Modeling & Analysis Approach

8/2/2019 Modeling & Analysis Approach

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www.maestromarine.com

Overview of the MAESTRO Modeling

and Analysis Approach

1 MAESTRO 2010


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www.maestromarine.comMAESTRO 20102

What is MAESTRO?

Beam Coarse Mesh Full-Ship Detail Full-Ship


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MAESTRO Approach

I. Model Organization

II. Importing Geometry

III. Creating Modules

IV. Loading the Model

V. Balancing the Model

VI. Solving the ModelVII. Structural Analysis/Evaluation


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Model Organization

Individual modules are joined tocreate the complete model


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Model Organization

Module Definitions

Reference/Opposite Ends Section Spacing/Number

Endpoints

Strakes

Stiffener Layout/Spacing


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Model Organization

Stiffened Plate Element

Geometric orthotropic formulation Retain critical information for limit

state analysis

Easy to change stiffener layout

Ideal for design space exploration

(optimization)


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Model Organization

Rapid Modeling/Modification

Most elements are associated with sections and lie onrailroad tracks (endpoints)

Elements are automatically updated when adding,deleting, and modifying sections



MAESTRO Approach









Importing Geometry

Import *.DXF, *.IDF, or *.GF files

Import strategic locations, such as module

reference and opposite end curves

MAESTRO construction geometry



MAESTRO Approach









Creating Modules

Endpoints

X, Y, Z

Cartesian and Cylindrical

Reference and Opposite



Creating Modules

Strakes General

Plating

Frames

Girders

Stiffeners Deletions



Creating Modules

Additional nodes

Springs

Rods

Additional Beams

Triangles

Additional Quads

RSplines

Compounds

Stiffener layout

Materials

Properties

Delete

Quick Creation



Creating Modules

Basic Ship Structural Properties Hull girder properties, e.g.

Inertias, Cross-sectional Area,Neutral Axis, Section Modulus,etc., can be recovered from themodel.

Longitudinal Effectiveness On/Off


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MAESTRO Approach








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Loading the Model

Lightship mass distribution Structural weight

Weight distribution

Hydrostatic Loads Still water

Waves

Tank Loads

Cargo Masses Forces

Moments

Accelerations (6 d.o.f.) Pressure Loads

Boundary Conditions


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Loading the Model

Self weight

Scaled StructuralWeight Per Section

Per Module

Whole Ship

WeightDistribution

Individual Masses


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Loading the Model

Hydrostatic loads

Stillwater or Waves Sinusoidal or Trochoidal

Wavelength

Amplitude

Phase

Trim and Heel


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Loading the Model

Tank Loads Specified Density

Percent Filled

Specified Mass

Specified Head

Tank Table


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Loading the Model

Cargo Masses

Masses distributed evenly among nodes or plate elements

Engines

Sonar

Deck Loads


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Loading the Model

Accelerations Translational and Rotational Acceleration (With/Without Gravity)

About Center of Gravity

About Center of Flotation

About Arbitrary Point

This provides the inertial loads for all masses (lightship and cargo)


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Loading the Model

Pressure Loads

Pressures can be constant or varying across panels

Pressures resulting from a liquid load can be imposed

(e.g. surface head due to green water, or prescribed

pressure on a bulkhead)


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Loading the Model

Hydrodynamic Loading


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Loading the Model

Boundary Conditions Restraints

Normal, 6 d.o.f. rigid body

motion

Automatic centerplane (half

models) for symmetric or

asymmetric loads

Other BCs (External Loads)

Vertical/Horizontal BM and

Shear Force

Torsional Moment


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MAESTRO Approach








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Balancing the Model

Balance Results


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MAESTRO Approach








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Solving the Model

Solvers Sparse

Iterative

Skyline

Beam Theory Eccentric Beam

Hybrid Beam

Failure Mode Evaluation MAESTRO

ULSAP Fine Mesh Models


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MAESTRO Approach








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Structural Analysis/Evaluation

Bare Plate Beam

Stiffened Panel Rod

Axial Stress

Element Stress Results


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Stresses are reported in the GUI; results can be queried and echoed to the output window

Stress results can also be exported to Excel, a text file, or the grid


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The structural response analysisprovides stress and displacement

results for the entire vessel


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Ability to align stress vectors in a uniformdirection when recovering stress in a given axis


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Limit State Analysis The formulation of MAESTROs limit states is covered in Ship Structural Analysis and

Design and Ultimate Limit State Design of Steel-Plated Structures

These constitute the theoretical manual for MAESTROs limit state


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1CONSTRUCTION OF THEFINITE ELEMENT MODEL

FINITE ELEMENT ANALYSISCalculate Load Effect (Q)

LIMIT STATE ANALYSISCalculate Limit Values of

Load Effects (QL)

OPTIMIZATION OBJECTIVE

DESIGN EVALUATIONConstraints satisfied?Objectives achieved?

2

3

4

5

6

SPECIFICATION OF LOADS,LOAD PARAMETERS,AND DESIGN WAVES

FORMULATE CONSTRAINTSg1 g2 g3 Q QL


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RESPONSE ANALYSIS

Q

LIMIT ANALYSIS

Q L

Partial SafetyFactors

g1 g2 g3= g


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Evaluation of the limit states is based upon the strength ratio:

g QQ

L

= r

where g = g1 g2 g3 (Partial Safety Factors)

The strength ratio can vary from zero to infinity, which is not useful

for driving optimization, so we use an adequacy parameter


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The adequacy parameter, g:

1 - r

1 + r=

g

This parameter varies from -1 to +1. Zero indicates that the structure,

under the defined loads, is optimum for that particular limit state.Negative values indicate that the structures response, with the user

defined safety factors, exceeds the limit state.


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Evaluation is automatic - all structural members areevaluated to the factors of safety chosen by the user

Different factors of safety can be specified for all

collapse limit states and for all serviceability limit

states, or specified on a limit state-by-limit state basis. In addition to the strakes, frames, and girders which

receive full evaluation... Additional panels, triangles, and additional beams receive limited evaluation

Struts and pillars are evaluated for Euler buckling

Evaluation Patches


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MAESTRO Adequacy Parameters ALPS/ULSAP Adequacy Parameters


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Automatic Evaluation Patch (Panel) Generation

A patch is a collection of elements with its boundary supported by

bulkheads or beams.


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Collects plate and beam elements

Automatic (or Manual) Evaluation Patch Generation

Represents the stiffened panels and correct panel parameters

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The entire structure can be

viewed at one time

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or only those memberswho have failed can be

shown (negative adequacy)

l l / l


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Individual members can be queried to

determine their specific adequacy

parameter results. This information

can be echoed to the output window.

Modeling & Analysis Approach

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