Search results for "Stresses"
showing 10 items of 55 documents
IL METODO DI PROVA “AIAS - TR” PER LA MISURA DELLE TENSIONI RESIDUE COSTANTI O VARIABILI CON LA TECNICA DEL FORO INCREMENTALE
2010
Viene presentata una sintesi dell’attività svolta dal Gruppo di lavoro AIAS “Tensioni Residue” nel periodo dal 2006 al 2009. Lo scopo dell’attività è stata l’elaborazione del metodo AIAS - TR 01 per la misura delle tensioni residue con il metodo del foro incrementale. La normativa tecnica esistente sull’argomento (ASTM E 837-08) [1] ha un campo di applicabilità ristretto; infatti essa non considera alcuni effetti che possono influenzare l’accuratezza della misura. Il metodo di prova (AIAS - TR 01) fornisce una visione d’insieme del metodo della rosetta forata, aggiornata all’attuale stato dell’arte (2009) sia a livello tecnologico che a livello teorico. Le principali innovazioni riguardano …
ERROR AND UNCERTAINTY ANALYSIS OF THE RESIDUAL STRESSES COMPUTED BY USING THE HOLE DRILLING METHOD
2011
The hole-drilling method is one of the most used techniques for the experimental analysis of the residual stresses in mechanical components. For both through-thickness uniform and non-uniform residual stresses, its practical application is standardised by the ASTM E837-08. For uniform residual stresses, to which the present work deals with, the use of the method in accordance with the ASTM limitations, leads to results with a bias of about 10%. Unfortunately, although some experimental parameters can be frequently out of the corresponding standard limitation, the user does not have appropriate procedures to correct the obtained results which, in accordance with the ASTM standard, have to be…
CFRP STRUCTURAL CAPACITORS: EFFECT OF DAMAGE AND MECHANICAL LOAD ON CAPACITANCE
2013
Aim of this work is to study the effect of mechanical load and damages, on the performance of structural capacitors, made by CFRP composite laminates with a PET dielectric film (treated with sodium hydroxide) inserted at the laminate middle-plane. Such capacitors have been characterized by ILSS and tensile tests and the properties so estimated were compared to those of the simple CFRP. By measuring the capacitance before mechanical loading, under loading and after unloading, it has been observed that, due to the damage of the CFRP layers, proved also by proper fractographic analysis, at high strain level the capacitance decreases although it exhibits a complete recovery after unloading. Suc…
Photovoltaic performance of amorphous silicon flexible solar modules under mechanical loading
2007
The applications of photovoltaic devices can be significantly expanded by directly integrating them into structures. Solar cells integrated into structures can help to power a variety of devices such as structural monitoring sensors and unmanned aerial vehicles (UAVs). However, little work has been reported in the literature on the performance of solar cells under deformation. Thus, a thorough investigation on the photovoltaic behavior of solar modules under mechanical loading is necessary in order to provide the optimal integration conditions for practical applications. The photovoltaic performance of commercially available amorphous silicon solar modules was tested under applied mechanica…
Il delitto di "caporalato" tra diritti minimi della persona e tutela del mercato del lavoro
2020
Il contributo analizza il reato di intermediazione illecita e sfruttamento lavorativo, offrendo un’analisi comparata con il sistema repressivo tedesco. Lo studio si sofferma, in particolare, sui limiti di legittimazione del diritto penale nella punizione dei fatti di “caporalato”, nel tentativo di scongiurare che l’intervento repressivo nelle dinamiche economiche e contrattuali, di natura sinallagmatica, possa assumere una portata tale da porsi in contrasto con il canone della sussidiarietà. A tal fine, si suggerisce una prospettiva ermeneutica che incentri il disvalore penale del reato di cui all’art. 603-bis c.p. sulla lesione dei diritti fondamentali del lavoratore – riconducibili agli a…
UN APPROCCIO BASATO SULLA MODELLAZIONE 3D E IL LIFE CYCLE ASSESSMENT PER UNA GESTIONE SOSTENIBILE DELLA MANUTENZIONE STRADALE
2021
Among several goals of the road agencies, one of the most relevant is the maintenance and rehabilitation of the road pavement. The growth of traffic, the longstanding lack of funding and, sometimes, an emergency-based planning of intervention, are common drivers leading to low level of pavement conditions in terms of ride quality and safety. In addition both cost and environmental concerns due to monitoring stage are relevant issues within the management system of local and urban road network, especially. With the purpose of implementing sustainability in the road pavement management, this paper provides an approach based on coupled low- cost 3D image modelling distress identification and L…
Non solo Platone. Il primato dell'oralità nel retore Alcidamante
2020
Il saggio è dedicato all’orazione Sugli autori dei discorsi scritti o sui sofisti, attribuita al retore Alcidamante, discepolo di Gorgia e attivo in Atene tra il 410 e il 365 a.C. Argomento dell’orazione è il serrato confronto tra due differenti modalità oratorie, l’autoschediazein (“parlare a braccio”) — cui Alcidamente accorda una netta superiorità — e il "gegrammena legein (“pronunciare discorsi scritti”). L’interesse di questo testo (databile con buona approssimazione intorno al 390 a. C) consiste essenzialmente nel rappresentare un punto di vista specificamente retorico sulla questione delle differenze tra scritto e parlato. Nonostante alcune significative convergenze con il ben più ce…
Photoelastic stress analysis assisted evaluation of fracture toughness in hydrothermally aged epoxies
2014
The present work has investigated the fracture toughness of a model DGEBA epoxy system subject to Hidro-Thermal aging. A Photoelastic Stress Analysis technique has been implemented, showing the evolution of stresses arising throughout the water uptake process due to the non-uniform swelling of the material. Gravimetric and Dynamic Mechanical Thermal Analyses have further complemented the characterization, showing the onset of plasticization effects with aging. The correlation of all previous characterizations has allowed to conclude that an increase of KIC fracture toughness is obtained at the fully saturated condition. In particular Photoelasticity has also revealed the onset of relevant s…
A second strain gradient elasticity theory with second velocity gradient inertia – Part I: Constitutive equations and quasi-static behavior
2013
Abstract A multi-cell homogenization procedure with four geometrically different groups of cell elements (respectively for the bulk, the boundary surface, the edge lines and the corner points of a body) is envisioned, which is able not only to extract the effective constitutive properties of a material, but also to assess the “surface effects” produced by the boundary surface on the near bulk material. Applied to an unbounded material in combination with the thermodynamics energy balance principles, this procedure leads to an equivalent continuum constitutively characterized by (ordinary, double and triple) generalized stresses and momenta. Also, applying this procedure to a (finite) body s…
On the mechanisms involved in the tensile strength of a dissimilar Ti6Al4V/316L laser welded assembly
2021
International audience; The aim of the present work is to analyze the thermomechanical behavior of dissimilar laser seams by means of FE modeling. The case of a Ti6Al4V/316L assembly with vanadium insert was considered. Effective mechanical properties of the main materials and cords were first estimated from NHT measurements. Modeling of the double pass laser welding process was performed first by considering shrinking of the two weld seams during manufacturing, to get the residual stress state in the welded assembly. Modeling of the tensile test was performed in a second step to study the assembly behavior during loading. In these modeling results, the mesh was the cross-section of the mic…