Analysis of Residual Stresses in Multi-Pass Welding Using Element Generation Technique

2006 ◽  
Vol 326-328 ◽  
pp. 1287-1290
Author(s):  
Jang Hyun Lee ◽  
Kyung Ho Lee ◽  
Chan Woo Lee

A finite element procedure to predict residual stresses on the multi-pass arc welding considering the multi-layered beads and solid–liquid phase transformation in the melted bead is implemented and experimentally validated. The nonlinearities of material properties are considered in the thermo-elasto-plastic distortion analysis. Element birth and death technique is used to simulate the weld metal added to base metal in both heat transfer and thermo-elasto-plastic analysis. Residual stresses and strains are computed for butt welding and T-joints fillet welding. The stress distributions calculated by proposed finite element analysis procedure are compared with the measured values of experiments and data available in the other studies. The efficiency of the proposed finite element analysis and experimental procedure is discussed and demonstrated.

2005 ◽  
Vol 127 (4) ◽  
pp. 713-721 ◽  
Author(s):  
Zefeng Wen ◽  
Xuesong Jin ◽  
Yanyao Jiang

A finite element analysis with the implementation of an advanced cyclic plasticity theory was conducted to study the elastic-plastic deformation under the nonsteady state rolling contact between a wheel and a rail. The consideration of nonsteady state rolling contact was restricted to a harmonic variation of the wheel-rail normal contact force. The normal contact pressure was idealized as the Hertzian distribution, and the tangential force presented by Carter was used. Detailed rolling contact stresses and strains were obtained for repeated rolling contact. The harmonic variation of the normal (vertical) contact force results in a wavy rolling contact surface profile. The results can help understand the influence of plastic deformation on the rail corrugation initiation and growth. The creepage or stick-slip condition greatly influences the residual stresses and strains. While the residual strains and surface displacements increased at a reduced rate with increasing rolling passes, the residual stresses stabilize after a limited number of rolling passes. The residual stresses and strains near the wave trough of the residual wavy deformation are higher than those near the wave crest.


Author(s):  
Gurinder Singh Brar ◽  
Rakesh Kumar

Welding is one of the most commonly used permanent joining processes in the piping and pressure vessel industry. During welding a very complex thermal cycle is applied to the weldment, which in turn causes irreversible elastic-plastic deformation and consequently gives rise to the residual stresses in and around fusion zone and heat affected zone (HAZ). Presence of residual stresses may be beneficial or harmful for the structural components depending on the nature and magnitude of stresses. The beneficial effect of compressive stresses have been widely used in industry as these are believed to increase fatigue strength of the component and reduce stress corrosion cracking and brittle fracture. In large steel fabrication industries such as shipbuilding, marine structures, aero-space industry, high speed train guide ways and pressure vessels and piping in chemical and petrochemical industry the problem of residual stresses and overall distortion has been and continue to be a major issue. It is well established fact that material response of structural components is substantially affected by the residual stresses when subjected to thermal and structural loads. Due to these residual stresses produced in and around the weld zone the strength and life of the component is reduced. As AISI 304 stainless steel has excellent properties like better corrosion resistance, high ductility, excellent drawing, forming and spinning properties, so it is almost used in all types of application like chemical equipment, flatware utensils, coal hopper, kitchen sinks, marine equipment etc. But because of the problems of residual stresses during the time of welding it is very essential to understand the behavior and nature of AISI 304 stainless steel material. So in order to overcome all these problems a 3-dimensional finite element model is developed in a commercially available FEA code by drafting an approximate geometry of the butt welded joint and then the finite element analysis is performed, so that one can understand the complete nature of residual stresses in butt welding of AISI 304 stainless steel plate. In this paper, butt welding simulations were performed on two AISI 304 stainless steel plates by gas tungsten arc welding (GTAW). Analysis of butt welded joint by commercially available finite element analysis code showed that butt weld produced by GTAW resulted in 782.84 MPa of residual stress in plates. In addition, the residual stress is plotted against axial distance to have a clear picture of the magnitude of residual stress in and around weld area.


Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1152
Author(s):  
Rafał Nowak ◽  
Anna Olejnik ◽  
Hanna Gerber ◽  
Roman Frątczak ◽  
Ewa Zawiślak

The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, the lack of updated reports about biomechanical effects in bone-borne appliances used in SARME is noticeable. Finite element analysis (FEA) was used for this study. Six facial skeleton models were created, five with various variants of osteotomy and one without osteotomy. Two different appliances for maxillary expansion were used for each model. The three-dimensional (3D) model of the facial skeleton was created on the basis of spiral computed tomography (CT) scans of a 32-year-old patient with maxillary constriction. The finite element model was built using ANSYS 15.0 software, in which the computations were carried out. Stress distributions and displacement values along the 3D axes were found for each osteotomy variant with the expansion of the tooth- and the bone-borne devices at a level of 0.5 mm. The investigation showed that in the case of a full osteotomy of the maxilla, as described by Bell and Epker in 1976, the method of fixing the appliance for maxillary expansion had no impact on the distribution of the reduced stresses according to Huber’s hypothesis in the facial skeleton. In the case of the bone-borne appliance, the load on the teeth, which may lead to periodontal and orthodontic complications, was eliminated. In the case of a full osteotomy of the maxilla, displacements in the buccolingual direction for all the variables of the bone-borne appliance were slightly bigger than for the tooth-borne appliance.


Author(s):  
James K. Wilkins

A project has been conducted to verify a finite element analysis procedure for studying the nonlinear behavior of 90°, stainless steel, 4 inch schedule 10, butt welding elbows. Two displacement controlled monotonic in-plane tests were conducted, one closing and one opening, and the loads, displacements, and strains at several locations were recorded. Stacked 90° tee rosette gages were used in both tests because of their ability to measure strain over a small area. ANSYS shell element 181 was used in the FEA reconciliations. The FEA models incorporated detailed geometric measurements of the specimens, including the welds, and material stress-strain data obtained from the attached straight piping. Initially, a mesh consisting of sixteen elements arrayed in 8 rings was used to analyze the elbow. The load-displacement correlation was quite good using this mesh, but the strain reconciliation was not. Analysis of the FEA results indicated that the axial and hoop strain gradients across the mid-section of the elbow were very high. In order to generate better strain correlations, the elbow mesh was refined in the mid-section of the elbow to include 48 elements per ring and an additional six rings, effectively increasing the element density by nine times. Using the refined mesh produced much better correlations with the strain data.


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