Search results for "CREEP"

Linear ViscoElastic (LVE) Behaviour of Pure Bitumen via Fractional Model

2012

AbstractBy fitting experimental data from static creep/recovery carried out on pure bitumen, it is shown that the fractional model proposed enables the description of both creep and recovery behaviour with fewer parameters than those needed by other models in the literature. In particular, the model is fitted to experimental data of complex modulus |G*| and phase angle δ° obtained from Dynamic Mechanical Analysis. Lastly, it is demonstrated that when the fractional model is used, complex modulus isotherms for a range of frequencies can be created simply starting from isochronals at f = 1Hz.

Un nuovo strumento per misurare il comportamento al creep in condizioni reali di sistemi polimerici

2011

Advanced Composites and Applications: Book of abstracts

2023

The section ‘Advanced Composites and Applications’ was organized by the Institute for Mechanics of Materials of the University of Latvia (LU MMI) on 16.02.2023 as a part of the annual 81th scientific conference of the University of Latvia. It was organized remotely in Zoom. The official language of the section was English. The duration of the presentation was 10 minutes. The section was devoted to the discussion of the recent results within following topics: structure and properties of polymers and polymer-based composites, long-term properties, creep, and environmental ageing, composites for advanced applications, mechanical aspects of technology, and multifunctional properties.

IN-LINE MONITORING OF THE PHOTOOXIDATION BEHAVIOUR OF PP/CLAY NANOCOMPOSITES THROUGH CREEP MEASUREMENTS

2016

The photooxidation of polymer systems is usually investigated by monitoring the change of chemical and molecular structure, morphology and macroscopic after a given period of UV exposition. In a previous paper, La Mantia et al. [1] presented a new apparatus that is able to monitor during the accelerated weathering the effect of the photooxidation on a polymer sample subjected not only to temperature, humidity and UV irradiation, but also to a mechanical stress, fully simulating real working conditions for plastic products. In this work, a polypropylene/organomodified clay nanocomposite has been subjects to the same test and the results compared with those obtained for the pure matrix.

Photooxidation behaviour of LDPE/Clay nanocomposite measured through creep curves

2016

The creep response of Polymer systems is typically investigated upon applying different loads, or under different temperature. However, no evidence exist of creep studies under different loads and temperatures and the simultaneos actionof accelerated weathering. In a previous paper La Mantia et al. [1] presented a new equipment that is able to subject polymer samples to creep under different loads, but also monitor the effect of photooxidation due to the temperature, humidity and UV irradiation, thus fully simulating the real operating conditions for polymer-based items. In tihs work a polyethylene/organomodified caly nanocompositehas been subjectedto combined creep-accelerated weathering c…

Molecular phylogeny of treecreepers (Certhia) detects hidden diversity†

2006

We sequenced a part of the mitochondrial cytochrome-b gene from the seven treecreeper species, including 18 subspecies, to reconstruct the phylogeny of the genus Certhia. Species status of all seven species could be affirmed. Certhia discolor, C. himalayana, C. nipalensis, and C. tianquanensis, the species with relatively small distribution ranges in southeast Asia and simple territorial song, are found at the base of all phylogenetic trees, although without good support. A comparatively recent sister species of C. tianquanensis is C. nipalensis, replacing C. discolor as closest relative. Certhia familiaris, C. brachydactyla and C. americana form a derived set of species (again only weak su…

Within territory abundance of red wood ants Formica rufa is associated with the body condition of nestlings in the Eurasian treecreeper Certhia famil…

2007

Studies on individual reproductive success in relation to interspecific competition between distantly related taxa are scarce. We studied whether the abundance of red wood ants Formica rufa -group is related to the breeding habitat selection, fecundity and offspring quality in the Eurasian treecreeper Certhia familiaris, an old-growth forest passerine. The nest-box occupancy data were gathered over a five-year study period, whereas the breeding performance analyses were based on a two-year data set. The abundance of wood ants, measured within 50 m around the nest-boxes, was not related to nest-box occupancy rate, fecundity or the physiological stress of nestlings. In contrast, the abundance…

Influence of pre-existing microstructure on mechanical properties of marine ice during compression experiments

2014

AbstractMarine ice is an important component of ice shelves in Antarctica. It accretes in substantial amounts at weak points and below ice shelves. It is likely to exhibit peculiar rheological properties, which are crucial to understanding its potential role in stabilizing ice-shelf flow. Due to its location and consolidation processes, marine ice can present a variety of textures which are likely to influence its rheological properties. We present a new dataset of unconfined uniaxial compression experiments on folded marine ice samples that have been cut at various angles to the folds. Texture and fabric analyses are described ‘before’ and ‘after’ the deformation experiment. It is shown th…

New evidence for the form and extent of the Pernicana Fault System (Mt. Etna) from structural and soil–gas surveying

1998

A multidisciplinary study based on structural and soil–gas surveys was carried out in order to investigate the relationship between soil CO2 degassing and the tectonic setting of the lower northeastern flank of Mt. Etna volcano. The results show that anomalous soil CO2 emissions occur mainly along faults trending WNW–ESE and also where these faults intersect the other main fault set (trending NE–SW) that displaces the study area. In particular, anomalies in CO2 degassing were revealed both along the Pernicana Fault and along another fault (Fiumefreddo Fault) which may represent the prolongation of the former towards the Ionian Sea coast. In the areas where these structures show evident surf…

Comportamento al creep di biocompositi a base di PLA in presenza di irraggiamento UV

2018

Negli ultimi anni, l’interesse nei confronti dei biocompositi (spesso chiamati “compositi verdi”), realizzati con matrici polimeriche biodegradabili/compostabili e riempitivi organico-naturali ha conosciuto un livello crescente di interesse, sia da parte del mondo accademico che dell’industria. La letteratura fornisce numerose informazioni riguardo il comportamento di tali materiali (in particolare, riguardo il comportamento meccanico), ma di contro sono disponibili solo pochi dati riguardo il comportamento a creep [1] e, a nostra conoscenza, non sono disponibili studi sistematici riguardo il comportamento a creep sotto azione di raggi ultravioletti. Ci siamo quindi occupati di condurre uno…