Formability and forming of advanced steels

The thesis identified how advanced high strength steels perform compared to conventional steels in terms of weight reduction and crash performance for automotive bodies. The novel production method of low pressure tube hydroforming was applied to form these advanced steels to reduce the press tonnage and fluid pressure compared to the conventional high pressure process. In addition analytical models were developed to predict the force and pressure in the low pressure process.

Three-dimensional tissue scaffolds from interbonded poly(e-caprolactone) fibrous matrices with controlled porosity

In this article, we report on the preparation and cell culture performance of a novel fibrous matrix that has an interbonded fiber architecture, excellent pore interconnectivity, and controlled pore size and porosity. The fibrous matrices were prepared by combining melt-bonding of short synthetic fibers with a template leaching technique. The microcomputed tomography and scanning electron microscopy imaging verified that the fibers in the matrix were highly bonded, forming unique isotropic pore architectures. The average pore size and porosity of the fibrous matrices were controlled by the fiber/template ratio. The matrices having the average pore size of 120, 207, 813, and 994 mm, with the respective porosity of 73%, 88%, 96%, and 97%, were investigated. The applicability of the matrix as a three-dimensional (3D) tissue scaffold for cell culture was demonstrated with two cell lines, rat skin fibroblast and Chinese hamster ovary, and the influences of the matrix porosity and surface area on the cell culture performance were examined. Both cell lines grew successfully in the matrices, but they showed different preferences in pore size and porosity. Compared with two-dimensional tissue culture plates, the cell number on 3D fibrous matrices was increased by 97.27% for the Chinese hamster ovary cells and 49.46% for the fibroblasts after 21 days of culture. The fibroblasts in the matrices not only grew along the fiber surface but also bridged among the fibers, which was much different from those on two-dimensional scaffolds. Such an interbonded fibrous matrix may be useful for developing new fiber-based 3D tissue scaffolds for various cell culture applications.

Forming and sustaining partnerships to provide integrated services for young people : an overview based on the headspace Geelong experience

Aim: To discuss critical considerations in the formation and maintenance of agency partnerships designed to provide integrated care for young people.

Methods: Two years after its establishment, an evaluation of the headspace Barwon collaboration and a review of the health-care and management literature on agency collaboration were conducted. The principal findings together with the authors' experience working at establishing and maintaining the partnership are used to discuss critical issues in forming and maintaining inter-agency partnerships.

Results: Structural and process considerations are necessary but not sufficient for the successful formation and maintenance of inter-agency partnerships and integrated care provision. Specifically, organizational culture change and staff engagement is a significant challenge and planning for this is essential and often neglected.

Conclusions: Although agreeing on common goals and objectives is an essential first step in forming partnerships designed to provide integrated care, goodwill is not enough, and the literature consistently shows that most collaborations fail to meet their objectives. Principles and lessons of organizational behaviour and management practices in the business sector can contribute a great deal to partnership planning.

Numerical simulations on warm forming of stainless steel with trip-effect

In steels with TRIP-effect, a phase transformation from the retained-austenite to martensite occurs during forming, and it significantly affects hardening behaviours. Such an effect is sensitive to the amount of strain as well as the temperature variation. For materials with a strong TRIP-effect, new forming techniques are needed to develop that can lead to lighter and stronger components in automotive industry. This paper presents a coupled thermo-mechanical finite element modelling and simulation of a warm deep drawing of austenitic stainless steel (including a TRIP-effect) using LS-DYNA and temperature effect on forming process of such materials is investigated.

Characterising material and process variation effects on springback robustness for a semi-cylindrical sheet metal forming process

Variation in the incoming sheet material and fluctuations in the press setup is unavoidable in many stamping plants. The effect of these variations can have a large influence on the quality of the final stamping, in particular, unpredictable springback of the sheet when the tooling is removed. While stochastic simulation techniques have been developed to simulate this problem, there has been little research that connects the influence of the noise sources to springback. This paper characterises the effect of material and process variation on the robustness of springback for a semi-cylindrical channel forming operation, which shares a similar cross-section profile as many automotive structural components. The study was conducted using the specialised sheet metal forming package AutoForm^TM Sigma, for which a series of stochastic simulations were performed with each of the noise sources incrementally introduced. The effective stress and effective strain scatter in a critical location of the part was examined and a response window, which indicates the respective process robustness, was defined. The incremental introduction of the noise sources allows the change in size of the stressstrain response window to be tracked. The results showed that changes to process variation parameters, such as BHP and friction coefficient, directly affect the strain component of the stressstrain response window by altering the magnitude of external work applied to forming system. Material variation, on the other hand, directly affected the stress component of the response window. A relationship between the effective stressstrain response window and the variation in springback was also established.

Material flow forming the shoulder flow zone using scroll shoulder tool during friction stir welding of thick section aluminum alloys

Scroll shoulder tools are widely used and they do not need to be tilted during friction stir welding (FSW). However, the detailed material flow, which is important for proper scroll shoulder tool design and subsequently for forming the defect-free shoulder flow zone, has not been fully explained. In the present study, features of material flow in shoulder flow zone, during FSW of thick 6061 aluminium (Al) plates using a scroll shoulder tool were investigated. It was observed that there is a simple layer-to-layer banded structure which appears in the bottom portion of shoulder flow zone, but disappears in the top portion of this weld zone. When the scroll shoulder tool is plunged into the workpiece to a determined depth, the workpiece material is extruded by the tool pin, and pushed up into the scroll groove beneath the shoulder forming the pick-up material. During the forward movement of the tool, the central portion of pick-up material was driven downward by the root portion of pin and then it detaches from the tip portion of pin in a layer-to-layer manner to form the weld.

Possible changes of pore size during nanofiltration

The textile industry plays an important role in the world economy as well as our daily life. However, the industry consuming a large quantity of water and generating huge amount of wastewater are unsustainable to the conservation of our precious resources and environment and need improvement. The wastewater, especially the one from spent cotton reactive dyebaths, contains high salt content, various dyes and high alkalinity. This study was carried out to investigate the feasibility of membrane filtration treating spent cotton reactive dye baths. A stirred cell with nanofiltration membrane was used aiming at reusing the reclaimed water. Spent dyebath solutions were synthesized containing hydrolyzed C. I. Reactive Black 5 and sodium chloride. When a piece of membrane was used repeatedly it was expected the flux would decrease after each usage due to fouling of impurities. However, it was found that the water flux increased while dye rejection decreased after each run. At pH 10, the dye rejection decreased significantly. It was proposed that the pore sizes of membrane might have changed during membrane filtration. An equation was derived calculating the possible changes of pore sizes.

Evidence of changes in membrane pore characteristics due to filtration of dye bath liquors

This study was carried out to investigate the treatment of various salt solutions and synthetic dye bath liquors by nanofiltration using Nanomax-50 membrane in a stirred cell with 150 mL working volume. Donnan exclusion was compared by filtering salts with monovalent and divalent cations and anions. This was done by comparing three salts including sodium chloride (NaCl), calcium chloride (CaCl2) and sodium sulphate (Na2SO4). The rejection order determined was Na2SO4>NaCl>CaCl2 which is typical of a negatively charged membrane where Donnan and steric exclusion play an important role in separation. Studies on the flux and rejection characteristics of sodium sulphate were undertaken for concentrations ranging from 10 to 40 gl−1 thereby replicating actual dye bath salt concentrations. Synthetic dye bath liquors were prepared using acidic dye (Acid Green 25) at a fixed concentration of 100 mgl−1 with 10 and 15 gl−1 of sodium sulphate solutions. While, the results showed evidence of flux decline due to increased resistance and decreased transmembrane pressure, pore enlargement occurred after the filtration experiments with sodium sulphate solutions greater than 20 gl−1. Pore enlargement was even more prominent in the two synthetic dye bath liquors filtered. Pore enlargement was determined by observing the pure water flux before and after filtering sodium sulphate solutions or dye bath liquors. An increase in pore diameter of 58 and 94 %was estimated when dye bath liquors containing 10 and 15 gl−1 of sodium sulphate, respectively were filtered through the membrane. The following equation was derived in estimating the pore enlargement, where de1 and de2 are the apparent diameter of membrane pore sizes before and after filtration of salt solutions or dye bath liquors and Rm1 and Rm2 are the membrane resistance of pure water flux before and after filtration of salt solutions or dye bath liquors. These results have important implications for the application of nanofiltration technology to textile wastewater treatment and reuse.

A Pseudomonas aeruginosa toxin that hijacks the host ubiquitin proteolytic system

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen chronically infecting the lungs of patients with chronic obstructive pulmonary disease (COPD), pneumonia, cystic fibrosis (CF), and bronchiectasis. Cif (PA2934), a bacterial toxin secreted in outer membrane vesicles (OMV) by P. aeruginosa, reduces CFTR-mediated chloride secretion by human airway epithelial cells, a key driving force for mucociliary clearance. The aim of this study was to investigate the mechanism whereby Cif reduces CFTR-mediated chloride secretion. Cif redirected endocytosed CFTR from recycling endosomes to lysosomes by stabilizing an inhibitory effect of G3BP1 on the deubiquitinating enzyme (DUB), USP10, thereby reducing USP10-mediated deubiquitination of CFTR and increasing the degradation of CFTR in lysosomes. This is the first example of a bacterial toxin that regulates the activity of a host DUB. These data suggest that the ability of P. aeruginosa to chronically infect the lungs of patients with COPD, pneumonia, CF, and bronchiectasis is due in part to the secretion of OMV containing Cif, which inhibits CFTR-mediated chloride secretion and thereby reduces the mucociliary clearance of pathogens.

Chemotoxicity of doxorubicin and surface expression of P-glycoprotein (MDR1) is regulated by the Pseudomonas aeruginosa toxin Cif

P-glycoprotein (Pgp), a member of the adenosine triphosphate-binding cassette (ABC) transporter superfamily, is a major drug efflux pump expressed in normal tissues, and is overexpressed in many human cancers. Overexpression of Pgp results in reduced intracellular drug concentration and cytotoxicity of chemotherapeutic drugs and is thought to contribute to multidrug resistance of cancer cells. The involvement of Pgp in clinical drug resistance has led to a search for molecules that block Pgp transporter activity to improve the efficacy and pharmacokinetics of therapeutic agents. We have recently identified and characterized a secreted toxin from Pseudomonas aeruginosa, designated cystic fibrosis transmembrane conductance regulator (CFTR) inhibitory factor (Cif). Cif reduces the apical membrane abundance of CFTR, also an ABC transporter, and inhibits the CFTR-mediated chloride ion secretion by human airway and kidney epithelial cells. We report presently that Cif also inhibits the apical membrane abundance of Pgp in kidney, airway, and intestinal epithelial cells but has no effect on plasma membrane abundance of multidrug resistance protein 1 or 2. Cif increased the drug sensitivity to doxorubicin in kidney cells expressing Pgp by 10-fold and increased the cellular accumulation of daunorubicin by 2-fold. Thus our studies show that Cif increases the sensitivity of Pgp-overexpressing cells to doxorubicin, consistent with the hypothesis that Cif affects Pgp functional expression. These results suggest that Cif may be useful to develop a new class of specific inhibitors of Pgp aimed at increasing the sensitivity of tumors to chemotherapeutic drugs, and at improving the bioavailability of Pgp transport substrates.

Modelling of bending-dominated forming processes of metal sheets

Theoretical solutions, finite element models, and experimental techniques are developed for three major sheet metal forming operations: bending (pure bending and cyclic bending), die bending, and deep drawing. These have been applied to two different commercial quality cold-rolled steels, one stainless steel, and one magnesium alloy.

Review of approximate analyses of sheet forming processes

Approximate models are often used for the following purposes: in on-line control systems of metal forming processes where calculation speed is critical; to obtain quick, quantitative information on the magnitude of the main variables in the early stages of process design; to illustrate the role of the major variables in the process; as an initial check on numerical modelling; and as a basis for quick calculations on processes in teaching and training packages. The models often share many similarities; for example, an arbitrary geometric assumption of deformation giving a simplified strain distribution, simple material property descriptions - such as an elastic, perfectly plastic law - and mathematical short cuts such as a linear approximation of a polynomial expression. In many cases, the output differs significantly from experiment and performance or efficiency factors are developed by experience to tune the models. In recent years, analytical models have been widely used at Deakin University in the design of experiments and equipment and as a pre-cursor to more detailed numerical analyses. Examples that are reviewed in this paper include deformation of sandwich material having a weak, elastic core, load prediction in deep drawing, bending of strip (particularly of ageing steel where kinking may occur), process analysis of low-pressure hydroforming of tubing, analysis of the rejection rates in stamping, and the determination of constitutive models by an inverse method applied to bending tests.

Springback data from stamping and simulating the forming of advanced high strength steel

This dataset is comprised of a spreadsheet of simulation result files, cross-section geometries of stamped parts, strain results of cross-section of stamped parts, simulation data (strain stress displacement energies), and variation data of material properties of a single coil. This data is a collection of both experimental and simulation results from industrial and laboratory stamping of advanced high strength steels (AHSS). The steels that were stamped were a typical high-strength low-alloy (HSLA) steel, a transformation-induced plasticity (TRIP) steel, a super HSLA steel, and a dual phase (DP) steel. The selected part was an automatic Ford Falcon front cross-member component using the Ford Geelong stamping plant. The variation of the material and stamped parts was also collected.

Comparison of bending of automotive steels in roll forming and in a V-die

Bending in a V-die has been used to indicate the outcome of bending in cold roll forming, although little direct correlation has been performed. In this work direct comparison of the springback in both processes was performed using six samples of automotive steels in a conventional roll forming line where the transverse springback is measured. A bend of similar radius was formed in a V-die and the springback determined. In general, the springback in V-die forming was greater than in roll forming, in some cases by a factor of 2. The theoretical springback angle was determined for all steels using a simple and approximate analytical equation and compared to the experimental roll forming and bending results. While for the roll forming process good agreement was achieved the theoretical values significantly underestimated springback in the V-bending process.