Dr. M. E. Barkey
Structural Durability and Fatigue Performance Group
at The University of Alabama

Strength Testing of Welded and Weld-Bonded Joints

Sponsor:  DaimlerChrysler, Auburn Hills, MI
Technical Manager:  Dr. Yung-Li Lee
Stress Lab and Durability Development


Contents     Barkey-Home page   Contact M. E. Barkey

Weld Strength page last updated 7 February 2005



Strength Test Project Description

A C-Channel Test (video)

Cross-Tension Test

Personnel



Strength Test Project Description

The ultimate load carrying capacity of spot welded joints depends on many factors including the
spot weld nugget diameter, sheet thickness, and base material properties.  Commonly, standard
tensile shear specimens made of flat plates joined with a single spot weld are used to evaluate the
strength of the joint.  However, these specimens are fairly flexible, and are usually only used in
tensile loading modes to avoid buckling.  Actual spot welded structures tend to behave differently
than these standard specimens, due the constraint of the nearby welds and structure.

The project with DaimlerChrysler will investigate the following:
 

-effect of two welds on the strength of the joint
-the use of C-channel specimens to induce more realistic structural stiffness
-the effects of various nugget sizes, spacings between welds, and edge distances of the spot welds
-the effect of spot welds alone versus spot welds and adhesives
-the effect of sheet thickness,
-and the effect different materials on the joint performance.
The testing will be done based on a fully developed DOE matrix, and an analytical model will
be developed to describe these behaviors.



A C-Channel Test

Specimens made with C-Channels do not exhibit the large amount of spot weld nugget rotation
often seen in standard tensile shear tests.  Click on the link below for a video of a strength test
of the joint.

video:  C-Channel Test

This joint failed at about 7000 lbs of force.  A single spot weld, standard tensile shear specimen
welded under the same nominal conditions failed at about 2500 lbs of force.
 
 


Thanks to:
 

Tim Connell (AEM Technician)
Joe and Ken  (COE Machine Shop)
 

Steven Zhang (PhD-ESM student)
        Steven thesis will be based on the work he does for this project.

Guoqing Wang (PhD-ESM student)
        Guoqing has helped make some trial welded samples.