Recovery of fatigue life using laser peening on 2024‐T351 aluminium sheet containing scratch damage: The role of residual stress

2019 ◽  
Vol 42 (5) ◽  
pp. 1161-1174 ◽  
Author(s):  
Niall A. Smyth ◽  
M. Burak Toparli ◽  
Michael E. Fitzpatrick ◽  
Phil E. Irving
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Laser Peening ◽  
Aluminium Sheet

Fatigue Life Recovery via Laser Shock Peening in Mechanically Damaged Aluminium Sheet; Experiments and Prediction Models

2014 ◽  
Vol 891-892 ◽  
pp. 980-985 ◽  
Author(s):  
Niall Smyth ◽  
Philip E. Irving
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Prediction Models ◽  
Load Cycle ◽  
Laser Shock Peening ◽  
Stress Fields ◽  
Hole Drilling ◽  
Laser Shock ◽  
Aluminium Sheet ◽  
Shock Peening

This paper reports the effectiveness of residual stress fields induced by laser shock peening (LSP) to recover pristine fatigue life. Scratches 50 and 150 μm deep with 5 μm root radii were introduced into samples of 2024-T351 aluminium sheet 2 mm thick using a diamond tipped tool. LSP was applied along the scratch in a band 5 mm wide. Residual stress fields induced were measured using incremental hole drilling. Compressive residual stress at the surface was-78 MPa increasing to-204 MPa at a depth of 220 μm. Fatigue tests were performed on peened, unpeened, pristine and scribed samples. Scratches reduced fatigue lives by factors up to 22 and LSP restored 74% of pristine life. Unpeened samples fractured at the scratches however peened samples did not fracture at the scratches but instead on the untreated rear face of the samples. Crack initiation still occurred at the root of the scribes on or close to the first load cycle in both peened and unpeened samples. In peened samples the crack at the root of the scribe did not progress to failure, suggesting that residual stress did not affect initiation behaviour but instead FCGR. A residual stress model is presented to predict crack behaviour in peened samples.

scholarly journals Effect of laser shock peening on residual stress and fatigue life of clad 2024 aluminium sheet containing scribe defects

2012 ◽  
Vol 548 ◽  
pp. 142-151 ◽  
Author(s):  
M. Dorman ◽  
M.B. Toparli ◽  
N. Smyth ◽  
A. Cini ◽  
M.E. Fitzpatrick ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Aluminium Sheet ◽  
Shock Peening

The Role of Residual Stress Measurement in the Development of Laser Peening *

2003 ◽  
Vol 11 (4) ◽  
pp. 195-200 ◽  
Author(s):  
Michael R. Hill ◽  
Adrian T. DeWald ◽  
Jon E. Rankin ◽  
Matthew J. Lee
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Residual Stress Measurement ◽  
Laser Peening

Residual Stress and Wave Reflectivity When Laser Peening Thin Curved Sections

2011 ◽  
Author(s):  
Arif Malik ◽  
Xiaopeng Lai ◽  
Kristina Langer
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Near Infrared ◽  
Experimental Testing ◽  
Turbine Blades ◽  
Value Added ◽  
Laser Peening ◽  
Widespread Application ◽  
Thin Sections

Laser Peening is an emerging technology that shows promise for extending the fatigue life of special-purpose metal components in the aerospace, automotive, medical, manufacturing, and other industries. While laser peening has been shown to extend the fatigue life of metal components such as turbine blades and other high value-added components, the technology is not yet understood well enough to deploy it cost-effectively, without extensive experimental testing, for widespread application in diverse industries. Because laser peening can adversely affect fatigue life if the process parameters are not selected appropriately, identification of tamping layers, pulse energy densities, shot patterns, and other parameters is critical to the component geometry, material, and loading. When laser peening thin sections, preliminary finite element studies indicate that reflectivity of shock waves can induces regions of residual stress or damage on opposing surfaces. Through a series of finite element simulations, this work explores the effects of stress wave reflectivity on component life for thin, curved, 6061-T6 aluminum alloy sections. The simulations are based on an 800 mJ, 5 ns pulsed, near-infrared laser, serves to define the pressure pulse boundary condition, and allow more reliable deployment of laser peening technology.

Fatigue life prediction of 316L stainless steel weld joint including the role of residual stress and its evolution: Experimental and modelling

2021 ◽  
Vol 143 ◽  
pp. 105997
Author(s):  
Wenchun Jiang ◽  
Xuefang Xie ◽  
Tianjiao Wang ◽  
Xiancheng Zhang ◽  
Shan-Tung Tu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Life ◽  
Life Prediction ◽  
316L Stainless Steel ◽  
Fatigue Life Prediction ◽  
Steel Weld ◽  
Stainless Steel Weld ◽  
Steel Weld Joint

The Fatigue Properties of Laser Shock Processed Aluminum Alloy 7050

2007 ◽  
Author(s):  
Shikun Zou ◽  
Ziwen Cao
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Plastic Strain ◽  
Base Material ◽  
Fatigue Properties ◽  
Hole Drilling ◽  
Drilling Process ◽  
Laser Peening ◽  
Laser Shock

In order to develop the application of laser shock processing (also named laser peening or LSP in short) as a strengthening technology for 7050 aluminum alloy fastener holes, the fatigue properties of laser shock-processed aluminum alloy specimens were investigated. At first, the dislocation density and surface residual stress induced in the shock affected zone was characterized and compared with that of the base material. Then, the fatigue specimens with stress-concentration hole (notch) were treated by LSP. The fatigue life of LSP-treated specimens were measured and compared with that of specimens made from base material without LSP. Fatigue tests were taken under special flight spectrum loading condition for mid-airframe. The results indicated that laser peening improved the fatigue life of all specimens tested. Specimens treated by LSP before hole-drilling had longer fatigue life than those specimens treated by LSP after hole-drilling. At last, the difference of both sequences was investigated by analyzing the plastic strain and residual stress induced by LSP. LSP induced both plastic strain and deformation at the surface layer. The plastic strain induced by LSP was shown to produce harmful orifices with sharp-angle near the edge of hole. The residual stress induced by LSP appears to remain compressive even after the hole-drilling process. In average, the fatigue life of specimens treated by LSP before hole-drilling was found to be 173% longer than that of untreated samples and approaching the life enhancement factor demonstrated by rod extrusion method (on specimens with large diameter holes).

Fatigue Performance of Laser Peened Materials

2005 ◽  
Author(s):  
Michael R. Hill ◽  
Theresa E. Pistochini ◽  
Adrian T. DeWald
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
High Strength ◽  
Fatigue Performance ◽  
Laser Peening ◽  
Metallic Materials ◽  
Stress Distributions ◽  
Joint Research ◽  
300M Steel ◽  
Life Improvement

Laser peening is an emerging technology for the surface treatment of metallic materials that is capable of enhancing resistance to fatigue failure. This paper describes some recent results from joint research programs conducted to generate data on residual stress and fatigue performance of laser peened materials. Specifically, we present data for residual stress imparted by laser peening and fatigue life improvement of laser peened coupons relative to as-machined coupons. These data are presented for a range of high-strength materials employed in aircraft and other demanding applications: BSTOA Ti-6A14V titanium alloy, 300M steel, MP35N Ni-Co-Cr-Mo alloy, and 7050-T7451 aluminum alloy. For each material, residual stress distributions were measured for treatment with different laser peening parameter sets. For particular laser peening parameter sets, stress versus life data were generated for as-machined and laser peened fatigue coupons, which quantifies fatigue life improvement attained by laser peening over a range of applied loads.

Random impact FEM simulation of irregularly-shaped media for parametric study of vibratory surface enhancement

2021 ◽  
pp. 095440542199012
Author(s):  
Jing Zhang ◽  
Joselito Yam Alcaraz ◽  
Swee-Hock Yeo ◽  
Arun Prasanth Nagalingam ◽  
Abhay Gopinath
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Parametric Study ◽  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Fem Simulation ◽  
Surface Finishing ◽  
Aerospace Materials ◽  
Surface Enhancement ◽  
Steel Balls

Aerospace materials experience high levels of mechanical and thermal loading, high/low cycle fatigue, and damage from foreign objects during service, which can lead to premature retirement. Mechanical surface treatments of metallic components, for example, fan blades and blisks, are proven to improve fatigue life, improve wear resistance and avoid stress corrosion by introducing work hardening, compressive residual stresses of sub-surface, and surface finishing. Vibropeening can enhance aerospace materials’ fatigue life involving the kinetic agitation of hardened steel media in a vibratory finishing machine that induces compressive stresses into the component sub-layers while keeping a finished surface. Spherical steel balls are the most widely used shape among steel-based media and have been explored for decades. However, they are not always versatile, which cannot access deep grooves, sharp corners, and intricate profiles. Steel ballcones or satellites, when mixed with round steel balls and other steel media (diagonals, pins, eclipses, cones), works very well in such areas that ball-shaped media are unable to reach. However, a methodology of study the effect of irregularly-shaped media in surface enhancement processes has not been established. This paper proposes a finite element-based model to present a methodology for the parametric study of vibratory surface enhancement with irregularly-shaped media and investigates residual stress profiles within a treated area of an Inconel component. The methodology is discussed in detail, which involves a stochastic simulation of orientation, impact force, and impact location. The contrasting effects of a high aspect ratio, or an edge contact, as opposed to rounded and oblique contacts are demonstrated, with further analysis on the superposition of these effects. Finally, the simulation results are compared with actual residual stress measurements and was found to have a max percent difference of 34% up to 20 [Formula: see text]m below the media surface.

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