Optimisation of composite boat hulls using first principles and design rules

The design process is becoming increasingly complex with designers balancing societal, environmental and political issues. Composite materials are attractive to designers due to excellent strength to weight ratio, low corrosion and ability to be tailored to the application. One problem with composite materials can be the low stiffness that they exhibit and as such for many applications they are stiffened. These stiffened structures create a complex engineering problem by which they must be designed to have the lowest cost and mass and yet withstand loads. This paper therefore examines the way in which rapid assessment of stiffened boat structures can be performed for the concept design stage. Navier grillage method is combined with genetic algorithms to produce panels optimised for mass and cost. These models are constrained using design rules, in this case ISO 12215 and Lloyd's Register Rules for Special Service Craft. The results show a method that produces a reasonable stiffened structure rapidly that could be used in advanced concept design or early detailed design to reduce design time

Race-time prediction for the Va’a paralympic sprint canoe

The 2016 Paralympic Games in Rio de Janeiro will see 200m sprint canoe events for the first time, using the Va’a class. The aim of this study is to predict race times for the Va’a over a 200m sprint event, through simulation of the hydrodynamic resistance of the hull (with outrigger) and the propulsion provided by the athlete. Such a simulation, once suitably validated, allows investigation of design and configuration changes on predicted race performance. The accuracy of the simulation is discussed through a comparison to times recorded for an athlete over a 200m race distanc

Implementation of a generic concurrent engineering environment framework for boatbuilding

Boatbuilding is a growth market with global competition and tight profit margins. Concurrent engineering is not presently prevalent within the boatbuilding industry and yet this is a technique that has found much success in other industries. A methodology has, therefore, been developed to aid design in the leisure boatbuilding industry. This environment uses collaborative engineering and automated communication to aid the passing of direct communication between all members of the design team. This paper determines the characteristics of importance within boatbuilding and relates these to a framework concurrent engineering environment aimed specifically at this industry. The current work focuses on the structural and production subsystems in an attempt to improve design for production. The use of concurrent engineering tools has been highlighted with an example

US Office of Naval Research, Solid Mechanics Program Review

The purpose of this extended abstract is to provide an overview of activities relating to performance assessments. The work described is wide ranging and not intended to provide a detailed account of any particular approach

A rapid method for reliability analysis of composite tophat stiffened structures using a first principles method and design rules

Composite materials are increasingly being used within engineering, especially in low weight applications. A significant drawback that these materials exhibit is their variability. There is a growing trend towards stochastic analysis of marine structures and this is even more important for scenarios that have a high variability. To implement these new techniques it is important to be able to, rapidly and accurately, determine reliability during the design phase. Therefore, a reliability analysis, utilising a rapid implementation, has been performed on plates that have been designed using two different sets of design rules and a first principles method. The results show that whilst, under the limits investigated, the reliability of the design rules are slightly safer than those found using first principles; the sensitivity analysis shows that each of the design rules generates a different reaction from each variable, encouraging different types of structures through their idiosyncrasies. Furthermore the method shown allows a rapid analysis to be performed on complex composite structures in a relatively short time frame using either first principles methods or design rules

Towards passive station holding of autonomous underwater vehicles inspired by fish behaviour in unsteady flows

Some species of fish are able to alter their mode of swimming to interact with naturally produced vortices; the use of these gaits reduces the energy expended by the fish. To analyse the feasibility of autonomous underwater vehicles (AUV) replicating these gaits, a series of experiments are performed with unpowered rigid and flexible bodies positioned in the Kármán wake of a rigid cylinder. Simple motion capture techniques are used to capture the bodies’ lateral and upstream motion in the flow. The results demonstrate that manufactured bodies are capable of passively mimicking fish behaviours, to a limited extent. More importantly, it was concluded that while significant upstream movement was possible for a manufactured object, it was achievable irrespective of the stiffness of the material. For AUVs operating in unsteady flow regimes an ability to utilise energy saving gaits may improve the range or operational time

Investigation into skin stiffener debonding of top-hat stiffened composite structures

Top-hat stiffened plates provide an efficient structure for engineering applications. During service debonding between the stiffener and the plate is often observed and parametric studies of open section stiffeners have shown that debond size and location have a significant effect on the damage mode of the panel. However, these studies do not consider the interaction of failure modes and do not assess the ultimate failure of the structure. In this paper top-hat stiffened composite structures are assessed considering debond damage between the stiffener and plate. A non-linear finite element model is used to perform a parametric study on the effect of both damage and the panel’s geometry on the failure modes, ultimate strength and its damage tolerance. Results show that top-hat stiffened panels exhibit a trend between ultimate strength and the debond size with crack initiation not necessarily propagating. Geometric imperfections accelerate buckling but can provide an arrest point for crack propagation

Optimisation of composite boat hulls using first principles and design rules

The design process is becoming increasingly complex with designers balancing societal, environmental and political issues. Composite materials are attractive to designers due to excellent strength to weight ratio, low corrosion and ability to be tailored to the application. One problem with composite materials can be the low stiffness that they exhibit and as such for many applications they are stiffened. These stiffened structures create a complex engineering problem by which they must be designed to have the lowest cost and mass and yet withstand loads. This paper therefore examines the way in which rapid assessment of stiffened boat structures can be performed for the concept design stage. Navier grillage method is combined with genetic algorithms to produce panels optimised for mass and cost. These models are constrained using design rules, in this case ISO 12215 and Lloyd's Register Rules for Special Service Craft. The results show a method that produces a reasonable stiffened structure rapidly that could be used in advanced concept design or early detailed design to reduce design time