0
TECHNICAL PAPERS

Modeling of Threaded Joints Using Anisotropic Elastic Continua

[+] Author and Article Information
Daniel J. Segalman

 Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-0847djsegal@sandia.gov

Michael J. Starr

 Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-0847

J. Appl. Mech 74(3), 575-585 (May 03, 2006) (11 pages) doi:10.1115/1.2424467 History: Received November 15, 2005; Revised May 03, 2006

Using fine material meshes in structural dynamics analysis is often impractical due to time step considerations. Unfortunately, fine meshes are typically required to capture the inherent physics in jointed connections. This is especially true in threaded connections which feature numerous contact interfaces and stress singularities. A systematic method is presented here for representing the threaded volume by a continuous, homogeneous, linear elastic, anisotropic equivalent material. The parameters of that equivalent material depend on thread geometry and the assumed contact condition between adjacent threads and are derived from detailed finite element simulations of a characteristic thread-pair unit cell. Numerical simulations using the equivalent material closely match the local stiffness through the load path calculated from the finely meshed thread models and also reproduce classical theoretical and experimental results from the literature.

FIGURES IN THIS ARTICLE
<>
Copyright © 2007 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Unit cell for a representative thread pair

Grahic Jump Location
Figure 2

The finely meshed thread test model for determining material properties in plane strain. The center thread pair is the cell on which the material parameters are calculated.

Grahic Jump Location
Figure 3

Simple plane strain bolt pull test designed to exercise the equivalent material model. Case 1 approximates that of a bolt in a large block. Case 2 is consistent with the boundary conditions of a tightened bolt/nut system. The model is cut along its plane of symmetry.

Grahic Jump Location
Figure 4

The four load cases employed to develop the equivalent material parameters

Grahic Jump Location
Figure 5

The finely meshed thread model employs 6309 hex elements, with 1219 of those elements located in the thread region

Grahic Jump Location
Figure 6

The coarsely meshed equivalent material model used for comparison in the following plots employs 1754 hex elements, with 230 of those elements located in the thread region. The thick solid lines in the insets are planes of discontinuity within the equivalent material.

Grahic Jump Location
Figure 7

Force versus displacement plot for three material cases: finely meshed welded threads, finely meshed frictionless threads, and coarsely meshed welded equivalent material. The displacement is measured at the nodes at which the displacement is imposed.

Grahic Jump Location
Figure 8

Shear stress along the midline of the thread region for three material cases: finely meshed welded threads, finely meshed frictionless threads, and coarsely meshed welded equivalent material

Grahic Jump Location
Figure 9

Integrated shear stress along the midline of the thread region for three material cases: finely meshed welded threads, finely meshed frictionless threads, and coarsely meshed welded equivalent material

Grahic Jump Location
Figure 10

Vertical displacement along the symmetry plane of the bolt model for three material cases: finely meshed welded threads, finely meshed frictionless threads, and coarsely meshed welded equivalent material. The vertical dashed line corresponds to the location of the bottom of the bolt cap.

Grahic Jump Location
Figure 11

Normal stress along the symmetry plane of the bolt model for three material cases: finely meshed welded threads, finely meshed frictionless threads, and coarsely meshed welded equivalent material. The vertical dashed line corresponds to the location of the bottom of the bolt cap.

Grahic Jump Location
Figure 12

Force versus displacement plot for four different mesh cases: welded thread model, fine equivalent material, intermediate equivalent material, and coarse equivalent material. The legend associates each case with a corresponding line in the force-displacement plot.

Grahic Jump Location
Figure 13

Shear stress along the midline of the thread region for two material cases: finely meshed welded threads and coarsely meshed welded equivalent material

Grahic Jump Location
Figure 14

Fraction of the load carried by the threads along the thread stack for the two boundary condition cases illustrated in Fig. 3. The welded thread model and welded equivalent model are shown for both cases. Sopwith’s derivation overlays the results for boundary condition case 2.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In