applied stresses.

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