Coupled Temperature Displacement Research Articles

Turning modeling and simulation of an aerospace grade aluminum alloy using two-dimensional and three-dimensional finite element method

This article presents the development of two-dimensional and three-dimensional finite element–based turning models, for better prediction of chip morphology and machined surface topology. Capabilities of a commercial finite element code Abaqus®/Explicit have been exploited to perform coupled temperature–displacement simulations of an aerospace grade aluminum alloy A2024-T351 machining. The findings show that two-dimensional cutting models predict chip morphologies and machined surface textures on a plane section (with unit thickness) passing through the center of workpiece width, and not at the edges. The contribution highlights the importance of three-dimensional machining models for a close corroboration of experimental and numerical results. Three-dimensional cutting simulations show that a small percentage of material volume flows toward workpiece edges (out of plane deformation), augmenting the contact pressures at the edges of tool rake face–workpiece interface. This enhances the burr formation process. Computational results concerning chip morphologies and cutting forces were found in good correlation with experimental ones. In the final part of the article, numerical simulation results with a modified version of a particular turning tool have been discussed. It has been found that the proposed geometry of the tool is helpful in reducing burr formation as well as cutting force amplitude during initial contact of cutting tool with the workpiece material.

A Finite Element Study of Chip Formation Process in Orthogonal Machining

This paper examines the plane strain 2D Finite Element (FE) modeling of segmented, as well as continuous chip formation while machining AISI 4340 with a negative rake carbide tool. The main objective is to simulate both the continuous and segmented chips from the same FE model based on FE code ABAQUS/Explicit. Both the adiabatic and coupled temperature displacement analysis has been performed to simulate the right kind of chip formation. It is observed that adiabatic hypothesis plays a critical role in the simulation of segmented chip formation based on adiabatic shearing. The numerical results dealing with distribution of stress, strain and temperature for segmented and continuous chip formations were compared and found to vary considerably from each other. The simulation results were also compared with other published results; thus validating the developed model.

Experimental investigation and finite element simulation of laser beam welding induced residual stresses and distortions in thin sheets of AA 6056-T4

Abstract Laser beam welding has recently found its application in the fabrication of aircraft structures where fuselage panels, made of thin sheets of AA 6056-T4 (an aluminium alloy), are welded with stiffeners of the same material in a T-joint configuration. The present work simulates laser beam welding induced residual stresses and distortions using industrially employed thermal and mechanical boundary conditions. Various measurements performed on small-scale welded test specimens provide a database of experimental results that serves as a benchmark for qualification of the simulation results. The welding simulation is performed with the commercial finite element software Abaqus and a Fortran programme encoding a conical heat source with Gaussian volumetric distribution of flux. A sequentially coupled temperature–displacement analysis is undertaken to simulate the weld pool geometry, transient temperature and displacement fields. The material is assumed to follow an elasto-plastic law with isotropic hardening behaviour (von Mises plasticity model). A comparison between the experimental and simulation results shows a good agreement. Finally, the residual stress and strain states in a T-joint are predicted.

Coupled temperature–displacement modelling of injection stretch-blow moulding of PET bottles using Buckley model

This study presents a fully coupled temperature–displacement finite element modelling of the injection stretch-blow moulding (ISBM) process of polyethylene terephthalate (PET) bottles using ABAQUS with a view to optimising the process conditions. A physically-based material model (Buckley model) was used to predict the mechanical behaviour of PET at temperatures slightly above its glass transition temperature. A model incorporating heat transfer between the stretch rod, the preform and the mould was built using axisymmetric solid elements. Extensive finite element analyses were carried out to predict the deformation, the distribution and history of strain and temperature during ISBM of a 20g–330ml bottle, which was made in an in situ test on a Sidel SB06 machine. Comparisons of numerical results with the measurements demonstrate that the model can satisfactorily model the sidewall thickness and material distributions. It is also shown that significant non-linear differentials exist in temperature and strain in both bottle thickness and length directions during the process. This justifies the employment of a volume approach to accurately predict the final mechanical properties of the bottles governed by the orientation and crystallinity which are highly temperature and strain dependent.

A coupled temperature–displacement model for predicting the long-term performance of offshore pipeline insulation systems

Insulation systems for offshore oil and gas pipelines operate in aggressive environments over lifetimes of about 20 years. The effectiveness of the insulation over the entire lifetime is essential to provide flow assurance. Fluid temperatures must be kept high enough to ensure that waxes or hydrates do not form and result in pipeline blockages.The operating environment for offshore pipelines will become more severe with planned developments in 2000m waters having well temperatures of up to 160°C. Insulation systems proposed for such deepwater wells are typically multilayered with foamed polymers providing most of the thermal resistance. The high hydrostatic pressures and well temperatures associated with deepwater wells can lead to a degradation of the thermal performance of foamed materials due to creep.The prediction of the long-term thermal behaviour is complex. The material characteristics of foams are dependent on the density, temperature and stress level, all of which change with time as the material creeps. This leads to a non-linear coupled thermal-structural response. This paper describes analytical models, which predict the system behaviour over time. These models have been implemented in a user-friendly design tool, named DISDANS. Good agreement is found between the model results and equivalent finite element models.

Evaluation of a pellet-clad mechanical interaction in mixed oxide fuels during power transients by using axisymmetric finite element modeling

MOX fuel rod behavior due to PCMI during power transients was evaluated using a finite element code, ABAQUS. Clad elongation is calculated through a coupled temperature–displacement analysis where a half-pellet is axisymmetrically modeled. Parametric study for the PCMI model is preliminary performed to identify the dominant factors and examine the applicable range of the model. The comparison of the predicted results with recent MOX in-pile data shows that the centerline temperature and clad elongation are evaluated within an acceptable range.

Thermomechanics of slow stable crack growth: closing the loop between experiments and computational modeling

Most of the plastic work done ahead of a running crack is dissipated as heat. Even for slow moving cracks the resulting temperature field is of interest since it carries quantitative information about the energy consumed in crack growth and a qualitative description of the distributed damage to the material. In this study, the temperature field ahead of a stable, Mode I, growing crack in a ductile material is imaged using an infrared camera. Thermal images are analyzed to compute energy flux to the crack. Coupled temperature–displacement FEA are performed to model these experiments and a good match with experiments is obtained.