Every loading condition on a ship or workboat starts with one question: is the vessel stable enough to sail? The fastest first answer is the transverse metacentric height, GM. This post sets out the hydrostatic fundamentals behind it, shows how free surface in slack tanks erodes it, explains how the inclining experiment fixes the lightship KG, and works through a loading condition for a small cargo vessel. It ends with the first checks against the IMO 2008 Intact Stability Code. It is a screening method, not a substitute for a full stability booklet. It also sits alongside our wider overview of marine engineering and naval architecture . Fundamentals: KB, BM, KM, KG and GM A floating vessel is in equilibrium when weight equals buoyancy and both act along the same vertical line. Buoyancy is the resultant of hydrostatic pressure on the hull, a topic we cover in pressure and fluid statics . When the vessel heels through a small angle, the underwater shape changes, and the centre of buo...
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Ceramics
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Ceramics
It is defined as, "when two metal react with each other to form a compound not solid solution".
Inorganic material (between metallic & non-metallic materials)
Firing or Burnt Stuff ⇉ Desired properties of ceramics are achieved at very high temperature heat treatment process.
Ceramic structure ⇉ more complex structure than metals and has at least 2 elements.
Characteristics of Ceramic Structure
Exhibit combinations of ionic and covalent bond.
Degree of ionic character depend on electronegativity.
Influence on Ceramic Structure
Magnitude of charge on each component (crystal should be neutral).
Relative sizes of cation and anions (cation radii < anion radii i.e. rC/rA < 1).
Coordination Configuration
It is defined as, "Maximum number of neighboring touching center atoms".
Stable Ceramic structure ⇉ form when anions surrounding a cation are in contact.
For a specific coordination number ⇉ critical or min. rC/rA has a constant value.
Computation of Cation-Anion Ratio
Consider Hard-Sphere model.
Size of an ion depend upon coordination number.
Charge on ion will influence its radius.
Types of Ceramic Structure
1. AX Type Crystal Structure
It is defined as, "materials in which there are equal number of cations and anions". Eg: NaCl (FCC), CsCl (BCC).
2. AmXp Type Ceramic Structure
It is defined as, "materials having different number of cations and anions (different charges on atoms)". Eg: CaF2 (FCC).
Defects in Ceramic Structure
Frankel Defect ⇉ Defect involve cation-vacancy or cation-interstitial pair.
Reynolds Number: Reynolds Number is the ratio of Inertial forces to the Viscous forces. By knowing this number, one can describe the flow whether the flow is laminar, turbulent or transitional flow. There are three possibilities of the range of Reynolds Number: If Reynolds number < 2100 or 2300 ⟺ Laminar Flow If Reynolds number > 4000 ⟺ Turbulent Flow If 2300 < Reynolds number < 4000 ⟺ Transitional Flow In case of different shapes other than circle, the formula for Reynolds Number remain the same however diameter involves in the formula become Hydraulic Diameter which is given by: For pipe: Critical Reynolds Number ⟾ The Reynolds number at which the flow becomes turbulent Re cr For different shapes, the hydraulic diameters are given by: Completely Filled Flow In Closed Channel: If pipe is is considered to filled completely with closed channel, then following are the conditions which...
Intersection Of Solids: Solids are obtained by the combination of of two or more basic solids. When two or more solids combine, a definite curve/line is seen at their intersection. This curve/line is called curve/line of intersection (COI / LOI) and it is the result of inter-penetration of solids. Applications Of Intersection Of Solids: Designing a sheet metal objects. Automobile Parts. Moulding patterns. Forged end of connecting road. Intersection of two contacting surface, etc. Inter-Penetration Of Solids: When one solids penetrates another solids then their surfaces intersect and at the junction of intersection a typical curve is formed, which remains common to both solids. This curve is called Curve of Intersection and it is a result of inter-penetration of solids. Cases Of Intersection Of Solids: First we need to discuss the general solution steps of how we draw intersection of solids diagram. So know, we are going to discuss the basic steps:...
Types Of Lines And Its Uses: There are three types of types on the basis of thickness and they are: Visible Lines ↝ It represents features that can be seen in the current view. Hidden Lines ↝ It represents features that cannot be seen in the current view. Center Line ↝ It represents symmetry, path of motion, centers of circles,, axis of asymmetrical parts. Dimension and Extension Lines ↝ It indicates the sizes and location of features on a drawing. Placement Of Dimension Lines: Dimension should be outside the view. Dimension should be applied to one view. Dimension should be placed in a view that shows the distance in its true length. Dimension lines should be placed, in general 10 mm (1/2 in) away from the outlines from the view. Parallel lines should be placed uniformly. Values should be midway (auto centered) between the arrow heads, except when a center-line interferes. Dime...
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