A Finite-Element Model for Residual Stresses and Deflections in Girth-Butt Welded Pipes

1978 ◽  
Vol 100 (3) ◽  
pp. 256-262 ◽  
Author(s):  
E. F. Rybicki ◽  
D. W. Schmueser ◽  
R. W. Stonesifer ◽  
J. J. Groom ◽  
H. W. Mishler
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Computational Models ◽  
Strain Range ◽  
Element Model ◽  
304 Stainless Steel ◽  
Transient Temperature ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Welded Pipe

Computational models for predicting transient temperature distributions, residual stresses, and residual deflections for girth-butt welds are described. Comparisons of predicted and measured temperatures for a two-pass welded pipe show agreement to within 9 percent and 17 percent of the measured values for passes one and two, respectively, the model for predicting residual stresses and residual deflections is based on a finite-element representation recognizing individual passes, temperature dependent elastic-plastic constitutive behavior, elastic unloading for material in the nonlinear stress-strain range, and changes in geometry due to the deformation of each weld pass. Load incrementation and incremental stress-strain relations are also used. Results for a two-pass girth-butt welded pipe show good correlation between residual stresses and residual deflections obtained from the computational model and data obtained from a welded 304 stainless steel pipe.

scholarly journals Field Variable Associations With Scratch Orientation Dependence of UHMWPE Wear: A Finite Element Analysis

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Matthew C. Paul ◽  
Liam P. Glennon ◽  
Thomas E. Baer ◽  
Thomas D. Brown
Keyword(s):  
Finite Element ◽  
Computational Models ◽  
Three Dimensional ◽  
Element Model ◽  
Field Variable ◽  
Orientation Dependence ◽  
Normal Strain ◽  
Stress Strain ◽  
Element Analysis ◽  
Local Direction

Scratches on the metal bearing surface of metal-on-polyethylene total joint replacements have been found to appreciably accelerate abrasive/adhesive wear of polyethylene, and constitute a source of the considerable variability of wear rate seen within clinical cohorts. Scratch orientation with respect to the local direction of relative surface sliding is presumably a factor affecting instantaneous debris liberation during articulation. A three-dimensional local finite element model was developed, of orientation-specific polyethylene articulation with a scratched metal counterface, to explore continuum-level stress/strain parameters potentially correlating with the orientation dependence of scratch wear in a corresponding physical experiment. Computed maximum stress values exceeded the yield strength of ultra-high molecular weight polyethylene (UHMWPE) for all scratch orientations but did not vary appreciably among scratch orientations. Two continuum-level parameters judged most consistent overall with the direction dependence of experimental wear were (1) cumulative compressive total normal strain in the direction of loading, and (2) maximum instantaneous compressive total normal strain transverse to the sliding direction. Such stress/strain metrics could be useful in global computational models of wear acceleration, as surrogates to incorporate anisotropy of local metal surface roughening.

A Comparative Multifield FEA and Experimental Study on the Enhanced Manufacturability of 6061-T6511 Aluminum Using dc Current

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Amir Khalilollahi ◽  
David H. Johnson ◽  
John T. Roth
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Tensile Specimen ◽  
Transient Temperature ◽  
Stress Strain ◽  
Strain Behavior ◽  
Deformation Force ◽  
Property Changes ◽  
Dc Current

An electric current, applied during deformation, has been shown to reduce the deformation force/energy, while also increasing the maximum achievable strain and decreasing springback. Considering this, the present work initiates the development of a finite element model to investigate electricity’s thermal/structural effects on a tensile specimen. The model allows the effect of joule-heating to be separated from other nonthermal property changes caused by the electricity. Comparison with experimental tensile testing with respect to the predicted stress-strain behavior and transient temperature profiles demonstrates the model predicts these behaviors adequately. A multifield large deformation finite element model is then developed. The model evaluates the stress-strain characteristics of the material while the specimen is carrying a large dc current and is being deformed, incorporating the effect of thermal softening. The simulation results are compared with surface infrared temperature measurements in order to verify the finite element model and then to actual deformation results in order to attain more qualitative and quantitative insight into the effects of the electric field.

Multi-Field FE Modeling of Resistive Heating in a 6061-T6511 Aluminum Specimen

2006 ◽  
Author(s):  
Amir Khalilollahi ◽  
David H. Johnson ◽  
John Roth
Keyword(s):  
Finite Element ◽  
Mechanical Energy ◽  
Element Model ◽  
Tensile Specimen ◽  
Effect Of Temperature ◽  
Transient Temperature ◽  
Fe Model ◽  
Stress Strain ◽  
Aluminum Specimen ◽  
Property Changes

Electric current's effect on material mechanical properties has been of interest since it can lessen the mechanical energy associated with deforming/working a material. The objective of this work is to have a representative model of the thermal/structural effects of electricity on a tensile specimen so that the simple effect of temperature can be separated from any mechanical material property changes due to the electric current. The finite element models in this study were generated and their results were compared to experimental data obtained from a representative tensile test. Comparison with the experimental results on material engineering stress-strain curves and transient temperature profiles offers assurance for the further use of FEA as a significant tool in understanding the electrical effects on material properties. A multi-field large deformation finite element model for a cylindrical tensile bar of 6061-T6511 aluminum is developed to evaluate the distribution of temperature within the specimen. The model also evaluates the stress-strain characteristics of the material while the specimen is carrying a large DC current and being deformed. The simulation results are compared to surface infrared temperature measurements in order to verify the FE model first and then to attain more qualitative and possibly quantitative insight into the effects of electric field.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

Delamination in the scoring and folding of paperboard

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO
Keyword(s):  
Finite Element ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Local Strain ◽  
Uniaxial Stress ◽  
Material Model ◽  
Element Model ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Fields

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.

Cord/Rubber Material Properties

1985 ◽  
Vol 58 (4) ◽  
pp. 830-856 ◽  
Author(s):  
R. J. Cembrola ◽  
T. J. Dudek
Keyword(s):  
Finite Element ◽  
Material Model ◽  
Rubber Composites ◽  
Stress Strain ◽  
Element Analysis ◽  
Rubber Layer ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Interlaminar Shear ◽  
Mechanics Of Composite Materials

Abstract Recent developments in nonlinear finite element methods (FEM) and mechanics of composite materials have made it possible to handle complex tire mechanics problems involving large deformations and moderate strains. The development of an accurate material model for cord/rubber composites is a necessary requirement for the application of these powerful finite element programs to practical problems but involves numerous complexities. Difficulties associated with the application of classical lamination theory to cord/rubber composites were reviewed. The complexity of the material characterization of cord/rubber composites by experimental means was also discussed. This complexity arises from the highly anisotropic properties of twisted cords and the nonlinear stress—strain behavior of the laminates. Micromechanics theories, which have been successfully applied to hard composites (i.e., graphite—epoxy) have been shown to be inadequate in predicting some of the properties of the calendered fabric ply material from the properties of the cord and rubber. Finite element models which include an interply rubber layer to account for the interlaminar shear have been shown to give a better representation of cord/rubber laminate behavior in tension and bending. The application of finite element analysis to more refined models of complex structures like tires, however, requires the development of a more realistic material model which would account for the nonlinear stress—strain properties of cord/rubber composites.

Estimation of Residual Stress in Spiral Welded Pipe: Regression and Numerical Model

2012 ◽  
Author(s):  
Abul Fazal M. Arif ◽  
Ahmad S. Al-Omari ◽  
Anwar K. Sheikh ◽  
Yagoub Al-Nassar ◽  
M. Anis
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Role ◽  
Large Diameter ◽  
Element Model ◽  
Regression Equation ◽  
Field Analysis ◽  
Welding Parameters ◽  
Splitting Test ◽  
Welded Pipe

Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.

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