Multi-scale modelling of DP590 steel

Dual Phase (DP) steel one of the Advanced High Strength Steels (AHSS) has a two phase microstructure where soft and hard phase acts together to offer a high strength composite effect. The high strength, however, must be balanced with ductility so that complex parts and designs can be manufactured from AHSS sheets. However, during forming certain grades of DP steel a sudden crack can occur without any intimation of necking. Thus, due to this abnormal forming behaviour, is difficult to accurately predict because most classical modelling approaches are not designed for such micro-structurally heterogeneous materials. These modelling approaches are generally based on an average representation of the material behaviour in a continuum mechanics formulation. This works for materials that are homogenous, or at least could be assumed to be homogenous at scales lower than the naked eye can see. However, for a material like AHSS, the microstructure plays a significant role in dictating the mechanical behaviour at the macro-scale. This paper studies the multi-scale modelling ofDP590 steel. It is found that the sufficient accuracy can be achieved from multi-scale modelling while comparing with the experiments.

Fracture of DP590 steel : a multi-scale modeling approach

Advanced high strength steel sheets are one of the higher strength advance material developed by the steel industry for automotive bodies. One of the categories of this advanced high strength steel is Dual Phase (DP) steel. This steel consists of a two phase microstructure where soft and hard phase acts together to offer a high strength composite effect. The combination of high strength and ductility exhibited by these sheets allows the design and manufacture of complex parts. However, during forming certain grades of DP steel sudden cracking can occur without any intimation of necking. This abnormal forming behavior is difficult to accurately predict because most classical modelling approaches are not designed for such micro-structurally heterogeneous materials. These modelling approaches are generally based on an average representation of the material behaviour in a continuum mechanics formulation. This works for materials that are homogenous, or at least could be assumed to be homogenous at scales lower than the naked eye can see. However, for a material like advanced high strength steel, the microstructure plays a significant role in dictating the mechanical behavior at the macro-scale. This paper studies the forming and fracture behavior through multi-scale modeling of DPO590 steel. It is found that the sufficient accuracy can be achieved from multi-scale modeling when comparing with experiments.

Effects of micro-structural parameters on mechanical properties of carbon nanotube polymer nanocomposites

A comparison between the elastic modulus of carbon nanotube (CNT) polymer nano composites predicted by classical micromechanics theories, based on continuum mechanics and experimental data, was made and the results revealed a great difference. To improve the accuracy of these models, a new two-step semi-analytical method was developed, which allowed consideration of the effect of the interphase, in addition to CNT and matrix, in the modeling of nanocomposites. Based on this developed method, the inuence of microstructural parameters, such as CNT volume fraction, CNT aspect ratio, partial and complete agglomerations of CNTs, and overlap and exfoliation of CNTs, on the overall elastic modulus of nanocomposites was investigated. ©2014 Sharif University of Technology. All rights reserved.

Counter-terrorism across the policing continuum

Over the past two decades private and hybrid forms of policing have grown considerably in Australia. As a result, governments have begun to recognize the role played by non-state police agencies and personnel in the provision of public order and safety, further extending and legitimizing non-state policing. In addition, the private ownership of critical infrastructure and 'communal spaces' has led to a central role for non-state police in the area of 'high policing' counter-terrorism. In response to changes to the auspices and providers of policing, state police were beginning to explore new ways of working with private and hybrid forms of policing, with the emergence of a new type of experiment in policing partnerships, the Police-Private Security Committee (POLSEC). This paper examines these trends and implications for ongoing developments in Australian policing.

Finding a 'safe' place on the risk continuum: a case study of pregnancy and birthing in Lao PDR (Lao People's Democratic Republic)

This paper addresses two questions. Firstly: are the risk regimes faced, and perceived, by pregnant women in rural Lao PDR substantially different from those experienced by pregnant women in western societies? Secondly, if the Lao experiences and perceptions are different, can improvements in maternal health in Lao PDR be achieved without Laotians inheriting the risk regimes of late modernity experienced by many women in western societies? Secondary analysis is undertaken of data collected in 2005 for the evaluation of a pilot maternity waiting home in Bolikhan, Lao PDR. The results suggest significantly different risk perceptions and experiences between Lao and western communities, based on contrasting views of embodiment, identity construction and cosmologies. In the Lao rural communities studied, there is little evidence yet of 'risk society' despite the introduction of western technologies and practices to improve maternal mortality and morbidity. It is argued that 'risk society' can be avoided.

The diet of powerful owls (Ninox strenua) and prey availability in a continuum of habitats from disturbed urban fringe to protected forest environments in south-eastern Australia

This study investigates the diet of six breeding pairs of powerful owls in the Yarra Valley Corridor in Victoria, Australia, and compares prey consumption with prey availability. The six sites represent a continuum of habitats, ranging from urban Melbourne, through the urban fringe interface to a more forested landscape. We found that powerful owls in the Yarra Valley Corridor are reliant almost exclusively on arboreal marsupial prey as their preferred diet, with 99% of their overall diet comprising four arboreal marsupial species. These four species (the common ringtail possum, common brushtail possum, sugar glider and greater glider) were also the most abundant species observed while spotlighting; however, their abundance varied along the continuum. There was a strong positive relationship with the presence of these species in the diet and their site-specific availability, indicating that the powerful owl is a generalist hunter, preying on the most available prey at a given site and in a given season. This study suggests that food resources are high in these disturbed urban fringe sites and it is unlikely that food availability in urban environments will limit the potential survival of urban powerful owls.

Improving on- and off-campus student performance in structural mechanics

This paper investigates the performance of 329 (173 on- and 186  off-campus) students enrolled in two structural mechanics units at Deakin University, a leader in engineering distance-education in Australia. The two units experience unacceptably high rates of failure. An analysis of the assignment, laboratory and examination marks is presented. Consideration is also given to the total marks. The results show that on-campus students perform better in structural mechanics than their off-campus counterparts. Plots of the student performance distributions for the three assessment methods are provided (for each unit) and high failure rates are linked to low examination marks. Students tend to perform best in assignments and worst in examinations. Parametric statistical tests show a correlation between the continuous assessment and examination marks. To motivate students to fully participate in continuous assessment tasks the authors therefore propose several changes to the assessment criteria and marking schemes.

Delivery and assessment strategies to improve on- and off-campus student performance in structural mechanics

This paper considers the delivery and assessment strategies used in two structural mechanics units at Deakin University, a leader in distance education in Australia. The two units have had unacceptably high rates of student failure. Student perceptions of the delivery method were analysed and an investigation was carried out of the performance of 329 (173 on- and 156 off-campus) students enrolled in the two units. An analysis of the assignment, laboratory and examination marks is presented. Consideration is also given to the total marks. The results show that on-campus students performed better in structural mechanics than their off-campus counterparts. Plots of the distributions of student performance for the three assessment methods are provided (for each unit) and high failure rates are linked to low examination marks. Students tended to perform best in assignments and worst in examinations. Parametric statistical tests show a correlation between the marks obtained in continuous assessment and in examinations, and it is therefore proposed that, in order to improve performance, the students must be encouraged to participate fully in all aspects of the course. Many students were unenthusiastic about laboratory practical sessions and did not think they aided their understanding of the theoretical material. Motivation to participate is often dependent on the perceived relevance of a given task and its contribution to the total mark and, thus, to help motivate students to participate fully in the continuous assessment tasks, the authors propose several changes to the delivery methods, as well as to assessment criteria and marking schemes.

Healthcare in continuum for an ageing population: national self monitoring or remote offshore monitoring for Australia?

Australia is a country, similar to other developed nations, confronting an ageing population with complex demographics. Ensuring continued healthcare for the ageing, while providing sufficient support for the already aged population requiring assistance, is at the forefront of the national agenda. Varied initiatives are with foci to leverage the advantages of lCTs leading to e-Health provisioning and assisted technologies. While these initiatives increasingly put budgetary constraints on local and federal governments, there is also a case for offshore resourcing of non-critical health services, to support, streamline and enhance the continuum of care, as the nation faces acute shortages of medical practitioners and nurses. However, privacy and confidentiality concerns in this context are a significant issue in Australia. In this paper, we take the position that if the National and state electronic health records system initiatives, are fully implemented, offshore resourcing can be a feasible complementary option resulting in a win-win situation of cutting costs and enabling the continuum of healthcare.

Is tendon pathology a continuum? A pathology model to explain the clinical presentation of load-induced tendinopathy

Overuse tendinopathy is problematic to manage clinically. People of different ages with tendons under diverse loads present with varying degrees of pain, irritability, and capacity to function. Recovery is similarly variable; some tendons recover with simple interventions, some remain resistant to all treatments.

The pathology of tendinopathy has been described as degenerative or failed healing. Neither of these descriptions fully explains the heterogeneity of presentation. This review proposes, and provides evidence for, a continuum of pathology. This model of pathology allows rational placement of treatments along the continuum.

A new model of tendinopathy and thoughtful treatment implementation may improve outcomes for those with tendinopathy. This model is presented for evaluation by clinicians and researchers.

Where did we go wrong? An examination of students treatment of experimental error in engineering mechanics laboratories

The ability of engineers and applied scientists to undertake experimental measurements is a fundamental requirement of the profession. However, it is not simply good enough to be able to perform experiments if we are not able to interpret the results. In this study, reports prepared by mechanical engineering students were examined to determine how students dealt with the disparity between experimental measurements and theoretical results in their Engineering Mechanics laboratories. Analysis of the reports, and discussions with students in their laboratory classes, revealed a superficial understanding or regard for experimental error. This superficial treatment of experimental error is, most likely, due to a number of factors that are discussed. Some possible strategies for addressing the issue are also examined.