Hertzian Contact Stress

Unusually high stresses may occur when a load is applied over a small area of contact. This phenomenon typically arises on a microscopic scale when a force is transmitted through two bodies in contact. Practical examples include contact of a wheel and a rail, valve...

Powder Metallurgy

Powder metallurgy (PM) is a relatively new manufacturing method, although there is some evidence it was practiced by ancient civilisations such as the Egyptians and the Incas. The technique, as we know it today, developed in the late nineteenth and early twentieth...

Drilling

Drilling is a very common operation used for making holes in a material. The tool used is called a drill or drill bit. The drill bit is made to rotate and moves into the material to form a hole. These tools can have high length to diameter ratios, thus allowing deep...

Introduction to Machining Operations

Traditional machining operations, such as drilling and milling, have involved the use of sharp cutting tools to form a piece of material into a desired shape. With time, other machining operations, referred to as non-traditional, have been developed. These no longer...

Resistor Combination

Resistors may be used to represent various electrical components used in practice. One such example is a light bulb that behaves like a resistor. It is therefore important to understand how current and voltages vary when resistors are in series or in parallel....

Stress Transformations

The stress in a body is defined as the force acting per unit area. In practice, due to the presence of multiple forces and the body geometry, stress values vary throughout the body and may lead to areas of stress concentrations. But we will show that even on a single...

Stress Concentration (Stress Riser)

In real world designs, parts are rarely simple in geometry and this may lead to areas of stress concentrations. They are also sometimes known as stress risers and can occur whenever there are abrupt changes in geometry or due to the presence of cracks in a material....

Abbe’s Principle of Alignment

The Abbe’s principle of alignment is named after the German Professor Earnst Abbe. In 1890, he proposed a set of rules for taking linear measurements.   His principle consists of the following 3 points :   1. For best results, a linear reading should...

Airy Points and Bessel Points

When simply supported at finite number of points, a beam will bend under its own weight. The shape it takes depends on the spacing between the supports and the cross-sectional and micro-structural uniformity of the beam. Airy Points Sir George Biddell Airy  showed...