Local plastic mechanisms in thin steel plates under in-plane compression

Thin-walled steel plates subjected to in-plane compression develop two types of local plastic mechanism, namely the roof-shaped mechanism and the so-called flip-disc mechanism, but the intriguing question of why two mechanisms should develop was not answered until recently. It was considered that the location of first yield point shifted from the centre of the plate to the midpoint of the longitudinal edge depending on the b/t ratio, imperfection level, and yield stress of steel, which then decided the type of mechanism. This paper has verified this hypothesis using analysis and laboratory experiments. An elastic analysis using Galerkin's method to solve Marguerre's equations was first used to determine the first yield point, based on which the local plastic mechanism/imperfection tolerance tables have been developed which give the type of mechanism as a function of b/t ratio, imperfection level and yield stress of steel. Laboratory experiments of thin-walled columns verified the imperfection tolerance tables and thus indirectly the hypothesis. Elastic and rigid-plastic curves were them used to predict the effect on the ultimate load due to the change of mechanism. A finite element analysis of selected cases also confirmed the results from simple analyses and experiments.

Ultimate load behaviour of box-columns under combined loading of axial compression and torsion

This paper describes a study of the theoretical and experimental behaviour of box-columns of varying b/t ratios under loadings of axial compression and torsion and their combinations. Details of the testing rigs and the testing methods, the results obtained such as the load-deflection curves and the interaction diagrams, and experimental observations regarding the behaviour of box-models and the types of local plastic mechanisms associated with each type of loading are presented. A simplified rigid-plastic analysis is carried out to study the collapse behaviour of box-columns under these loadings, based on the observed plastic mechanisms, and the results are compared with those of experiments.

Strength of stiffened plates with openings

The load-deflection and ultimate strength behaviour of longitudinally stiffened plates with openings was studied using a second-order elastic post-buckling analysis and a rigid-plastic analysis. The ultimate strength was predicted from the intersection point of elastic and rigid-plastic curves and the Perry strut formula. Comparison with experimental results shows that satisfactory prediction of ultimate strength can be obtained by this simple method. Effects of the size of opening, the initial geometrical imperfections and the plate slenderness ratio on the strength of perforated stiffened plates were also studied.

Design of stiffened plates with openings

The load-deflection and ultimate strength behaviour of longitudinally stiffened plates with openings was studied using a second-order elastic post-buckling analysis and a rigid-plastic analysis. The ultimate strength was predicted from the intersection point of elastic and rigid-plastic curves and the Perry strut formula. Comparison with experimental results shows that satisfactory prediction of ultimate strength can be obtained by this simple method. Effects of the size of opening, the initial geometrical imperfections and the plate slenderness ratio on the strength of perforated stiffened plates were also studied.

Development of a high-speed sensing and detection system for automatic removal of packages with leaky seals from a high-speed food processing and packaging line

Contamination of packaged foods due to micro-organisms entering through air leaks can cause serious public health issues and cost companies large amounts of money due to product recalls, consumer impact and subsequent loss of market share. The main source of contamination is leaks in packaging which allow air, moisture and microorganisms to enter the package. In the food processing and packaging industry worldwide, there is an increasing demand for cost effective state of the art inspection technologies that are capable of reliably detecting leaky seals and delivering products at six-sigma. The new technology will develop non-destructive testing technology using digital imaging and sensing combined with a differential vacuum technique to assess seal integrity of food packages on a high-speed production line. The cost of leaky packages in Australian food industries is estimated close to AUD $35 Million per year. Contamination of packaged foods due to micro-organisms entering through air leaks can cause serious public health issues and cost companies large sums of money due to product recalls, compensation claims and loss of market share. The main source of contamination is leaks in packaging which allow air, moisture and micro-organisms to enter the package. Flexible plastic packages are widely used, and are the least expensive form of retaining the quality of the product. These packets can be used to seal, and therefore maximise, the shelf life of both dry and moist products. The seals of food packages need to be airtight so that the food content is not contaminated due to contact with microorganisms that enter as a result of air leakage. Airtight seals also extend the shelf life of packaged foods, and manufacturers attempt to prevent food products with leaky seals being sold to consumers. There are many current NDT (non-destructive testing) methods of testing the seal of flexible packages best suited to random sampling, and for laboratory purposes. The three most commonly used methods are vacuum/pressure decay, bubble test, and helium leak detection. Although these methods can detect very fine leaks, they are limited by their high processing time and are not viable in a production line. Two nondestructive in-line packaging inspection machines are currently available and are discussed in the literature review. The detailed design and development of the High-Speed Sensing and Detection System (HSDS) is the fundamental requirement of this project and the future prototype and production unit. Successful laboratory testing was completed and a methodical design procedure was needed for a successful concept. The Mechanical tests confirmed the vacuum hypothesis and seal integrity with good consistent results. Electrically, the testing also provided solid results to enable the researcher to move the project forward with a certain amount of confidence. The laboratory design testing allowed the researcher to confirm theoretical assumptions before moving into the detailed design phase. Discussion on the development of the alternative concepts in both mechanical and electrical disciplines enables the researcher to make an informed decision. Each major mechanical and electrical component is detailed through the research and design process. The design procedure methodically works through the various major functions both from a mechanical and electrical perspective. It opens up alternative ideas for the major components that although are sometimes not practical in this application, show that the researcher has exhausted all engineering and functionality thoughts. Further concepts were then designed and developed for the entire HSDS unit based on previous practice and theory. In the future, it would be envisaged that both the Prototype and Production version of the HSDS would utilise standard industry available components, manufactured and distributed locally. Future research and testing of the prototype unit could result in a successful trial unit being incorporated in a working food processing production environment. Recommendations and future works are discussed, along with options in other food processing and packaging disciplines, and other areas in the non-food processing industry.

Revitalising the Australian Shipping Industry through Tax Reform: Alchemy or Piracy?

The Australian Federal Government has recently passed reforms to the shipping industry. These reforms are aimed at removing barriers to investment in Australian shipping, fostering global competitiveness and securing a stable maritime skills base. The shipping reform package adopts a two pronged approach designed to achieve its stated goals by providing both a ‘stick’ and ‘carrot’ to industry participants. First, the ‘stick’ is delivered via the provision of tighter regulation of coastal trading operations through a new licencing system, along with the introduction of a civil penalty regime and an increase in existing penalties. Second, the ‘carrot’ is delivered via taxation incentives available to vessels registered in Australia where the registrant meets certain specified criteria. These incentives, introduced through amendments to the Income Tax Assessment Act 1997 and the Income Tax Assessment Act 1936 and contained in the Tax Laws Amendment (Shipping Reform) Act 2012, provide five key tax incentives to the shipping industry. From 1 July 2012, amendments give effect to an income tax exemption for qualifying ship operators, accelerated depreciation of vessels, roll-over relief from income tax on the sale of a vessel, an employer refundable tax offset, and an exemption from royalty withholding tax for payments made for the lease of certain shipping vessels.

Going beyond ‘misfit’ as a reason for ERP package customisation

In an attempt to deal with the potential problems presented by existing information systems, a shift towards the implementation of ERP packages has been witnessed. The common view, particularly the one espoused by vendors, is that ERP packages are most successfully implemented when the standard model is adopted. Yet, despite this, customisation activity still occurs reportedly due to misalignment between the functionality of the package and the requirements of those in the implementing organisation. However, it is recognised that systems development and organisational decision-making are activities influenced by the perspectives of the various groups and individuals involved in the process. Thus, as customisation can be seen as part of systems development, and has to be decided upon, it should be thought about in the same way. In this study, two ERP projects are used to examine different reasons why customisation might take place. These reasons are then built upon through reference to the ERP and more general packaged software literature. The study suggests that whilst a common reason for customising ERP packages might be concerned with functionality misfits, it is important to look further into why these may occur, as there are clearly other reasons for customisation stemming from the multiplicity of social groups involved in the process.

Analysing governance categories used on project alliances in the construction industry

In Australia, collaborative contracts, and in particular, project alliances, have been increasingly used to govern infrastructure projects. These contracts use formal and informal governance mechanisms to manage the delivery of infrastructure projects. Formal mechanisms such as financial risk sharing are specified in the contract, while informal mechanisms such as integrated teams are not. Given that the literature contains a multiplicity of often untestable definitions, this paper reports on a review of the literature to operationalize the concepts of formal and informal governance. This work is the first phase of a study that will examine the optimal balance of formal and informal governance structures. Desk-top review of leading journals in the areas of construction management and business management, as well as recent government documents and industry guidelines, was undertaken to to conceptualise and operationalize formal and informal governance mechanisms. The study primarily draws on transaction-cost economics (e.g. Williamson 1979; Williamson 1991), relational contract theory (Feinman 2000; Macneil 2000) and social psychology theory (e.g. Gulati 1995). Content analysis of the literature was undertaken to identify key governance mechanisms. Content analysis is a commonly used methodology in the social sciences area. It provides rich data through the systematic and objective review of literature (Krippendorff 2004). NVivo 9, a qualitative data analysis software package, was used to assist in this process. A previous study by the authors identified that formal governance mechanisms can be classified into seven measurable categories: (1) negotiated cost, (2) competitive cost, (3) commercial framework, (4) risk and reward sharing, (5) qualitative performance, (6) collaborative multi-party agreement, and (7) early contractor involvement. Similarly, informal governance mechanisms can be classified into four measureable categories: (1) leadership structure, (2) integrated team, (3) team workshops, and (4) joint management system. This paper explores and further defines the key operational characteristics of each mechanism category, highlighting its impact on value for money in alliance project delivery. The paper’s contribution is that it provides the basis for future research to compare the impact of a range of individual mechanisms within each category, as a means of improving the performance of construction projects.

Nonlinear analysis of plastic ball grid array solder joints

A nonlinear finite element analysis was carried out to investigate the viscoplastic deformation of solder joints in a ball grid array (BGA) package under temperature cycle. The effects of constraint on print circuit board (PCB) and stiffness of substrate on the deformation behaviour of the solder joints were also studied. A relative damage stress was adopted to analyze the potential failure sites in the solder joints. The results indicated that high inelastic strain and strain energy density were developed in the joints close to the package center. On the other hand, high constraint and high relative damage stress were associated with the joint closest to the edge of the silicon chip. The joint closest to the edge of the silicon chip was regarded as the most susceptible failure site if cavitation instability is the dominant failure mechanism. Increase the external constraint on the print circuit board (PCB) causes a slight increase in stress triaxiality (m/eq) and relative damage stress in the joint closest to the edge of silicon die. The relative damage stress is not sensitive to the Young’s modulus of the substrate.

The learning capability of construction organisations engaged in collaborative contracting - Literature Review [industry report]

Background Value for money (VfM) on collaborative construction projects is dependent on the learning capabilities of the organisations and people involved. Within the context of infrastructure delivery, there is little research about the impact of organisational learning capability on project value. The literature contains a multiplicity of often un-testable definitions about organisational learning abilities. This paper defines learning capability as a dynamic capability that participant organisations purposely develop to add value to collaborative projects. The paper reports on a literature review that proposes a framework that conceptualises learning capability to explore the topic. This work is the first phase of a large-scale national survey funded by the Alliancing Association of Australasia and the Australian Research Council. Methodology Desk-top review of leading journals in the areas of strategic management, strategic alliances and construction management, as well as recent government documents and industry guidelines, was undertaken to synthesise, conceptualise and operationalise the concept of learning capability. The study primarily draws on the theoretical perspectives of the resource-based view of the firm (e.g. Barney 1991; Wernerfelt 1984), absorptive capacity (e.g. Cohen and Levinthal 1990; Zahra and George 2002); and dynamic capabilities (e.g. Helfat et al. 2007; Teece et al. 1997; Winter 2003). Content analysis of the literature was undertaken to identify key learning routines. Content analysis is a commonly used methodology in the social sciences area. It provides rich data through the systematic and objective review of literature (Krippendorff 2004). NVivo 9, a qualitative data analysis software package, was used to assist in this process. Findings and Future Research The review process resulted in a framework for the conceptualisation of learning capability that shows three phases of learning: (1) exploratory learning, (2) transformative learning and (3) exploitative learning. These phases combine both internal and external learning routines to influence project performance outcomes and thus VfM delivered under collaborative contracts. Sitting within these phases are eight categories of learning capability comprising knowledge articulation, identification, acquisition, dissemination, codification, internationalisation, transformation and application. The learning routines sitting within each category will be disaggregated in future research as the basis for measureable items in a large-scale survey study. The survey will examine the extent to which various learning routines influence project outcomes, as well as the relationships between them. This will involve identifying the routines that exist within organisations in the construction industry, their resourcing and rate of renewal, together with the extent of use and perceived value within the organisation. The target population is currently estimated to be around 1,000 professionals with experience in relational contracting in Australia. This future research will build on the learning capability framework to provide data that will assist construction organisations seeking to maximise VfM on construction projects.

Understanding Formal and Informal Governance on Infrastructure Projects - Literature Review [industry report]

In Australia, collaborative contracts have been increasingly used to govern infrastructure projects. These contracts combine formal and informal mechanisms to manage project delivery. Formal mechanisms (e.g. financial risk sharing) are specified in the contract, while informal mechanisms (e.g. integrated team) are not. The paper reports on a literature review to operationalise the concepts of formal and informal governance, as the literature contains a multiplicity of, often un-testable, definitions. This work is the first phase of a study that will examine the optimal balance of formal and informal governance structures. Desk-top review of leading journals in the areas of construction management and business management, as well as recent government documents and industry guidelines, was undertaken to to conceptualise and operatinalise formal and informal governance mechanisms. The study primarily draws on transaction-cost economics (e.g. Williamson 1979; 1991), relational contract theory (Feinman 2000; Macneil 2000) and social psychology theory (e.g. Gulati 1995). Content analysis of the literature was undertaken to identify key governance mechanisms. Content analysis is a commonly used methodology in the social sciences area. It provides rich data through the systematic and objective review of literature (Krippendorff 2004). NVivo 9, a qualitative data analysis software package, was used to assist in this process. Formal governance mechanisms were found to be usefully broken down into four measurable categories: (1) target cost arrangement (2) financial risk and reward sharing regime (3) transparent financials and (4) collaborative multi-party agreement Informal governance mechanisms were found to be usefully broken down into three measurable categories: (1) leadership structure (2) integrated team (3) joint management system We expect these categories to effectively capture the key governance drivers of outcomes on infrastructure projects. These categories will be further refined and broken down into individual governance mechanisms for assessment through a large-scale Australian survey planned for late 2012. These individual mechanisms will feature in the questionnaire that QUT will deliver to AAA in October 2012.

Some surface profiles of a strip after plane-strain indentation by rigid bodies with serrated surfaces

This paper is concerned with the surface profiles of a strip after rigid bodies with serrated (saw-teeth) surfaces indent the strip and are subsequently removed. Plane-strain conditions are assumed. This has application in roughness transfer of final metal forming process. The effects of the semi-angle of the teeth, the depth of indentation and the friction on the contact surface on the profile are considered.