RMIT University

About: RMIT University is a education organization based out in Melbourne, Victoria, Australia. It is known for research contribution in the topics: Population & Health care. The organization has 40468 authors who have published 82923 publications receiving 1729499 citations. The organization is also known as: Royal Melbourne Institute of Technology & Melbourne Technical College.

A mechanistic interpretation of the comparative in-plane mechanical properties of 3D woven, stitched and pinned composites

Abstract: A comparison of substantial published data for 3D woven, stitched and pinned composites quantifies the advantages and disadvantages of these different types of through-thickness reinforcement for in-plane mechanical properties. Stitching or 3D weaving can either improve or degrade the tension, compression, flexure and interlaminar shear properties, usually by less than 20%. Furthermore, the property changes are not strongly influenced by the volume content or diameter of the through-thickness reinforcement for these two processes. One implication of this result is that high levels of through-thickness reinforcement can be incorporated where needed to achieve high impact damage resistance. In contrast, pinning always degrades in-plane properties and fatigue performance, to a degree that increases monotonically with the volume content and diameter of the pins. Property trends are interpreted where possible in terms of known failure mechanisms and expectations from modelling. Some major gaps in data and mechanistic understanding are identified, with specific suggestions for new standards for recording data and new types of experiments.

Recycling waste rubber tyres in construction materials and associated environmental considerations: A review

Abstract: Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Waste tyres in landfill and stockpiles are renowned for leaching toxic chemicals into the surrounding environment, acting as breeding grounds for mosquitoes, and fuelling inextinguishable fires. The properties of waste tyre rubber and engineering applications have been previously reported in a range of publications with respect to the environmental, economic, and technical factors. This study compiles and reviews this research with a focus on geotechnical engineering applications, such as earthworks and infrastructure construction. The applications of waste rubber in construction materials includes cementitious concrete, asphalt concrete, and granular materials for earth structures. Crumb rubber, when used as a sand replacement in flowable concrete fill, improved ductility and strength-to-weight ratio. A 40 MPa concrete mix with 0.6% rubber crumb content exhibited optimal strength and air entrainment capabilities, displaying minimal damage after 56 freeze/thaw cycles. Rubber, as a partial replacement for aggregate in road base and sub-base layers, adversely affected the California Bearing Ratio (CBR) of the graded aggregate base course. Rubber-soil mixtures as the interface of foundation and structure yielded a 60–70 % reduction in vertical and horizontal ground accelerations when subjected to earthquake simulation modelling. There is concern regarding the toxicity of waste rubber incorporated products due to leachates of heavy metals and other chemicals common in tyres. Further comprehensive studies in this area are needed. Leachate studies should be conducted under different pH and liquid to solid ratios.

Cooperative Co-evolution with delta grouping for large scale non-separable function optimization

Abstract: Many evolutionary algorithms have been proposed for large scale optimization. Parameter interaction in non-separable problems is a major source of performance loss specially on large scale problems. Cooperative Co-evolution(CC) has been proposed as a natural solution for large scale optimization problems, but lack of a systematic way of decomposing large scale non-separable problems is a major obstacle for CC frameworks. The aim of this paper is to propose a systematic way of capturing interacting variables for a more effective problem decomposition suitable for cooperative co-evolutionary frameworks. Grouping interacting variables in different subcomponents in a CC framework imposes a limit to the extent interacting variables can be optimized to their optimum values, in other words it limits the improvement interval of interacting variables. This is the central idea of the newly proposed technique which is called delta method. Delta method measures the averaged difference in a certain variable across the entire population and uses it for identifying interacting variables. The experimental results show that this new technique is more effective than the existing random grouping method.