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Research Needs in Ship Structures

Research Needs in Ship Structures. Matthew Collette University of Michigan mdcoll@umich.edu msdl.engin.umich.edu November 18 th , 2011. Improved Lifecycle Forecasting. Design stage Better metrics linked to actual costs and failures

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Research Needs in Ship Structures

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  1. Research Needs in Ship Structures Matthew Collette University of Michigan mdcoll@umich.edu msdl.engin.umich.edu November 18th, 2011

  2. Improved Lifecycle Forecasting • Design stage • Better metrics linked to actual costs and failures • Complement existing, effective, but safety-oriented acceptance criteria (allowable stress, LRFD, etc.) • Design beyond the rules • What to do with voyage monitoring data? • What if it is “worse” than assumed? – updated safety margin • How to use the (potentially terabytes) of data to make more money or improve performance? • Warning signs that if you build it, they may not come….. • Life extension programs • What does reaching safe-life fatigue limit mean? • What to do with increasing risk profile? How to justify vs. new construction?

  3. Simplified Methods for Damaged Structures • Rapid ultimate strength tools today almost always based/similar to Smith method (ULTSTR etc.) • Assumed intact transverse frames that will force buckling of longitudinal panels only • After damage (collision, grounding, explosion) frames often compromised • Non-linear FEA • How to support design optimization or casualty response? • Better toolset needed – ULTSTR(D) U.S.S. Radford – photo from SSC Case Study IV www.shipstructure.org

  4. Aluminum Structures • New material topology • HAZ – welds – local material inhomogeneity and tensile tearing • Alloy-dependent properties • Fracture criteria and fracture arrest • New material challenges • Sensitization of 5xxx alloys in mill and in service • 5xxx extrusions? • 6xxx corrosion limits? • Better toolset needed “…the aluminium extrusions had fractured along the weld lines and that there was a lack of plastic deformation (…) the structure appeared to have failed along the welds rather than deforming in a controlled manner‟” The Right Honourable Lord Cullen, Ladbroke Grove accident report, excerpt by Dr. Kotsikos, NewRail, Newcastle University

  5. Optimization, Verification, and Decision Making • Better multi-objective optimizers • Early design stage trade between weight, performance, cost, durability etc. • Need to be fast and robust • Visualize and communicate trade space • Validate – beyond software V&V • Procedure – we now often link different codes and standards • Are code assumptions compatible ? • Essential always ad-hoc ?

  6. People ~ Personal Sense • Universities world-wide – hard to find marine structures specialists to teach, research • Compared to hydrodynamics, far fewer PhD students in most programs in US and Europe • Experts for industrial applications • Next generation of professors • Growing need for SSC and T&R to elevate profile and excite young people to work on these challenges

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