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Automated Stress Separation Along Stress Trajectories
No full textA procedure for the separation of principal stresses in automated photoelasticity is presented. It is based on the integration of indefinite equations of equilibrium along stress trajectories, also known as Lamè-Maxwell equations. A new algorithm for precise and reliable stress trajectory calculation, which is an essential feature of the procedure, has also been developed. Automated stress separation is carried out along stress trajectories starting from free boundaries. Experimental tests were performed on a disc in diametral compression and on a ring with internally applied pressure. Full-field principal stress values were obtained and results were compared with those from the theory of elasticity and with those obtained from the classical shear difference method. It was shown that the proposed method is more accurate and less affected by the presence of residual stresses or experimental errors at the boundaries than the shear difference method. In addition, the method requires little human interaction and is therefore well-suited for automated photoelasticity
Lineamenti idrogeologici, qualità finalizzata e rischio di inquinamento delle risorse idriche della Comunità Collinare del Friuli
No full textThree-dimensional strain analysis of single-lap bolted joints in thick composites using fibre-optic gauges and the finite-element method
Get PDFBolted joints involving composite plates used to be almost entirely dedicated to aerospace applications. As the need for energy conservation has increased, the field of composite bolted joints has found new applications in ground armoured vehicles. Thick panels able to withstand large in-plane and impact loads are critical. The present investigation evaluates the interior strain field, through the thickness, of a composite plate connected to an aluminium panel with a single-lap bolted joint. The area of interest is the bearing plane region close to the hole because of the presence of stress concentrations that heavily modify the stress field. Experimental data for the bolted joint were recorded by fibre-optic strain gauges that were embedded in the bearing plane of the composite plate. Numerical analyses were performed using ANSYS as a pre-processor and LS-DYNA as a solver. The overall goal was to evaluate the magnitude of contact strains around the hole and through the thickness of the composite. These values were analysed and compared with the finite-element method results: the finite-element analysis correlated reasonably well with the experiments. An investigation of error causes was also carried out, in particular to evaluate the influence of incorrect gauge positioning and the effect of friction coefficients. General design considerations were finally provided, based on the complete three-dimensional finite-element analysis
Alkali-silica potentially reactive minerals in Lazio and Campania alluvial deposits (Italy).
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
GIUNZIONI BULLONATE FRA COMPOSITO E ALLUMINIO: STUDIO DEL GIOCO MEDIANTE FIBRE OTTICHE INGLOBATE NELLO SPESSORE
No full textLe giunzioni bullonate di elementi in composito sono state da sempre utilizzate per applicazioni impegnative. Sono stati annegati estensimetri a fibra ottica nello spessore di un pannello in composito in prossimità della superficie di contatto piastra-bullone in un giunto ibrido composito-alluminio. Sono state eseguite diverse prove di trazione su provini single-lap joint con differenti valori del gioco tra bullone e foro. Le prove consentono di determinare una relazione fra il gioco tra bullone e foro e i valori delle deformazioni misurate dagli estensimetri a fibra ottica. Risulta che ad un incremento dei valori del gioco corrisponde un incremento dei valori di deformazione in prossimità del foro con conseguente riduzione di efficacia della giunzione stessa
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