Overview of the MAESTRO System

Transcription

1 Overview of the MAESTRO System 1

2 Historical Highlights Early Stages of Development and Fielding Professor Owen Hughes conceived and developed MAESTRO Wrote and published (Wylie/SNAME) textbook Ship Structural Design Began moving MAESTRO into user community Initial Cycle of Distribution, Navies: United States, The Netherlands, The United Kingdom Commercial design organizations Middle Period of Distribution, Navies total of 16 including Canada, Australia, Germany Ship Classification Societies American Bureau of Shipping, Lloyds Register, Bureau Veritas, China Class, Croatian Register of Shipping Commercial User Base expanded to companies University Licenses 20+ universities worldwide Recent Highlights, Continued distribution throughout commercial industry Established links with Professor Jeom Paik and ALPS limit states analyses Expanded to handle larger models, faster, with improved solvers 2

3 What is MAESTRO? Beam Coarse Mesh Full-Ship Detail Full-Ship 3

4 Rationally-based Structural Design design directly and entirely based on structural theory and computer-based methods of structural analysis and optimization to achieve an optimum structure based on a designer-selected measure of merit. A true design process must be capable of accepting an objective, of actively moving towards it, and of achieving it to the fullest extent possible. 4 MAESTRO Academic Conference 2010

5 Main Capabilities MAESTRO is a complete ship structural design system. Global Design Analysis Rapid Structural Modeling Ship-based Loading Finite Element Analysis Structural Failure Evaluation Structural Scantling Optimization Hull Girder Ultimate Strength Natural Frequency Corrosion Local Design Analysis Integrated Coarse Mesh/Fine mesh Analysis 3 rd Party Import/Export Automated Global BCs 3rd Party Data Exchange Hydrodynamic Load Interface Import/Export Nastran Data Geometry Import 5

6 Structural Modeling = Ship hull consists of a series of segments: cargo holds, compartments FEMs are large and complex, and construction should be done in a carefully planned levels and sequences Modules are helpful as they are ideal high-level building blocks 6 MAESTRO Academic Conference 2010

7 The MAESTRO Module Modeling Components Reference/Opposite Ends Section Spacing/Number Endpoints Frames, Girders, & Strakes Stiffener Layout/Spacing 7

8 Ship Hull Girder Properties Basic Ship Structural Properties Hull girder properties, e.g. Inertias, Cross-sectional Area, Neutral Axis, Section Modulus, etc., can be recovered from the model. Longitudinal Effectiveness On/Off 8

9 Ship Based Loading Lightship mass distribution Structural weight Weight distribution Hydrostatic Loads Still water Waves Tank Loads External bending moment and shear force Cargo Masses Forces Moments Accelerations (6 d.o.f.) Pressure Loads Mass/Inertia Based Loads Hydrodynamic Loads 9

10 Ship-based Loading 10

11 Finite Element Analysis Obtain the stresses throughout the model for all defined load cases. 11

12 Structural Failure Evaluation (Limit States) Evaluate the entire ship for all of the different possible failure modes for each load case. Evaluation Types MAESTRO ALPS/ULSAP ALPS/HULL 12

13 Structural Failure Evaluation (Limit States) Limit State Analysis The formulation of MAESTRO s 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 MAESTRO s limit state 13

14 Structural Failure Evaluation (Limit States) Evaluation is automatic - all structural members are evaluated 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 14

15 Structural Failure Evaluation (Limit States) MAESTRO Adequacy Parameters ALPS/ULSAP Adequacy Parameters 15

16 Structural Failure Evaluation (Limit States) Automatic Evaluation Patch (Panel) Generation A patch is a collection of elements with its boundary supported by bulkheads or beams. 16

17 Structural Failure Evaluation (Limit States) Collects plate and beam elements Automatic (or Manual) Evaluation Patch Generation Represents the stiffened panels and correct panel parameters 17

18 Hull Girder Ultimate Strength ALPS/HULL, 2D (available now) ALPS/HULL, 3D (near term implementation) 18

19 Cost Units Optimization Uses sequential linear programing (SLIP2) Optimization eliminates any structural inadequacies While achieving user-specified objectives Least Weight Least Cost Weighted combination Rationally-based Design Process (Optimization) Iterates structure through design cycles to revise scantlings Re-runs the finite element analysis Re-evaluates the structural adequacy of each member for all failure modes and load cases Process continues unit the structure has converged to an optimum design that has no structural inadequacies Cycles SLIP2 is able to solve problems involving a large number of constraints of various types and in which the objective may be any user-specified non-linear function of the design variables. 19 MAESTRO Academic Conference 2010

20 Rationally-based Structural Design 1 CONSTRUCTION OF THE FINITE ELEMENT MODEL 2 SPECIFICATION OF LOADS, LOAD PARAMETERS, AND DESIGN WAVES 3 FINITE ELEMENT ANALYSIS Calculate Load Effect (Q) 4 LIMIT STATE ANALYSIS Calculate Limit Values of Load Effects (Q L ) 6 OPTIMIZATION OBJECTIVE 5 FORMULATE CONSTRAINTS g 1 g 2 g 3 Q Q L DESIGN EVALUATION Constraints satisfied? Objectives achieved? 20

21 Fine Mesh Analysis Fully integrated fine mesh modeling and analysis capability. Ability to import FEMAP/NASTRAN detailed models. 21

22 Fine Mesh Analysis MAESTRO Embedded Analysis Integrated local models into the global model through Rspline elements Solve coarse mesh model and fine mesh models MAESTRO Top-Down Analysis Multiple models in a region (1) solve coarse mesh model, (2) impose coarse mesh model nodal displacements as boundary conditions, (3) solve fine mesh models 3 rd Party Top-Down Analysis Export fine mesh models with boundary conditions 22

23 Natural Frequency Analysis Perform a natural frequency analysis with or without added mass 23

24 Corrosion Corrosion is defined as an additive property to the original structure Associated via a Load Case Net thickness is automatically used in FEA and Limit State Analysis 24

25 3 rd Party Data Exchange Hydrodynamic Code Interface, such as PreCal, Wamit, VERES, Lamp, Mora, etc. 25

26 3 rd Party Data Exchange Import/Export Nastran Data 26

27 MAESTRO Benefits Easy to create, modify, and maintain coarse mesh model Ship based loading Tanks Hydrostatics Hydrodynamic Interface Structural Panel Evaluation Paradigm Integrated & Switchable Structural Criteria Coarse mesh / Fine mesh coexistence 27

28 Contact US DRS Defense Solutions, LLC Advanced Marine Technology Center (AMTC) Stevensville, MD Phone: Fax: Web: 28