Owen F Hughes

Professor Emeritus

Research Expertise

Ocean Engineering

Professional History

1988-present, Professor of Ocean Structures, Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University; 1979-1988, Professor of Ocean Structures, 1973-1979, Senior Lecturer, 1963-1973, Lecturer, Naval Architecture, University of New South Wales, Australia.

Awards and Honors

2004 Dean's Award for Excellence in Teaching

Professional Leadership

AOE Ocean Engineering Committee, AOE Promotion and Tenure Committee, Virginia Tech. Member, Royal Institute of Naval Architects. Member, Society of Naval Architects and Marine Engineers. 1983 NavSea Research Professor, US Naval Academy. Past Chairman of SNAME Panel HS-4 "Design Procedures and Philosophy" and of the ISSC Committee on Computer-Aided Design. Currently a member of the ISSC Committee on Structural Design of High Speed Vessels.

Research Interests

Computer-based Structural Design of High Performance Ships

The AOE Department is the home of the computer program MAESTRO (Method for Analysis, Evaluation and STRuctural Optimization). Developed by Prof. Hughes, MAESTRO performs first-principles structural design of innovative and high performance vehicles such as high speed ferries, multihull ships and warships. MAESTRO is used by 13 navies, by various structural safety authorities, and by over 80 structural designers and shipyards in Europe, North America, Asia, and Australia. It is also a valuable research tool, and it is the basis for three ONR-sponsored research projects to develop improved naval ships of the future. The overall objective is to produce structural design methods and algorithms for advanced naval ships that can achieve significant savings and advantageous tradeoffs in the conflicting attributes of structural weight, safety, and survivability. The following is a brief description of the three projects.

Generalize the "strake-based" strategy of structural optimization to transverse structure and the structure of multi-hull ships.

As shown in Figure 1, MAESTRO's basic unit of structural optimization is a "strake", which consists of a lengthwise row of stiffened panels, a lengthwise girder along either edge, and the transverse frame segments between the panels. The figure also shows the 14 design variables that are optimized in each strake. In the first project this same concept will be applied to transverse structure, the aim being to develop a design optimization method for "transverse strakes", as shown in Figure 2.

Develop Algorithms for Modeling, Buckling Analysis, and Optimal Stiffening and Sizing of Blast-Resistant Panels So That They Also Carry Operational Loads.

ONR-sponsored research has developed sandwich panels with metal "textile" (or micro-truss) cores that have excellent resistance to air blast loads. For weight savings it is crucial that such panels should also be able to carry the same operational loads as ordinary panels. Because of their micro-truss structure, the static properties of these panels' stiffness, Poisson's ratio, yield strength, and buckling modes and strengths are different from ordinary stiffened panels. These differences will influence the 3-D load paths in the ship. If these blast-resistant panels are to be used in an efficient dual-role manner, they must be included in the early-stage, coarse mesh, whole-ship MAESTRO model, in order to learn what operational loads they carry and to make sure that these loads do not cause yielding or buckling. This gives rise to three sub-tasks:

1. Develop Coarse Mesh Finite Elements for Micro-truss Sandwich Panels
Initially we will seek to adapt and extend the multi-layer elements in MAESTRO that are presently used for modeling composite panels and sandwich panels. If adaptation/extension is not possible we will develop an entirely new element.

2. Develop Algorithms For In-Plane Buckling Modes And Strengths
The algorithms must be able to deal with: (a) non-linear buckling due to simultaneous yielding, (b) a 3-D pattern of loads, (c) interaction between buckling modes, and (d) possible external stiffening. We will seek to develop these algorithms by using a combination of nonlinear orthotropic plate theory and existing buckling strength algorithms for stiffened panels and for layered and sandwich panels.

3. Develop a Method for Determining Optimal
Stiffening and Sizing of Dual-Role Panels Both the blast performance and the buckling strength are strongly influenced by the length and width of the panels. It is better for both cost and weight if the panels can be large. Ideally they should at least be as large as the spacing of the transverse frames and longitudinal girders of the ship. However, with such sizes external stiffening becomes crucial for buckling strength. In this task we will use Neural Network theory, the panel buckling algorithms, and the "rubber ship" capability of MAESTRO to develop the method and to explore the very strong tradeoffs in cost and weight, while maintaining the key dual capabilities of providing blast protection and carrying operational loads.

Develop A Buckling Failure Algorithm for Cross-Stiffened Panels

Ship structure often has large cross-stiffened panels, including several heavy beams in both directions (besides the plate stiffeners). Depending on the beam proportions and the loads, this overall panel may buckle before the smaller panels. At present this is avoided by making the beams very heavy. There is currently no accurate and yet practical method for calculating the buckling load of a cross-stiffened panel. Unless an algorithm is developed, structural optimization can lead to an inadequate safety margin for this buckling mode. We intend to develop this algorithm using a combination of plastic-hinge theory and beam-column buckling analysis.