A Design Methodology to Take Credit for Residual Stresses in Fatigue Limited Designs

2009 ◽  
pp. 69-69-16
Author(s):  
P. Prevéy ◽  
N. Jayaraman
Keyword(s):  
Residual Stresses ◽  
Design Methodology

Effect of post-processing on microstructure and mechanical properties of Alloy 718 fabricated using powder bed fusion additive manufacturing processes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sareh Götelid ◽  
Taoran Ma ◽  
Christophe Lyphout ◽  
Jesper Vang ◽  
Emil Stålnacke ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Residual Stresses ◽  
Design Methodology ◽  
Hot Isostatic Pressing ◽  
Powder Bed Fusion ◽  
Content Type ◽  
Powder Bed ◽  
Nickel Based Superalloy ◽  
Compressive Stresses

Purpose This study aims to investigate additive manufacturing of nickel-based superalloy IN718 made by powder bed fusion processes: powder bed fusion laser beam (PBF-LB) and powder bed fusion electron beam (PBF-EB). Design/methodology/approach This work has focused on the influence of building methods and post-fabrication processes on the final part properties, including microstructure, surface quality, residual stresses and mechanical properties. Findings PBF-LB produced a much smoother surface. Blasting and shot peening (SP) reduced the roughness even more but did not affect the PBF-EB surface finish as much. As-printed PBF-EB parts have low residual stresses in all directions, whereas it was much higher for PBF-LB. However, heat treatment removed the stresses and SP created compressive stresses for samples from both PBF processes. The standard Arcam process parameter for PBF-EB for IN718 is not fully optimized, which leads to porosity and inferior mechanical properties. However, impact toughness after hot isostatic pressing was surprisingly high. Originality/value The two processes gave different results and also responses to post-treatments, which could be of advantage or disadvantage for different applications. Suggestions for improving the properties of parts produced by each method are presented.

Introduction of Residual Stresses to Enhance Fatigue Performance in the Initial Design

2004 ◽  
Author(s):  
Paul Preve´y ◽  
N. Jayaraman ◽  
Ravi Ravindranath
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Shot Peening ◽  
Design Methodology ◽  
Damage Tolerance ◽  
Fatigue Performance ◽  
Trailing Edge ◽  
Laser Shock Processing ◽  
Damage Initiation ◽  
Design Protocol

High cycle fatigue (HCF) performance of turbine engine components has been known for decades to benefit from compressive surface residual stresses introduced through shot peening. However, credit for the fatigue benefits of shot peening has not been taken into account in the design of components. Rather shot peening has been used primarily to safe guard against HCF damage initiation. Recently, laser shock processing (LSP) and low plasticity burnishing (LPB) have been shown to provide spectacular fatigue and damage tolerance improvement by introducing deep (through-thickness) compression in critical areas. Until now, the fatigue benefits of these new surface treatments have been introduced during repair to improve an existing design. The present paper describes a design methodology and testing protocol* to take appropriate credit for the introduction of beneficial residual stresses into a component design to achieve optimal fatigue performance. A detailed design protocol has been developed that relates the introduction of a residual stress distribution using LPB for targeted HCF performance. This design protocol is applied to feature specimens designed to simulate the fatigue conditions at the trailing edge of a 1st stage low pressure compressor vane to provide optimal trailing edge damage tolerance. The use of finite element modeling, linear elastic fracture mechanics, and x-ray diffraction documentation of the residual stress field to develop LPB processing parameters is described. A novel adaptation of the traditional Haigh diagram to estimate the compressive residual stress magnitude and distribution to achieve optimal fatigue performance is described. Fatigue results on vane-edge feature samples are compared with analytical predictions provided by the design methodology. The potential for designing reduced section thickness of structural components leading to weight savings is discussed.

Method to evaluate residual stresses in the laser cutting process

2002 ◽  
Vol 12 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Y. Zamachtchikov ◽  
F. Breaban ◽  
P. Vantomme ◽  
A. Deffontaine
Keyword(s):  
Residual Stresses ◽  
Laser Cutting ◽  
Cutting Process

Prediction of residual stresses and springback after bending of a textured aluminium plate

2003 ◽  
Vol 105 ◽  
pp. 175-182 ◽  
Author(s):  
L. Delannay ◽  
R. E. Logé ◽  
Y. Chastel ◽  
P. Van Houtte
Keyword(s):  
Residual Stresses

Accuracy in the design methodology of abstracts

2003 ◽  
Vol 84 (2) ◽  
pp. 303-303
Author(s):  
Maurice Bernaiche ◽  
Michael Andary
Keyword(s):  
Design Methodology

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

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