Mohrs Circle and Strain Gauge Rosette Lab Report

Mohrs Circle and Strain Gauge Rosette - Lab Report Example An aluminium alloy beam, clamped at one end within a rig containing a cam whose full-range rotation leads to a repeatable tip deflection of = 0.5" = 12.7 mm, as shown in Figure1. The beam has dimensions as follows: breadth b = 25.4 mm, depth d = 6.35 mm and length (to the cam) L = 254 mm. Three strain gauges are mounted on the upper surface at 94 mm from the clamped end; these gauges are mounted at 15, 45, and 75 with respect to the longitudinal, x-axis, of the beam, as shown in Figure 2. Each of these gauges can be selected using a switchboard, to be one arm of a Wheatstone bridge arrangement [1 research and give reference ], with a dummy strain gauge providing temperature compensation. The Wheatstone bridge is a divided bridge circuit used to measure electrical resistance; these minute changes in resistance correspond to strain in a strain gage in what is known as a bonded resistance strain gage [2] From a), determine the principal strains I and II, as well as the direction of maximum shear strain. Also, determine the value of Poisson's ratio, , for the material. In this experiment I should theoretically be equal and in the direction of x. Inevitably there will be experimental errors so your result may be different. In the discussion section (6.), discuss possible reasons why the maximum strain obtained may not be predicted to occur in the x-direction,