An analytical solution for jointed tunnel linings in elastic soil or rock

2008 ◽  
Vol 45 (11) ◽  
pp. 1572-1593 ◽  
Author(s):  
Hany El Naggar ◽  
Sean D. Hinchberger
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Segmental Lining ◽  
Sophisticated Method ◽  
Walled Cylinder ◽  
Elastic Soil

This paper presents a closed-form solution for tunnel linings that can be idealized as an inner jointed segmental lining and an outer thick-walled cylinder embedded in a homogeneous infinite elastic soil or rock. Solutions for moment and thrust have been derived for cases involving slip and no slip at the lining–ground and lining–lining interfaces. In addition, the closed-form solution is verified by comparing it with finite element results where it is shown to agree well with this more sophisticated method of analysis.

A closed-form solution for composite tunnel linings in a homogeneous infinite isotropic elastic medium

2008 ◽  
Vol 45 (2) ◽  
pp. 266-287 ◽  
Author(s):  
Hany El Naggar ◽  
Sean D. Hinchberger ◽  
K. Y. Lo
Keyword(s):  
Closed Form ◽  
Elastic Medium ◽  
Closed Form Solution ◽  
Form Solution ◽  
Tunnel Lining ◽  
Linear Elastic ◽  
Isotropic Elastic Medium ◽  
Thin Walled ◽  
Walled Cylinder ◽  
Elastic Soil

This paper presents a closed-form solution for composite tunnel linings in a homogeneous infinite isotropic elastic medium. The tunnel lining is treated as an inner thin-walled shell and an outer thick-walled cylinder embedded in linear elastic soil or rock. Solutions for moment and thrust have been derived for cases involving slip and no slip at the lining–ground interface and lining–lining interface. A case involving a composite tunnel lining is studied to illustrate the usefulness of the solution.

Validation of Nitinol SMA Characteristics Using Finite Element Analysis and Closed Form Solutions

2013 ◽  
Vol 856 ◽  
pp. 147-152
Author(s):  
S.H. Adarsh ◽  
U.S. Mallikarjun
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Fe Analysis ◽  
Element Analysis ◽  
Complex Behaviour ◽  
Closed Form Solutions

Shape Memory Alloys (SMA) are promising materials for actuation in space applications, because of the relatively large deformations and forces that they offer. However, their complex behaviour and interaction of several physical domains (electrical, thermal and mechanical), the study of SMA behaviour is a challenging field. Present work aims at correlating the Finite Element (FE) analysis of SMA with closed form solutions and experimental data. Though sufficient literature is available on closed form solution of SMA, not much detail is available on the Finite element Analysis. In the present work an attempt is made for characterization of SMA through solving the governing equations by established closed form solution, and finally correlating FE results with these data. Extensive experiments were conducted on 0.3mm diameter NiTinol SMA wire at various temperatures and stress conditions and these results were compared with FE analysis conducted using MSC.Marc. A comparison of results from finite element analysis with the experimental data exhibits fairly good agreement.

A New Accurate Closed-Form Analytical Solution for Junction Temperature of High-Powered Devices

2014 ◽  
Vol 136 (1) ◽  
Author(s):  
J. H. L. Ling ◽  
A. A. O. Tay
Keyword(s):  
Analytical Solution ◽  
Closed Form ◽  
Material Properties ◽  
Heat Dissipation ◽  
Field Effect Transistors ◽  
Closed Form Solution ◽  
Form Solution ◽  
Junction Temperature ◽  
Design Parameters ◽  
Closed Form Analytical Solution

The peak junction temperature has a profound effect on the operational lifetime and performance of high powered microwave devices. Although numerical analysis can help to estimate the peak junction temperature, it can be computationally expensive and time consuming when investigating the effect of the device geometry and material properties on the performance of the device. On the other hand, a closed-form analytical method will allow similar studies to be done easily and quickly. Although some previous analytical solutions have been proposed, the solutions either require over-long computational times or are not so accurate. In this paper, an accurate closed-form analytical solution for the junction temperature of power amplifier field effect transistors (FETs) or monolithic microwave integrated circuits (MMICs) is presented. Its derivation is based on the Green's function integral method on a point heat source developed through the method of images. Unlike most previous works, the location of the heat dissipation region is assumed to be embedded under the gate. Since it is a closed-form solution, the junction temperature as well as the temperature distribution around the gate can be easily calculated. Consequently, the effect of various design parameters and material properties affecting the junction temperature of the device can be easily investigated. This work is also applicable to multifinger devices by employing superposition techniques and has been shown to agree well with both numerical and experimental results.

On the Analytical Solution of Externally Pressurized Porous Gas Journal Bearings

1978 ◽  
Vol 100 (3) ◽  
pp. 442-444 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Analytical Solution ◽  
Pressure Distribution ◽  
Closed Form ◽  
Closed Form Solution ◽  
Journal Bearings ◽  
Form Solution ◽  
Performance Characteristics ◽  
Gas Bearing ◽  
Good Agreement

A closed form solution of pressure distribution which leads to the determination of bearing performance characteristics of an externally pressurized porous gas bearing without journal rotation is obtained. A good agreement with a similar available solution confirms the validity of the method.

Generalized and Simplified Linear Closed-Form Solution of an Active Tensegrity Unit in the Form of Octahedral Cell

2014 ◽  
Vol 969 ◽  
pp. 192-198
Author(s):  
Stanislav Kmeť ◽  
Peter Platko
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Analysis ◽  
Closed Form ◽  
Closed Form Solution ◽  
Point Load ◽  
Form Solution ◽  
Cable System ◽  
Form Analysis ◽  
Tensile Forces

Results of the generalized and simplified linear closed form solution of an active or adaptive tensegrity unit, as well as its numerical analysis using finite element method are presented in the paper. The shape of the unit is an octahedral cell with a square base and it is formed by thirteen members (four bottom and four top cables, four edge struts and one central strut). The central strut is designed as an actuator that allows for an adjustment of the shape of the unit which leads to changes of tensile forces in the cables. Due to the diagonal symmetry of the 3D tensegrity unit the closed-form analysis is based on the 2D solution of the equivalent planar biconvex cable system with one central strut under a vertical point load.

scholarly journals Analytical solution for bending vibration of a thin-walled cylinder rolling on a time-varying force

2018 ◽  
Vol 5 (7) ◽  
pp. 180639
Author(s):  
A. Le Bot ◽  
G. Duval ◽  
P. Klein ◽  
J. Lelong
Keyword(s):  
Analytical Solution ◽  
Vibrational Energy ◽  
Normal Modes ◽  
Closed Form Solution ◽  
Form Solution ◽  
Time Varying ◽  
Bending Vibration ◽  
Simply Supported ◽  
Random Forces ◽  
Walled Cylinder

This paper presents the analytical solution of radial vibration of a rolling cylinder submitted to a time-varying point force. In the simplest situation of simply supported edges and zero in-plane vibration, the cylinder is equivalent to an orthotropic pre-stressed plate resting on a visco-elastic foundation. We give the closed-form solution of vibration as a series of normal modes whose coefficients are explicitly calculated. Cases of both deterministic and random forces are examined. We analyse the effect of rolling speed on merging of vibrational energy induced by Doppler's effect for the example of rolling tyre.

Formulation of surface temperature for laser evaporative pulse heating: The time exponentially decaying pulse case

2002 ◽  
Vol 216 (3) ◽  
pp. 289-299 ◽  
Author(s):  
B S Yilbas ◽  
M Kalyon
Keyword(s):  
Analytical Solution ◽  
Closed Form ◽  
Closed Form Solution ◽  
Solid Substrate ◽  
Form Solution ◽  
Solution Temperature ◽  
Heating Process ◽  
Pulse Parameter ◽  
Pulse Profile ◽  
Transform Method

Modelling of the laser heating process is fruitful, since it enhances the understanding of the physical processes involved and minimizes the experimental cost. In the present study, an analytical solution for the temperature distribution inside the solid substrate is obtained using a Laplace transform method. A time exponentially decaying laser pulse profile is introduced in the analysis. The phase change process and recession velocity are accommodated to account for the evaporation at the surface. The closed-form solution obtained is compared with the analytical solution obtained previously for a conduction limited heating case. It is found that the closed-form solution obtained from the present study reduces to a previously obtained analytical solution when the pulse parameter, β∗, is set to zero in the closed-form solution. Temperature predictions from simulations agree well with the results obtained from the closed-form solution.

Study of Combined Heat and Mass Transfer From Fins Using Non-Dimensional Finite Element Formulation

2013 ◽  
Author(s):  
Sulaman Pashah ◽  
Syed M. Zubair ◽  
Abul Fazal M. Arif
Keyword(s):  
Mass Transfer ◽  
Finite Element ◽  
Closed Form ◽  
Heat And Mass Transfer ◽  
Closed Form Solution ◽  
Base Material ◽  
Form Solution ◽  
Element Formulation ◽  
Dimensionless Parameters ◽  
Dimensional Finite Element

The use of dimensional analysis and dimensionless parameters is very common in the field of heat transfer. The paper presents a non-dimensional finite element capable of modeling combined heat and mass transfer from fins. The aim of the formulation is to get solution of the fin problems that do not have a closed form solution. The performance of a fin is described through its efficiency and numerous closed form solutions for fin efficiency under combined heat and mass transfer are available in the literature. Deriving a closed form solution for geometric or material complexities is somewhat a difficult task. An example is variable profile composite fin. A composite fin is composed of base material or substrate with a coating layer. Finite element approach can handle such complexity with relatively ease, Therefore the main objective is to developed formulation for mass transfer problems. The formulation is derived in dimensionless form to extend the applicability of finite element results to a class of problems with same governing dimensionless parameters. The derived formulation is then applied to study the combined heat and mass transfer for variable profile composite fins under fully wet condition.

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