scholarly journals An Experimental and Finite Element Approach for a Better Understanding of Ti-6Al-4V Behavior When Machining under Cryogenic Environment

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2796
Author(s):  
Roland Bejjani ◽  
Charlie Salame ◽  
Mikael Olsson
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Element Model ◽  
Industrial Applications ◽  
Separation Distance ◽  
Cryogenic Machining ◽  
Diffusion Wear ◽  
Cutting Insert ◽  
Nozzle Position ◽  
Two Parameters

Due to increasing demand in manufacturing industries, process optimization has become a major area of focus for researchers. This research optimizes the cryogenic machining of aerospace titanium alloy Ti-6Al-4V for industrial applications by studying the effect of varying the nozzle position using two parameters: the nozzle’s separation distance from the tool–chip interface and its inclination angle with respect to the tool rake face. A finite element model (FEM) and computational fluid dynamics (CFD) model are used to simulate the cryogenic impingement of cryogenic carbon dioxide on the tool–workpiece geometry. Experiments are conducted to evaluate cutting forces, tool wear, and surface roughness of the workpiece, and the results are related to the CFD and FEM analyses. The nozzle location is shown to have a significant impact on the cutting temperatures and forces, reducing them by up to 45% and 46%, respectively, while the dominant parameter affecting the results is shown to be the separation distance. Cryogenic machining is shown to decrease adhesion-diffusion wear as well as macroscopic brittle chipping of the cutting insert compared to dry turning, while the workpiece surface roughness is found to decrease by 44% in the case of cryogenic machining.

A pragmatic approach for the evaluation of depth-sensing indentation in the self-similar regime

2021 ◽  
pp. 1-24
Author(s):  
Hamidreza Mahdavi ◽  
Konstantinos Poulios ◽  
Christian F. Niordson
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Depth Sensing ◽  
Finite Element Software ◽  
Element Simulation ◽  
Unique Material ◽  
Reverse Analysis ◽  
Supplementary Material ◽  
Two Parameters ◽  
Force Displacement

Abstract This work evaluates and revisits elements from the depth-sensing indentation literature by means of carefully chosen practical indentation cases, simulated numerically and compared to experiments. The aim is to close a series of debated subjects, which constitute major sources of inaccuracies in the evaluation of depth-sensing indentation data in practice. Firstly, own examples and references from the literature are presented in order to demonstrate how crucial self-similarity detection and blunting distance compensation are, for establishing a rigorous link between experiments and simple sharp-indenter models. Moreover, it is demonstrated, once again, in terms of clear and practical examples, that no more than two parameters are necessary to achieve an excellent match between a sharp indenter finite element simulation and experimental force-displacement data. The clear conclusion is that reverse analysis methods promising to deliver a set of three unique material parameters from depth-sensing indentation cannot be reliable. Lastly, in light of the broad availability of modern finite element software, we also suggest to avoid the rigid indenter approximation, as it is shown to lead to unnecessary inaccuracies. All conclusions from the critical literature review performed lead to a new semi-analytical reverse analysis method, based on available dimensionless functions from the literature and a calibration against case specific finite element simulations. Implementations of the finite element model employed are released as supplementary material, for two major finite element software packages.

Determination of Optimum Sensor Positions for Defect Detection on Revolving Machines by a Finite Element Vibration Analysis

2000 ◽  
Author(s):  
F. Bogard ◽  
K. Debray ◽  
Y. Q. Guo ◽  
A. Pavan
Keyword(s):  
Finite Element ◽  
Spectral Analysis ◽  
Element Model ◽  
Industrial Applications ◽  
Vibration Monitoring ◽  
Tangent Stiffness Matrix ◽  
Main Research ◽  
Optimum Sensor ◽  
Sensor Positions

Abstract The vibration monitoring is largely used to detect the defects in the revolving machines. The determination of the best sensor positions is one of main research goals in the domain of the conditional maintenance. This paper proposes a numerical methodology based on a finite element model and a spectral analysis in order to find optimum sensor positions. The bearing is considered as a key component in vibration propagation from the moving parts to static ones. In this paper, we use an analytical bearing model and its numerical implementation in a FE code. The tangent stiffness matrix of the bearing element is calculated by the Newton-Raphson method and then introduced into the modal and spectral analysis. The technique of “Mode Shape Summation Plot” (MSSP) is adopted to find the most sensitive zones to usual defects. The proposed numerical approach gives good agreements with the experimental results. A real grinder modeling shows its interesting industrial applications.

scholarly journals The Mechanism of Position-Mode Side Guide in Correcting Camber in Roughing Process of a Hot Strip Mill

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 504 ◽  
Author(s):  
Han-Kai Hsu ◽  
Jong-Ning Aoh
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Separation Distance ◽  
Time Sequence ◽  
Hot Strip Mill ◽  
Schematic Model ◽  
Cross Sectional ◽  
Hot Strip ◽  
Roughing Mill ◽  
Horizontal Roller

The mechanism of the position-mode side guide in correcting slab centerline profile and camber in the roughing process of a hot strip mill (HSM) was analyzed using finite element simulation. The finite element model was established based on the actual size of the roughing mill and on the actual actuating time sequence of the roughing mill in China Steel Corporation (CSC), Kaohsiung. This work could be the first to give an insight into the mechanism of side guides in correcting the slab camber. Time sequence analysis was explored to visualize the progress of centerline profile variation and the interaction between the slab and the related roughing mill components at different moments. The history of reaction forces exerted on the slab was analyzed to explain the interaction between roughing mill components and the slab. The effect of the separation distance of side guide and the effect of the slab wedge on the centerline profile was investigated. A schematic model illustrating the reactions and the resulting moments exerted on the slab was created. By examining the force history, the cross-sectional strain/stress distribution, and the roll force across the horizontal roller, the correcting mechanism of the side guide could be elucidated. The simulation results provide further knowledge in selection and dimension design of side guide to improve the effectiveness of side guide in correcting the slab profile.

scholarly journals Evaluation of Normal Pressures during Filling in Steel Hoppers with Eccentric Outlet

2020 ◽  
Vol 9 (3) ◽  
pp. 138-149
Author(s):  
Alireza Moazezi Mehretehran ◽  
Shervin Maleki
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Physical Space ◽  
Industrial Applications ◽  
Filling Process ◽  
Material Parameters ◽  
Starting Point ◽  
Shallow Side ◽  
Two Parameters ◽  
Complicated Geometries

Filling pressures are a necessary starting point in the design of silos and hoppers. The hoppers with complicated geometries are common in industrial applications due to physical space constraints and the need to interface with other processing equipment. The current paper deals with the effect of outlet eccentricity on normal pressures formed in steel hoppers during distributed filling process. Using finite element method, progressive filling process in hoppers was simulated and by changing the percentage of outlet eccentricity, the variation of pressure distribution was fully studied. The results showed an increase in the normal pressures of shallow side compared with the steep side of eccentric hopper. To quantify the pressure asymmetry, two parameters were introduced and they were evaluated for practical range of material parameters and steel hoppers dimensions. The results obtained are of interest since they facilitate the design of silos and hoppers with eccentric outlet.

scholarly journals Strength of the shaft/hub joint using a finite element model

2019 ◽  
pp. 9-18
Author(s):  
Manuel Salgado-Cruz ◽  
Claudia Cortés-García ◽  
Dariusz Slawomir Szwedowicz-Wasik ◽  
Eladio Martínez-Rayón
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Contact Stiffness ◽  
Load Capacity ◽  
Element Model ◽  
Numerical Results ◽  
Normal Contact ◽  
Interference Fit ◽  
Axial Load Capacity ◽  
Normal Contact Stiffness

This article describes the effect of the roughness size on the axial slip strength between the parts of shaft/hub joints with interference fit. The surface roughness was obtained from a turning process with different finishes (fine, medium and rough). A finite element modeling was developed, which uses a normal contact stiffness equivalent to the size of the surface roughness between the joint pieces to represent the real contact. In order to validate the numerical model, theoretical results of contactpressure and extraction force of the shaft/hub joint with smooth elements were compared with the corresponding numerical results obtained. The numerical results from studies that considered the size of the surface roughness showed that the axial load capacity of the joint decreased with larger roughness.

scholarly journals Surface Roughness 3D Modelling and its Association With Leak Tightness for a Metal-to-Metal Contacting Surface

2017 ◽  
Author(s):  
Ali A. Anwar ◽  
William Dempster ◽  
Yevgen Gorash ◽  
David Nash
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Element Model ◽  
Dynamics Model ◽  
Relief Valve ◽  
Pressure Relief ◽  
Fea Model ◽  
Gas Leak ◽  
Leak Tightness ◽  
Fluid Interaction

This paper presents an overview of a numerical method developed to allow one-way structure-fluid interaction of a scanned representative surface of a Pressure Relief Valve (PRV) measuring 100 μm by 100 μm to be incorporated into a coupled finite element and computational fluid dynamics model to investigate gas leak rates through micro-gaps in full size metal-to-metal contacting components. The virtual representative surface is created via a real scan using a 3D micro coordinate and surface roughness measurement system. The scan of the physical surface is converted to a CAD format and a finite element model generated which is deformed for a given loading condition. The micro-gaps of the deformed FEA model are extracted and imported into the CFD solver to find the resulting volumetric/mass flow rate for the same set of pressure conditions. This coupled approach allows the leakage rate to be found based on only the surface roughness of metal-to-metal sealing surfaces. This methodology can now be expanded to understand the behaviour and response of metal-to-metal deformable contacting surface components under pressure. Thereafter, the design objective is to minimise or eliminate component leakage.

scholarly journals Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 993
Author(s):  
Naeim Ghavidelnia ◽  
Mahdi Bodaghi ◽  
Reza Hedayati
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Poisson’S Ratio ◽  
Element Model ◽  
Industrial Applications ◽  
Poisson's Ratio ◽  
Geometrical Parameters ◽  
Mechanical Metamaterials ◽  
Strength And Stiffness ◽  
The One

Mechanical metamaterials are man-made rationally-designed structures that present unprecedented mechanical properties not found in nature. One of the most well-known mechanical metamaterials is auxetics, which demonstrates negative Poisson’s ratio (NPR) behavior that is very beneficial in several industrial applications. In this study, a specific type of auxetic metamaterial structure namely idealized 3D re-entrant structure is studied analytically, numerically, and experimentally. The noted structure is constructed of three types of struts—one loaded purely axially and two loaded simultaneously flexurally and axially, which are inclined and are spatially defined by angles θ and φ. Analytical relationships for elastic modulus, yield stress, and Poisson’s ratio of the 3D re-entrant unit cell are derived based on two well-known beam theories namely Euler–Bernoulli and Timoshenko. Moreover, two finite element approaches one based on beam elements and one based on volumetric elements are implemented. Furthermore, several specimens are additively manufactured (3D printed) and tested under compression. The analytical results had good agreement with the experimental results on the one hand and the volumetric finite element model results on the other hand. Moreover, the effect of various geometrical parameters on the mechanical properties of the structure was studied, and the results demonstrated that angle θ (related to tension-dominated struts) has the highest influence on the sign of Poisson’s ratio and its extent, while angle φ (related to compression-dominated struts) has the lowest influence on the Poisson’s ratio. Nevertheless, the compression-dominated struts (defined by angle φ) provide strength and stiffness for the structure. The results also demonstrated that the structure could have zero Poisson’s ratio for a specific range of θ and φ angles. Finally, a lightened 3D re-entrant structure is introduced, and its results are compared to those of the idealized 3D re-entrant structure.

Bending behavior of steel octagon-web beam

2020 ◽  
Vol 23 (12) ◽  
pp. 2694-2708
Author(s):  
Shan Chang ◽  
Ming Yang ◽  
Linjie Tian ◽  
Pengfei Yuan
Keyword(s):  
Finite Element ◽  
Test Specimen ◽  
Steel Structures ◽  
Element Model ◽  
Expansion Ratio ◽  
Bending Test ◽  
Scale Model ◽  
Failure Patterns ◽  
Bending Behavior ◽  
Two Parameters

Due to the improvement of steel properties, many steel structures with attractive appearance emerge unceasingly. In this article, a new structure of steel octagon-web beam which has the similar appearance with honeycomb beam was presented. The mechanical characteristics of steel octagon-web beam under bending loads were analyzed theoretically. Based on the Vierendeel truss theory in deflection calculation of honeycomb beam, the deflection calculation method of steel octagon-web beam which was validated by finite element method was studied. Two parameters affecting deflection of steel octagon-web beam, such as opening type and expansion ratio, were analyzed. A scale model of steel octagon-web beam was manufactured in order to study bending behavior of the structure. The failure patterns of test specimen under four-point bending test are the buckling of deck and web. A nonlinear finite element model of test specimen whose results were compared with test was established by software ABAQUS 2017. The stresses of slabs under ultimate load have reached yield stress, which shows steel octagon-web beam has good flexural performance.

A Combined Experimental and Numerical Study of the Effect of Surface Roughness on Nanoindentation

2019 ◽  
Vol 11 (07) ◽  
pp. 1950070
Author(s):  
M. Nazemian ◽  
M. Chamani ◽  
M. Baghani
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Finite Element ◽  
Rough Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Element Analysis ◽  
Three Dimensional Finite Element ◽  
Effect Of Surface

Gold and copper thin films are widely used in microelectromechanical system (MEMS) and nanoelectromechanical system (NEMS) devices. Nanoindentation has been developed in mechanical characterization of thin films in recent years. Several researchers have examined the effect of surface roughness on nanoindentation results. It is proved that the surface roughness has great importance in nanoindentation of thin films. In this paper, the surface topography of thin films is simulated using the extracted data from the atomic force microscopy (AFM) images. Nanoindentation on a rough surface is simulated using a three-dimensional finite-element model. The results are compared with the results of finite-element analysis on a smooth surface and the experimental results. The results revealed that the surface roughness plays a key role in nanoindentation of thin films, especially at low indentation depths. There was good compatibility between the results of finite-element simulation on the rough surface and those of experiments. It is observed that on rough films, at low indentation depths, the geometry of the location where the nanoindentation is performed is of major importance.

Construction of Contact Model of Wheelset Assembly Surface Based on ABAQUS

2014 ◽  
Vol 577 ◽  
pp. 236-239
Author(s):  
Jun Xiao ◽  
Kai Qiang Zhou ◽  
Ren Zhou ◽  
Zhen Dong Lu ◽  
Meng Meng Yang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Friction Coefficient ◽  
Strain State ◽  
Element Model ◽  
Improve Quality ◽  
Finite Element Software ◽  
Press Fit ◽  
Mating Surface

In order to improve quality of wheelset assembly, a method for calculating interference between two sliding asperities that corresponding to the wheelset assembly interference is presented. A finite element model of sliding spherical asperity has been built with the finite element software ABAQUS to analyze the interaction among mating surface roughness, stress-strain state and press-fit curve. This study shows that final fitting force greatly increases with roughness when roughness is lower then 1.8μm and it is unpredicted when roughness is higher. Contact stress and friction coefficient between mating surfaces increase with roughness.

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