Transport notes

University of Virginia **We aren't endorsed by this school
Jun 21, 2023
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Effects on engineering innovation in transport on society As transport increased in capacity and efficiency, vast changes were made to the performance of commerce, trade, social and cultural perceptions and practices, and to war. The internal combustion engine gradually replaced the horse as the preferred means of transport and roads improved as increasingly heavier cars began to be driven at higher speeds. Urban transport systems are essential to economic activity and to the quality of life in cities. Help reduce social exclusion and support local commerce. But, brought congestion, pollution and land use issues to the financing of public transport. Improvements are trying to be made by: o Cleaner vehicle technologies o Road toll and collection technologies o Encouraging people to shift from cars to public transport or non-motorised transport Environmental effects of transport systems Cars: Air pollution: Cars emit nitrogen oxides, sulphur dioxide, carbon dioxide and monoxide as exhaust resulting in poor air quality. Landscaping: Construction of roads, freeways and tunnels influence the shape of cities and landscapes. Trains Railway construction: Tree feeling and the blasting of rock are involved in making tunnels and subways. Air pollution: Steam trains had a high pollution rate due to a 5-10% efficiency. Electric trains cause pollution to be produced in power stations Yet trains still have a smaller impact than cars as it can move much more people at a time with less road space required. Bicycles This is the solution to environmental problems, such as pollution and the greenhouse effect. Efficient travel methods Non-polluting Human power is a renewable energy source Environmental implications from the use of materials in Transport Vehicle production - producing vehicles releases a significant amount of pollutants. To stop this, changes need to be made such as: o Review of painting and coating practices o Elimination of heavy metals and other damaging substances o Design of vehicles for recyclability and maximum use of recycled materials Rubber tyres - tyre wear produces particles which end up in air and water sources. These particles contain a complex mixture of compounds, including metals, alkanes, aromatic hydrocarbons, benzothiazoles, long chain fatty acids and triterpanes. Air particles have long been implicated in increased asthma and respiratory problems. Semiconductors - this can produce fossil fuels and chemical consumption when in production. It also produces waste treatment and disposal problems. Copper, in particular generates a large amount of waste.
Forests - have been greatly affected by large scale transport developments. The uses of timber resulted in the clearing of large areas of forests. This removal has impacted on native fauna by reducing their habitat. Steel - has been the main transport material since 1856. The thirst for steel has seen the establishment of large steelworks, which often affect the local atmosphere with the large amount of pollutants produced in working and refining steel. Cast Iron - has had a similar impact to steel but is used to a lower extent today. Essentially similar metallurgically to the iron from the blast furnace, it still requires vast amounts of iron-ore and coal and coke. Aluminium - has increased in use. It is refined from an ore, bauxite, which is mined in an open cut manner, also affecting the local atmosphere and environment. Polymer - its usage has exploded since WWII, because polymers offer lightweight transport machinery which improves fuel efficiency. To protect the environment, the extensive use of polymers must be backed up by the recycling of old equipment, as polymers greatly contribute to landfill. Engineering materials Hardness Tests - Refers to the resistance of a material to scratching or abrasion. It also refers to resistance to indentation, penetration or cutting. Brinell Tests - Use a hardened steel or tungsten carbide ball to produce indentation on materials such as castings and forgings. Rockwell Tests - Measures the depth of impression from a specific indentor. Testing is fast and reliable on metals, alloys, small precision parts, wires and plastics. Vickers Tests - Use variable loads and a diamond pyramid indentor, enabling the use of one scale to test a range of materials. Used for testing small precision parts, thin materials, wires, coatings. Determines depth of case hardening. Knoop Tests - Explore microhardness by making one long and one short diagonal with a pyramidal diamond indentor. Scleroscope tests - Rebound tests that measure losses in kinetic energy from a falling diamond-tipped metal 'tup' Leeb hardness test - Rebound test used for on-site hardness testing due to its portability Durometer Hardness Test - Undertake on polymers and involves the pressing of an indentor into the surface of the test piece. Impact Tests Izod impact test or the Charpy impact test are common for metals In these tests a test piece of standardised dimensions is obtained from the material to be evaluated and a notch machined into the surface to a 'V' or 'U' profile. The sample is subsequently fractured by impact with a pendulum and the swing height the pendulum attains following the sample fracture is used as a measure of the energy absorbed. Hardness testing in vehicle components Used extensively to evaluate the effectiveness of various heat treatment processes. Application for case hardening involve engine crankshafts, cams and camshafts.
Hardness testing is used to ensure uniform and correct surface hardness in these situations where wear resistance is imperative to vehicle performance. o The depth of the 'case' needs to be assessed. - Destructive examination - Can be determined by examining a test piece that has been case hardened Tyre hardness is a critical factor is vehicle efficiency and performance. o Soft tyres wear faster than harder tyres but the latter sacrifice traction for longevity. o A durometer is used to measure hardness and readings of 1-100 are utilised with 100 being the hardest. Pencil hardness tests are used for testing lacquers or coatings applied to vehicles. o Pencils of harness are drawn across the test surface at a fixed angle and pressure, coatings are examined for their scratch resistance. Barcol hardness measures the penetration resistance of soft materials such as rigid plastics using a sharp, pointed, flat-tipped indentor. Can also be used to determine the degree of cure of thermosetting materials. o Conical indentors are used for elastomers or soft plastic materials such as plasticised PVC. Frictional Force - the force that acts in the opposite direction to the body's direction of motion; F =mg Static friction - an object that is either not moving, or at the point of moving (μ s ). Coefficient of friction - the dimensionless ratio of the frictional force (F f ) and the normal force (N) pressing two bodies together; μ = F f / N. Normal force - the force that acts perpendicular to the surface on which the object is resting (N). Angle of static friction - an object positioned on a flat surface generates a normal reaction that is equal and opposite to its weight. Angle of repose - the angle of the inclined plane at which the object begins to slide down without any external force acting on it. We can determine whether an object will slide; μ = tanØ Ø = tan -1 μ. Work, Energy and Power Work Work occurs when a force causes motion. If no work/deformation occurs, then no work is done. The formula for work is: Work (W) = Force (F) x Displacement of the Object (s)
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