Failure of resistance spot welds | Fracture of solids | PEM Fuel cell | Bio-medical engineering | Structure joints
Research in Professor Chao¡¦s Group
Resistance Spot Welds (RSW):
RSW is the
primary joining method for thin metal sheets and has been used
in all passenger vehicles since mid-20 century. It is
however the weakest link under fatigue and crash conditions.
Working with steel and auto industries, we study the fabrication
issue, fatigue life, and crash strength (i.e. strain rate
effect) of the RSW made of many grades of steels, e.g.
mild steel, AHSS (Advanced High Strength Steels).
Investigations have focused on (1) failure mode, e.g. pullout vs
interfacial failure, (2) prediction of static failure strength,
(3) prediction of dynamic failure strength, (4) how to implement
the test data into finite element numerical simulation, and (5)
prediction of fatigue life of RSW.
¡§Ultimate Strength and Failure Mechanisms of Resistance Spot
Weld Subjected to Tensile, Shear and Combined Tensile/Shear
Loads,¡¨ ASME Journal of Engineering Materials and Technology,
pp.125-132, vol. 125, 2003.
Chao, Y.J., ¡§Failure
of Spot Welds: Interfacial versus Pullout,¡¨ Science and
Technology of Welding and Joining, 133-137, 8(2), 2003.
Miller, K. W., Chao, Y.J., Martinez, A.,
Zhu, X., Liu, S. and Wang, P.C., ¡§Quasi-static and Impact
Strength of Fatigue Damaged Spot Welds,¡¨ in Welding and
Joining, SP-1766, Editor: J. Pan, SAE paper
2003-01-0610, paper presented at the SAE 2003 World Congress &
Exhibition, March 3-6, 2003, Detroit, MI, USA.
.K. W. Miller, Y .J.
Chao, and P. C. Wang, ¡§A Comparison of Testing Techniques for
Spot Weld Strength,¡¨ Proceedings of the Sheet Metal Welding
Conference IX, paper 1-6, American Welding Society, Detroit,
Michigan, October 18-20, 2000.
Miller, K, W., Chao, Y.J., and Wang, P.C., ¡§Strength of spot
welded joints pairs as determined by layout,¡¨ Society of
Automotive Engineering Paper #2000-01-2676, 2000 International
Body Engineering Conference and Exposition, Cobo Center,
Detroit, Michigan, October 2-5, 2000.