As stated earlier a bearing of a line is the angle made by the line with respect to a reference direction, the reference direction being known as meridian. The direction shown by a freely suspended and properly balanced magnetic needle is called magnetic meridian and the horizontal angle made by a line with This meridian…
The stress-strain relation of any material is obtained by conducting tension test in the laboratories on standard specimen. Different materials behave differently and their behaviour in tension and in compression differ slightly. Behaviour in Tension Mild steel. Figure 8.8 shows a typical tensile test specimen of mild steel. Its ends are gripped into universal testing…
In this chapter general meaning of stress is explained. Expressions for stresses and strains is derived with the following assumptions: 1. For the range of forces applied the material is elastic i.e. it can regain its original shape and size, if the applied force is removed. 2. Material is homogeneous i.e. every particle of the…
Resistance to various applied forces is referred as mechanical properties. Some of these properties are briefly presented below: 1. Properties related to axial loading: For designing structural elements to resist the applied loads, the following strength properties should be known: (a) Tensile strength: If an element is subjected to pulling forces, the resistance developed per unit area…
The principle materials used in building structures and machines include metals and their alloys, concrete, wood, stones, bricks and other clay products, bituminous materials and plastics. The products finally produced with these materials should be strong enough to resist the forces coming on it without undergoing deformation so as to put it out of use….
A simple machine is a device with the help of which heavy loads are lifted by applying small effects in a convenient direction. Pulley used to lift water from a well and screw jacks used to lift motor car are some of the common examples of simple machines. In this chapter some of the terms…
The transmission of power by means of belt or rope drives is possible because of friction which exists between the wheels and the belt. Similarly, band brakes stops the rotating discs because of friction between the belt and the disc. All along the contact surface the frictional resistance develops. Hence, the tension in the rope…
Angle of Friction Consider the block shown in Fig. 5.2 subject to pull P. Let F be the frictional force developed and N the normal reaction. Thus, at contact surface, the reactions are F and N. They can be combined to get the resultant reaction R which acts at angle θ to normal reaction. This…
When a body moves or tends to move over another body, a force opposing the motion develops at the contact surfaces. The force which opposes the movement or the tendency of movement is called the frictional force or simply friction. So far, in earlier chapters, we had ignored this force and considered contacting surfaces are…
For simple figures, moment of inertia can be obtained by writing the general expression for an element and then carrying out integration so as to cover the entire area. This procedure is illustrated with the following three cases: (1) Moment of inertia of a rectangle about the centroidal axis (2) Moment of inertia of a…