LO2 Structures Flashcards
What is the role of a classification society?
To provide classification, statutory certification and services acting on behalf of a flag state.
What is ductility?
The ability of a material to deform easily upon the application of a tensile force.
What is notch toughness?
materials that have a greater ability to resist cracking (incorporated into the strake).
What is material hardness?
The ability of a material to resist surface abrasion.
What is tensile stress?
The stress state on a material that leads to expansion.
What are the advantages to mild steel?
-Relatively cheap.
-Easily cut, shaped and worked cold.
-Easily welded and riveted.
What are the disadvantages to mild steel?
High rate of corrosion.
What is meant by alloy steel?
A steel that is alloyed with a variety of elements to improve its mechanical properties.
What are the advantages of high tensile steel?
-Saving structural weight.
-Saving in weld material.
-The possibility to build larger prefabrication units.
What are the disadvantages of high tensile steel?
-Smaller allowable amount of wastage by corrosion.
-Increased bending.
-Greater cared required when welding.
-Increase in vibration.
Why is aluminium suitable for prismatic free standing tanks
thin material thickness allows for a greater tank volume.
What are the advantages of using aluminium for ship construction?
-Weight saving.
-Stability (lowers G).
-Resistance to corrosion.
-Non-magnetic property.
-Notch toughness at low temperatures.
What are the disadvantages of using aluminium for ship construction?
-Higher cost.
-Low melting point.
-Galvanic corrosion.
-Vibration
What are the advantages of using stainless steel for ship construction?
-Higher strengths.
-Maintains bright appearance.
-Corrosion resistant qualities.
What are the disadvantages of using stainless steel for ship construction?
-Weld decay.
-Pitting corrosion.
-Unable to be used below the waterline.
What is stress?
The ability of a material to transmit a load.
What is strain?
The proportional deformation produced in a material under the influence of stress.
What is elastic strain?
-Appears in material when strain is applied.
-(Is reversable)
What is Young’s model (E)?
The ratio between the stress applied and the strain it produces.
What is the yield point?
The point in which a material will experience plastic strain.
What is proof stress?
Stress that is sufficient to produce under load.
What tests can be carried out to sample steel to deem it suitable for ship construction?
-Ultra sonic test.
-V notch test.
-Creep test.
What is creep?
The continuing deformation of a material with the passage of time when the material is subjected to constant stress.
What is fatigue?
Where a crack is initiated and progresses as a result of repeated stresses.
