Marine Structures Design

The MSDL is a growing group of faculty and students focused on developing the next generation of structural design and analysis tools for the marine industry.

Our work includes: the creation of rapid and accurate strength methods for lightweight aluminum marine structures, building unique evolutionary optimization approaches for rapid trade-space exploration of structural design options and configurations, as well developing novel tools to allow in service re-assessment of structures and updatable lifecycle cost, reliability, and capability forecasts. We combine modern numerical analysis techniques, stochastic and probabilistic methods, with an exclusive focus on the marine domain. Our deep understanding of the marine industry and the marine design problem allows us to develop innovative advances in technology that are compatible with the needs of naval architects working in the most challenging areas of ship and ocean structure design and maintenance.

Our newest paper has been published in Marine Structures!

Mark Groden, Matt Collette, Fusing fleet in-service measurements using Bayesian networks, Marine Structures, Volume 54, July 2017, Pages 38-49, ISSN 0951-8339, http://doi.org/10.1016/j.marstruc.2017.03.001.

Correctly estimating future failures in aging ship structures is a significant challenge. This manuscript explores a model updating approach based on fusing different visually observable physical records of structural degradation: permanent set of plating and fatigue crack initiation. A probabilistic S-N fatigue model is coupled to a permanent set model via a Bayesian network. Observations of permanent set and fatigue cracks are entered as evidence into this network. Through Bayesian inference, the network updates underlying loading and fatigue capacity models. These updated models are then used to forecast future failures. The proposed model is tested against Monte Carlo simulated service history data on five vessels from a larger fleet. The fusion of permanent set and fatigue together produces a more accurate estimate of future failures than using either failure mode alone. The benefit of fusing multiple visually observable measurements to update underlying structural models to provide fleet-wide prognosis appears promising, with further improvements possible with additional refinement.

Free version of paper until May 24, 2017 

We'll see you in Lisbon at MARSTRUCT 2017, presenting

Experimental testing of under matched aluminum welds in tension
C. Wincott, R. Wiwel, K. Zhang, J. McCormick & M. Collette 

The tensile response of undermatched welds in aluminum marine structures has not been subjected to extensive exploration. In this work, the in-plane response of a common shell-to-frame fillet weld connection is studied experimentally. The test program featured 5086 and 6061 alloys. Extensive material characterization was first carried out, including tensile tests at 0, 45, and 90 degrees to the rolling or extruding direction of the alloy, cross-weld hardness profiles and heat-affected zone (HAZ) characterization. 18 specimens were tested varying weld size and alloy, with three replicates of each connection. The results indicate that the weld type and size has a significant impact on the strength of the connection, and that welds in the 6000-series alloys are severely impact-ed. Implications of these findings on hull-girder level ultimate strength calculations and finite element models are also discussed.