Comprehensive Solutions for the Response of Freestanding Beams With Tensile Residual Stress Subject to Point-Loading

2013 ◽  
Vol 81 (3) ◽  
Author(s):  
John Gaskins ◽  
N. Scott Barker ◽  
Matthew R. Begley
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Explicit Form ◽  
Critical Loads ◽  
Entire Range ◽  
Elastic Beam ◽  
Materials Characterization ◽  
Tensile Residual Stress ◽  
Stress Levels ◽  
Nonlinear Membrane

This paper provides comprehensive solutions for the load-deflection response of an elastic beam with tensile residual stresses subjected to point-loading. A highly accurate explicit approximation is derived from the exact implicit solution for moderate rotations, which greatly facilitates property extraction and the design of devices for materials characterization, actuation, and sensing. The approximation has less than 6% error across the entire range of loads, displacements, geometry, and residual stress levels. An illustration of the application of the theory is provided for microfabricated nickel beams. The explicit form provides straightforward estimates for the critical loads and deflection defining the limits where classical asymptotic limits (e.g., pretensioned membrane, plate, and nonlinear membrane) will be accurate. Regimes maps are presented that identify critical loads, displacements, and properties correspond to these behaviors. Finally, the explicit form also enables straightforward estimations of bending strains relative to stretching, which is useful in the design of materials experiments that can be approximated as uniform straining of the beams.

Modeling and Prediction of Residual Stresses in Additive Layer Manufacturing by Microplasma Transferred Arc Process Using Finite Element Simulation

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Sagar H. Nikam ◽  
N. K. Jain
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Temperature Distribution ◽  
Residual Stresses ◽  
Substrate Material ◽  
Tensile Residual Stress ◽  
Additive Layer Manufacturing ◽  
Element Simulation ◽  
Layer Manufacturing ◽  
Transferred Arc

Prediction of residual stresses induced by any additive layer manufacturing process greatly helps in preventing thermal cracking and distortion formed in the substrate and deposition material. This paper presents the development of a model for the prediction of residual stresses using three-dimensional finite element simulation (3D-FES) and their experimental validation in a single-track and double-track deposition of Ti-6Al-4V powder on AISI 4130 substrate by the microplasma transferred arc (µ-PTA) powder deposition process. It involved 3D-FES of the temperature distribution and thermal cycles that were validated experimentally using three K-type thermocouples mounted along the deposition direction. Temperature distribution, thermal cycles, and residual stresses are predicted in terms of the µ-PTA process parameters and temperature-dependent properties of substrate and deposition materials. Influence of a number of deposition tracks on the residual stresses is also studied. Results reveal that (i) tensile residual stress is higher at the bonding between the deposition and substrate and attains a minimum value at the midpoint of a deposition track; (ii) maximum tensile residual stress occurs in the substrate material at its interface with deposition track. This primarily causes distortion and thermal cracks; (iii) maximum compressive residual stress occurs approximately at mid-height of the substrate material; and (iv) deposition of a subsequent track relieves tensile residual stress induced by the previously deposited track.

Estimation of Residual Stress Levels in Fitness for Service Evaluations of Linepipe

2018 ◽  
Author(s):  
Robert Andrews ◽  
Simon Slater
Keyword(s):  
Residual Stress ◽  
Carbon Steel ◽  
Residual Stresses ◽  
Parent Material ◽  
Plastic Strains ◽  
Stress Distributions ◽  
Butt Welding ◽  
Stress Levels ◽  
High Level ◽  
Welding Processes

Codified fitness for service methods such as API 579 or BS 7910 require consideration of residual stresses in fracture assessments, and guidance is given for upper bound residual stress distributions in common weld geometries. However, these distributions are not appropriate for some welding processes currently or historically used in the manufacture of linepipe, such as high frequency induction welding or flash butt welding. In addition, some linepipe manufacturing routes generate large plastic strains which result in high residual forming stresses, or mechanically relax residual stresses generated in earlier stages of production. This paper first reviews the code recommendations for the effects of plastic strains and stresses from high level pressure testing on residuals stresses. The paper then briefly describes the major methods of producing carbon steel linepipe and provides recommended residual stress levels for the seam weld and parent material of linepipe using the code recommendations. These are based on assumed uniform residual stresses combined with mechanical stress relaxation due to manufacturing steps such as cold expansion and hydrostatic testing. The recommendations are compared with measured residual stress levels from the open literature. Proposals are given for reduced residual stress levels when assessing axial cracks in carbon steel linepipe.

Re-cold expansion process simulation to impart the residual stresses around fastener holes in 6061 A-T6 aluminium alloy

2008 ◽  
Vol 222 (11) ◽  
pp. 1325-1332 ◽  
Author(s):  
J S Jang ◽  
D W Kim
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Process Simulation ◽  
Fatigue Cracks ◽  
External Loading ◽  
Process Conditions ◽  
Expansion Process ◽  
Fatigue Crack Nucleation ◽  
Cold Expansion ◽  
Stress Levels

Cold expansion processes are widely used in aerospace structures to eliminate or delay fatigue crack nucleation and to improve fatigue life. Fastener holes, in which the fatigue cracks initiate from stress concentrations, are plastically expanded using a mandrel pulled through the hole. Cold expansion technology has been applied to enhance low-cycle fatigue performance in repair as well as production applications. Repair of aircraft structures is a key component to extend aircraft service life. Re-cold expansion process conditions such as the degree of cold expansion should be determined to impart the beneficial compressive residual stresses around the holes under tensile loadings. In this paper, a process simulation using three-dimensional finite element analysis is conducted to determine the residual stress imparted by re-cold expansion in the fastener holes under the external loading conditions. Three levels of re-cold expansion under three external loading levels are performed in this numerical investigation. It is shown that the re-cold expansion process with at least 6 per cent of the degree of cold expansion imparts deep residual stresses around the hole so that the resulting stress levels on the hole entry side remain compressive under applied external stress levels between 100 and 200 MPa. In addition, residual stress redistribution under various applied external stresses is discussed.

Residual Stress and Stress Corrosion Cracking of High Pressure Hydrocarbon Transmission Pipelines

2006 ◽  
Author(s):  
Greg Van Boven ◽  
Ronald Rogge ◽  
Weixing Chen
Keyword(s):  
Residual Stress ◽  
High Pressure ◽  
Residual Stresses ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Stress Gradient ◽  
Corrosion Cracking ◽  
Tensile Residual Stress ◽  
Surface Residual Stress ◽  
Residual Stress Gradient

Stress corrosion cracking (SCC) can occur on the exterior surface of high pressure hydrocarbon transmission pipelines fabricated from low carbon steels. Both the initiation of SCC and the ability of SCC to progressively increase in depth is a complex and poorly understood phenomena. Previous empirical evidence suggests that residual stresses may be involved in this initiation and growth process. This paper describes a laboratory research project designed to investigate the correlation between residual stress and SCC. In this project, tensile test specimens with increasing levels of compressive and tensile residual stress on the surface and through the thickness of the specimen were fabricated. These stresses were sufficiently large as to dominate the other slight variations in material properties that may occur on identically formed test specimens. The residual stresses were then mapped across the length and through the depth of the specimens by a non-destructive neutron diffraction technique. A SCC initiation process was applied to the specimens. It was found that the formation of micro-pitting, to a depth up to 200 μm, occurred preferentially in areas where tensile residual stresses were the highest (about 300 MPa). Initiation of SCC, although found all at the bottom of this micro-pitting, occurred with a 71% normalized frequency in locations where the surface residual stress was in the range of 150 MPa to 200 MPa. Experimental data revealed that cracks generated in near-neutral pH environments can be readily blunted, due to both plastic deformation (room temperature creep) and extensive dissolution. As a result, a high positive tensile residual stress gradient is necessary for developing cracks in pipeline steels exposed to near-neutral pH environments. The tensile residual stress represents a large mechanical driving force for initial crack nucleation and short crack growth. Active cracks may become dormant as the near-surface residual stress gradient changes from a high to a low tensile stress or if the stress becomes compressive due to self-equilibration through the wall thickness direction. Special conditions may exist in pipeline steels where crack dormancy may not occur within a short distance to the surface, which may include, for example, the presence of a large tensile residual stress gradient over a longer distance, particular microstructures conducive to galvanic corrosion, and special environmental conditions susceptible to hydrogen-induced cracking.

Residual Stresses in Locally Long Fiber Reinforced Aluminum Parts

2011 ◽  
Vol 284-286 ◽  
pp. 284-292 ◽  
Author(s):  
Shao Chun Sun ◽  
Zhi Yuan Chen ◽  
Qiang Wu ◽  
De Xin Ma ◽  
Yu Tao Zhao
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Residual Stresses ◽  
Tensile Residual Stress ◽  
Fiber Reinforced ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fem Method ◽  
The Matrix ◽  
Compressive Residual Stresses

In locally long fiber reinforced aluminum parts two types residual stresses exist. They are the microscopic residual stress between fiber and matrix and the macroscopic residual stress between reinforced and unreinforced zones. The residual stresses between fiber and matrix in γ-Al2O3 long fiber reinforced aluminum alloy Al-6-1-1 were measured with X-ray Diffraction process as well as simulated with FEM method. The results indicated that the residual stresses in both fiber and matrix were distributed very unequally. The maximum tensile residual stress occurred at the boundary in the matrix and the maximum compressive residual stresses occurred near the boundary in the fiber. The macroscopic residual stresses between the reinforced and unreinforced zones were also measured with borehole method as well as simulated with FEM. It was found that the macroscopic residual stresses at most locations in both the reinforced and unreinforced zones were not harmfully high. However in both reinforced and unreinforced zones there were small sub-zones of very large tensile residual stresses.

Measurement of Residual Stress in Reactor Nozzle Mock-Ups Containing Dissimilar Metal Welds

2014 ◽  
Author(s):  
Adrian T. DeWald ◽  
Michael R. Hill ◽  
Michael L. Benson ◽  
David L. Rudland
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Tensile Residual Stress ◽  
Contour Method ◽  
Two Dimensional ◽  
Weld Residual Stress ◽  
Accelerate Growth ◽  
Primary Water ◽  
Spatially Varying

Weld residual stresses can significantly impact the performance of structural components. Tensile residual stresses are of particular concern due to their ability to accelerate failure. For example, the presence of tensile residual stress can cause initiation and accelerate growth of primary water stress corrosion cracking (PWSCC). The contour method is a residual stress measurement technique capable of generating two dimensional maps of residual stress, which is particularly useful when applied to welds since they typically contain spatially varying residual stress distributions. The two-dimensional capability of the contour method enables detailed visualization of complex weld residual stress fields. This data can be used to identify locations and magnitude of tensile residual stress hot-spots. This paper provides a summary of the contour method and presents detailed results of contour method measurements made on a mock-up from the NRC/EPRI weld residual stress (WRS) program [1].

Optimized Conditions for Tensile Residual Stress Reducing Weld Using Water-Shower Cooling

2003 ◽  
Author(s):  
Nobuyoshi Yanagida ◽  
Kunio Enomoto ◽  
Hideya Anzai
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Residual Stresses ◽  
Heat Input ◽  
Fem Analysis ◽  
Tensile Residual Stress ◽  
Input Quantity ◽  
Preheating Temperature ◽  
Optimized Conditions

To reduce tensile residual stress in a welded region, we developed a new cooling method that applies a water shower behind the welding torch. When this method is applied to the welding of austenitic stainless-steel, the welding and cooling conditions mainly determine how much the residual stress can be reduced. To optimize these conditions, we first used FEM to determine the effects of preheating temperature, heat input quantity, and water-shower area on the residual stress, and found that, to decrease tensile residual stress, preheating temperature should be high, heat input low, and the water-shower large. To confirm the effectiveness of these optimized conditions, residual stresses under optimized or non-optimized conditions were experimentally measured. It was found that the residual stresses were tensile under the non-optimized conditions, but compressive under the optimized ones. These measurements agree well with the FEM analysis. It can therefore be concluded that the optimized conditions are valid and appropriate for reducing residual stress in an austenitic stainless-steel weld.

Autofrettaged Cylindrical Vessels and Bauschinger Effect: An Analytical Frame for Evaluating Residual Stress Distributions

2001 ◽  
Vol 124 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Paolo Livieri ◽  
Paolo Lazzarin
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Explicit Form ◽  
Analytical Solutions ◽  
Bauschinger Effect ◽  
Superposition Principle ◽  
Pressure Vessels ◽  
Material Behavior ◽  
Stress Distributions ◽  
Hardening Law

The paper reports analytical solutions valid for residual stresses in cylindrical pressure vessels subjected to autofrettage. The material behavior is thought of as obeying a generic monotonic σ−ε curve and exhibiting the Bauschinger effect during the unloading phase. Under linear and power-hardening conditions, the solution is given in an explicit form. The circumstances under which it is possible to apply the superposition principle also in the presence of localized plasticity are clearly identified. When possible, the final stresses can be obtained by using in an appropriate manner the stress expressions related to the loading phase. Finally, the influence on residual stresses, both of the hardening law and of the shape of the unloading σ−ε curve, is discussed.

Residual Stress Improvement in Multi-Layer Welding of Austenitic Stainless Steel Plates by Using Water-Shower Cooling During Welding Process

2006 ◽  
Author(s):  
Nobuyoshi Yanagida ◽  
Hiroo Koide
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Residual Stresses ◽  
Welding Process ◽  
Steel Plates ◽  
Tensile Residual Stress ◽  
Welding Torch ◽  
Measurement Results ◽  
Effective Conditions

To reduce tensile residual stress in a welded region, we have developed a new cooling method that applies a water-shower behind the welding torch. When this method is applied to multi-layer welding of austenitic stainless steel plates, cooling conditions mainly determine how much the residual stress can be reduced. To determine the conditions, we first used FEM to evaluate the effects of water-shower cooling and interpass temperature on the residual stress. In addition, we found effective conditions for reducing tensile residual stress. To verify the validity of the conditions, three plates were welded with or without water shower cooling. Residual stresses of the plates were measured experimentally. It was found that tensile residual stresses occurred on the surface of the welds and that they were reduced when the water-shower was applied at the last pass. These measurement results agree well with the FEM analyses. It can therefore be concluded that water-shower cooling during the last welding pass is appropriate for reducing tensile residual stress in austenitic stainless steel at a multi-pass weld.

scholarly journals Application of low transformation-temperature filler to reduce the residual stresses in welded component

2019 ◽  
Vol 13 (1) ◽  
pp. 4536-4557 ◽  
Author(s):  
K. Azizpour ◽  
H. Moshayedi ◽  
I. Sattari-far
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Transformation Temperature ◽  
Weld Zone ◽  
Weld Line ◽  
Element Model ◽  
Tensile Residual Stress ◽  
Hole Drilling ◽  
Welded Structures

Tensile residual stress is a major issue in integrity of the welded structures. Undesirable tensile residual stress in welding may reduce fracture toughness and fatigue life of welded structures. The low transformation-temperature (LTT) fillers, due to introducing compressive residual stresses caused by prior martensitic transformation, can reduce tensile residual stresses in the weld zone. The effects of using LTT fillers on welding residual stresses of high strength steel sheets are studied and compared with conventional fillers. 3D finite element simulations including coupled thermal-metallurgical-mechanical analyses are developed using SYSWELD software to predict the welding residual stresses. For validation of the finite element model, the residual stresses are measured through hole drilling strain gage method. The results indicate that using the LTT fillers cause a decrease of the longitudinal tensile residual stresses of the weld metal from 554 MPa to 216 MPa in comparison with conventional fillers. The transverse residual stresses of the weld line are changed from tensile 156 MPa to compressive 289 MPa with using LTT fillers instead of conventional fillers.

Sign in / Sign up

Export Citation Format

Share Document