Category: Mechanical Measurement

Uncertainty of measurement is the doubt that exists about the result of any measurement. You might think that well-made rulers, clocks, and thermometers should be trustworthy and give the right answers. But for every measurement even the most careful, there is always a margin of doubt. In everyday speech, this might be expressed as ‘give… Continue reading UNCERTAINTIES OF MEASUREMENT

No measurement is exact. When a quantity is measured, the outcome depends on the measuring system, the measurement procedure, the skill of the operator, the environment, and other effects. Even if the quantity were to be measured several times, in the same way and in the same circumstances, a different measured value would in general… Continue reading MEASUREMENT ERRORS

Suppose the angle of twist on the shaft due to application of torque T is θ, which can be directly read by pointer and scale (Figure 18.15). The value of torque applied is directly related to angle of twist as Figure 18.15 Torque Measurement by Pointer and Scale where L is the length of the shaft; J is polar moment of inertia; and G is… Continue reading Torque Measurement by Pointer and Scale

A Prony brake (Figure 18.13) develops mechanical friction on the periphery of a rotating pulley by means of brake blocks that are squeezed against the wheel by tightening the bolts until the friction torque F · R balances the torque W · L.   Torque, T = F × R = W × L Figure 18.13 Prony Brake Dynamometer

A torque is a vector product of force and radial distance that measures the tendency of a force to rotate an object about an axis or centre. A dynamometer is a device for measuring mechanical force, or power, transmitted by a rotating shaft. Since power is the product of torque and angular speed, all power-measuring… Continue reading TORQUE MEASUREMENT

Cantilever beam can be used for measurement up to 10 kg of weight. One end of the cantilever is fixed, while the other end is free; load is applied at this end, as shown in Figure 18.12. Figure 18.12 Cantilever Beam The strain developed at the fixed end is given by the expression: where l = Length of the… Continue reading Cantilever Beam

Load Cell: Force can be measured easily from a load cell. Weigh bridge is one of the most common applications of load cell. Here two strain gauges are fixed so as to measure the longitudinal strain, while two other measuring the transverse strain, as shown in Figure 18.11. The strain gauges, measuring the similar strain (say, tensile) are… Continue reading FORCE MEASUREMENT

There are several methods of measuring strain; the most common is a strain gauge, a device whose electrical resistance varies in proportion to the amount of strain produced in the device. For example, the piezoresistive strain gauge is a semiconductor device whose resistance varies non-linearly with strain produced. The most widely used gauge is the… Continue reading Strain Gauge

The proper design of load carrying components such as shafts, pressure vessels, and support structures for machines requires information about the distribution of forces within the particular component. The experimental analysis of stress is accomplished by measuring the deformation of a part under load and inferring the existing state of stress from the measured deflections.… Continue reading STRAIN MEASUREMENT