Suppose the bimetallic strip in Prob. 8.3 is used to indicate temperatures of 150, 200, and 300?F. The tip of the strip is connected to an appropriate mechanism, which amplifies the deflection so that it may be read accurately. The uncertainty in the length of the strip is ±0.01 in, and the uncertainty in the thickness of each material is ±0.0002 in. The perpendicular deflection from the 100?F position is taken as an indication of the temperature. Calculate the uncertainty in each of the above temperatures, assuming zero uncertainty in all the material properties; that is, calculate the uncertainty in the deflection at each of these temperatures.

Prob. 8.3

The bimetallic strip material of Example 8.1 is to be used in an on-off-temperature-control device, which will operate at a nominal temperature of 200?F. Calculate the deflection at the end of a 4-in strip for deviations of ±1 and 2?F from the nominal temperature.

Example 8.1

A bimetallic strip is constructed of strips of yellow brass and Invar bonded together at 30?C. Each has a thickness of 0.3 mm. Calculate the radius of curvature when a 6.0-cm strip is subjected to a temperature of 100?C.