Social and Behavioral Sciences Commons^™

Hd R&D Field Evaluation: Light Soil Sifter, U.S. Humanitarian Demining Research And Development

Global CWD Repository

The light/sandy soil sifting project is evaluating the feasibility and operational suitability of using commercial beach-cleaning technologies to remove mines and clutter from sandy and mechanically prepared soils. Demining applications envisioned for these systems are removal of mines from sandy and other light soils, raking surface soil to collect clutter, and assisting with inspection and quality assurance behind mechanical clearance equipment. Distribution Statement A: Approved for public release.

Hd R&D Field Evaluation: Traxx, U.S. Humanitarian Demining Research And Development

Global CWD Repository

Traxx is an extremely compact, remote controlled vehicle capable of working in and around slopes of up to 60 degrees. It is equipped with a variety of commercial vegetation cutting implements and custom designed mine clearing tools. At less than 1.3 tons Traxx is easily transported to remote sites and capable of climbing and working on the most challenging hillsides. The factory equipped remote control has a working range of more than 300 meters and the 1.3 meter brush cutting attachments has demonstrated excellent capability for cutting saplings and heavy brush with little residual debris. Distribution Statement A: Approved for …

Mechanical Improvised Explosive Device Removal In The Urban Environment, David Parry

Global CWD Repository

The safe removal and disposal of conventional weapons from civilian populated areas in a post conflict scenario is fraught with dangerous, complex and wide-ranging challenges. The worldwide proliferation of improvised explosive devices has added to the existing burden of landmine clearance already being undertaken by various organizations. Part of the solution to these challenges is to remove improvised explosive devices using mechanical methods to reduce the likelihood and consequence of the risks that personnel face when carrying out this extremely hazardous task.

The mechanical removal of improvised explosive devices is an emerging methodology that is based on an established model …

Mechanical Properties Of Micro-Steel Fibre Reinforced Magnesium Potassium Phosphate Cement Composite, Hu Feng, M Neaz Sheikh, Muhammad N. S Hadi, Danying Gao, Jun Zhao

Faculty of Engineering and Information Sciences - Papers: Part B

This paper presents the mechanical properties of micro-steel fibre (MSF) reinforced magnesium potassium phosphate cement (MPPC) composites with multi-composite retarder. The compressive strength, flexural strength, flexural toughness and flexural ductility of the MSF reinforced MPPC composite (MSFRMC) were experimentally explored. The variables of the experiment included sand-cement mass ratio, water-cement mass ratio, curing time and fibre volume fraction. In addition, the effect of different types of cement on the mechanical properties of MSF reinforced composites was investigated. It was found that with the increase of water content in the MPPC paste, the average compressive strength, flexural strength and flexural toughness …

Characterization And Mechanical Properties Of Α-Al2o3 Particle Reinforced Aluminium Matrix Composites, Synthesized Via Uniball Magneto-Milling And Uniaxial Hot Pressing, Buraq Talib Shalash Al-Mosawi, David Wexler, Andrzej Calka

Faculty of Engineering and Information Sciences - Papers: Part A

Al-based composite powders containing 2, 4, 7 and 10 volume fraction of α-Al₂O₃ were prepared using the uniball controlled magneto-milling method and were then uniaxially hot pressed at (600 ± 10)°C under 70 MPa for 15 min. The resulting composites were greater than 99% theoretical density with enhanced mechanical properties. Detailed characterization was performed using: X-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, electrical conductivity, compression, ultra-micro indentation testing and pin on drum wear testing at ambient temperature. Microstructure-mechanical property correlations were obtained as functions of α-Al₂O₃ volume fraction. It was found …

Strain-Induced Ferrite Formation And Its Effect On Mechanical Properties Of A Dual Phase Steel Produced Using Laboratory Simulated Strip Casting, Zhiping Xiong, Ahmed A. Saleh, Andrii Kostryzhev, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part B

Thermo-mechanical processing of a strip cast dual phase (DP) steel was carried out using a Gleeble thermo-mechanical simulator. The effect of deformation temperatures in the range from 1050 to 700 °C on the microstructure evolution was investigated using optical, scanning and transmission electron microscopy along with electron backscattering diffraction (EBSD). Strain-induced ferrite (SIF) formation was observed following austenite deformation (∼0.41 reduction) in the 800–700 °C temperature range, leading to a ferrite grain refinement down to 3.1 ± 2.3 μm. A novel segmentation procedure was applied to separate selected EBSD maps into polygonal ferrite, SIF and second phase regions (bainite/martensite). Following …

Effect Of Deformation On Microstructure And Mechanical Properties Of Dual Phase Steel Produced Via Strip Casting Simulation, Zhiping Xiong, Andrii Kostryzhev, Nicole Stanford, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

The strip casting is a recently appeared technology with a potential to significantly reduce energy consumption in steel production, compared to hot rolling and cold rolling. However, the quantitative dependences of the steel microstructure and mechanical properties on strip casting parameters are unknown and require investigation. In the present work we studied the effects of strain and interrupted cooling temperature on microstructure and mechanical properties in conventional dual phase steel (0.08C-0.81Si-1.47Mn-0.03Al wt%). The strip casting process was simulated using a Gleeble 3500 thermo-mechanical simulator. The steel microstructures were studied using optical, scanning and transmission electron microscopy. Mechanical properties were measured …

Mechanical Recoverability And Damage Process Of Ionic-Covalent Paam-Alginate Hybrid Hydrogels, Hai Xin, Hugh Ralph Brown, Sina Naficy, Geoffrey M. Spinks

Faculty of Engineering and Information Sciences - Papers: Part A

Hydrogels consisting of interpenetrating networks of ionically and covalently crosslinked polymers showed high toughness and mechanical recoverability as a result of the dissociation and re-formation of ionic crosslinks. The present investigation aimed to provide a quantitative study on the mechanical recoverability and damage process of an example hybrid gel of calcium crosslinked alginate and covalently crosslinked polyacrylamide. Three series of load/unload tests were performed sequentially with the mechanical properties of the gel fully retrieved between the 2nd and 3rd load/unload series while only the partial recovery of mechanical properties was evident from the 1st to 2nd series. The load/unload curves …

Mechanical Properties And Tribological Behavior Of Aluminum Matrix Composites Reinforced With In-Situ Alb2 Particles, Linlin Yuan, Jingtao Han, Jing Liu, Zhengyi Jiang

Faculty of Engineering and Information Sciences - Papers: Part A

Aluminum matrix composites (AMCs) reinforced with in-situ AlB₂ particles have been fabricated using a combination of powder metallurgy, hot rolling and solution treatment. The effects of boron content (7 and 12 wt%), hot rolling and heat treatment parameters on the microstructures and mechanical properties of the composites were investigated by means of scanning electron microscopy (SEM), tensile test and micro-hardness measurements. The friction coefficient, wear behavior and scratch morphology of the AMCs and pure aluminum were also studied using scratch tests. The hardness and wear properties are higher in a case of composites when compared to unreinforced matrix material.

Rapid Transformation Of Hexagonal To Cubic Silicon Carbide (Sic) By Electric Discharge Assisted Mechanical Milling, Iis Siti Aisyah, Monika Wyszomirska, Andrzej Calka, David Wexler

Faculty of Engineering and Information Sciences - Papers: Part A

Silicon carbide powder was successfully transformed from hexagonal SiC into cubic SiC using the electric discharge assisted mechanical milling (EDAMM) method. The milling process was conducted in nitrogen plasma at atmospheric pressure. The effects of pulsed alternating current (AC) and direct current (DC) discharge on product formation were investigated. Products were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and nanohardness. It was found that hexagonal SiC can be transformed into cubic SiC under EDAMM processing, near complete transformation occurring within 5 min when applying AC mode electrical pulses, and within 10 min when applying DC mode discharges.

Microstructures And Mechanical Properties Of Trip Steel Produced By Strip Casting Simulated In The Laboratory, Zhiping Xiong, Andrii Kostryzhev, Ahmed A. Saleh, Liang Chen, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

Conventional transformation induced plasticity (TRIP) steel (0.17C-1.52Si-1.61Mn-0.03Al, wt%) was produced via strip casting technology simulated in the laboratory. Effects of holding temperature, holding time and cooling rate on ferrite formation were studied via analysis of the continuous cooling transformation diagram obtained here. A typical microstructure for conventional TRIP steels consisting of ~ 0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite was obtained. However, coarse prior austenite grain size of ~80 μm led to large polygonal ferrite grain size of ~17 μm, coarse second phase regions of ~21 μm size, small amount of retained austenite (0.02-0.045) and the …

Special Rolling Techniques For Improvement Of Mechanical Properties Of Ultrafine-Grained Metal Sheets: A Review, Hai Liang Yu, Cheng Lu, Anh Kiet Tieu, Hui Jun Li, Ajit R. Godbole, Shi-Hong Zhang

Faculty of Engineering and Information Sciences - Papers: Part A

Interest in ultrafine-grained (UFG) materials has grown rapidly in past 20 years. This review focuses on the application of special rolling techniques for improvement of the mechanical properties of UFG metal sheets. These techniques include asymmetric rolling, cryorolling, asymmetric cryorolling, cross-accumulative roll bonding, and skin-pass rolling. The techniques also include a combination of processes such as equal channel angular press and subsequent rolling, combined high-pressure torsion and subsequent rolling, as well as combined accumulative roll bonding and subsequent asymmetric rolling. We also discuss the main mechanisms leading to improvement in the ductility of UFG materials related to the special rolling …

Enhanced Mechanical Properties Of Arb-Processed Aluminum Alloy 6061 Sheets By Subsequent Asymmetric Cryorolling And Ageing, Hai Liang Yu, Lihong Su, Cheng Lu, Anh Kiet Tieu, Hui Jun Li, Jintao Li, Ajit R. Godbole, Charlie Kong

Faculty of Engineering and Information Sciences - Papers: Part A

Grain size and precipitations affect the strength and ductility of ultrafine-grained materials. In this study, aluminum alloy 6061 sheets were fabricated using the accumulative roll bonding (ARB) technique. The ARB-processed sheets were subsequently subjected to cryorolling and asymmetric cryorolling. The sheets were further aged at 100 °C for 48 h. Mechanical tests show that a combination of asymmetric cryorolling and ageing results in significant improvement in both the ductility and the strength of the ARB-processed sheets. The microstructures of the sheets at different stages of the process were also analyzed using optical microscopy, scanning electron microscopy, transmission electron microscopy and …

Microstructure And Mechanical Properties Of Strip Cast Trip Steel Subjected To Thermo-Mechanical Simulation, Zhiping Xiong, Andrii Kostryzhev, Liang Chen, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

Instead of hot rolling and cold rolling followed by annealing, strip casting is a more economic and environmentally friendly way to produce transformation-induced plasticity (TRIP) steels. According to industrial practice of strip casting, rapid cooling in this work was achieved using a dip tester, and a Gleeble 3500 thermo-mechanical simulator was used to carry out the processing route. A typical microstructure of TRIP steels, which included ~0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite, was obtained. The effects of deformation (0.41 reduction) above non-recrystallisation temperature, isothermal bainite transformation temperature and the size of second phase region on …

Microscale Mechanical Behaviour Of Ultra-Fine-Grained Materials Processed By High-Pressure Torsion, Klaus-Dieter Liss

Faculty of Engineering and Information Sciences - Papers: Part A

A special networking seminar was given by Associate Professor Megumi Kawasaki from Hanyang University, South Korea. The seminar covered microscale mechanical behaviour of ultrafine- grained materials processed by high-pressure torsion, and was co-organised by the School of Mechanical, Materials and Mechatronic Engineering (MMME), University of Wollongong and Materials Australia NSW. The event was hosted on 20 September 2016 at a sponsored networking tea by MMME.

Mechanical Fatigue Performance Of Pcl-Chondroprogenitor Constructs After Cell Culture Under Bioreactor Mechanical Stimulus, J A. Panadero, Vitor Sencadas, Sonia C.M. Silva, Clarisse Ribeiro, Vítor Correia, F M. Gama, J L. Gomez Ribelles, Senentxu Lanceros-Méndez

Faculty of Engineering and Information Sciences - Papers: Part A

In tissue engineering of cartilage, polymeric scaffolds are implanted in the damaged tissue and subjected to repeated compression loading cycles. The possibility of failure due to mechanical fatigue has not been properly addressed in these scaffolds. Nevertheless, the macroporous scaffold is susceptible to failure after repeated loading- unloading cycles. This is related to inherent discontinuities in the material due to the micropore structure of the macropore walls that act as stress concentration points. In this work, chondrogenic precursor cells have been seeded in poly-e-caprolactone (PCL) scaffolds with fibrin and some were submitted to free swelling culture and others to cyclic …

Applications Of Controllable Smart Fluids To Mechanical Systems, Seung-Bok Choi, Norman Wereley, Weihua Li, Miao Yu, Jeong-Hoi Koo

Miao Yu

For this special issue, 20 papers have been received, and three of which have been withdrawn. After strict review processes by the world-wide experts on the smart fluids technology, 10 papers have been accepted and are published here.The published papers cover various application devices and systems, which can be controllable to achieve desired performances by applying the external fields to the smart fluid domains. A brief summary of each application item proposed in the published papers is given as follows.

Simulink Model For Examining Dynamic Interactions Involving Electro-Mechanical Oscillations In Distribution Systems, Dothinka Ranamuka Rallage, Ashish P. Agalgaonkar, Kashem M. Muttaqi

Faculty of Engineering and Information Sciences - Papers: Part A

In Australian medium voltage (MV) distribution networks, the majority of embedded local generation (LG) uses synchronous machine based technology. LG units with a synchronous generator can easily be dispatched and controlled to provide or absorb reactive power and thereby locally supporting the system voltage and increasing the voltage stability margin. The fast response from a synchronous machine based LG unit exciter will ensure fast voltage recovery. This will significantly improve the transient voltage stability. Also, the synchronous machine based LG units can provide inertial support to the system. Furthermore, some of these LG technologies work as standby power supplies all …

In Vitro Mechanical Fatigue Behavior Of Poly-Ɛ-Caprolactone Macroporous Scaffolds For Cartilage Tissue Engineering: Influence Of Pore Filling By A Poly(Vinyl Alcohol) Gel, J A. Panadero, L Vikingsson, J L. Gomez Ribelles, Senentxu Lanceros-Méndez, Vitor Sencadas

Faculty of Engineering and Information Sciences - Papers: Part A

Polymeric scaffolds used in regenerative therapies are implanted in the damaged tissue and submitted to repeated loading cycles. In the case of articular cartilage engineering, an implanted scaffold is typically subjected to long-term dynamic compression. The evolution of the mechanical properties of the scaffold during bioresorption has been deeply studied in the past, but the possibility of failure due to mechanical fatigue has not been properly addressed. Nevertheless, the macroporous scaffold is susceptible to failure after repeated loading-unloading cycles. In this work fatigue studies of polycaprolactone scaffolds were carried by subjecting the scaffold to repeated compression cycles in conditions simulating …

The Effects Of Vacuum Annealing Temperatures On The Microstructure, Mechanical Properties And Electrical Resistivity Of Mg-3al-1zn Alloy Ribbons, Fenghua Chen, Qingxue Huang, Zhengyi Jiang, Jingwei Zhao, Binyu Sun, Yugui Li

Faculty of Engineering and Information Sciences - Papers: Part A

This paper investigates the influence of vacuum annealing temperature on the microstructure, mechanical properties and electrical resistivity of Mg-3Al-1Zn rapid solidification (RS) magnesium ribbons. The results indicate that when the annealing temperature is increased, the grain size of the ribbons is dramatically reduced from 10 to 1 μm. The highest break stress and micro-hardness is obtained at 673 K. These effects are ascribed to the dispersion strengthening caused by the high amount of fine nanoparticles distributed in the material. Electrical resistivity-temperature (ρ-T) curves have been used to provide useful information about the effects of the annealing temperature on the grain …

Grain Size Effect Of Thickness/Average Grain Size On Mechanical Behaviour, Fracture Mechanism And Constitutive Model For Phosphor Bronze Foil, Zhi Fang, Zhengyi Jiang, Xiaogang Wang, Cunlong Zhou, Dongbin Wei, Xianghua Liu

Faculty of Engineering and Information Sciences - Papers: Part A

Size effects play a significant role in microforming process, and any dimensional change can have a great impact on materials' mechanical properties. In this paper, the size effects on deformation behaviour and fracture of phosphor foil were investigated in the form of grain size effect: the ratio of materials' thickness (T) to average grain size (D) by micro tensile tests. The ratio was designed to be closed to but larger than, less than and equal to 1, respectively. The results show that the amount of plastic deformation decreases with the decrease of the ratio of T/D, which indicates that the …

Time-Dependent Mechanical Properties Of Tough Ionic-Covalent Hybrid Hydrogels, Hai Xin, Hugh Ralph Brown, Sina Naficy, Geoffrey M. Spinks

Faculty of Engineering and Information Sciences - Papers: Part A

Hybrid gels featuring interpenetrating covalent and ionic crosslinked networks have recently been shown to exhibit both high toughness and recoverability of strain-induced network damage. The high toughness results from the energy dissipated as entropically strained network strands are released by the dissociation of ionic crosslinks. As in the so-called double network hydrogels, the toughening process is inherently linked to network damage. This damage, however, can be recovered to a large degree in hybrid gels due to the reformation of ionic associations when the gel is unloaded. The stability of the ionic network under load is here investigated and it is …

A Combined Experimental-Numerical Approach For Determining Mechanical Properties Of Aluminum Subjects To Nanoindentation, Mao Liu, Cheng Lu, A Kiet Tieu, Ching-Tun Peng, Charlie Kong

Faculty of Engineering and Information Sciences - Papers: Part A

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the mechanical properties and micro-texture evolution of single-crystal aluminum induced by a sharp Berkovich indenter. The load-displacement curves, pile-up patterns and lattice rotation angles from simulation are consistent with the experimental results. The pile-up phenomenon and lattice rotation have been discussed based on the theory of crystal plasticity. In addition, a polycrystal tensile CPFEM model has been established to explore the relationship between indentation hardness and yield stress. The elastic constraint factor C is slightly larger than conventional value 3 due to the strain hardening.

Effect Of Pre-Quenching Process On Microstructure And Mechanical Properties In A Nb-Microalloyed Low Carbon Q-P Steel, Jun Zhang, Hua Ding, Jingwei Zhao

Faculty of Engineering and Information Sciences - Papers: Part A

A refined microstructure consisting of martensite and retained austenite at room temperature has been produced in a Nb-microalloyed low carbon Si-Mn steel by a novel heat-treatment, pre-quenching prior to quenching and partitioning processes (Q&Q-P). The results showed that compared with the conventional quenching and partitioning steel the mechanical properties of steel obtained by the novel treatment have been significantly improved, with a good combination of ultimate tensile strength (1000MPa) and total elongation (above 30%). Meanwhile, the volume fraction of retained austenite has been increased. It was found that the improvement of mechanical properties was mainly attributed to the enhanced TRIP …

Graphene Cryogel Papers With Enhanced Mechanical Strength For High Performance Lithium Battery Anodes, Kewei Shu, Caiyun Wang, Meng Wang, Chen Zhao, Gordon G. Wallace

Gordon Wallace

A porous graphene paper was prepared by pressing a graphene cryogel, followed by thermal reduction at 220 °C. The cryogel was formed by freeze-drying a solution containing chemically reduced graphene and graphene oxide (CRG/GO). The formed graphene cryogel papers deliver a much higher discharge capacity and rate capability than that from conventional graphene papers fabricated by filtration. These new structures have a discharge capacity higher than 400 mA h g−1 at a current density of 2000 mA g−1 in sharp contrast to 229 mA h g−1 at 50 mA g−1 obtained from conventional graphene papers. These greatly improved electrochemical properties …

Graphene Cryogel Papers With Enhanced Mechanical Strength For High Performance Lithium Battery Anodes, Kewei Shu, Caiyun Wang, Meng Wang, Chen Zhao, Gordon G. Wallace

Faculty of Science, Medicine and Health - Papers: part A

A porous graphene paper was prepared by pressing a graphene cryogel, followed by thermal reduction at 220 °C. The cryogel was formed by freeze-drying a solution containing chemically reduced graphene and graphene oxide (CRG/GO). The formed graphene cryogel papers deliver a much higher discharge capacity and rate capability than that from conventional graphene papers fabricated by filtration. These new structures have a discharge capacity higher than 400 mA h g−1 at a current density of 2000 mA g−1 in sharp contrast to 229 mA h g−1 at 50 mA g−1 obtained from conventional graphene papers. These greatly improved electrochemical properties …

Microstructural Evolution And Mechanical Property Of Aa5050 Alloy Deformed By Accumulative Roll Bonding, Kuiyu Cheng, Cheng Lu, A Kiet Tieu, Hongtao Zhu

Faculty of Engineering and Information Sciences - Papers: Part A

In this study, ultrafine-grained AA5050 sheets were fabricated by the accumulative roll bonding (ARB) process. Transmission electron microscope observations showed that at the early stage of ARB, the grain size was reduced in the normal direction and became elongated along the rolling direction. The elongated grains were cut out by dense dislocations, which then tangled and condensed, resulting in the formation of dislocation cells. As the deformation proceeded, the dislocation cells evolved to sub-grain boundaries and then grain boundaries. The ultrafinegrained microstructure was obtained via four ARB cycles. The tensile tests at 473 K and 523 K (200 degrees C …

Effects Of Temperature And Strain Rate On Microstructure And Mechanical Properties Of High Chromium Cast Iron/Low Carbon Steel Bimetal Prepared By Hot Diffusion-Compression Bonding, Xingjian Gao, Zhengyi Jiang, Dongbin Wei, Sihai Jiao, Dengfu Chen, Jianzhong Xu, Xiaoming Zhang, Dianyao Gong

Faculty of Engineering and Information Sciences - Papers: Part A

The objective of this study is to develop a hot diffusion-compression bonding process for cladding low carbon steel (LCS) to high chromium cast iron (HCCI) in solid-state. The influence of temperature (950-1150 degrees C) and strain rate (0.001-1 s (1)) on microstructure, hardness and bond strength of the HCCI/LCS bimetal were investigated. The interface microstructure reveals that the unbonded region can only be found for 950 degrees C due to lack of diffusion, while the intergrowth between the constituent metals occurred at and above 1100 degrees C. When bonding temperature increases to 1150 degrees C, a carbide-free zone was observed …

Molecular Weight Distribution Of Network Strands In Double Network Hydrogels Estimated By Mechanical Testing, Hai Xin, Hugh Ralph Brown, Geoffrey M. Spinks

Faculty of Engineering and Information Sciences - Papers: Part A

The remarkably high toughness of double network (DN) hydrogels is related to the energy dissipation that occurs due to the scission of network strands in the most tightly crosslinked of its two interpenetrating networks. The loading curve during tensile testing of DN hydrogels usually takes a complex shape and sometimes shows yielding. Wang and Hong recently proposed a model [1] based on the successive scission of the shortest remaining elastically active strands during tensile loading that predicts the shape of the loading curve of one DN hydrogel reasonably well. In the present study, the model was modified slightly and applied …

A Validated Thermo Mechanical Fem Model Of Bead-On-Plate Welding, Djarot Darmadi, A Kiet Tieu, John Norrish

Faculty of Engineering and Information Sciences - Papers: Part A

This paper is presenting accurate FEM model of bead-on-plate welds of 316L stainless steels through thermo-mechanical analysis. The model was composed using ANSYS Parametric Design Language (APDL) program. In thermal analysis, mixed mode of volumetric thermal load was used to represent moving heat source. Growing weld bead was accommodated in both the thermal and mechanical models using birth and death technique. Melting phenomenon was modelled by low stiffness and zero plastic strain of melting elements. Results from thermal analysis and subsequent mechanical analysis have been validated. Good agreements of predicted temperature histories, temperature field and residual stress with experimental results …