Simulation of Partial Autofrettage by Thermal Loads

1980 ◽  
Vol 102 (3) ◽  
pp. 314-318 ◽  
Author(s):  
M. A. Hussain ◽  
S. L. Pu ◽  
J. D. Vasilakis ◽  
P. O’Hara
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Finite Elements ◽  
Residual Stresses ◽  
Finite Differences ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Intensity Factors ◽  
Stress Patterns ◽  
Walled Cylinder

The effect of favorable residual stresses of an autofrettaged tube is well known [1]. In many instances there is redistribution of these stresses due to changes of geometrical configurations such as the presence of keyways, riflings, cracks, etc. The problem, in general, can be studied by discretization carrried out either by finite elements or by finite differences; however, it is usually not possible to incorporate the redistributed residual stress patterns due to the presence of such geometrical changes. This difficulty is overcome by simulation of residual stresses by certain active loadings. The simulation by dislocation and equivalent thermal loading for a fully autofrettaged tube is well known. In this paper we extend the thermal loading to simulate a partially autofrettaged case. Thermal stresses due to the simulated thermal loading computed from finite elements (NASTRAN) and finite differences are in excellent agreement with residual stresses for various degrees of overstrain. The simplicity of the method to incorporate the redistribution of residual stress due to the presence of geometrical discontinuities is illustrated by a finite element (APES) computation of stress intensity factors at an OD crack tip in a partially autofrettaged, thick-walled cylinder.

Crack Non-Circularity and Finite Erosion Effects on the 3D SIFs of a Bauschinger Modified Pressurized Thick-Walled Cylinder

2015 ◽  
Author(s):  
Qin Ma ◽  
Cesar Levy ◽  
Mordechai Perl
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Numerical Analysis ◽  
Material Properties ◽  
Thermal Loading ◽  
Circular Crack ◽  
Finite Element Package ◽  
Pressurized Cylinder ◽  
Walled Cylinder

Our previous studies have demonstrated that the 3D SIFs of a pressurized cylinder can be greatly affected by many factors. While an autofrettage process may introduce favorable residual stresses at the bore of the cylinder, other factors such as erosions and cracks, once introduced, may greatly reduce the effectiveness of the autofrettage results. In this study, we focus on how the non-circularity of cracks affects the 3D SIFs for a cylinder that contains finite erosions while keeping other conditions and material properties unchanged. Numerical analysis was performed using ANSYS, a standard commercially available finite element package. The residual stress due to any autofrettage process was simulated using the equivalent thermal loading. A closer look was given to problems with different crack configurations and how non-circularity of cracks affects the overall fatigue life of the cylinder when combined with other factors in comparison with circular crack only configurations.

Development of Predicted Stress and Strain during Conventional and after Mitigation of Welded Aluminium-Manganese Alloy

2013 ◽  
Vol 762 ◽  
pp. 596-601
Author(s):  
F. Soul ◽  
M. Ateeg
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Thermal Stresses ◽  
Stress And Strain ◽  
Manganese Alloy ◽  
Element Analysis ◽  
Longitudinal Residual Stress ◽  
Mitigation Technique

The trend in automotive, aircraft, and marine industries is the increasing use of sheet materials to reduce weight in components and optimize materials performance. Welding is the main fabrication and assembly process in many of these industrial applications. However, in using thin-shell structures in such applications, welding may results in significant residual stresses and out-of-plane distortion. Transient thermal stresses, residual stresses, and distortion sometimes cause cracking and mismatching of joints. High tensile residual stresses are undesirable since they can contribute to fatigue failure. The analysis and measurement of temperature and stresses in component are often too complex to conduct in practise, and thus finite element models provide feasible approach to examine these matters. In this paper, finite element analysis has been performed using the ANSYS package to study the behaviour of longitudinal residual stress and strain in a welded thin aluminium-manganese alloy. The model presented simulates conventional welding and welding with the introduction of welding mitigation technique for enhancement of heat transfer, in which a trailing heat sink was applied. The thermal profiles obtained using the mitigation technique is completely different from those obtained in the conventional cooling. The localized transient residual stress and through-thickness strain after applying a cooling sink are discussed. The transient residual stress behaviour was highly affected by the modified temperature distribution and magnitude due to introducing the heat transfer enhancement.

The evaluation of stress intensity factors for plane cracks in residual stress fields

1993 ◽  
Vol 28 (3) ◽  
pp. 145-152 ◽  
Author(s):  
M D B Wilks ◽  
D Nowell ◽  
D A Hills
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Intensity ◽  
Residual Stresses ◽  
Crack Closure ◽  
Efficient Method ◽  
Stress Intensity Factors ◽  
Stress Fields ◽  
Intensity Factors ◽  
Distributed Dislocations

A reliable, efficient method is described for modelling plane cracks in arbitary residual stress fields, using the technique of distributed dislocations. This allows correctly for re-distribution of residual stresses as the crack grows. Problems where crack closure occur are discussed, and implications for solution by finite element procedures are inferred and confirmed by comparison.

Characterising Residual Stresses in Rectangular Beam Specimens Following Thermo-Mechanical Loading

2006 ◽  
Author(s):  
Ali Mirzaee-Sisan ◽  
Christopher E. Truman ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Stress Field ◽  
Residual Stresses ◽  
Mechanical Loading ◽  
Ferritic Steel ◽  
Thermal Stresses ◽  
Residual Stress Field ◽  
Rectangular Beam

The neutron diffraction (ND) technique was used to characterise residual stress fields in thin rectangular beam specimens containing residual stresses induced thermo-mechanically by partial quenching. Two types of material were considered, type 316H stainless steel and A533B ferritic steel. The work was motivated by a need to investigate the influence of residual stress on the fracture behaviour of steels. During quenching, specimens experienced a severe temperature gradient which induced thermal stresses resulting in plastic strains and a subsequent residual stress field. An extensive finite element (FE) analysis was undertaken to predict the residual stress following thermo-mechanical loading. It was shown that partial quenching generated a considerable residual stress field in 316H stainless steel. However, the level of residual stresses in the A533B steel specimens was lower than that 316H stainless steel specimens. There was acceptable agreement between the finite element simulations and measurements with simulations generally predicting higher tensile residual stresses following partial quenching than those measured in the 316H stainless steel, and lower tensile residual stresses than those measured in the A533B ferritic steel.

scholarly journals Residual Stress Measurements in Mo/CuCrZr Tiles Using Neutron Diffraction

2008 ◽  
Vol 59 ◽  
pp. 299-303
Author(s):  
K. Mergia ◽  
Marco Grattarola ◽  
S. Messoloras ◽  
Carlo Gualco ◽  
Michael Hofmann
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Heat Sink ◽  
High Yield ◽  
Fusion Reactors ◽  
Plasma Facing Components ◽  
Induced Stresses ◽  
Compliant Layer

In plasma facing components (PFC) for nuclear fusion reactors tungsten or carbon based tiles need to be cooled through a heat sink. The joint between the PFC and the heat sink can be realized using a brazing process through the employment of compliant layer of either a low yield material, like copper, or a high yield material, like molybdenum. Experimental verification of the induced stresses during the brazing process is of vital importance. Strains and residual stresses have been measured in Mo/CuCrZr brazed tiles using neutron diffraction. The strains and stresses were measured in Mo tile along the weld direction and at different distances from it. The experimental results are compared with Finite Element Simulations.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Finite Element Modeling for Prediction of Residual Stresses in Fiber Reinforced Metal Matrix Composites

1993 ◽  
Author(s):  
Partha Rangaswamy ◽  
N. Jayaraman
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Matrix Material ◽  
Unit Cell ◽  
Experimental Results ◽  
Matrix Composites ◽  
Layer Removal

Abstract In metal matrix composites residual stresses developing during the cool-down process after consolidation due to mismatch in thermal expansion coefficients between the ceramic fibers and metal matrix have been predicted using finite element analysis. Conventionally, unit cell models consisting of a quarter fiber surrounded by the matrix material have been developed for analyzing this problem. Such models have successfully predicted the stresses at the fiber-matrix interface. However, experimental work to measure residual stresses have always been on surfaces far away from the interface region. In this paper, models based on the conventional unit cell (one quarter fiber), one fiber, two fibers have been analyzed. In addition, using the element birth/death options available in the FEM code, the surface layer removal process that is conventionally used in the residual stress measuring technique has been simulated in the model. Such layer removal technique allows us to determine the average surface residual stress after each layer is removed and a direct comparison with experimental results are therefore possible. The predictions are compared with experimental results of an eight-ply unidirectional composite with Ti-24Al-11 Nb as matrix material reinforced with SCS-6 fibers.

FEM Simulation of the Residual Stress in the Machined Surface Layer for High-Speed Machining

2006 ◽  
Vol 315-316 ◽  
pp. 140-144 ◽  
Author(s):  
Su Yu Wang ◽  
Xing Ai ◽  
Jun Zhao ◽  
Z.J. Lv
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Surface Layer ◽  
Residual Stresses ◽  
High Speed ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
High Speed Machining ◽  
Machined Surface ◽  
Cutting Model

An orthogonal cutting model was presented to simulate high-speed machining (HSM) process based on metal cutting theory and finite element method (FEM). The residual stresses in the machined surface layer were obtained with various cutting speeds using finite element simulation. The variations of residual stresses in the cutting direction and beneath the workpiece surface were studied. It is shown that the thermal load produced at higher cutting speed is the primary factor affecting the residual stress in the machined surface layer.

Process - Property Correlation of Friction Stir Welding of Marine Grade Aluminium Alloy 5083 Using Finite Element Analysis

2021 ◽  
Vol 163 (A2) ◽  
Author(s):  
M Sahu ◽  
A Paul ◽  
S Ganguly
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Finite Element ◽  
Friction Stir Welding ◽  
Residual Stresses ◽  
Process Variables ◽  
Friction Stir ◽  
Stress Region ◽  
Longitudinal Residual Stress ◽  
Process Property

In this article, a 3D finite element based thermo-mechanical model for friction stir welding (FSW) of a marine-grade aluminium alloy 5083 is proposed. The model demonstrates the thermal evaluation and the distribution of residual stresses and strains under the variation of process variables. The temperature profile of the weld joint during the FSW process and the mechanical properties of the joints are also experimentally evaluated. The necessary calibration of the model for the correct implementation of the thermal loading, mechanical loading, and boundary conditions was performed using the experimental results. The model simulation and experimental results are analyses in view of the process-property correlation study. The residual stress was evaluated along, and across the weld, centreline referred as longitudinal and transverse residual stresses, respectively. The magnitude of longitudinal residual stress is noted 60-80% higher than that of the transverse direction. The longitudinal residual stress generated a tensile oval shaped stress region around the tool shoulder confined to a maximum distance of about 25mm from the axis of the tool along the weld line. It encompasses the weld-nugget to thermo-mechanically affected zone (TMAZ), while the parent metal region is mostly experiences the compressive residual stresses. However, the transverse residual stress region appears like wing shaped region spread out in both the advancing and retreating side of the weld and occupying approximately double the area as compared to the longitudinal residual stresses. Overall, the study revealed a corelation between the FSW process variables such as welding speed and the tool rotational speed with the residual stress and the mechanical properties of the joint.

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