Measuring "Impact Load" in Ft-Lbs of a Resistance Welded Joint

The unit is foot-pounds. That makes it a *torque*. The "pounds" means "force which one pound of mass exerts downwards when in Earth's gravity". The SI (Systeme International) unit of torque is the "Nm" (Newton metre). A torque is a "twist". Like what you apply to a spanner. A torque wrench might be calibrated in foot-pounds.

There is no way a foot-pound have a physically different interpretation which makes it an impact, is there? You could drop one pound through

10feet onto the thing, or 10pounds through one foot of height and that would physically make sense. That would make "impact" into "impact energy". But where would you specify the mfalling mass to strike? Never heard of this, though. I'm a scientist trying to use my imagination here.

With twist. If you had your component with just one of these spot welds and had it vertical - if you hung 10lbs of mass horizontally one foot from the weld that would give you 10ft-lbs. Or 5lbs 2ft from the weld would also be 10ft-lbs.

Hope this helpful.

Richard S.

The Merc wrote:

Refer to ASTM E23 to learn about "impact testing" which is (in the US) reported in ft.lbs. of energy absorbed (Joules in SI units) at a specified temperature.

Not sure how this would be applied to the case at hand, but I did want to clear up that ft.lbs can be measuring impact.

Hmmm-*work* has units of foot-pounds, and that's not torque. Ever solve any kinematics problems using the principle of work and energy?

interpretation

through

Torque is measured in ft/lbs and represents force, not work. Work over time can be expressed in watts or horsepower. If memory serves, one horsepower equals 33,000 ft/lbs moved one foot (or about 750 watts) over one minute's time.

While the term "work" includes torque in the equation, when someone talks about "ft/lbs." without a component of time they're talking about torque.

Peter