Hi Nancy,
Youngs Modulus is another name for Modulus of Elasticity [E], named so after
the first discoverer of the elastic behavior graphed in a stress-strain
diagram.
For non-creeping metals E is a unique constant; however, because the
creep-behavior of solder at the Ts we are using it it does not have a unique
stress-strain diagram or a constant E--they are T- and strain-rate-dependent
and you therefore have an infinite number of such diagrams/Es.
A crosshead is the moving [upper] clamp of a tensile test machine and its
rate of travel applying strain to the test specimen is referred to as
crosshead speed--it determines the strain rate.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 386-437-8747, Fax: 386-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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