Search results for "Transports"
showing 10 items of 485 documents
Coating Toughness Estimation through a Laser Shock Testing in Ni-Cr-B-Si-C Coatings
2018
In the nuclear field, efforts are made to find substitutes to cobalt hardfacing alloys since these alloys have a principal drawback, the transmutation from stable 59Co to 60Co under neutron irradiation. In case of wear, fragments could be deposed on the surface of primary circuit and thus contaminate it, causing a real issue for deconstruction.
Enhancement of Static and Fatigue Strength of Short Sisal Fiber Biocomposites by Low Fraction Nanotubes
2021
AbstractThanks to good mechanical performances, high availability, low cost and low weight, the agave sisalana fiber allows to obtain biocomposites characterised by high specific properties, potentially very attractive for the replacement of synthetic materials in various industrial fields. Unfortunately, due to the low strength versus transversal damage processes mainly related to the matrix brittleness and/or to the low fiber/matrix adhesion, the tensile performance of random short fiber biocomposites are quite low, and to date most of the fiber treatments proposed in literature to improve the fiber-matrix adhesion, have not led to very satisfactory results. In order to overcome such a dr…
Non associative damage interface model for mixed mode delamination and frictional contact
2019
Abstract The present paper proposes a new interface constitutive model based on the non-associative damage mechanics and frictional plasticity. The model is developed in a thermodynamically consistent framework, with three independent damage variables. The non associative flow rules drive the concurrent evolution of the three damage variables. The interface model provides two independent values for the mode I fracture energy and the mode II fracture energy and it is able to accurately reproduce arbitrary mixed mode fracture conditions. The model can also take into account the presence of frictional effects both at the fully debonded zones and at the partially debonded ones. The experimental…
Analytical Solution of the 4ENF Test with Interlaminar Frictional Effects and Evaluation of Mode II Delamination Toughness
2018
The present paper proposes an analytical solution of the four points bend end-notched flexure test (4ENF) with frictional contact between the delamination surfaces. The analytical solution was developed in the framework of the classic Euler-Bernoulli bending beam theory with orthotropic linear elastic constitutive behavior. The frictional contact was modeled as rigid-perfectly plastic with the Mohr-Coulomb activation function and the nonassociative flow rule. The elastic solution of the partially cracked beam subjected to the four points bending test with frictional contact was developed, and the Mode II delamination toughness was analytically determined by means of the Griffith approach, a…
Effects of fiber orientation of adjacent plies on the mode I crack propagation in a carbon-epoxy laminates
2011
Abstract The influence of ply orientation on the resistance to mode I delamination of multidirectional composite laminates can be assessed by Double Cantilever Beam (DCB) tests. However, one of the difficulties associated with such a study is the change in overall elastic parameters occurring when modifying local ply orientations. The present work uses laminates with special stacking sequences allowing for isolating the orientation parameter. Multidirectional DCB specimens were designed so as to obtain an uncoupled quasi isotropic and quasi-homogeneous elastic behavior, with the same properties for the entire laminate and the two sub laminates separated by the pre crack at mid-plane. The re…
Evaluation of toughness by finite fracture mechanics from crack onset strain of brittle coatings on polymers
2008
Crack onset strain measurements of a confined layer in tension provide the means for layer toughness estimation. The procedure can be simplified if steady-state conditions prevail starting from the commencement of crack propagation, an assumption frequently employed in energy release rate evaluation. It is demonstrated, by numerical analysis of experimental data, that an estimate of the defect size in the film is needed in order to reliably evaluate its fracture toughness from the crack onset strain. Only if microcracks of sufficient size are present in the brittle layer, the steady-state energy release rate at the crack onset strain can be identified with layer toughness. Otherwise, the to…
Micromechanisms of load transfer in a unidirectional carbon fibre-reinforced epoxy composite due to fibre failures: Part 3. Multiscale reconstruction…
2008
International audience; This third article describes a multiscale process which takes into account the most important microscopic phenomena associated with composite degradation, including fibre fractures and interfacial debonding, overloading of fibres neighbouring a fibre break as well as viscoelastic behaviour of the matrix. The results have been used to accurately predict the macroscopic failure of unidirectional carbon fibre-reinforced epoxy and quantify damage accumulation in pressure vessels made of the same material. The approach described has allowed the acoustic emission activity resulting from fibres breaks to be evaluated and shown how the residual lifetimes of such vessels, whe…
Uzņēmējdarbības procesu reorganizācija transporta kompānijā SIA "InAuto" pasliktinātu tirgus apstākļu dēļ
2016
Darba par tēmu «Uzņēmejdarbības procesu reorganizācija transporta kompānijā SIA “InAuto” pasliktinātu tirgus apstākļu dēļ» pamatā ir dotā uzņēmuma problēmu un to risināšanas piedāvājumu meklējumi. Par darba mērķi kļuva uzņēmuma pamatproblāmas meklējumi, ko var pozitīvi ietekmēt tā vadītājs - reorganizējot pakalpojumu. Lai atklātu problēmas, darbā tika veiktas vairākas plašas analīzes, tādas kā uzņēmuma vertikālā un horizontālā analīze, rezultāti ir atspoguļoti rezultātu tabulās un grafikos. Uz analīzes pamata ir izdarīti secinājumi. Balstoties uz personīgo pieredzi, autore, papildinot to ar teorētiskajām zināšanām, kas iegūtas uzņēmuma izpētes gaitā, piedāvā savu atklāto uznēmuma problēmu r…
Sabiedriskā transporta nozares stratēģiskās attīstības scenāriji.
2022
Maģistra darba temats ir “Sabiedriskā transporta nozares stratēģiskās attīstības scenāriji”. Maģistra darba mērķis ir, pētījuma ietvaros, izstrādāt vienu kopējo iespējamo sabiedriskā transporta scenāriju. Darba uzdevumi ir noteikti atbilstoši izvēlētajam mērķim. Darbs sastāv no 3 nodaļām un 11 apakšnodaļām. Pirmajā nodaļā apskatīta teorētiskā bāze par scenāriju izstrādi. Darba otrajā nodaļā analizēti sabiedriskā transporta nozares attīstības ietekmējošie normatīvie akti Latvijā. Trešajā nodaļā izstrādāti trīs atšķirīgi scenāriji, apkopots ekspertu vērtējums par tiem. Pamatojoties uz ekspertīzes rezultātiem, izstrādāts vienots kombinētais scenārijs sabiedriskā transporta nozares attīstībai, …
Izmantojamo informācijas sistēmu novērtēšana loģistikas uzņēmumā SIA "Kreiss"
2019
Mūsdienu loģistika nav iedomājama bez informācijas sistēmu aktīvas izmantošanas. Ir grūti iedomāties preču piegādes ķēdes darba veidošanu un organizēšanu bez intensīvas, nepārtrauktas informācijas apmaiņas, bez ātras reaģēšanas uz tirgus vajadzībām. Diplomdarba aktualitāte ir saistīta ar to, ka mūsdienās informācijas sistēmu un tehnoloģiju, programmatūras, tīkla attīstības dēļ, ikdienu palielinās konkurētspējošu uzņēmumu skaits. Diplomdarba mērķis ir iepazīties un izpētīt informācijas sistēmu vides praktiskos risinājumus uzņēmumā SIA “Kreiss”, kā arī izteikt priekšlikums uzņēmuma informācijas sistēmu uzlabošanai. Darba uzdevumi: izpētīt uzņēmumā izmantotās informācijas sistēmas un tehnoloģi…