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On the Collapse of Long Thick-Walled Circular Tubes under Biaxial Loading


Madhavan, Raghu (1988) On the Collapse of Long Thick-Walled Circular Tubes under Biaxial Loading. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/VPAC-QV51.


The collapse phenomenon of long, thick-walled tubes subjected to axial tension and external pressure is investigated. A combined experimental and analytic approach is adopted. The diameter to thickness ratio (DA) of the tubes studied is in the range 10-40.

A series of collapse tests are conducted using thick-walled, small diameter tubes of two different materials. Careful measurements of geometrical and material parameters are carried out before each collapse test. Tension-Pressure collapse envelopes are obtained for tubes of different D/t and loading paths. Collapse tests involving initially ovalized tubes are also carried out. The results show that collapse strength is strongly influenced by initial ovality.

A two-dimensional model is used for predicting the collapse strength. The limit point behavior of a long tube with initial geometric imperfections has been modeled. The tube is assumed to be under generalized plane strain conditions and the possible variations of material and geometric parameters along the length are not considered. Hill's anisotropic plasticity theory involving a quadratic yield function is used to model the anisotropies in yield shown by drawn tubes. A power law creep model is employed to assess the effect of primary creep on collapse strength.

The interaction between collapse pressure and tension is found to depend on both material and geometric parameters. The yield behavior of the tube material strongly affects the collapse phenomenon. Initial ovality of the tube is shown to be a very important geometric parameter that influences collapse strength. The effect of primary creep on collapse is shown to be not very significant, for the type of materials used (304 stainless steel and 6061-O aluminum).

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Mechanical Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Babcock, Charles D. (advisor)
  • Knauss, Wolfgang Gustav (co-advisor)
Thesis Committee:
  • Knauss, Wolfgang Gustav (chair)
  • Hall, John F.
  • Knowles, James K.
  • Rosakis, Ares J.
  • Singer, Josef
  • Babcock, Charles D.
Defense Date:10 March 1988
Funding AgencyGrant Number
American Gas AssociationUNSPECIFIED
Brown & Root InternationalUNSPECIFIED
Standard Oil of Ohio (SOHIO)UNSPECIFIED
Record Number:CaltechETD:etd-11062007-080516
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4421
Deposited By: Imported from ETD-db
Deposited On:21 Nov 2007
Last Modified:03 Feb 2020 19:27

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