Analysis of bonded joints for small craft and marine applications

This Thesis investigates the possibility of replacing, in small craft and recreative boats, some of the more traditionally made joints (using tabbing) with ones made using structural adhesives (adhesive used where the load applied may cause the separation of the adherends [2]), which have the potential to be quicker to produce and have good fatigue resistance. It also focuses on methods that are available to a small and medium size boatbuilding or boat design company in order to design and produce a general safe, light weight adhesive joint. Several static tests were conducted in order to identify the characteristics of the materials to be joined and the properties of the adhesives investigated. A summary of the analytical theories available in order to determine the characteristics of the joints are presented and compared, and several finite element models have been investigated in order to determine the suitability of this method when using adhesive materials. This Thesis focuses first on Single-Lap joints, not only as a joint, but also as a way to compare the characteristics of the adhesives to be used. Three types of adhesives have been tested, two commercially available (Plexus MA550 and Sikaflex 252) and one commonly found on boatbuilding yards, a mixture of vinyl ester and Epiglass HT120 (a silica based filler). It was found that the Plexus MA550 adhesive performed well across different substrates (aluminium and composites) followed closely in performance by the vinyl ester/filler mixture. Very promising results were obtained when a carrier fabric was used inside the adhesive layer. Secondly, a very common type of joint, the T-joint, has been anti - symmetrically tested. A comparison has been made between a more traditionally produced joint (using a small fillet made from vinyl ester and microballoons based filler and EU-glass tabbing) with a joint produced using a fillet made from the above adhesives. It was found that the results from samples with the fillet using the vinyl ester/filler mixture are the closest to the benchmark samples and it seems to be the best candidate to replace the traditional joint, given the strength, failure mode, price and the availability. The joint using a Sikaflex 252 fillet has shown the most interesting results such that none of the materials forming the joint suffered any visible damage after deformation. The joint using a R20mm Plexus MA550 fillet has benefited from the stiffness and the good adhesion characteristics of the adhesive but in all the tests the panels joined ware damaged earlier than for the benchmark samples

Optimum Repartition of Transport Capacities in the Logistic System using Dynamic Programming

Transportations take an essential role in logistics, interconnecting the majority of processes and operations within logistic system. The efficient use of transportation capacity is a priority whose achievement can diminish logistic costs. This objective is today difficult to achieve due to increasing complexity of transportation monitoring and coordination. This complexity is determined by transportation number and diversity, by the volume and diversity of orders, by increasing the targets to be supplied.Dynamic programming represents a highly useful tool for logistic managers, considering that its specific techniques and methods are oriented toward solving problems related to resource optimum allocation and utilization.The present paper presents briefly a series of theoretical elements of dynamic programming applied in logistics, based on which it is shown a mathematic model to determine the optimum policy for transport capacity repartition for the area attached to a logistic centre, through three distribution centres

Optimum Repartition of Transport Capacities in the Logistic System using Dynamic Programming

Transportations take an essential role in logistics, interconnecting the majority of processes and operations within logistic system. The efficient use of transportation capacity is a priority whose achievement can diminish logistic costs. This objective is today difficult to achieve due to increasing complexity of transportation monitoring and coordination. This complexity is determined by transportation number and diversity, by the volume and diversity of orders, by increasing the targets to be supplied. Dynamic programming represents a highly useful tool for logistic managers, considering that its specific techniques and methods are oriented toward solving problems related to resource optimum allocation and utilization. The present paper presents briefly a series of theoretical elements of dynamic programming applied in logistics, based on which it is shown a mathematic model to determine the optimum policy for transport capacity repartition for the area attached to a logistic centre, through three distribution centres.distribution centre; logistics; number of customers; stage; dynamic programming.