scholarly journals Prediction and Measurement of Machining Distortion in Aluminium Alloy 7085

2014 ◽  
Vol 996 ◽  
pp. 640-645 ◽  
Author(s):  
Zhang Zheng ◽  
Liang Li ◽  
Yin Fei Yang ◽  
Ning He ◽  
Wei Zhao
Keyword(s):  
Numerical Methods ◽  
Stress Field ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Experimental Verification ◽  
Structural Part ◽  
Cold Compression ◽  
Manufacturing Operations ◽  
Part Distortion ◽  
Good Agreement

It is essential to accurately predict or model the residual stresses in a material resulting from various manufacturing operations. Numerical methods were used in this study to predict the residual stresses after quenching and cold compression of an Al 7085 forged block. Experimental verification was provided by comparing the measured distortions due to a relaxation of the residual stresses with the predictions obtained by using a simulated stress field. The validation was carried out on a simplified structural part. The measured and simulated distortions were found to be in good agreement with each other. The results indicated that part distortion is attributable to the relaxation of bulk residual stresses.

Residual Stress Relief in the Aluminium Alloy 7075

2017 ◽  
Vol 905 ◽  
pp. 31-39 ◽  
Author(s):  
Jeremy S. Robinson ◽  
Christopher E. Truman ◽  
Thilo Pirling ◽  
Tobias Panzner
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Stress Relief ◽  
Residual Stress Distribution ◽  
Cold Compression ◽  
Heat Treated ◽  
Minimum Residual

The residual stresses in heat treated 7075 aluminium alloy blocks have been characterised using two neutron diffraction strain scanning instruments. The influence of uniaxial cold compression (1-10%) on relieving the residual stress has been determined. Increasing the magnitude of cold compression from 1 to 10% has been shown to have a beneficial effect on the residual stress distribution by reducing the range between the maximum and minimum residual stresses. The effect of over aging 7075 on residual stress has also been characterised using neutron diffraction and this was found to reduce the residual stress by 25-40%. A relationship between {311} peaks widths and amount of cold compression was also observed.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

Influence of the Interface and Residual Stresses on the Apparent Fracture Toughness of Layered Ceramic Composites Based on Alumina-Zirconia

2014 ◽  
Vol 606 ◽  
pp. 209-212
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composites ◽  
Layered Composites ◽  
Material Interfaces ◽  
Linear Elastic ◽  
Apparent Fracture Toughness ◽  
Elastic Fracture ◽  
Layered Ceramic ◽  
Good Agreement

This paper deals with the fracture behaviour of layered ceramic composite with residual stresses. The main goal is to investigate the effect of residual stresses and material interfaces on crack propagation by more complex 3D finite element models. The crack behaviour was described by analytical procedures based on linear elastic fracture mechanics (LEFM) and generalized LEFM. The influence of laminate composition with residual stresses on critical values for crack propagation through the laminate interfaces was also determined. Good agreement has been found to exist between numerical results and experimental data. The results obtained can be used for a design of new layered composites with improved resistance against crack propagation.

Surface Modification Analysis after Shot Peening of AA 7075 in Different States

2013 ◽  
Vol 768-769 ◽  
pp. 519-525 ◽  
Author(s):  
Sebastjan Žagar ◽  
Janez Grum
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Shot Peening ◽  
Fatigue Testing ◽  
Stress Profile ◽  
Treatment Conditions ◽  
Stress Profiles ◽  
Compressive Residual Stresses

The paper deals with the effect of different shot peening (SP) treatment conditions on the ENAW 7075-T651 aluminium alloy. Suitable residual stress profile increases the applicability and life cycle of mechanical parts, treated by shot peening. The objective of the research was to establish the optimal parameters of the shot peening treatment of the aluminium alloy in different precipitation hardened states with regard to residual stress profiles in dynamic loading. Main deformations and main residual stresses were calculated on the basis of electrical resistance. The resulting residual stress profiles reveal that stresses throughout the thin surface layer of all shot peened specimens are of compressive nature. The differences can be observed in the depth of shot peening and the profile of compressive residual stresses. Under all treatment conditions, the obtained maximum value of compressive residual stress ranges between -200 MPa and -300 MPa at a depth between 250 μm and 300 μm. Comparison of different temperature-hardened aluminium alloys shows that changes in the Almen intensity values have greater effect than coverage in the depth and profile of compressive residual stresses. Positive stress ratio of R=0.1 was selected. Wöhler curves were determined in the areas of maximum bending loads between 30 - 65 % of material's tensile strength, measured at thinner cross-sections of individual specimens. The results of material fatigue testing differ from the level of shot peening on the surface layer.

Solitons propagation dynamics in a saturable PT-symmetric fractional medium

2021 ◽  
Author(s):  
Davood Hajitaghi Tehrani ◽  
Mehdi Solaimani ◽  
Mahboubeh Ghalandari ◽  
Bahman Babayar Razlighi
Keyword(s):  
Monte Carlo ◽  
Numerical Methods ◽  
Physical Properties ◽  
Maximum Intensity ◽  
Step Method ◽  
Saturation Parameter ◽  
Potential Depth ◽  
Fractional System ◽  
Nonlinear Fractional Schrödinger Equation ◽  
Good Agreement

Abstract In the current research, the propagation of solitons in a saturable PT-symmetric fractional system is studied by solving nonlinear fractional Schrödinger equation. Three numerical methods are employed for this purpose, namely Monte Carlo based Euler-Lagrange variational schema, split-step method, and extrapolation approach. The results show good agreement and accuracy. The effect of different parameters such as potential depth, Levy indices, and saturation parameter, on the physical properties of the systems such as maximum intensity and soliton width oscillations are considered.

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