Rotor Dynamic Analysis of Tie-Bolt Fastened Rotor Based on Elastic-Plastic Contact

2011 ◽  
Author(s):  
He Peng ◽  
Zhansheng Liu ◽  
Guilong Wang ◽  
Min Zhang
Keyword(s):  
Contact Stiffness ◽  
Contact Model ◽  
Elastic Contact ◽  
Critical Speeds ◽  
Elastic Plastic ◽  
Equivalent Bending Stiffness ◽  
The Difference ◽  
Rigid Plane ◽  
Contact Situation ◽  
Rotor Dynamic

The tie-bolt fastened rotor which is assembled by rods distributed circumferentially is modeled and analyzed by finite element method with the consideration of elastic-plastic contact between discs. Based on elastic-plastic contact model between an elastic hemisphere and a rigid plane, the contact between discs is investigated by the statistical contact model of rough surfaces, and the contact stiffness is derived. The equivalent bending stiffness between discs is acquired. With the increase of the load between the two contact surfaces, the difference between the contact stiffness of purely elastic contact and elastic-plastic model is compared. With the obtained contact stiffness, the equation of motion for the tie-bolt fastened rotor system is formed and the critical speeds are calculated. It indicates that the contact stiffness between discs increases as the load increases. The contact stiffness of elastic-plastic contact model is lower than that of the elastic contact model, and the difference between the two models increases with load. With the stiffness of elastic-plastic contact, the critical speeds of tie-bolt fastened rotor are lower than that of the pure elastic contact situation.

scholarly journals A Static Friction Model for Unlubricated Contact of Random Rough Surfaces at Micro/Nano Scale

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 368
Author(s):  
Shengguang Zhu ◽  
Liyong Ni
Keyword(s):  
Rough Surfaces ◽  
Static Friction ◽  
Friction Model ◽  
Elastic Contact ◽  
Nano Scale ◽  
Random Rough Surfaces ◽  
Proposed Model ◽  
Dissipation Mechanism ◽  
Rigid Plane ◽  
Contact Situation

A novel static friction model for the unlubricated contact of random rough surfaces at micro/nano scale is presented. This model is based on the energy dissipation mechanism that states that changes in the potential of the surfaces in contact lead to friction. Furthermore, it employs the statistical theory of two nominally flat rough surfaces in contact, which assumes that the contact between the equivalent rough peaks and the rigid flat plane satisfies the condition of interfacial friction. Additionally, it proposes a statistical coefficient of positional correlation that represents the contact situation between the equivalent rough surface and the rigid plane. Finally, this model is compared with the static friction model established by Kogut and Etsion (KE model). The results of the proposed model agree well with those of the KE model in the fully elastic contact zone. For the calculation of dry static friction of rough surfaces in contact, previous models have mainly been based on classical contact mechanics; however, this model introduces the potential barrier theory and statistics to address this and provides a new way to calculate unlubricated friction for rough surfaces in contact.

Elastic Contact Model Accounting for Both Asperity and Substrate Compliance With Application to Patterned Media

2007 ◽  
Author(s):  
Chang-Dong Yeo ◽  
Andreas A. Polycarpou
Keyword(s):  
Bulk Material ◽  
Contact Stiffness ◽  
Contact Model ◽  
Elastic Contact ◽  
Element Analysis ◽  
Patterned Media ◽  
Single Asperity ◽  
Proposed Model ◽  
Stiffness Model ◽  
Bulk Substrate

An improved elastic contact stiffness model for a single asperity system is proposed to account for the effects of both bulk substrate and asperity deformations between two contacting surfaces. Depending upon the applied load, as well as the geometrical and physical properties of the asperity and bulk material, the bulk substrate can have a considerable contribution to the overall contact stiffness. Finite element analysis is performed to verify the proposed analytical model. The single asperity model is extended to rough surfaces in contact. The contact stiffness values from the proposed model are compared to those from the GW model. The proposed contact model can be directly relevant to analyze the contact behavior of modern patterned media.

A statistical model of elastic-plastic contact between rough surfaces

2019 ◽  
Vol 43 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Guang Zhao ◽  
Sheng-xiang Li ◽  
Zhi-liang Xiong ◽  
Wen-dong Gao ◽  
Qing-kai Han
Keyword(s):  
Plastic Deformation ◽  
Interface Design ◽  
Present Model ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Contact Point ◽  
Contact Model ◽  
Elastic Plastic ◽  
Classical Models ◽  
Asperity Deformation

In a mechanical interface, the contact surface topography has an important influence on the contact stiffness. In the contact processes of asperities, elastic-plastic change can lead to discontinuity and lack of smoothness at a critical contact point. The result is a large difference between the elastic-plastic deformation and the actual asperity deformation. Based on Hertz contact theory, the heights of asperities on a rough surface obey a Gaussian distribution. To take into consideration the continuity of elastic-plastic asperity deformation, we divide the elastic-plastic deformation into three stages: pre-elastic-plastic, mid-elastic-plastic, and post-elastic-plastic deformation. This establishes an elastic-plastic contact model of asperity at a continuous critical point. The contact model of a single asperity fits well with the Kogut–Etsion model and the Zhao–Maietta–Chang model, and the variation trend is consistent. At a lower plastic index, the present model coincides with classical models of contact area and contact load. At a higher plastic index, the simulation results of the present model differ from the Greenwood–Williamson model and the Chang–Etsion–Bogy model but are similar to results from the Kogut–Etsion and Zhao–Maietta–Chang models. This study provides a more accurate microscopic contact model for rough surfaces and a theoretical framework for interface design and analysis.

scholarly journals Two cosine wave elastic-plastic contact model

2020 ◽  
Vol 103 (4) ◽  
pp. 003685042098061
Author(s):  
Tieneng Guo ◽  
Xu Hua ◽  
Lingjun Meng ◽  
Zhijie Yan ◽  
Liwei Peng
Keyword(s):  
Mechanical Model ◽  
Deformation Process ◽  
Mechanical Characteristics ◽  
Contact Theory ◽  
Elastic Contact ◽  
The Finite Element Method ◽  
Elastic Plastic ◽  
Mechanics Model ◽  
The Difference ◽  
The Relationship

Based on Hertz elastic contact theory, the contact mechanics model of two cosine wave is established. The mechanical characteristics of the model in the elastic, elastic-plastic, and plastic stages were studied. The influence of load on contact deformation and other characteristics is considered. The finite element method is used to analyze the deformation process of the model, and the results are compared with those of the mechanical model. The effects of amplitude and wavelength of cosine wave on its mechanical characteristics are discussed. The results show that the model reflects the relationship between the load and the mechanical characteristics of the model, and the difference of amplitude and wavelength will affect this characteristic.

scholarly journals Finite Pure Plane Strain Bending of Inhomogeneous Anisotropic Sheets

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 145
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeong-Maw Hwang
Keyword(s):  
Plane Strain ◽  
Yield Criterion ◽  
Large Strains ◽  
Rigid Plastic ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Starting Point ◽  
The Difference ◽  
Inside Radius ◽  
Elastic Unloading

The present paper concerns the general solution for finite plane strain pure bending of incompressible, orthotropic sheets. In contrast to available solutions, the new solution is valid for inhomogeneous distributions of plastic properties. The solution is semi-analytic. A numerical treatment is only necessary for solving transcendent equations and evaluating ordinary integrals. The solution’s starting point is a transformation between Eulerian and Lagrangian coordinates that is valid for a wide class of constitutive equations. The symmetric distribution relative to the center line of the sheet is separately treated where it is advantageous. It is shown that this type of symmetry simplifies the solution. Hill’s quadratic yield criterion is adopted. Both elastic/plastic and rigid/plastic solutions are derived. Elastic unloading is also considered, and it is shown that reverse plastic yielding occurs at a relatively large inside radius. An illustrative example uses real experimental data. The distribution of plastic properties is symmetric in this example. It is shown that the difference between the elastic/plastic and rigid/plastic solutions is negligible, except at the very beginning of the process. However, the rigid/plastic solution is much simpler and, therefore, can be recommended for practical use at large strains, including calculating the residual stresses.

On Thick-Walled Cylinder Under Internal Pressure

2003 ◽  
Vol 125 (3) ◽  
pp. 267-273 ◽  
Author(s):  
W. Zhao ◽  
R. Seshadri ◽  
R. N. Dubey
Keyword(s):  
Internal Pressure ◽  
Strain Curve ◽  
Stress Strain ◽  
Piecewise Linearization ◽  
Elastic Plastic ◽  
Plastic Cylinder ◽  
Parametric Functions ◽  
The Difference ◽  
New Formulation ◽  
Walled Cylinder

A technique for elastic-plastic analysis of a thick-walled elastic-plastic cylinder under internal pressure is proposed. It involves two parametric functions and piecewise linearization of the stress-strain curve. A deformation type of relationship is combined with Hooke’s law in such a way that stress-strain law has the same form in all linear segments, but each segment involves different material parameters. Elastic values are used to describe elastic part of deformation during loading and also during unloading. The technique involves the use of deformed geometry to satisfy the boundary and other relevant conditions. The value of strain energy required for deformation is found to depend on whether initial or final geometry is used to satisfy the boundary conditions. In the case of low work-hardening solid, the difference is significant and cannot be ignored. As well, it is shown that the new formulation is appropriate for elastic-plastic fracture calculations.

Wheel-Rail Multi-Point Contact Method for Railway Turnouts

2011 ◽  
Vol 97-98 ◽  
pp. 378-381
Author(s):  
Zhi Wei Chen ◽  
Linan Li ◽  
Shi Gang Sun ◽  
Jun Long Zhou
Keyword(s):  
Calculation Method ◽  
Normal Force ◽  
Contact Point ◽  
Point Contact ◽  
Contact Model ◽  
Contact Method ◽  
Elastic Contact ◽  
Simulation Calculation ◽  
Acute Change

A calculation method of wheel-rail multi-point contact based on the elastic contact model is introduced. Moreover, the simulation calculation of vehicles passing through branch lines of No.18 turnouts is carried out. The result showed that the acute change of wheel-rail normal force caused by the transfers of wheel-rail contact point between two rails can be avoid by wheel-rail multi-point contact method, and the transfers of wheel-rail normal force between two rails is smoother. The validity of wheel-rail multi-point contact method is verified.

An elastic–plastic contact model of ellipsoid bodies

2006 ◽  
Vol 21 (3) ◽  
pp. 262-271 ◽  
Author(s):  
J. Jamari ◽  
D. J. Schipper
Keyword(s):  
Contact Model ◽  
Elastic Plastic ◽  
Ellipsoid Bodies
Sign in / Sign up

Export Citation Format

Share Document