Optimisation of large complex structures in an early design stage considering accidental loads
‘Designers create and Engineers analyse’ (Erichsen (1989)). This separation is still valid for most of today’s design and analysis tasks carried out for ship and offshore structures as the structural design, i.e. dimensioning of the structural components and their analysis, is today mostly conducted independently from other disciplines on the basis of an agreed conceptual design. Thus, necessary analyses are performed after the global design parameters are defined and analysis models are derived from this conceptual design. This approach is known as ‘engineering analysis’. In engineering analysis the basic components of a conceptual design analysed individually may be altered, but the influence of these alterations on other aspects is in most cases not assessed, because such analyses are complex and costly. This hinders the identification of true optima, because modifications are always based on the preceding, but not necessarily best, alternative. A better alternative is to identify the optimal design based on safety and operational objectives, whereby the final design depends on the requirements of each discipline leading to a new and currently unknown design. This holistic approach called ‘engineering design’ requires efficient analysis techniques in all involved disciplines for the fast and repetitive assessment of changes and to identify further optimisation potential. However, OPTICS cannot cover all disciplines and concentrates on the development of an efficient analysis method for the structural design. This is a considerable contribution on the path to engineering design. In addition OPTICS takes into account accidental loads. If a marine structure is subjected to service and/or accidental loads that are higher than the loads the structure was designed for, it may fail and the consequences can be severe. Failure reaches from small fractures within and/or on the outer hull of the structure up to breaking the entire structure into parts. Consequently, we must prevent such failure by design and thus account for possible accidental loads and responses already during the conceptual design stage with direct load and response calculations. Therefore, this project seeks to develop an efficient modelling and analysis approach suitable for the optimisation of large complex structures (OPTICS) in an early design stage considering also accidental loads.