Search results for " loading"

Shakedown design of structures under dynamic loading

2010

The optimal (minimum volume) design of elastic plastic structures under static and dynamic loads is studied. The minimum volume design is reached accounting for different resistance limits: it is required that the optimal structure simultaneously satisfies the elastic shakedown limit and the instantaneous collapse limit, or alternatively the elastic and the plastic shakedown limits, adopting for each limit condition a suitably chosen load combination and some appropriate load amplifiers. The load combinations are characterized by the presence of fixed loads, quasi-statical cyclic loads and dynamic (seismic) loads. Reference is made to the Italian Code related to structural analysis and desi…

Shakedown Under Thermomechanical Loads

2014

A shakedown theory for elastic–perfectly plastic structures subjected to thermomechanical loads varying within a given range is outlined under the assumption of temperature-dependent yield stress, but temperature-independent elastic moduli and thermal expansion coefficient are considered. Inertia and creep effects, along with thermal coupling phenomena, are considered negligible. A nonstandard constitutive model is used in which a central role is played by the yield function-assumed convex in the stress–temperature space. The inherent flow mechanism obeys the normality rule and includes, beside the standard plastic strain rates, an extra scalar variable work conjugate of the temperature, co…

Influence of custom-made and prefabricated insoles before and after an intense run

2017

[EN] Each time the foot contacts the ground during running there is a rapid deceleration that results in a shock wave that is transmitted from the foot to the head. The fatigue of the musculoskeletal system during running may decrease the ability of the body to absorb those shock waves and increase the risk of injury. Insoles are commonly prescribed to prevent injuries, and both custom-made and prefabricated insoles have been observed to reduce shock accelerations during running. However, no study to date has included a direct comparison of their behaviour measured over the same group of athletes, and therefore great controversy still exists regarding their effectiveness in reducing impact …

Consistent shakedown theorems for materials with temperature dependent yield functions

2000

The (elastic) shakedown problem for structures subjected to loads and temperature variations is addressed in the hypothesis of elastic-plastic rate-independent associative material models with temperature-dependent yield functions. Assuming the yield functions convex in the stress/temperature space, a thermodynamically consistent small-deformation thermo-plasticity theory is provided, in which the set of state and evolutive variables includes the temperature and the plastic entropy rate. Within the latter theory the known static (Prager's) and kinematic (König's) shakedown theorems - which hold for yield functions convex in the stress space - are restated in an appropriate consistent format…

Experimental Tests of Fatigue Induced Delamination in Gfrp and Cfrp Laminates

2007

This work deals with the experimental analysis of the delamination phenomena in various composite materials under different loading conditions. Quasi-static and fatigue tests are performed on specimens made of glass-fibre reinforced plastic (GFRP) and carbon-fibre reinforced plastic (CFRP). In particular, under both quasi-static and fatigue loading, single fracture modes I and II (using standard DCB and ENF test configurations) and mixed modes I+II (using the MMB test configuration) with several mode mixtures, have been analysed. Further experiments of delamination growth with mode mixture that varies with the crack length, will be performed.

Halloysite nanotubes filled with salicylic acid and sodium diclofenac: effects of vacuum pumping on loading and release properties

2021

AbstractIn this work, we investigated the effects of the vacuum pumping on both the loading efficiencies and the release kinetics of halloysite nanotubes filled with drug molecules dissolved in ethanol. As model drugs, salicylic acid and sodium diclofenac were selected. For comparison, the loading of the drug molecules was conducted on platy kaolinite to explore the key role of the hollow tubular morphology on the filling mechanism of halloysite. The effects of the pressure conditions used in the loading protocol were interpreted and discussed on the basis of the thermodynamic results provided by Knudsen thermogravimetry, which demonstrated the ethanol confinement inside the halloysite cavi…

Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

Customized Titanium Lattice Structure in Three-Dimensional Alveolar Defect: An Initial Case Letter

2018

The aim of this initial case report was to provide a new protocol for the clinical application of a patient-specific titanium lattice structure (Yxoss CBR®, ReOSS, Filderstadt, Germany) for customized bone regeneration. To obtain a 3-dimensional reconstruction of a posterior mandible segment in a 61-year-old woman, a patient-specific titanium customized lattice structure was used. As graft material autogenous bone tissue mixed with xenogenic alloplastic material (Bio Oss®, Geistlich Pharma, Wolhusen, Switzerland) was obtained for reconstruction. After a healing period of 6 months, the titanium lattice structure was removed and implant placement (Camlog Screw Line, 3.8/11, Camlog, Wimsheim, …

Self-Radiolysis of Tritiated Water Stored in Zeolites 4A: Production and Behavior of H 2 and O 2

2015

International audience; Radiolysis of confined water and self-radiolysis of tritiated water give rise to several unanswered questions. To take into account this double specificity, we studied systems of zeolites 4A containing tritiated water at different water loading ratios. Two tritiated waters were synthesized at the volumetric activities of 27 and 60 TBq L −1. For each one, five samples were prepared, differentiated by their water loading ratios, expressed in percentage, close to 4%, 7%, 11%, 14%, and 19%. The study of the radiolysis in those systems revealed a double role of zeolites 4A: first, they increase the decomposition of water. Then they enhance the recombination of the major s…

Mathematical models for Multi Container Loading Problems with practical constraints

2019

Abstract We address the multi container loading problem of a company that serves its customers’ orders by building pallets with the required products and loading them into trucks. The problem is solved by using integer linear models. To be useful in practice, our models consider three types of constraints: geometric constraints, so that pallets lie completely inside the trucks and do not overlap; weight constraints, defining the maximum weights supported by a truck and by each axle, as well as the position of the centre of gravity of the cargo; and dynamic stability constraints. These last constraints forbid empty spaces between pallets to avoid cargo displacement when the truck is moving, …