Mechanical and frictional properties of coconut husk powder reinforced polymer immersed in a simulated acidic medium for oil/gas applications

Polymeric materials are constantly exposed to aggressive environments, negatively impacting their mechanical and chemical properties. In salt, acid, or alkaline solutions, polymer materials degrade due to surface flaws, microcracks, or other irregularities. For the first time, this study considers the behaviour of coconut powder/coir-reinforced synthetic LDPE hybrid composite immersed in an aggressive (acidic) medium for 15, 30 and 45 days. The structural, mechanical, and frictional behaviour of the developed coir/coconut husk powder/LDPE hybrid composites were measured after ageing in hydrochloric acid (HCl) as potential materials for oil and gas applications. From the XRD patterns, the prominent reflections in the control samples increased with the acid ageing days, while less prominent reflections characterized the hybrid composites. The hardness of the reinforced samples immersed for 30 and 45 days (30B and 45A) showed the highest values of 0.28 Hv, while the control samples immersed for 15 days had the least hardness. The reinforced samples immersed for 15 and 30 days (15B and 30B) showed the lowest and highest fracture toughness, respectively. The control samples were observed to absorb little water after immersion for 144 h. The result showed that although the reinforced hybrid composites showed better mechanical properties, with an increase in the days of immersion in an aggressive medium, the properties became compromised compared to the un-reinforced samples. Hence, the applications of the produced reinforced polymers in the oil and gas industries may be limited.

Datasets on the elastic and mechanical properties of hydroxyapatite: A first principle investigation, experiments, and pedagogical perspective

The purpose of this data article is to report the quantum mechanical analysis by generalized gradient approximation (GGA) exchange-correlation functional using density functional theory (DFT). The predictions were based on the elastic constants and mechanical properties of stoichiometric hydroxyapatite (HAp) crystal. The elastic stiffness constants in hexagonal symmetry were obtained by fitting the Hookes' law for the energy-strain and stress-stain relations. Some of the theoretical datasets were compared to measured mechanical properties of produced HAp pellets obtained through micro and nanoindentation experiments. The datasets show considerable anisotropy in the stress-strain behaviour and are discussed in the context of the mechanical properties of HAp which are useful for tissue engineering. We also provide a pedagogical snapshot on the use of the datasets herein to teach and interpret DFT based atomistic simulations in a typical blended online teaching set-up for engineering students using a new pedagogy, CACPLA (Communicate, Active, Collaborate, Practice, Learning and Assessment).

Teaching bioengineering using a blended online teaching and learning strategy: a new pedagogy for adapting classrooms in developing countries

Research and academia have been recently affected by the Coronavirus (COVID-19), and physical classrooms and laboratory experiments have been affected significantly due to the recent laboratory closures. This has led to innovative approaches to curb this problem. To address these difficulties in teaching bioengineering related courses that is of significant interest to students of the Faculty of Engineering in Ahmadu Bello University, Zaria, Nigeria, and of course, useful for engineering-based higher education institutions (HEI), a transitional pedagogy: Communicate, Active, Collaborate, Problem-based Solving, Learning and Assessment (CACPLA), which encompasses blended learning, was developed as a new teaching and learning strategy. In this study, we show that this new strategy can initiate a steady transition from physical classrooms to full online instruction for some subjects in engineering. This method has been trialled as an exercise for a module as part of an envisioned biomedical engineering degree programme which can be integrated with local industries and research institutions in sub-Saharan Africa. The teaching materials and environment were carefully designed and 253 students of third and final year classes participated as the experimental group. Also, the effect of critical thinking, pre-lecture, and post lecture on the overall performance of the students was assessed. Two questionnaires were designed for data collection, (a) for technical questions, (b) for receptiveness. The result of a student survey suggests favourable reception of the teaching methodology, which aided their understanding of the general bioengineering concept as applied to the materials chemistry and mechanical measurements context. It was noticed that 80% of the students indicated that the blended learning method was sufficient in achieving the learning outcomes of the study. The method is envisioned as a useful and sustainable complement to traditional teaching pedagogies and workshops due to the convenience and relatively high accessibility to Zoom and Google Meet Apps which can be readily employed without incurring significant costs.

Experimental data on the characterization of hydroxyapatite synthesized from biowastes

The purpose of the dataset is to present the morphological features, elemental composition and functional groups of hydroxyapatite (HAp) synthesized from non-separated biowastes (animal bones) by a modified facile heat treatment method up to a maximum temperature of 1100 °C. The synthesized powders were characterized using scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). These evaluations were to reveal the surface features, elemental composition and identify the functional groups of the synthesized powders. After heat treatment of the raw biowastes to 900 °C, 1000 °C, and 1100 °C (regime of heat treatment), the morphological features of the samples exhibited a more densely packed microstructure at the highest sintering temperature (1100 °C). The elemental composition as evaluated by EDX on a weight and atomic basis for all samples provided information on the calcium to phosphate transforms into apatite with a Ca/P ratio of 3.60, 2.04, 2.50 and 2.32 wt % and 2.79, 1.58, 1.94 and 1.78 at. % respectively for raw biowastes (RB) to sintered samples (HA-900, HA-1000 and, HA-1100 °C). The FTIR data showed phosphate and hydroxyl peaks in the thermally treated samples and all the samples produced characteristic stretching modes of O–H bands at about 3417 cm⁻¹ which are noticed in all FTIR spectra of HAp.

PRELIMINARY MULTIDOMAIN MODELLING AND SIMULATION STUDY OF A HORIZONTAL AXIS WIND TURBINE (HAWT) TOWER VIBRATION

Renewable energy sources have gained much attention due to the recent energy crisis and the urge to get clean energy. Among the main options being studied, wind energy is a strong contender because of its reliability due to the maturity of the technology, good infrastructure and relative cost competitiveness. It is also interesting to note that there are physical limits to the potential height of a wind turbine tower since the mechanical structure of wind turbines are thus very flexible and tend to oscillate. This makes the design of wind turbines a demanding task. In this paper, the oscillation of a wind turbine tower due to imbalance in the masses of the blades is modeled in maplesim and the effect of the tower height on its oscillation was simulated. For a wind turbine with three rotor blades, two of which have masses of 10 kg, a mass moment of inertia of approximately 20 kg/m2 and one of the blades has a moment of inertia which is 1% less than the other blades. The simulation showed the most stable system for the most energy capture for this case study to be a rotor speed of 5.5rad/s at a height of 10m. At this angular frequency the deflection of the top of the wind turbine was approximately 1mm.  http://dx.doi.org/10.4314/njt.v36i1.16