0
TECHNICAL PAPERS

Study of Bolt Load Loss in Bolted Aluminum Joints

[+] Author and Article Information
T. Jaglinski

Materials Science Program, University of Wisconsin-Madison, 147 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706-1687tmjaglinski@engr.wisc.edu

A. Nimityongskul

Engineering Mechanics Program, University of Wisconsin-Madison, 147 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706-1687apnimityongs@engr.wisc.edu

R. Schmitz

Engineering Mechanics Program, University of Wisconsin-Madison, 147 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706-1687robert.schmitz@ata-e.com

R. S. Lakes

Department of Engineering Physics, Biomedical Engineering Department, Rheology Research Center, University of Wisconsin-Madison, 147 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706-1687lakes@engr.wisc.edu

J. Eng. Mater. Technol 129(1), 48-54 (May 02, 2006) (7 pages) doi:10.1115/1.2400262 History: Received April 28, 2005; Revised May 02, 2006

Bolted joints are used widely in mechanical design and represent a weak link in a system where loss of joint clamping force can lead to degraded product performance or human injury. To meet current market demands, designers require reliable material data and analysis tools for their industry specific materials. The viscoelastic response of bolted aluminum joints used in the small die-cast engine industry at elevated temperatures was studied. Bolt load-loss tests were performed using strain gages in situ. It was found that after a week at temperature, most bolts lost 100% of their initial prestress. Nonlinear constitutive equations utilizing parameters obtained from uniaxial creep and relaxation tests were used in a simple one-dimensional model to predict the bolt load loss. The model cannot predict the detailed response and overpredicts retained bolt stress for bolt holes that are not preconditioned. For preconditioned holes, the behavior is intermediate between creep and relaxation.

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

Example of the die-cast engine head joint studied. This geometry was typical of the eutectic Al–Si alloy head joint.

Grahic Jump Location
Figure 2

Typical test bolt and gage assembly

Grahic Jump Location
Figure 3

Comparison between nonlinear superposition model (solid lines) and uniaxial data (open point shapes) for (a) creep at several stresses and (b) relaxation at several strains, were both are at a temperature of 220°C.

Grahic Jump Location
Figure 4

Typical thermal response for the bolted joints tested in this study. Steady-state temperatures are not achieved until 1–2h into a given test. Note the time reference labels, which will be included without text in subsequent figures.

Grahic Jump Location
Figure 5

Measured bolt stress for all tests from the first flange for three temperatures; the joint did not reach thermal equilibrium until 1–2h after placement into the preheated furnace. All tests were run in unused holes.

Grahic Jump Location
Figure 6

Measured bolt stress for the second block tested at 260°C showing (a) three tests using the manufacturing method in unused holes and (b) three tests run in preconditioned holes. Tests marked a and b were run concurrently (in different holes). Test 7b lost electrical contact before one week had elapsed.

Grahic Jump Location
Figure 7

Measured bolt stress for the third block tested at (a) 240°C and (b) 220°C. All tests except for 8 in (a) were preconditioned. Again, tests marked a and b were run concurrently (in different holes). Note, in (b) the results for tests 11b and 13 lie almost on top of each other.

Grahic Jump Location
Figure 8

Comparison of the bolt load response for preconditioned holes from the second and third blocks at three different temperatures. Tests 7a (260°C), 10b (240°C), and 13 (220°C) are shown.

Grahic Jump Location
Figure 9

Representative bolt load response during cool down from 220°C to room temperature for tests 12 and 13, which showed retained bolt load.

Grahic Jump Location
Figure 10

Theoretical predictions (thick lines) beginning from the peak thermal load as the step input condition for (a) the first flange and (b) the second flange at 260°C. All tests in this figure were tightened once and placed in the oven. Behavior based on the relaxation formulation (dashed line in (b)) significantly deviates from the experiment and is only shown in for test 4a for comparison.

Grahic Jump Location
Figure 11

Theoretical behavior from peak thermal load for preconditioned holes from the second and third flanges for 260°C and 220°C. Experimental behavior lies between behavior based on creep (thick lines) and relaxation (dashed lines); similar behavior is seen for 240°C but is not shown for clarity.

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