Materials Engineering

High Volume Fly Ash – Self Compacting Concrete (HVFA-SCC) merupakan solusi untuk mengurangi penggunaan semen, dan tuntutan beton yang dapat mengalir tanpa menggunakan alat pemadatan. Penelitian ini dimaksudkan untuk menganalisis lentur pada balok beton bertulang High Volume Fly Ash – Self Compacting Concrete (HVFA-SCC) dengan 60% fly ash yang akan dibandingkan dengan balok beton bertulang beton normal yang diuji pada umur 28 hari. Benda uji yang digunakan adalah balok beton bertulang dengan luas penampang 10 cm x 18,5 cm dengan panjang 155 cm. Pengujian kapasitas lentur menggunakan loading frame dengan 2 titik pembebanan dengan jarak antar beban sebesar 45 cm. Dari pengujian ini didapatkan grafik hubungan beban-lendutan serta perhitungan kapasitas lentur balok beton HVFA-SCC 60%. Berdasarkan hasil penelitian ini kapasitas lentur pada pengujian balok beton bertulang HVFA-SCC 60% memiliki nilai yang lebih besar dibandingkan dengan kapasitas lentur hasil pengujian beton normal.

We discuss situations where thermogravimetric/Fourier transform infrared (TG/FT-IR) plots are obtained which differ substantially from the expected ones. The most common of these situations involves samples that release atmospheric components (H2O, CO2) at low temperatures. It is shown that the phenomena are mainly related to the purging action of the carrier gas, which strongly influences the spectroscopic portion of the TG/FT-IR plot. Such an influence, as well as the different situations originating from it, is discussed and explained on the basis of an analogy with the operational mode of a conventional dispersive spectrometer.

In this work, we report on solution-based p-i-n-type planar-structured CH3NH3PbI3 perovskite photovoltaic (PV) cells, in which precrystallized NiO nanoparticles (NPs) without post-treatment are used to form a hole transport layer (HTL). X-ray diffraction and high-resolution transmission electron microscopy showed the crystallinity of the NPs, and atomic force microscopy and scanning electron microscopy confirmed the uniform surfaces of the resultant NiO thin film and the subsequent perovskite photoactive layer. Compared to the conventional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) HTL, the NiO HTL had excellent energy-level alignment with that of CH3NH3PbI3 and improved electron-blocking capability, as analyzed by photoelectron spectroscopy and diode modeling, resulting in Voc ~0.13 V higher than conventional PSS-based devices. Consequently, a power conversion efficiency (PCE) of 15.4% with a high fill factor (FF, 0.74), short-circuit current density (Jsc, 20.2 ...

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOTPSS) is an organic conductive polymer which has a great potential to replace metallic conductors in thin film electronics. This paper reports the experimental findings on the electromechanical performance of conductive PEDOTPSS thin films on a stretchable and flexible low modulus polymer substrate, polydimethylsiloxane (PDMS), having random micro-bumpy roughness features. All films were fabricated using the method of dip coating, which is cost effective and also favorable for mass production. The main goal of the study is to quantify the stretchability and bendability of dip coated PEDOTPSS thin films on PDMS substrate having random micro-bumpy type of roughness features. The films displayed almost constant resistance up to 10% axial strain and were also found to remain conductive when bent up to a diameter of 2 mm.

Functionally graded material that consists of gradually changed dual-phase compositions along the thickness direction of its structure has been introduced as an answer to sharp interfaces problems occur while the processing. In order to observe the morphological and shrinkage due to the sintering process, the Ni/Al2O3 FG samples were manufactured via powder metallurgy routes under argon atmosphere. This study reveals that the sintering temperature does affects the sintering behaviors including the microstructures and radial dimensions of the FG plates. The numerical simulation is found to be useful to predict the stress concentration area within the structures and consequently improve the design of the FG plates.

Here are considered composite materials reinforced which strong fibres, which have an important property that they are anisotropic, and in many cases this anisotropy may be very strong, in the sense that mechanical properties are strongly dependent on direction. Such materials are highly resistant to deformation by extension in the fibre direction compared to other deformation modes. Thus material has been modelled as a transversely isotropic for which the extensional modulus in the fibre direction is much greater than that in a direction perpendicular to the fibres. Material is modelled as coordinate free and such model is employed for examination of waves propagating in an infinite plate reinforced by strong fibres. Wave propagation in layer reinforced by one family of fibres with wave direction parallel with stress free boundaries, but otherwise with angle arbitrary to fibre direction, are examined here. The dispersion relations, in specific carbon fibres - epoxy resin composites...

This paper focused on analysing actual state-of-the-art personal protective equipment (PPE) used in humanitarian demining for the determination of potential gaps to provide improvements to increase the safety and, simultaneously, performance of PPE. The essential requirements and technical standards for PPEs used in humanitarian demining operations were analysed as a basis for gap identification. Furthermore based on the defined gap and risk analysis, the effect of accelerated ageing and simulation of the use of soft ballistic inserts designed with p-aramid woven fabrics was performed. The research provided new inputs for improvements in the standardisation of PPE with respect to performance and safety validation in a laboratory environment. Moreover the gap analysis resulted in strictly identified gap areas for PPE improvement in usability, functionality and safety.

The main purpose of the research is to develop a mathematical model that would aid the prediction of critical equipment failure period, determine the maintenance probability as well as analyze maintenance cost under different operating conditions and maintenance grouping strategy so that the most cost-effective grouping strategy is obtained. In the study, equipment failure probability was utilized in determining maintenance cost under different maintenance grouping strategies (dynamic, opportunistic and static maintenance grouping strategies). Condition monitored data of the critical equipment (a single-stage centrifugal compressor) components was collected at Warri Refinery and Petrochemical Company, Ekpan-Warri, Nigeria. This data was used to validate the developed model. The result shows that the maintenance cost is affected by both equipment speed condition and the maintenance grouping strategy adopted. It was generally observed that the failure probabilities for static and dyna...