Abstract

The use of advanced numerical simulations in the mechanical characterization of a new design of modular barge system allows to optimize both development process and final design. The case study presented herein illustrates how non-linear analyses on a detailed Finite Element Model of a Modular Barge System allowed to simplify its design and certification processes in comparison with a more traditional and conservative analytical approach or in comparison with an iterative and costly approach relying on extensive physical tests. Detailed Finite Element Analyses (FEA) allowed to efficiently size the structure of the module, identifying the limiting elements. Finite Element discretization allows to virtually assess effect of any loading on the whole design, taking into account the local effect of particular features; with more precision than if a less discretized and more analytical approach is taken. Welded connections have been identified as critical within the modular unit; detailed FEA allowed to represent precisely the geometry of each joint and study the impact of specific aspects such as weld bead penetration. Finite element representation could then be correlated on smaller scales tests, more accessible and more efficient. Connections between independent modular units have been identified as critical and potentially affecting the capacity of the system. Global to local detailed modeling allowed to design and assess the strength of an innovative connection system, easily useable on-site. The use of non-linear analysis allows to take into account the progressive application of loading and non-linear effects such as the evolution of stiffness matrix and material properties. Precise Stress distribution generated by non-linear analysis allows an efficient mass saving by pinpointing areas where mass is not used efficiently. In this case, buckling of main structural elements have been identified as limiting the capacity of a single unit. Detailed non-linear analyses allowed to simulate the behaviour of the unit and showed its collapsing due to buckling at the critical load level. Based on the detailed model of a single unit, multiple units assemblies in different configurations were analyzed to document the maximum resistant shear load and the maximum resistant moment sustainable by each connection configuration and each unit. Numerical Modelling can also save time and money as it can surrogate to a physical prototype within the establishment and acceptance of load rating of the design by standards regulators. The rating established allows the use of the modular units in future designs of barges without extensive structural investigations. The detailed non-linear analyses showing the collapsing behaviour of the connection at a critical load level and establishing the capacity of the system has been accepted by Lloyd’s Register in lieu of physical testing. Finite Element Modelling reduced the need for mechanical testing and prototyping, allowing multiple iterations to be carried out numerically; and thus, saved a great amount of time in the design process. Moreover, it allowed the rating of the system without the full-scale test. Equivalent physical testing would have required important resources in terms of both time and material, due to the size of the units and the load levels to be generated. The implications of such physical testing might have compromised the feasibility of the overall design process. This paper illustrates the use of advanced finite element analysis in the load rating of a new modular barge system design. Different design steps showcasing the use of advance non-linear analyses are presented. It emphasizes on how the advanced analyses allowed to reduce time and budget dedicated to development process and how the final design is optimized by this approach.