Effect of strain rate on indentation behaviour of kenaf-based fibre metal laminates

Kenaf natural fibre has become the subject of interest for a wide range of engineering sectors due to its biodegradable and robust mechanical properties [1, 2]. Akil et. al. [3] presented a review on kenaf fibre reinforced composites and mentioned that the application of kenaf fibre-reinforced composite as an alternative composite material is highly plausible with both lightweight and low cost as its main advantages. This situation has lead researchers to investigate the potential offered by kenaf fibre reinforced composites [4-6]. However, research on kenaf-based fibre metal laminates (FMLs) is still not clear and thus demands extensive research investigation. In this study, the effect of strain rate on the indentation behaviour of the FMLs subjected to static indentation loading was investigated. The fibre metal laminates were made of chopped strand mat kenaf fibre with epoxy resin composite and 0.6 mm thickness of 1100-O aluminium alloy sheet by using vacuum infusion process (VIP) and hydraulic pressing technique. Several samples of 2/1 lay-up and 3/2 lay-up of FMLs were prepared for indentation tests. The experiments were conducted by using a universal testing machine with strain rate of 1 mm/min, 10 mm/min and 100 mm/min

Linear-nonlinear stiffness responses of carbon fiber-reinforced polymer composite materials and structures: a numerical study

The stiffness response or load-deformation/displacement behavior is the most important mechanical behavior that frequently being utilized for validation of the mathematical-physical models representing the mechanical behavior of solid objects in numerical method, compared to actual experimental data. This numerical study aims to investigate the linear-nonlinear stiffness behavior of carbon fiber-reinforced polymer (CFRP) composites at material and structural levels, and its dependency to the sets of individual/group elastic and damage model parameters. In this regard, a validated constitutive damage model, elastic-damage properties as reference data, and simulation process, that account for elastic, yielding, and damage evolution, are considered in the finite element model development process. The linear-nonlinear stiffness responses of four cases are examined, including a unidirectional CFRP composite laminate (material level) under tensile load, and also three multidirectional composite structures under flexural loads. The result indicated a direct dependency of the stiffness response at the material level to the elastic properties. However, the stiffness behavior of the composite structures depends both on the structural configuration, geometry, lay-ups as well as the mechanical properties of the CFRP composite. The value of maximum reaction force and displacement of the composite structures, as well as the nonlinear response of the structures are highly dependent not only to the mechanical properties, but also to the geometry and the configuration of the structures

Reduction of motorcycle's drum brake squeal noise using constrained layer damping (CLD)

Brake noise, particularly squeal is the most annoying and disturbing sound to the people, With a large number of motorcycles used in Malaysia, the level of squeal noise can be very high, especially during busy or heavy traffics due to high numbers of braking applications, Thus, this paper aims to reduce potential squeal noises generated by a rear drum brake assembly of motorcycles using constrained layer damping (CLD), A three dimensional finite element (FE) model of the drum brake assembly that consists of a drum and two brake shoes is developed and analysed, Complex eigenvalue analysis (CEA) is employed to determine stability of the drum brake assembly, where positive real parts of the eigenvalues indicate an unstable modes and its associated imaginary parts indicate an unstable (squeal) frequencies. In order to reduce squeal noise, four constrained layer damping (CLD) models have been proposed and assessed, The complex eigenvalue results show that the CLD2 and CLD4 models can fully eliminate unstable mode at a frequency of6120 Hz, while in frequency of 2051Hz the positive real part has been reduced from +222 to + 199 for CLD2 and + 182 for CLD4, The CEA results indicate that proper CLD designs can be used to reduce drum brake squeal noise in the motorcycles

Characterization of hybrid yarn/fabrics from of kenaf-kevlar fibers

In this work, new hybridization method used to fabricate different hybrid yarn by using untreated and treated kenaf fiber and Kevlar yarn until development of hybrid fabrics. The hybrid yarn consists of various combination of kenaf and kevlar fiber with the composition ratio of 70% kenaf: 30% kevlar, 50% kenaf:50% kevlar and 30% kenaf:70% kevlar were weaved and also 100% kenaf and 100% kevlar yarns were weaved as the control data to compared with hybrid fabric. The woven of Kenaf-Kevlar composition were carried out by the weaving of hybrid yarn in weft and warp direction. Tensile properties of kenaf fiber, kevlar fiber, hybrid yarn and hybrid fabric were measured by using Universal Testing Machine. Morphology of all fibers-treated and untreated kenaf and kevlar were analyzed by using scanning electron microscopy (SEM). The obtained result showed that 30%Kenaf:70%Kevlar hybrid yarn and fabric has the highest strength (48.511 cN/Tex) and modulus (1815.570 cN/Tex) among the hybrid but its value 70% lower than 100% Kevlar fabric. Both treated Kenaf and Kevlar fibers showed fine surface and light weighted as compared with untreated fibers. The preliminary research results have shown that development of hybrid materials from natural fibers has the potential to be utilized for high performance composite applications

A study of fasting type 2 diabetes mellitus patients with acute complications during Ramadan in Hospital Tengku Ampuan Afzan, Kuantan, Pahang

Introduction: A large number of Muslims fast during the holy month of Ramadan worldwide. A specific approach is needed to manage diabetic patients who intend to fast during Ramadan because of potential harm. Thus, the study aimed to describe the sociodemography and the characteristic of fasting diabetic patients admitted due to acute diabetic complications during Ramadan. Materials and Methods: A cross-sectional study was conducted among fasting diabetic patients in Hospital Tengku Ampuan Afzan (HTAA) who were admitted due to severe hypoglycemia, diabetic ketoacidosis, hyperglycemic hyperosmolar syndrome and uncontrolled diabetes mellitus during the month of Ramadan 2017/1438H. Subjects were interviewed and blood investigation results were obtained from medical records and recorded in patients' case report. Results: Thirteen patients who were admitted due to acute complications of diabetics during Ramadan were included in this study. Of these, 38.5% had severe hypoglycemia, 23.1% diabetic ketoacidosis, 15.4% hyperglycemia hyperosmolar syndrome and 23.1% uncontrolled diabetes mellitus. All of the patients had a long standing diabetes mellitus (median duration of 10 years). HbA1C was high (11.5%) among hyperglycemic subjects. Types of treatment and previous history of severe hypoglycemia prior to Ramadan were the only independent factors identified to be related with acute complications of diabetes during fasting month (p=0.030 and p=0.032 respectively). Insulin, either alone or in combination with oral hypoglycemic agent, was associated with higher number of hypoglycemic event. Conclusion: The significant risk factors found were consistent with other studies. A thorough, individualized and holistic approach is needed in managing patients with diabetes who intend to fast

Water Warriors Living Lab: Towards an integrated “Heartware - Hardware – Software” Approach to Water Management

This paper presents the experience of the Water Warriors Living Lab, a bottom-up sustainable campus action research initiative in applying the integrated ‘Heartware - Hardware – Software’ approach for water management at the University of Malaya since the year 2013. It advances the proposition that a heartware approach is needed to enhance campus sustainability efforts, in addition to the more strategic hardware and software approaches. The paper describes how the Water Warrior’s experience in applying the heartware approach has been a strengthening factor in resolving water conservation issues at the university (specifically in lake management), and discusses important lessons learned to date. Our theoretical and empirical insights can hopefully provide renewed appreciation on how local, organic and humanistic factors can be essential ingredients for the long term ‘sustainability’ of campus sustainability efforts.Keyword: Campus sustainability, living lab, water management, heartware, bottom-u

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV

We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.Peer reviewe

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of B-c(2S)(+) and B-c*(2S)(+) cross section ratios in proton-proton collisions at root s=13 TeV

Peer reviewe