A numerical and experimental analysis on the mechanical behavior of bolted joints between pultruded profiles and T-Stubs of glass fiber reinforced polymer

2010 - 2011In the last decades, FRP composites have been widely used for constructing entire civil structures. One of the challenging issues for building with pultruded FRP composites is understanding the behavior of bolted joints. In this paper, the results of a numerical analysis performed on different types of bolted composite joints with different geometry and subjected to tensile loads are reported. The aim of this study is to examine the distribution of shear stresses among the different bolts by varying the number of rows of bolts as well as the number of bolts per row. The study also considers the presence of variable diameter washers and their influence on the bearing stresses of composites with different fibre orientations. For verification of the validity of the analytical models, numerical results are compared to experimental results reported elsewhere. The results of this study showed that in multi-bolt joints, the load is not distributed equally due to varying bolt position, bolt-hole clearance, bolt-torque or tightening of the bolt, friction between member plates and at washer-plate interface. The results also indicated that in the presence of washers, the stress distributions in the fibre direction, varying fibre inclinations, are decreasing for each value of washer pressure [edited by author]X n.s

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist

Stress analysis of multi-bolted joints for FRP pultruded composite structures

In the last decades, FRP composites have been widely used for constructing entire civil structures. One of the challenging issues for building with pultruded FRP composites is understanding the behaviour of bolted joints. In this paper, the results of a numerical analysis performed on different types of bolted composite joints with different geometry and subjected to tensile loads are reported. The aim of this study is to examine the distribution of shear stresses among the different bolts by varying the number of rows of bolts as well as the number of bolts per row. The study also considers the presence of variable diameter washers and their influence on the bearing stresses of composites with different fibre orientations. For verification of the validity of the analytical models, numerical results are compared to experimental results reported elsewhere. The results of this study showed that in multi-bolt joints, the load is not distributed equally due to varying bolt position, bolt-hole clearance, bolt-torque or tightening of the bolt, friction between member plates and at washer-plate interface. The results also indicated that in the presence of washers, the stress distributions in the fibre direction, varying fibre inclinations, are decreasing for each value of washer pressure

INFLUENZA DELLA PRESSIONE ESERCITATA DA RONDELLERIGIDE SULLA ROTTURA PER RIFOLLAMENTO DICONNESSIONI BULLONATE TRA LAMINATI COMPOSITIFIBRORINFORZATI: PRIMI RISULTATI SPERIMENTALI

Questo lavoro ha per oggetto un’indagine sperimentale sull’influenza della pressione esercitata da rondelle rigide sulla rottura di unioni bullonate tra laminati compositi fibrorinforzati. In particolare, sono presentati i primi risultati ottenuti da prove su laminati unidirezionali in fibra di vetro al variare dell’angolo di fibratura per un prefissato valore del diametro della rondella. L’indagine sperimentale ha evidenziato come la modalità di rottura del laminato e la sua resistenza siano fortemente influenzati dalla azione esercitata dalle rondelle

Development of a regenerative braking control strategy for hybridized solar vehicle

This paper focuses on the development of a braking control strategy that allows the best tradeoff between mechanical and regenerative braking on a hybridized vehicle. The research work is part of a project for the development of an automotive hybridization kit aimed at converting conventional cars into Through The Road hybrid solar vehicles. The main aspect of the project is the integration of state-of-the-art components (i.e. in-wheel motors, photovoltaic panels, batteries) with the development of an optimal controller for power management. A mild parallel hybrid structure is obtained by substituting/integrating the rear wheels with in-wheel motors and adding photovoltaic panels and a lithium-ion battery. A hybridizing equipment prototype, patented by the University of Salerno, is installed on a FIAT Grande Punto. A model useful for real-time braking control has been developed, starting from vehicle longitudinal model and considering dynamic weight distribution in front and rear axles and related wheel slipping effects. Different braking strategies have then been investigated, in order to maximize the benefits of regenerative braking

3D finite element non linear analysis on the stress state at bone-implant interface in dental osteointegrated implants

Purposes. The aim of the study was to assess by means a 3D finite element linear and non-linear analysis mechanical interaction between an implant-supported crown and surrounding tissues. Materials and methods. A three-dimensional FEM model was developed. Four different material combinations for the abutment and the core were evaluated: Y-TZP - Y-TZP, Y-TZP - microhybrid composite, T - microhybrid composite; T and Y-TZP. 250 N and 450 N loads over a 0,5 mm2 areas with different angles (0° and 45°) and locations were applied on the occlusal surface of the framework and the distribution of equivalent von Mises stress was investigated. Using the most critical scenario, the influence of the gradual failure of the cement layer, due to increasing load, on the bone –implant interface, were investigated. Results. The worst physiological loading condition was the one associated with a horizontal component (45°, 250 N). The 0°, 450 N load (relating to accidental or pathological condition) induced stress concentrations in the cortical bone comparable with those obtained for the tilted load, but with a greater extension to the cancellous bone. Y-TZP prosthetic elements determined minimum values of stress, due to vertical loads at the interface, while the microhybrid composite ones determined minimum stresses due to horizontal loads. Conclusion. Different material combinations for the abutment and the core influenced weakly the stress state at bone-implant interface, with a dependency closely related to the loading mode. The implant – prostheses system stress distribution depended on material choice. Furthermore progressive 45° loads with the gradual failure of the cement layer did not influence Von Mises stresses at bone-implant-interface