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Engineering Systems Concepts
Published in Graeme Dandy, David Walker, Trevor Daniell, Robert Warner, Planning and Design of Engineering Systems, 2018
Graeme Dandy, David Walker, Trevor Daniell, Robert Warner
Nevertheless, some system coefficients may be found to change slowly in time, not in response to the applied inputs but because the system itself is gradually changing. For example, some engineering materials change their properties in time. The modulus of elasticity of concrete increases slowly with time, because of complex chemical changes that occur in the material. This is an important coefficient in the modelling of concrete structures. Progressive changes in system coefficients can occur if there is deterioration, as for example when there is corrosion of steel, abrasive removal of layers of material in a pipe, or scouring and erosion of the bed of a stream. If one or more of the system coefficients vary significantly in time, then it may be advisable to restructure the model of the system, treating the varying quantities not as coefficients but as system variables. This is the case when stream erosion is so severe that a stream bed moves progressively over time, thus changing the geometry of the system. When this occurs it becomes necessary to move on from a fixed bed model to a movable bed model to deal with erosion.
Abrasive Blasting and Heavy Metal Contamination
Published in Ole Øystein Knudsen, Amy Forsgren, Corrosion Control Through Organic Coatings, 2017
Ole Øystein Knudsen, Amy Forsgren
Iron (or steel) can stabilize lead in paint debris so that the rate at which it leaches out into water is greatly reduced. Generally, 5%– 10% (by weight) of iron or steel abrasive added to a nonferrous abrasive is believed to be sufficient to stabilize most pulverized lead paints [2].
Reciprocating Sliding Wear Behavior of 60NiTi As Compared to 440C Steel under Lubricated and Unlubricated Conditions
Published in Tribology Transactions, 2018
Khashayar Khanlari, Maziar Ramezani, Piaras Kelly, Peng Cao, Thomas Neitzert
Some morphologies of the unlubricated worn surfaces are provided in Figs. 3a–3d. As can be seen, abrasive wear was the main wear mechanism for 440 C steel. In 440 C steel, abrasive wear was governed by plastic deformation resulting in ploughing grooves under both low and high loads (Figs. 3b, 3d, and 3f). Different from the steel, grooves on the worn surfaces of 60NiTi did not show much ploughing and plastic deformation (Figs. 3a, 3c, and 3e). As seen in Fig. 4, the wear surface in 60NiTi consisted of a series of parallel grooves, scratch marks, and fine wear debris, which is also characteristic of abrasive wear (Zhang and Farhat (28)) but on a different (higher wear rate) scale than for the 440 C specimens. The wear for 60NiTi appears to be abrasive wear, which is possibly enhanced by adhesion between the WC ball and the 60NiTi, as will be discussed in more detail later.