Viscosity of Bituminous Materials Viscosity and Rheology of Binders The viscosity of a liquid is the property that retards flow, so when a force is applied to a liquid, the higher the viscosity, the slower will be its movement. The viscosity of bitumen is dependent upon both its chemical make-up and its structure. In sol-type […]
Atomic Structure of Elements Atoms, the building block of elements, consist of a nucleus surrounded by a cloud of orbiting electrons. The nucleus consists of positively charged protons and neutral neutrons, and so has a net positive charge that holds the negatively charged electrons, which revolve around it, in position by an electrostatic attraction. The
Air System of Diesel Engine Fuel, by itself, is of no use whatsoever: it needs oxygen from the air outside in order to burn. At the most basic level, this happens of its own accord: as the piston falls during the induction stroke, air rushes in past the open inlet valve to fill the expanding
Diesel Engine Working Diesel engines don’t have souls or wills of their own, but depend on a sequence of simple processes. The most fundamental of all those processes takes place deep inside the engine. It’s the one that gives internal combustion engines their name, because it involves burning air and fuel inside a confined space.
Fuel Supply System in Diesel Engine Diesel fuel doesn’t burn very easily, and in order to burn quickly, cleanly and reliably it has to be in the form of fine droplets, like an aerosol spray. You’ll remember from the previous chapter that the air in a diesel’s cylinders is made hot by being compressed to
Design is the process of choosing the geometric shape, materials, manufacturing method, and other details needed to completely describe a machine, vehicle, structure, or other engineered item. This process involves a wide range of activities and objectives. It is first necessary to assure that the item is capable of performing its intended function. For example,
Bending and Torsion Tests Various bending and torsion tests are widely used for evaluating the elastic modulus, strength, shear modulus, shear strength, and other properties of materials. These tests differ in a critical way from tension and compression tests, in that the stresses and strains are not uniform over the cross section of the test
Notch Impact Test Notch-impact tests provide information on the resistance of a material to sudden fracture where a sharp stress raiser or flaw is present. In addition to providing information not available from any other simple mechanical test, these tests are quick and inexpensive, so they are frequently employed. Notch Impact Test In various standard
Hardness Testing Methods In engineering, hardness is most commonly defined as the resistance of a material to indentation. Indentation is the pressing of a hard round ball or point against the material sample with a known force so that a depression is made. The depression, or indentation, results from plastic deformation beneath the indenter, as
Some materials have dramatically different behavior in compression than in tension, and in some cases these materials are used primarily to resist compressive stresses. Examples include concrete and building stone. Data from compression tests are therefore often needed for engineering applications. Compression tests have many similarities to tension tests in the manner of conducting the