General Properties of Titanium Alloys

Titanium, though discovered as an element in 1791, commercially produced titanium has been available only since the 1940s, so it is among the newest of engineering metals. Titanium can be the answer to an engineer’s prayer in some cases. It has an upper service temperature limit of 1200 to 1400°F (650 to 750°C), weighs half as much as steel (0.16 lb/in3 {4429 kg/m3}), and is as strong as a medium-strength steel (135 kpsi {930 MPa} typical). Its Young’s modulus is 16 to 18 Mpsi (110 to 124 GPa), or about 60% that of steel. Its specific strength approaches that of the strongest alloy steels and exceeds that of medium-strength steels by a factor of 2. Its specific stiffness is greater than that of steel, making it as good or better in limiting deflections. It is also nonmagnetic.

General Properties of Cast Iron Alloys

Cast Iron

Cast irons constitute a whole family of materials. Their main advantages are relatively low cost and ease of fabrication. Some are weak in tension compared to steels but, like most cast materials, have high compressive strengths. Their densities are slightly lower than steel at about 0.25 lb/in3 (6920 kg/m3). Most cast irons do not exhibit a linear stress-strain relationship below the elastic limit; they do not obey Hooke’s law. Their modulus of elasticity E is estimated by drawing a line from the origin through a point on the curve at 1/4 the ultimate tensile strength and is in the range of 14–25 Mpsi (97– 172 MPa). Cast iron’s chemical composition differs from steel principally in its higher carbon content, being between 2 and 4.5%. The large amount of carbon, present in some cast irons as graphite, makes some of these alloys easy to pour as a casting liquid and also easy to machine as a solid. The most common means of fabrication is sand casting with subsequent machining operations. Cast irons are not easily welded, however.

Types of Couplings Used in Shafts

Couplings are mechanical elements that ‘couples’ two drive elements which enables motion to be transferred from one element to another. The driven elements are normally shafts. Application of couplings are mainly seen in automobiles, for example the drive shaft which connects the engine and the rear axle in an automobile is connected by means of a universal joint.

In order to transmit torque between two shafts that either tend to lie in the same line or slightly misaligned, a coupling is used. There are various types of coupling available based on the area of application. They are generally categorized in the following varieties

Internal Combustion Engines

Introduction

The internal combustion engines are the engines in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine the expansion of the high temperature and high pressure gases produced by combustion apply direct force to some component of the engine. The force is applied typically to pistons, turbine blades or a nozzle.