scholarly journals Elastic-Plastic Stresses in Shrink Fit with A Solid Shaft

2019 ◽  
Vol 286 ◽  
pp. 02001
Author(s):  
Amal Mouâa ◽  
Nor Eddine Laghzale ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Pressure ◽  
Gas Turbines ◽  
Accurate Estimate ◽  
Material Behavior ◽  
Analytic Method ◽  
Plastic Range ◽  
Hardening Material ◽  
Elastic Plastic ◽  
Shrink Fit ◽  
Distribution Of Stresses

Shrink fit joining a solid shaft and a cylinder requires an accurate estimate of the residual contact pressure to transmit high powers, as in the case of gas turbines. Such torques require deformations of materials beyond their elastic limits. This paper presents an analytical model that analyses the stresses in a shrink fit assembly consisting of a solid shaft and a cylindrical hub operating in the elastic-plastic range. Assuming the hub to have a nonlinear work-hardening material behavior, the distribution of stresses as functions of the interference, and the effect of geometry on contact pressure and on interference are exhibited. To validate the analytic method, Finite Element Method was used.

Effect of Reverse Yielding on the Residual Contact Pressure in Tube-to-Tubesheet Joints

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Mehdi Kazeminia
Keyword(s):  
Finite Elements ◽  
Contact Pressure ◽  
Deformation Theory ◽  
Material Behavior ◽  
Analytical Prediction ◽  
Hardening Material ◽  
Expansion Pressure ◽  
Reverse Yielding ◽  
Materials Used ◽  
Von Mises

The analytical prediction of the contact stress in tube-to-tubesheet joints subjected to hydraulic expansion is conducted without any consideration to reverse yielding that can occur inside the tube. Most existing models consider the tube and tubesheet to unload elastically when the expansion pressure is released. These models are therefore less conservative as they overestimate the contact pressure. An analytical model that considers strain-hardening material behavior of the tube and tubesheet and accounts for reverse yielding has been developed. The model is based on Henckey deformation theory and the Von Mises yield criteria. The paper shows that reverse yielding that is present in tubes during hydraulic expansion unloading makes the joint less rigid and causes a decrease in the contact pressure depending on the gap clearance and the materials used. A good correlation between the analytical and finite elements results is obtained on different treated cases which gives confidence on the developed model.

A semi-analytic method for elastic/plastic shrink-fit analysis and design

2015 ◽  
Vol 50 (4) ◽  
pp. 243-251 ◽  
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeau-Ren Jeng
Keyword(s):  
Analytic Method ◽  
Analysis And Design ◽  
Elastic Plastic ◽  
Shrink Fit

Effect of Reverse Yielding on the Residual Contact Stresses of Tube-to-Tubesheet Joints Subjected to Hydraulic Expansion

2015 ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Mehdi Kazeminia
Keyword(s):  
Contact Pressure ◽  
Contact Stress ◽  
Deformation Theory ◽  
Material Behavior ◽  
Analytical Prediction ◽  
Hardening Material ◽  
Expansion Pressure ◽  
Reverse Yielding ◽  
Materials Used ◽  
Von Mises

The analytical prediction of the contact stress in tube-to-tubesheet joints subjected to hydraulic expansion is conducted without any consideration to reverse yielding that can occur inside the tube. Most existing models consider the tube and tubesheet to unload elastically when the expansion pressure is released. These models are therefore less conservative as the overestimate the contact pressure. An analytical model that considers strain-hardening material behavior of the tube and tubesheet and accounts for reverse yielding has been developed. The model is based on Henckey deformation theory and the Von Mises yield criteria. The paper shows that reverse yielding that is present in tubes during hydraulic expansion unloading makes the joint less rigid and causes a decrease in the contact pressure depending on the gap clearance and the materials used. A good correlation between the analytical and FEM results is obtained on different treated cases which gives confidence on the developed model.

Effects of a Temperature Cycle on an Elastic-Plastic Shrink Fit with Solid Inclusion

2000 ◽  
Vol 16 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Werner Mack ◽  
Manfred Plöchl ◽  
Udo Gamer
Keyword(s):  
Stress Distribution ◽  
Plastic Material ◽  
Yield Condition ◽  
Material Behavior ◽  
Temperature Cycle ◽  
Solid Inclusion ◽  
Flow Rule ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Shrink Fit

ABSTRACTThe stress distribution in a shrink fit with solid inclusion subject to homogeneous heating and subsequent cooling is investigated. It is presumed that both components are in a state of plane stress and exhibit the same elastic-plastic material behavior. Based on Tresca's yield condition and the associated flow rule, the modification of the stress distribution is studied analytically. In particular, the reduction of the interface pressure — and therefore of the transferable moment — caused by the occurrence of plastic deformation is discussed, and the criteria for the avoidance of yielding of the inclusion or full plasticization of the hub are given.

Determining Elastic-Plastic Properties of Al6061-T6 from Micro-Indentation Technique

2013 ◽  
Vol 592-593 ◽  
pp. 610-613
Author(s):  
Sina Amiri ◽  
Nora Lecis ◽  
Andrea Manes ◽  
Davide Mombelli ◽  
Marco Giglio
Keyword(s):  
Manufacturing Process ◽  
Optimization Procedure ◽  
Test System ◽  
Standard Test ◽  
Material Behavior ◽  
Plastic Properties ◽  
Representative Strain ◽  
Elastic Plastic ◽  
Dimensionless Analysis ◽  
Micro Indentation

Different approaches have been proposed in order to determine the material behavior of ductile materials. Since, the mechanical properties of a mechanical component are modified during manufacturing process due to plastic deformation, heat treatment and etc, a non-destructive indentation experimental procedure addressed to predict the elastic-plastic properties of material after manufacturing process is of interest. This is especially true for small size components where it is complex to extract specimens to test on standard test system. Based on dimensionless analysis and the concept of a representative strain, different approaches have been proposed to determine the material properties of power law materials by using indentation process. In this work, the Johnson-Cook (JC) constitutive model of the aluminum alloy Al6061-T6 is characterized by means of a well-defined optimization procedure based on micro-indentation testing and high fidelity finite element models and an optimization procedure but without the concept of dimensionless analysis and a representative strain. This methodology allows determining a set of JC constants for Al6061-T6. The obtained results have good agreement with parameters calibrated by means of universal standard tests and reverse engineering approach.

Improving the Long-Term Performance of Elastomeric Seals by Material Behavior Design

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ryan B. Sefkow ◽  
Nicholas J. Maciejewski ◽  
Barney E. Klamecki
Keyword(s):  
Energy Density ◽  
Contact Pressure ◽  
Strain Energy ◽  
Applied Pressure ◽  
Material Behavior ◽  
Time Dependent ◽  
Ring Section ◽  
Stiff Material ◽  
Elastomeric Seals

Previously it was shown that including smaller inset regions of less stiff material in the larger O-ring section at locations of high stress results in lower strain energy density in the section. This lower energy content is expected to lead to improved long-term seal performance due to less permanent material deformation and so less loss of seal-housing contact pressure. The shape of the inset region, the time-dependent change in material properties, and hence change in seal behavior over time in use were not considered. In this research experimental and numerical simulation studies were conducted to characterize the time-dependent performance of O-ring section designs with small inset regions of different mechanical behaviors than the larger surrounding section. Seal performance in terms of the rate of loss of contact pressure of modified designs and a baseline elastic, one-material design was calculated in finite element models using experimentally measured time-dependent material behavior. The elastic strain energy fields in O-ring sections were calculated under applied pressure and applied displacement loadings. The highest stress, strain, and strain energy regions in O-rings are near seal-gland surface contacts with significantly lower stress in regions of applied pressure. If the size of the modified region of the seal is comparable to the size of the highest energy density region, the shape of the inset is not a major factor in determining overall seal section behavior. The rate of loss of seal-housing contact pressure over time was less for the modified design O-ring sections compared with the baseline seal design. The time-dependent performance of elastomeric seals can be improved by designing seals based on variation of mechanical behavior of the seal over the seal section. Improvement in retention of sealing contact pressure is expected for seal designs with less stiff material in regions of high strain energy density.

Design Optimization of Ultra-Low Flying Head-Disk Interfaces Using an Improved Elastic-Plastic Rough Surface Model

2006 ◽  
Vol 128 (4) ◽  
pp. 801-810 ◽  
Author(s):  
Allison Y. Suh ◽  
Sung-Chang Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Surface Model ◽  
Successful Implementation ◽  
Contact Conditions ◽  
Friction Forces ◽  
Interfacial Forces ◽  
Elastic Plastic ◽  
The Mean ◽  
Improved Model

Sub-5nm flying head-disk interfaces (HDIs) designed to attain extremely high areal recording densities of the order of Tbit∕in2 are susceptible to strong adhesive forces, which can lead to subsequent contact, bouncing vibration, and high friction. Accurate prediction of the relevant interfacial forces can help ensure successful implementation of ultra-low flying HDIs. In this study, an improved rough surface model is developed to estimate the adhesive, contact, and friction forces as well as the mean contact pressure relevant to sub-5nm HDIs. The improved model was applied to four different HDIs of varying roughness and contact conditions, and was compared to the sub-boundary lubrication rough surface model. It was found that the interfacial forces in HDIs undergoing primarily elastic-plastic and plastic contact are more accurately predicted with the improved model, while under predominantly elastic contact conditions, the two models give similar results. The improved model was then used to systematically investigate the effect of roughness parameters on the interfacial forces and mean contact pressure (response). The trends in the responses were investigated via a series of regression models using a full 33 factorial design. It was found that the adhesive and net normal interfacial forces increase with increasing mean radius R of asperities when the mean separation is small (≈0.5nm), i.e., pseudo-contacting interface, but it increases primarily with increasing root-mean-square (rms) surface height roughness between 2 and 4nm, i.e., pseudo-flying interface. Also, increasing rms roughness and decreasing R, increases the contact force and mean contact pressure, while the same design decreases the friction force. As the directions of optimization for minimizing the individual interfacial forces are not the same, simultaneous optimization is required for a successful ultra-low flying HDI design.

scholarly journals A Three-Dimensional Semianalytical Model for Elastic-Plastic Sliding Contacts

2007 ◽  
Vol 129 (4) ◽  
pp. 761-771 ◽  
Author(s):  
Daniel Nélias ◽  
Eduard Antaluca ◽  
Vincent Boucly ◽  
Spiridon Cretu
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Computing Time ◽  
Three Dimensional ◽  
Gradient Methods ◽  
Reciprocal Theorem ◽  
Contact Pressure Distribution ◽  
Sliding Contacts ◽  
Elastic Plastic ◽  
Residual Strains

A three-dimensional numerical model based on a semianalytical method in the framework of small strains and small displacements is presented for solving an elastic-plastic contact with surface traction. A Coulomb’s law is assumed for the friction, as commonly used for sliding contacts. The effects of the contact pressure distribution and residual strain on the geometry of the contacting surfaces are derived from Betti’s reciprocal theorem with initial strain. The main advantage of this approach over the classical finite element method (FEM) is the computing time, which is reduced by several orders of magnitude. The contact problem, which is one of the most time-consuming procedures in the elastic-plastic algorithm, is obtained using a method based on the variational principle and accelerated by means of the discrete convolution fast Fourier transform (FFT) and conjugate gradient methods. The FFT technique is also involved in the calculation of internal strains and stresses. A return-mapping algorithm with an elastic predictor∕plastic corrector scheme and a von Mises criterion is used in the plasticity loop. The model is first validated by comparison with results obtained by the FEM. The effect of the friction coefficient on the contact pressure distribution, subsurface stress field, and residual strains is also presented and discussed.

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