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Research Papers

Optimization of a Platform With Respect to Force Contact Conditions

[+] Author and Article Information
Dieter Bestle

Engineering Mechanics and Vehicle Dynamics, BTU Cottbus, 03013 Cottbus, Germanybestle@tu-cottbus.de

J. Comput. Nonlinear Dynam 3(4), 041011 (Sep 04, 2008) (8 pages) doi:10.1115/1.2960472 History: Received May 25, 2007; Revised January 15, 2008; Published September 04, 2008

Chimneys in operating power plants cannot be demolished in the classical way by dynamite. A new technology has been invented where they are cut off starting from the top and where the pieces of the reinforced concrete chimney are dropped through the inner pipe of the chimney. In order to avoid the falling down of pieces on the outer side, a ring platform is attached to the chimney by pure force contact, which allows semi-automatic climbing up and down. The paper addresses two crucial design decisions concerning the ring platform: the design of the contact geometry and the shape of the ring structure. Both design problems are formulated as multicriterion optimization problems where the first one can be solved partially in an analytical way whereas the second one has to be solved numerically. It will be shown how the problems can be formulated in various ways depending on the technical requirements.

Copyright © 2008 by American Society of Mechanical Engineers
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References

Figures

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Figure 4

Claw in its nominal (a), disturbed (b), and tilted (c) positions

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Figure 5

Kinematics of a claw in its tilted position

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Figure 6

Optimal solutions for the multicriterion contact problem

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Figure 7

Claw with circular contour line

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Figure 8

Optimized contact shapes for μ0=0.5: circular arc (gray) and exact solution (black)

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Figure 9

Claw with general contour line

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Figure 16

EP-optima for D=25 m and μ0=0.5 resulting from the recursive knee search

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Figure 17

Optimal cable force and selected radii for varying chimney diameters D

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Figure 18

Cable polygon with identical (○) and optimized (×) claws for chimney diameter range D∊[15,22]

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Figure 19

Contact ratios for identical (○) and optimized (×) claws at bounds of diameter range D∊[15,22]

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Figure 20

Contact ratios for the full range D∊[15,22]

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Figure 1

Hydraulic cutters and ring platform on top of a chimney

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Figure 2

Geometry of the ring platform

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Figure 3

Climbing sequence for one console of the ring structure

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Figure 10

Load ratios Gk/Gtot on the contact points

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Figure 11

Geometry of the cable polygon

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Figure 12

Cable polygon (a) and contact ratios (b) for chimney diameter D=25 m and restricted deviations rmax=0.15 m with identical (○) and optimized (×) claws

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Figure 13

Cable polygon (a) and contact ratios (b) for chimney diameter D=25 m and unrestricted deviations with identical (○) and optimized (×) claws

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Figure 14

EP-optima for D=25 m and μ0=0.5 resulting from the compromise method: converged (black) and nonconverged (gray) solutions

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Figure 15

Boundary intersection method and knee search

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