scholarly journals Characterization of Residual Stresses in 718 Turbine Discs by Neutron Diffraction and Finite Element Modelling

2011 ◽  
Vol 278 ◽  
pp. 102-107 ◽  
Author(s):  
Peter Staron ◽  
Ulrike Cihak ◽  
Helmut Clemens ◽  
Martin Stockinger ◽  
Andreas Schreyer
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Heat Transfer Coefficient ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Transfer Coefficient ◽  
Thin Plate ◽  
Stress Distributions ◽  
Element Simulation

The results of our investigations on residual stresses in commercially produced forged IN 718 compressor discs are reviewed. The residual stresses in the discs with a diameter of 320 mm and a thickness of up to 25 mm were studied using neutron diffraction to verify the predictions of a finite element simulation, which was used to model forging and cooling of the discs. In addition to the disc, a thin plate of the same material was also studied for testing the influence of specimen geometry on the model predictions. While the model results for the disc were not strongly influenced by the heat transfer coefficient, the stress distributions in the thin plate could only be predicted satisfactorily by using a temperature-dependent heat transfer coefficient that was derived from temperature measurements during quenching. Eventually, this led to an improvement of the FE simulation used for optimizing the production process.

Finite Element Simulation of Cutting Forces in Turning Ti6Al4V Using DEFORM 3D

2013 ◽  
Author(s):  
Kosaraju Satyanarayana ◽  
Anne Venu Gopal ◽  
Popuri Bangaru Babu
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Cutting Forces ◽  
Experimental Results ◽  
Shear Friction ◽  
Shear Friction Factor ◽  
Deform 3D

Titanium alloys are widely used in aerospace industry due to their excellent mechanical properties though they are classified as difficult to machine materials. As the experimental tests are costly and time demanding, metal cutting modeling provides an alternative way for better understanding of machining processes under different cutting conditions. In the present work, a finite element modeling software, DEFORM 3D has been used to simulate the machining of titanium alloy Ti6Al4V to predict the cutting forces. Experiments were conducted on a precision lathe machine using Ti6Al4V as workpiece material and TiAlN coated inserts as cutting tool. L9 orthogonal array based on design of experiments was used to evaluate the effect of process parameters such as cutting speed and feed with a constant depth of cut 0.25 mm and also the tool geometry such as rake angle on cutting force and temperature. These results were then used for estimation of heat transfer coefficient and shear friction factor constant, which are used as boundary conditions in the process of simulation. Upon simulations a relative error of maximum 9.07% was observed when compared with experimental results. A methodology was adopted to standardize these constants for a given process by taking average values of shear friction factor and heat transfer coefficient, which are used for further simulations within the range of parameters used during experimentation. A maximum error of 9.94% was observed when these simulation results are compared with that of experimental results.

scholarly journals An experimental-numerical method for transient infrared measurement of film cooling effectiveness and heat transfer coefficient in a single test

2019 ◽  
Vol 123 (1270) ◽  
pp. 1982-1998
Author(s):  
Nicholas E. Holgate ◽  
Peter T. Ireland ◽  
Eduardo Romero
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Guide Vane ◽  
Test Surface ◽  
Transfer Coefficients ◽  
Conduction Model ◽  
Film Cooling Effectiveness

ABSTRACTAn experimental technique for assessing film cooling performance is proposed which can determine both film effectiveness and heat transfer coefficient distributions from a single infrared experiment. First, the film effectiveness is determined in the experiment’s steady-state phase on a series of film-cooled nozzle guide vane leading edge geometries made of a low thermal conductivity foam. Then, the effectiveness is used to calculate the distribution of the transient phase driving gas temperatures, which is applied to a finite element conduction model. Heat transfer coefficients are guessed and iteratively refined until the surface temperature histories predicted by the finite element model match those which were experimentally observed. Unlike conventional methods based on one-dimensional analytical heat transfer solutions, this approach does not require assumptions about the material thickness underlying the test surface or the uniformity with depth of its initial temperature distribution. This relieves certain experimental constraints and reduces uncertainty in results.

Analyses of Flow Field and Heat Exchange about Limestone Grain in the Preheater

2014 ◽  
Vol 915-916 ◽  
pp. 974-977
Author(s):  
Yong Gang Liu ◽  
Xiao Yang Zhang ◽  
Jing Yang Zheng ◽  
Jin Fa Xie
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Particle Model ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient ◽  
Hot Air ◽  
Heat Transfer Theory

According to the structural features of the vertical preheater, the 2-dimention finite element models are set up for the section of the preheater with different arrangement and diameters for the limestone grains. The situation of gas-solid two-phase flow between the limestone grains and the hot air in the preheater is simulated by the discrete particle model. Based on the heat transfer theory, the convection heat transfer coefficient between the limestone grains and the hot air is deduced by means of the experimental correlation of the air cross-flow tube bundles. On the simulation of the 2-dimention finite element model of the vertical preheater based on the FLOTRAN module of ANSYS, the temperature field, pressure field and velocity field of the limestone grains are obtained. The results show that there is a little change of convection heat transfer coefficient by varying the arrangement of limestone grains. The convection heat transfer coefficient is improved by employing the limestone grains with little diameter. The larger the gap between the grains is, the larger the convection heat transfer coefficient is.

Prediction of the Tensile Thermal Stress Generation Conditions for Laser Irradiation of Thin Plate Glass with Forced Cooling Based on the Plane Stress Model

2018 ◽  
Vol 12 (4) ◽  
pp. 590-602 ◽  
Author(s):  
Akira Chiba ◽  
◽  
Souta Matsusaka ◽  
Hirofumi Hidai ◽  
Noboru Morita
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Stress ◽  
Transfer Coefficient ◽  
Thin Plate ◽  
Plane Stress ◽  
Plate Glass ◽  
Stress Model ◽  
Forced Cooling ◽  
Tensile Thermal Stress

The tensile thermal stress generated by laser irradiation with forced cooling is critical in the cleavage processing of thin plate glass. In this study, we predicted the conditions for generating tensile thermal stress in laser-induced cleavage of thin plate glass using numerical models from the viewpoint of the cooling and heating areas. An unsteady two-dimensional model was used to predict the temperature distribution and an unsteady plane stress model was used to predict the thermal stress. To generate tensile thermal stress, a cooling area is required behind the heating area. A specific scanning speed is required to yield the maximum tensile stress between the heating and cooling areas. A weak heat transfer coefficient in the cooling area generates tensile thermal stress only in the direction perpendicular to (y direction) the scanning direction of the heat source (x direction). A strong heat transfer coefficient generates tensile thermal stress in both the x and y directions. These tensile thermal stresses are surrounded by horseshoe-shaped compressive thermal stress. The tensile thermal stress can be controlled by selecting an appropriate cooling method for the cooling area.

The interfacial heat transfer coefficient in hot die forging of titanium alloy

1998 ◽  
Vol 212 (6) ◽  
pp. 485-496 ◽  
Author(s):  
Z M Hu ◽  
J W Brooks ◽  
T A Dean
Keyword(s):  
Heat Transfer ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Titanium Alloy ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hot Forging ◽  
Element Model ◽  
Interfacial Heat Transfer Coefficient ◽  
Element Analysis

An investigation of die temperature changes and the heat transfer coefficient during hot forging of titanium alloy has been carried out using experiments and a thermal-plastic coupled finite element analysis. Hot Ti-6A1–4V rings were forged between two heated flat dies made of Inconel alloy IN718. The bottom die was instrumented with high-response thermocouples on its surface and subsurface. The recorded temperatures were analysed and used to determine the interface heat transfer coefficient between the die and the workpiece in conjunction with the thermal-plastic coupled finite element analysis using a reverse algorithm. The coefficients determined were then used in a finite element model for the analysis of the upsetting process and the results produced were in good agreement with the experimental data.

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