Bending behaviour of corrugated web beams

The paper is devoted to the behaviour of mild steel structural beams with corrugated web subjected to three-point bending. Semicircular web corrugation in the cross-sectional plane (horizontal) and across the span of the beam (vertical) were investigated both experimental and computationally using finite element technique. In the finite element analysis, test specimen was modelled using commercially available finite element software LUSAS and a non-linear analysis was performed. Corrugation radius of 22.5 and 4 mm thickness, with constant corrugation amplitude to cycle length ratio (H/λ) and flange thickness of 6 mm were selected as the base sizes. The plane web beams, welded and ordinary rolled, were also tested with both methods to develop the benchmark results. The comparisons between the experimental and the finite element analysis results were satisfactory. It was noted that the vertical-corrugated web beam (VCRx) could carry between 13.3 and 32.8% higher moment comparing to the plane and horizontal-corrugated web beams, for the range of corrugation radius taken. Besides that, larger corrugation radius could sustain higher bending load up to the yielding stage. This attributed to the increment of the second moment of area (I) that has influence on the direct bending stresses (σ_zz). In addition, reduction in weight could be achieved by using the vertical-corrugated web. This is true for the corrugation shapes and sizes taken throughout this study.     

Vibration of rotating functionally graded Timoshenko nano-beams with nonlinear thermal distribution

The vibration analysis of rotating, functionally graded Timoshenko nano-beams under an in-plane nonlinear thermal loading is studied for the first time. The formulation is based on Eringen's nonlocal elasticity theory. Hamilton's principle is used for the derivation of the equations. The governing equations are solved by the differential quadrature method. The nano-beam is under axial load due to the rotation and thermal effects, and the boundary conditions are considered as cantilever and propped cantilever. The thermal distribution is considered to be nonlinear and material properties are temperature-dependent and are changing continuously through the thickness according to the power-law form.     

Nonlinear free and forced vibrations of graphene nanoplatelet reinforced microbeams with geometrical imperfection

Microsystem Technologies - Nonlinear free/forced vibration of a functionally graded graphene nanoplatelet (GNP) reinforced microbeam having geometrical imperfection which is rested on a non-linear...     

Experimental study of the transient adsorption/desorption characteristics of silica gel particles in fluidized bed

Transient adsorption/desorption characteristics of spherical particles of silica gel (about 3 mm in diameter) in a fluidized bed have been studied experimentally. To control the humidity of inlet air, a humidifier is designed and fitted in a proper location in the system. The system is well instrumented to measure the inlet and outlet air parameters as well as bed temperatures during the experiments.     

Economic cost models of integrated APC controlled SPC charts

In this paper, an economic cost model is proposed for processes integrating both automatic process control (APC) and statistical process control (SPC) for quality monitoring and control. Both the special cause and common cause variations are reduced by applying integrated APC and SPC. Traditionally, the integrated processes using APC and SPC are evaluated by the average run length (ARL). However, ARL may not be appropriate as a measurement of the economic design since it does not take into consideration the run length variation. Also, there are few studies that compare the cost models of such an integrated control system and the effect of cost parameters using different APC controllers. Therefore, we develop an economic cost model using non-homogenous Poisson process to describe the occurrence of an APC adjustment and develop a long run expected cost to investigate the use of different controllers in such integrated systems. Numerical examples are presented to demonstrate the applicability of the proposed model.     

Organometallic tris(8-hydroxyquinoline)aluminum complexes as buffer layers and dopants in inverted organic solar cells

Tris(8-hydroxyquinoline)aluminum (Alq₃) is a frequently used material for organic light emitting diodes. The electronic properties and solubility can be tuned by chemical tailoring of the quinoline part, which makes it an interesting candidate for organic solar cells. Steady-state absorption and fluorescence, as well as time-resolved fluorescence properties of the parent Alq₃ and a series of complexes consisting of derivatives, such as 4-substituted pyrazol, methylpyrazol, arylvinyl, and pyridinoanthrene moieties, of the quinoline ligand, were studied in solutions and in thin films. Suitability of the complexes as anodic buffer layers or dopants in inverted organic solar cells based on the well known bulk heterojunction of poly(3-hexylthiophene) (P3HT) and phenyl-C₆₁-butyric acid methyl ester (PCBM) was tested. The devices equipped with the derivatives showed higher power conversion efficiency (η) compared to the photocells containing the parent Alq₃. Open circuit voltage (V_oc) was increased when the derivatives were utilized as the anodic buffer layer. Doping of the P3HT:PCBM with a small amount of Alq₃ or its derivative improved short circuit current density, V_oc, fill factor, and η, while the series resistance decreased. In addition, the devices were stable in air over several weeks without encapsulation. Possible mechanisms leading to the improvements in the photovoltaic performance by using the parent Alq₃ or its derivative as buffer layer or dopant are discussed.     

Thermo elastic analysis of a functionally graded rotating disk with small and large deflections

A functionally graded (FG) rotating disk with axisymmetric bending and steady-state thermal loading is studied. The material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents. First-order shear deformation Mindlin plate and von Karman theories are employed. New set of equilibrium equations with small and large deflections are developed. Using small deflection theory an exact solution for displacement field is given. Solutions are obtained in series form in case of large deflection. Mechanical responses are compared small deflection versus large deflection as well as homogeneous versus FG disks. It is observed that for particular values of the grading index n of material properties mechanical responses in FG disk can be smaller than in a homogeneous disk. It is seen that given the non-dimensional maximum vertical displacement w_max/h close to 0.4 for a homogeneous (full-ceramic in this study) disk greater errors in the mechanical responses for FG disks would be introduced if one uses small deflection theory.     

Stylus contact time during measurement—An effective factor in accuracy

An experimental study was carried out to determine formulae showing the effect of instantaneous and time local deformation at the point of contact between stylus and measured surface on the precision and accuracy of both measuring standard slip gauges and brass workpieces.Such formulae are useful in practice as new correction functions for the precision and accuracy of measurement. Using styli with spherically ended tips of various diameters as used in practice a wide range of measuring forces, different surface finishes of brass workpieces and time of measuring were investigated.     

Crushing response of composite corrugated tubes to quasi-static axial loading

This paper is devoted to examine the crushing behaviour of axially crushed composite corrugated tubes. Two types of composites were tested, namely, carbon fibre/epoxy in a filament form and glass fibre/epoxy in woven roving form. A series of experiments was conducted for tubes with corrugation angle (β) ranging from 10° to 40°. Typical failure histories of their failure mechanisms are presented and discussed. The results showed that the crushing behaviour of composite corrugated tube is found to be sensitive to the change in corrugation angle and fibre type. Carbon/epoxy tubes with corrugation angle of 40° displayed the highest specific energy absorption capability. It is also found that introducing of corrugation could significantly enhance the energy absorption capability of composite tubes in a uniform manner.