Basic Statements 12 Flashcards
Cargo carrying ships are designed with optimum transport work as the main design goal
True
The classification rulebooks are summaries/descriptions of ships that have survived i.e. design solutions are based primarily on experience and trial and error.
True
“Effective breadth” is one way to weight optimize a stiffened panel structure
False - Carrying effective load
The main objective with transverse bulkheads is to maintain the shape of the hull girder.
True
The design of the hull girder is normally driven by shear force.
False - Driven by bending moments
The section modulus of the hull girder determines its longitudinal strength
True
The objective with secondary strength elements (stiffeners, beams, longitudinals) is to maintain the shape of the hull girder on the local level.
False
Double bottom structures are preferred because they can carry more load compared to single bottom structures.
False - To prevent pollution, if an accident occurs
Thick plate thickness inside structures is needed to maintain reasonable shear stresses
True
Classification societies always give real load cases in the rulebooks
False - General/typical load cases
Important strength criteria to consider in ship design are buckling, yielding and brittle fracture but NOT fatigue
False - Fatigue is an important factor
Stiffeners can be used to prevent plate areas from distorting under the influence of shearing loads
True
Design loads for trading ships are similar to FPSOs (Float Production Storage and Offloading)
False - they are not similar
Structural collapse followed by sinking constitutes approximately one fourth of all ship losses
True
Four types of limit states are relevant: SLS, ULS, FLS and ALS
True - SLS = Serviceability limit state ULS = Ultimate limit state FLS = Fatigue limit state ALS = Accidental limit state
Age-related degradation of material and structure properties does not affect the limit states
False
A stiffened panel may collapse in six different types of modes
True
Initial imperfection such as welding-induced residual stresses or sideways initial distortion of stiffeners do not affect ULS
False
Numerical methods such as the nonlinear FEM give always the true answers to an ULS analysis.
False - Due to mathematical errors, discretization errors and other typical computational errors.
Mesh density in a FE model has negligible influence on the ULS
False
Reliability-based design and uncertainty analysis are important tools in safety-based analysis using ULS models
True
There are international standards how to calculate ULS for ships and offshore structures
False - There are no standards yet
There exists clear modeling guidelines how to carry out an ULS analysis by means of FE analysis
False - There are no guidelines yet
