Science and Technology Studies Commons^™

Numerical Modelling Of Track Behavior Capturing Particle Breakage Under Dynamic Loading, Ngoc Trung Ngo, Buddhima Indraratna

Faculty of Engineering and Information Sciences - Papers: Part B

No abstract provided.

A Laboratory Study On Fluidization Of Subgrade Under Cyclic Train Loading, Buddhima Indraratna, Mandeep Singh, Thanh Trung Nguyen, Serge Leroueil, Aruni Lakmali Abeywickrama Bamunusing Kankanamge, Richard B. Kelly, Tim Neville

Faculty of Engineering and Information Sciences - Papers: Part B

A long term issue that has hampered the efficient operation of heavy haul tracks is the migration of fluidized fines from the shallow soft subgrade to the overlying ballast, i.e., mud pumping. This paper presents a series of undrained cyclic triaxial tests, where realistic cyclic loading conditions were simulated at low confining pressure that is typical of shallow subgrade beneath a ballast track. Subgrade soil specimens with a low plasticity index collected from a field site with recent history of mud pumping were tested at frequencies from 1.0 to 5.0 Hz and a cyclic stress ratio (CSR) from 0.1 to …

Improved Performance Of Ballasted Tracks Under Impact Loading By Recycled Rubber Mats, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Faculty of Engineering and Information Sciences - Papers: Part B

Ballasted tracks at transition locations such as approaches to bridges and road crossings experience increasing degradation and deformation due to dynamic and high impact forces, a key factor that decreases the stability and longevity of railroads. One solution to minimise ballast degradation at the transition zones is using rubber energy absorbing drainage sheets (READS) manufactured from recycled tyres. When placed beneath the ballast layer, READS distributes the load over wider area and attenuate of the load over a longer duration thus decreasing maximum stress, apart from reducing the energy transferred to the ballast and other substructure components. Subsequently, the track …

Performance Evaluation Of Intermittently Cfrp Wrapped Square And Circularised Square Reinforced Concrete Columns Under Different Loading Conditions, Anh Duc Mai, M Neaz Sheikh, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part B

This paper presents the results of an experimental investigation on square and circularised square rein-forced concrete (RC) columns intermittently wrapped with carbon fibre reinforced polymer (CFRP)under different loading conditions. Twelve RC specimens consisting of eight square RC specimenswith 150mm150mm cross-section and 800mm height and four circularised square RC specimenswith 212mm diameter and 800 mm height were tested under concentric axial load, eccentric axialload and four-point flexural load. The test results showed that intermittent wrapping increased thestrength and ductility of square RC specimens. The test results also showed that circularisation com-bined with intermittent wrapping significantly improved the strength and ductility of …

Experimental And Numerical Studies Of Square Concrete-Filled Double Steel Tubular Short Columns Under Eccentric Loading, Mizen Ahmed, Qing Quan Liang, Vipulkumar I. Patel, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part B

Square concrete-filled double steel tubular (CFDST) beam-columns consisting of an internal circular steel tube have increasingly been utilized in composite building structures because of their high structural performance. This paper describes experimental and numerical studies on the structural responses of square thin-walled CFDST columns loaded eccentrically. Tests on twenty short square CFDST columns were undertaken that included sixteen columns under eccentric loading and four columns under concentric loading. The parameters examined in the experiments included the cross-sectional dimensions, the width-to-thickness ratios of outer and internal tubes and loading eccentricity. The measured ultimate strengths, load-shortening responses, load-lateral displacement curves, stress-strain curves …

Application Of Fractional Calculus In Modelling Ballast Deformation Under Cyclic Loading, Yifei Sun, Buddhima Indraratna, John Philip Carter, Timothy R. Marchant, Sanjay Nimbalkar

Faculty of Engineering and Information Sciences - Papers: Part A

Most constitutive models can only simulate cumulative deformation after a limited number of cycles. However, railroad ballast usually experiences a large number of train passages that cause history-dependent long-term deformation. Fractional calculus is an efficient tool for modelling this phenomenon and therefore is incorporated into a constitutive model for predicting the cumulative deformation. The proposed model is further validated by comparing the model predictions with a series of corresponding experimental results. It is observed that the proposed model can realistically simulate the cumulative deformation of ballast from the onset of loading up to a large number of load cycles.

Use Of Synthetic Inclusions For Enhanced Behaviour Of Railway Ballast Under Impact Loading, Fernanda Bessa Ferreira, Buddhima Indraratna

Faculty of Engineering and Information Sciences - Papers: Part B

Ballasted rail tracks form one of the largest worldwide networks catering to passenger and freight transportation. However, track deterioration associated with severe dynamic wheel loads is inevitable over the years leading to high maintenance costs. Geosynthetics and energy-absorbing rubber mats have increasingly been applied in rail track foundations to improve track stability and reduce the life-cycle cost of the railway system. This paper presents the results of an experimental study carried out using a high-capacity drop-weight impact testing apparatus to investigate the deformation and degradation response of railway ballast under impact loading conditions. The effectiveness of the geogrid reinforcement in …

Experimental Investigation Of The Behaviour Of Concrete Beams Reinforced With Gfrp Bars Under Static And Impact Loading, Matthew Goldston, Alex M. Remennikov, M Neaz Sheikh

Faculty of Engineering and Information Sciences - Papers: Part A

Composite materials, including Fibre Reinforced Polymer (FRP) bars, have been gaining momentum as alternatives to traditional steel reinforcements in civil and structural engineering sectors. FRP materials are non-corrosive, non-conductive, and lightweight and possess high longitudinal tensile strength, which are advantageous for their use in civil infrastructure. This paper presents the results of an experimental investigation into the effects of the use of glass FRP (GFRP) bars as internal reinforcement on the behaviour of concrete beams. Both static and dynamic (impact) behaviours of the beam have been investigated. Twelve GFRP reinforced concrete (RC) beams were designed, cast and tested. Six GFRP …

On The Feasibility Of Partial Slip Reversal And De-Twinning During The Cyclic Loading Of Twip Steel, Ahmed A. Saleh, Bjorn Clausen, Donald W. Brown, Elena V. Pereloma, Christopher H. J Davies, Carlos N. Tome, Azdiar A. Gazder

Faculty of Engineering and Information Sciences - Papers: Part A

A recently modified Elasto-Plastic Self-Consistent (EPSC) model which empirically accounts for both intergranular and intragranular back stresses has been successfully used to simulate the cyclic (tension-compression) loading behaviour of an Fe-24Mn-3Al-2Si-1Ni-0.06C TWinning Induced Plasticity (TWIP) steel between strain limits of ±1%. Lattice strain measurements acquired via in-situ neutron diffraction were used to further validate the modelling results. An improved prediction of the pronounced Bauschinger effect during unloading is achieved when the reversibility of partial slip in the 〈112〉 direction is accounted for. This result indicates a potential contribution of the stress-induced separation of partial dislocations to the observed early yielding …

Experimental Study On Frp Tube Reinforced Concrete Columns Under Different Loading Conditions, Weiqiang Wang, M Neaz Sheikh, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part A

The behavior of fiber-reinforced polymer (FRP) tube reinforced concrete (FTRC) columns under different loading conditions was investigated in this study. Four groups of 16 specimens were cast and tested. Specimens in the first group (the reference group) were re- inforced with longitudinal steel bars and steel helices (Group REF). Specimens in the second group were reinforced with intact glass FRP tubes (Group IT). Specimens in the third group were also reinforced with intact glass FRP tubes. In addition, polymer grid was embedded into the concrete cover to reduce the cover spalling (Group ITG). Specimens in the fourth group were reinforced …

An In-Situ Neutron Diffraction Study Of A Multi-Phase Transformation And Twinning-Induced Plasticity Steel During Cyclic Loading, Ahmed A. Saleh, Donald W. Brown, Elena V. Pereloma, Bjorn Clausen, Christopher H. J Davies, Carlos N. Tome, Azdiar A. Gazder

Faculty of Engineering and Information Sciences - Papers: Part A

In-situ neutron diffraction during cyclic tension-compression loading (þ3.5% to 2.8%) of a 17Mn-3Al-2Si-1Ni-0.06C steel that exhibits concurrent transformation and twinning -induced plasticity effects indicated a significant contribution of intragranular back stresses to the observed Bauschinger effect. Rietveld analysis revealed a higher rate of martensitic transformation during tension compared to compression. Throughout cycling, a0-martensite exhibited the highest phase strains such that it bears an increasing portion of the macroscopic load as its weight fraction evolves. On the other hand, the e-martensite strain remained compressive as it accommodated most of the internal strains caused by the shape misfit associated with the c!e …

Molecular Dynamics Study On The Grain Boundary Dislocation Source In Nanocrystalline Copper Under Tensile Loading, Liang Zhang, Cheng Lu, A Kiet Tieu, Linqing Pei, Xing Zhao, Kuiyu Cheng

Faculty of Engineering and Information Sciences - Papers: Part A

Grain boundary (GB) is the interface between different oriented crystals of the same material, and it can have a significant effect on the many properties of materials. When the average or entire range of grain size is reduced to less than 100 nm, the conventional plastic deformation mechanisms dominated by dislocation processes become difficult and GBmediated deformation mechanisms become increasingly important. One of the mechanisms that can play a profound role in the strength and plasticity of metallic polycrystalline materials is the heterogeneous nucleation and emission of dislocations from GB. In this study, we conducted molecular dynamics simulations to study …

Influence Of Loading Conditions During Tensile Testing On Acoustic Emission, Turbadrakh Chuluunbat, Cheng Lu, Andrii Kostryzhev, A Kiet Tieu

Faculty of Engineering and Information Sciences - Papers: Part A

The Acoustic Emission (AE) monitoring technique is widely used in mechanical and material research for detection of plastic deformation, fracture initiation and crack growth. However, the influence of AE features (such as signal amplitude, frequency, rise time and duration) on the fracture parameters (such as brittle or ductile mode of propagation and fracture propagation speed) is not completely understood. In this paper, the effect of loading conditions on fracture behavior was studied using AE monitoring during tensile testing of an aluminum alloy specimen. The fracture development was observed using a high speed video camera and was analyzed using the finite …

Behaviour Of Clay-Fouled Ballast Under Cyclic Loading, Nayoma Tennakoon, Buddhima Indraratna

Faculty of Engineering and Information Sciences - Papers: Part A

Expansion of the rail network in congested coastal Australia compels track construction on soft clayey subgrade, including fine-grained estuarine soils. In such low-lying areas, where the water table is close to the ground surface, the saturated soft subgrade is often subjected to pumping (mud slurry) under the application of cyclic wheel loads, thereby causing fouling of the overlying ballast. This technical note presents the results of a series of large-scale, drained, cyclic, triaxial tests conducted on clay-fouled ballast. The impact of fouling on the stress-strain behaviour, resilient modulus and degradation of ballast is discussed.

Numerical Analysis Of High-Strength Concrete-Filled Steel Tubular Slender Beam-Columns Under Cyclic Loading, Vipulkumar Patel, Qing Quan Liang, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part A

The effects of cyclic local buckling on the behavior of concrete-filled steel tubular (CFST) slender beam-columns under cyclic loading were approximately considered in existing analytical methods by modifying the stress– strain curve for the steel tube in compression. These methods, however, cannot simulate the progressive cyclic local buckling of the steel tubes. This paper presents a new efficient numerical model for predicting the cyclic performance of high strength rectangular CFST slender beam-columns accounting for the effects of progressive cyclic local buckling of steel tube walls under stress gradients. Uniaxial cyclic constitutive laws for the concrete core and steel tubes are …

The Response Of Axially Restrained Non-Composite Steel-Concrete-Steel Sandwich Panels Due To Large Impact Loading, Alex M. Remennikov, Sih Ying Kong, Brian Uy

Alex Remennikov

In conventional steel-concrete-steel (SCS) construction, the external steel plates are connected to the concrete infill by welded shear stud connectors. This paper describes a programme of experimental and numerical investigations on reduced-scale non-composite SCS panels with axially restrained connections. The experimental results have demonstrated that the non-composite SCS panels are capable of developing enhanced load-carrying capacity through the tensile membrane resistance of the steel faceplates. This type of construction was found to exhibit highly ductile response and be able to sustain large end rotations of up to 18° without collapse. High fidelity finite element models for SCS panels under impact …

Impact Of Mains Connected Three-Phase Induction Motor Loading Levels On Network Voltage Unbalance Attenuation, Upuli Jayatunga, Sarath Perera, Philip Ciufo

Dr Philip Ciufo

Voltage unbalance (VU) in power systems should be managed in a systematic manner in order to minimise its adverse effects on both customer equipment and supply utilities. It is a well known fact that three-phase induction motor performance can be significantly affected in the presence of supply voltage unbalance. It is also known that three-phase induction motors can help to reduce pre-existing network voltage unbalance levels. Recently undertaken research aligned with IEC/TR 61000-3-13:2008 Technical Report on voltage unbalance management (emission allocation and emission assessment) have quantified the contribution made by induction motors to the net voltage unbalance at a point …

The Response Of Axially Restrained Non-Composite Steel-Concrete-Steel Sandwich Panels Due To Large Impact Loading, Alex M. Remennikov, Sih Ying Kong, Brian Uy

Faculty of Engineering and Information Sciences - Papers: Part A

In conventional steel-concrete-steel (SCS) construction, the external steel plates are connected to the concrete infill by welded shear stud connectors. This paper describes a programme of experimental and numerical investigations on reduced-scale non-composite SCS panels with axially restrained connections. The experimental results have demonstrated that the non-composite SCS panels are capable of developing enhanced load-carrying capacity through the tensile membrane resistance of the steel faceplates. This type of construction was found to exhibit highly ductile response and be able to sustain large end rotations of up to 18° without collapse. High fidelity finite element models for SCS panels under impact …

A Density- And Stress-Dependent Elasto-Plastic Model For Sands Subjected To Monotonic Undrained Torsional Shear Loading, G Chiaro, J Koseki, L. I Nalin De Silva

Faculty of Engineering and Information Sciences - Papers: Part A

A density- and stress-dependent elasto-plastic model for saturated sands undergoing monotonic undrained torsional shear loading is presented in this paper. The model is developed under an extended general hyperbolic equation (GHE) approach, in which the void ratio and stress level dependence upon stress-strain response of sand is incorporated. Most importantly, a state-dependent stress-dilatancy relationship is introduced to account for the effect of density on the stress ratio. Such a stress-dilatancy relation is used for modeling the excess pore water pressure generation in undrained shear conditions as the mirror effect of volumetric change in drained shear conditions. In this paper, details …

Sizing Optimization Of Trapezoidal Corrugated Roof Sheeting, Supporting Solar Panels, Under Wind Loading, P Sharafi, Lip H. Teh, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part A

The dimensions of trapezoidal roof sheeting supporting solar panels are optimized so that a minimum amount of steel is required for a specific range of wind loads. Sheets of different grades and different thicknesses along with different ranges of wind speeds are considered. In order to simulate the behavior of the corrugated sheets analysis is carried out for two limit states: strength and serviceability. For both limit states, the objective is to minimize the weight per unit area of the panels. First, optimum cross-section is obtained to meet the strength conditions. Then the deflection is controlled for serviceability. The optimum …

On The Evolution And Modelling Of Lattice Strains During The Cyclic Loading Of Twip Steel, Ahmed A. Saleh, Elena V. Pereloma, Bjorn Clausen, Donald W. Brown, Carlos N. Tome, Azdiar A. Gazder

Faculty of Engineering and Information Sciences - Papers: Part A

The evolution of lattice strains in fully annealed Fe–24Mn–3Al–2Si–1Ni–0.06C twinning-induced plasticity (TWIP) steel is investigated via in situ neutron diffraction during cyclic (tension–compression) loading between strain limits of ±1%. The pronounced Bauschinger effect observed upon load reversal is accounted for by a combination of the intergranular residual stresses and the intragranular sources of back stress, such as dislocation pile-ups at the intersection of stacking faults. The recently modified elasto-plastic self-consistent (EPSC) model which empirically accounts for both intergranular and intragranular back stresses has been successfully used to simulate the macroscopic stress–strain response and the evolution of the lattice strains. The …

Performance Of Cfrp Wrapped Square Reinforced Concrete Columns Subjected To Eccentric Loading, Ida Bagus Rai Widiarsa, Muhammad N. S Hadi

Faculty of Engineering and Information Sciences - Papers: Part A

Strengthening concrete columns with fibre-reinforced polymers (FRP) has been studied extensively, but the majority of published studies have focused on circular columns. Most concrete columns in the field have square or rectangular cross sections and resist eccentric loading as well. The objective of this study is to investigate the performance of square reinforced concrete (RC) columns wrapped with carbon FRP subjected to eccentric loading. The influence of two parameters was studied including the number of FRP layers and the magnitude of eccentricity. Compression testing was conducted on twelve short square RC columns wrapped with CFRP composites. The columns had a …

The Critical Role Of Mechanism-Based Models For Understanding And Predicting Liposomal Drug Loading, Binding And Release Kinetics, Sweta Modi

Theses and Dissertations--Pharmacy

Liposomal delivery systems hold considerable promise for improvement of cancer therapy provided that critical formulation design criteria can be met. The main objective of the current project was to enable quality by design in the formulation of liposomal delivery systems by developing comprehensive, mechanism-based mathematical models of drug loading, binding and release kinetics that take into account not only the therapeutic requirement but the physicochemical properties of the drug, the bilayer membrane, and the intraliposomal microenvironment.

Membrane binding of the drug affects both drug loading and release from liposomes. The influence of bilayer composition and phase structure on the partitioning …

Impact Of Mains Connected Three-Phase Induction Motor Loading Levels On Network Voltage Unbalance Attenuation, Upuli Jayatunga, Sarath Perera, Philip Ciufo

Faculty of Engineering and Information Sciences - Papers: Part A

Voltage unbalance (VU) in power systems should be managed in a systematic manner in order to minimise its adverse effects on both customer equipment and supply utilities. It is a well known fact that three-phase induction motor performance can be significantly affected in the presence of supply voltage unbalance. It is also known that three-phase induction motors can help to reduce pre-existing network voltage unbalance levels. Recently undertaken research aligned with IEC/TR 61000-3-13:2008 Technical Report on voltage unbalance management (emission allocation and emission assessment) have quantified the contribution made by induction motors to the net voltage unbalance at a point …

Behaviour Of Hybrid Double-Skin Tubular Columns Subjected To Combined Axial Compression And Cyclic Lateral Loading, Bing Zhang, J G. Teng, Tao Yu

Faculty of Engineering and Information Sciences - Papers: Part A

Hybrid FRP-concrete-steel double-skin tubular columns (hybrid DSTCs) are a new form of hybrid columns developed at The Hong Kong Polytechnic University. They consist of an outer tube made of fibre reinforced polymer (FRP) and an inner tube made of steel, with the space between filled with concrete. In these hybrid DSTCs, the three constituent materials are optimally combined to achieve several advantages not available with existing forms of columns, including their superior corrosion and seismic performance. This paper presents the test results of a series of large-scale hybrid DSTCs subjected to combined axial and cyclic lateral loads, with an emphasis …

Behaviour Of Cfrp Wrapped Square Rc Columns Under Eccentric Loading, Xu Lei, Thong Minh Pham, Muhammad N. Hadi

Faculty of Engineering and Information Sciences - Papers: Part A

Fibre Reinforced Polymer (FRP) is an excellent material to strengthen existing structures. However, the confinement efficiency of FRP - confined square columns is relatively low compared to circular columns due to stress concentration at the sharp corners. This paper presents a new techniqu e aimed to maximise the efficiency of FRP confinement for square concrete columns : circularisation using segmental circular concrete covers . Sixteen square reinforced concrete columns were cast. Four were used as a reference group; four were rounded 20 mm at each corner and wrapped with three layers of CFRP simulating the conventional methods; the rest eight …

Evolution Of Internal Crack In Bcc Fe Under Compressive Loading, Dongbin Wei, Zhengyi Jiang, Jingtao Han

Faculty of Engineering and Information Sciences - Papers: Part A

A molecular dynamics model has been developed to investigate the evolution of the internal crack of nano scale during heating or compressive loading in BCC Fe. The initial configuration does not contain any pre-existing dislocations. In the case of heating, temperature shows a significant effect on crack evolution and the critical temperature at which the crack healing becomes possible is 673 K. In the case of compressive loading, the crack can be healed at 40 K at a load- ing rate 0.025 × 1018 Pa·m1/2/s in 6 × 10−12 s. The diffusion of Fe atoms into the crack area results …

Effects Of Shoe Heel Height On Loading And Muscle Activity For Trans-Tibial Amputees During Standing, Xiaohong Jia, Rencheng Wang, Winson Lee

Faculty of Engineering and Information Sciences - Papers: Part A

This study accesses the effects of shoe heel heights on loading, muscle activity, and plantar foot pressure of trans-tibial amputees during standing. Five male subjects with unilateral trans-tibial amputation volunteered to participate in this study. Three pairs of shoes with zero, 20 mm, and 40 mm heel heights were used. The loading line of the prosthetic side, the plantar foot pressure, and the surface electromyography (EMG) of 10 muscles were simultaneously recorded. With increasing shoe heel heights during standing, the loading line of the prosthetic side shifted from the anterior to the posterior side of the knee center, the peak …

Loading Capabilities Assesment Of Power Transmission Lines, P Hu, Michael Negnevitsky, Kashem M. Muttaqi

Faculty of Engineering and Information Sciences - Papers: Part A

This paper reviews the factors that affect the loading capabilities of the transmission line over the short duration. The paper demonstrates how to determine the impact of various parameters on the permissible loading of bare conductors of a power transmission line. Methods for calculating these factors are presented. A sample of a practical application is also included in order to show how these factors affect the loading capabilities of a transmission line.