Search results for "Mechanical Engineering & Transports"
showing 10 items of 408 documents
The effect of partial exfoliation of multilayer silicate filler particles on the elastic properties of a polymer composite
2018
Abstract A method for stepwise calculation the elastic constants of a three-phase composite, including the polymer matrix, the fully exfoliated silicate nanolayers and the platelike silicate particles in the form of multilayer intercalated stacks is considered. A theoretical analysis is carried out by using the Mori–Tanaka theory of an equivalent medium. The influence of degree of exfoliation (the ratio of exfoliated filler content to the total filler content) on the reinforcing efficiency is studied and discussed. A comparative analysis of experimental data of elastic modulus for a rigid polyurethane/montmorillonite composite and prediction results is carried out. It is shown, that with gr…
Prediction method of electrical conductivity of nano-modified glass fibre reinforced plastics
2019
Glass fibre reinforced plastics (GFRP) is non-conductive construction material, however with carbon nanotubes (CNT) modifying it can get additional functionality due to its gained electrical conductivity. Main aim of the study is to check functionality of the prediction method of electrical conductivity of GFRP with nano-modified epoxy matrix using structural approach. GFRP composites under investigation were based on unidirectional (UD) Glass fiber and two matrixes modified with carbon nanotubes. Electrical conductivity of epoxy resin modified by CNT (concentrations < 1%) was modelled using structural approach. Electrical conductivity of unidirectional GFRP layer was measured experimentall…
Estimation of the elastic constants of highly porous cellular plastics reinforced with fibres embedded in foam struts
2015
In order to enhance the mechanical properties of polymer foams, fillers of different materials and sizes are being applied. Fibrous fillers shorter than the characteristic foam cell dimensions have the potential of efficient reinforcement, due to their high aspect ratio, without detrimentally interfering with foam structure. A theoretical model is developed for evaluation of the effect of filler on foam stiffness. The elastic response of rigid polymer foams filled with short fibres, of length commensurable with that of foam struts, is modelled by using the orientational averaging technique. Explicit expressions for components of the stiffness tensor of composite foams are derived in terms …
Fractional viscoelastic characterization of laminated glass beams under time-varying loading
2021
Abstract Laminated glass is a composite made of elastic glass layers sandwiching thin viscoelastic polymeric interlayers. There are several types of polymers, traditionally modelled as linear viscoelastic materials using a Prony’s series of units in the Maxwell-Wiechert arrangement. We show that one single element with fractional viscoelastic properties (two constitutive parameters that depend on environmental temperature), is sufficient to provide an accurate description of the polymer response under arbitrary time-varying actions. This is a great advantage over the classical viscoelastic characterization, which requires at least 10–15 terms in the Prony’s series, each one characterized by…
Mode I interlaminar fracture toughness of thin-ply laminates with CNT webs at the crack interface
2019
Abstract Pristine and functionalized carbon nanotube (CNT) webs were introduced at the interlaminar region of two different thin-ply carbon fibre reinforced polymer systems (NTPT 402 prepreg, and TeXtreme/SE84LV). The Mode I interlaminar fracture toughness (ILFT) for the NTPT 402 material was substantially lower. In contrast when SE84LV resin was used, the resistance curves were virtually unchanged and with no depreciation in the steady state value of the ILFT. This demonstrates that a careful choice of the resin is essential to permit the embedding of CNT webs in thin-ply laminates without compromising structural performance and opens a new way towards the development of multifunctional th…
Smart Micro-Grid Performance using Renewable Energy
2020
The aim of this research is to determine the performance of PV panels, wind turbines, battery storage and power imported from the grid to the system which will ensure a reliable energy supply, as well as the technical feasibility of a smart microgrid system. Indonesia’s renewable energy potential for electricity reaches 443 GW, where solar energy is the largest potential, namely 4.8 KWh m–2 or equivalent to 112 000 GWp, but only 10 MWp has been utilized. The most basic problem in this system, namely, the uncertainty of wind energy and solar energy, one of the most vital factors in the optimal size of a renewable energy-based smart microgrid system is the reliability of the system being buil…
Generalized heat equation and transitions between different heat-transport regimes in narrow stripes
2019
Abstract In the framework of weakly nonlocal thermodynamic theory, in this paper we derive a nonlocal and nonlinear heat-transport equation beyond the Fourier law by means of thermodynamic considerations in agreement with the second law. The obtained equation describes the transitions among different heat-transport regimes. The stability of the solution of that equation is also analyzed in a special case.
Fibre break failure processes in unidirectional composites: evaluation of critical damage states
2016
Earlier work which successfully modelled the kinetics of fibre breakage in unidirectional composites under monotonic tensile loading has been extended to quantify the kinetics of fibre failure during both monotonic and sustained tensile loading. In both cases, failure was seen to occur when a critical density of large clusters (more than 16 fibres are broken within the representative volume element) of fibre breaks developed. However, in monotonic loading failure occurred very quickly after the first development of these large clusters, whereas under sustained loading the composite could accommodate greater levels of large clusters because of the lower applied load. This article is part of …
An implicit mesh discontinuous Galerkin formulation for higher-order plate theories
2019
In this work, a discontinuous Galerkin formulation for higher-order plate theories is presented. The starting point of the formulation is the strong form of the governing equations, which are derived in the context of the Generalized Unified Formulation and the Equivalent Single Layer approach from the Principle of Virtual Displacements. To express the problem within the discontinuous Galerkin framework, an auxiliary flux variable is introduced and the governing equations are rewritten as a system of first-order partial differential equations, which are weakly stated over each mesh element. The link among neighboring mesh elements is then retrieved by introducing suitably defined numerical …
Improvement of the technological process of carbonated spring water by implementing the quality and food safety management standards
2019
Bottled spring water must be health providing, clean, without microorganisms, parasites or substances. The design, manufacturing and management of processes, related to spring water bottling involves controlling the safety issues that may arise in the production processes. These aspects are not sufficient to prevent hazards and they must be related to the implementation of a quality and food safety systems. The aim of the paper is to improve the technological process of carbonated spring water in Monopolis S.A Company, by implementing the quality and food safety management standards. The methodology is based on the implementation requirements of the HACCP principles, included in ISO 22000 s…