Effect of aluminium sheet surface conditions on feasibility and quality of resistance spot welding

A study investigating the effect of sheet surface condition on resistance spot welding (RSW) of aluminium has been carried out. This concentrates on two automotive aluminium alloys; AA5754 and AA6111, used for structural and closure applications respectively. The results show the marked effect that surface condition can have on the RSW process. For AA5754 sheet incomplete removal of a ‘disrupted surface layer’ prior to surface pretreatment is shown to have a detrimental effect on the RSW process. The solid wax lubricant used to assist metal forming leads to unpredictable changes in contact resistance, and consequently affects the process stability. For AA6111 closures the final surface topography can influence the RSW process. Standard ‘mill’ and electro-discharge textured (EDT) finish sheet surfaces were examined and preliminary results suggest that both are suitable for welding. The successful application of RSW of aluminium sheet requires careful consideration of the sheet surface condition. This requires close collaboration between material suppliers and automotive manufacturers

A comparison of the mechanical behaviour of self-piercing riveted and resistance spot welded aluminium sheets for the automotive industry

The increased application of lightweight materials, such as aluminium has initiated many investigations into new joining techniques for aluminium alloys. The resistance spot welding (RSW) concept for aluminium has always attracted many researchers from different organizations. Self-piercing riveting (SPR) is the major production process used to join aluminium sheet body structures for the automotive industry. The research team at the University of Warwick has investigated these two major joining technologies for aluminium assembly. The paper reported here gives an in depth comparison of the mechanical behaviour for each joint type under different loading conditions. It covers symmetrical and asymmetrical assembly from thin gauge of 1.0 mm to thick gauge of 3.0 mm. The results suggest that generally RSW can provide similar strength performance to SPR with the exception of T-peel; the energy to maximum load needs be considered ‘case to case’ and is dependent largely on loading conditions and the failure mode particularly with respect to SPR. The spread of results for SPR is generally smaller than for RSW, and the performance of SPR joints improves as the thickness increases

Mechanisms of deep penetration of soft solids, with application to the injection and wounding of skin

Micromechanical models are developed for the deep penetration of a soft solid by a flat-bottomed and by a sharp-tipped cylindrical punch. The soft solid is taken to represent mammalian skin and silicone rubbers, and is treated as an incompressible, hyperelastic, isotropic solid described by a one-term Ogden strain energy function. Penetration of the soft solid by a flat-bottomed punch is by the formation of a mode-II ring crack that propagates ahead of the penetrator tip. The sharp-tipped punch penetrates by the formation of a planar mode-I crack at the punch tip, followed by wedging open of the crack by the advancing punch. For both modes of punch advance the steady-state penetration load is calculated by equating the work done in advancing the punch to the sum of the fracture work and the strain energy stored in the solid. For the case of a sharp penetrator, this calculation is performed by considering the opening of a plane-strain crack by a wedge using a finite-element approach. Analytical methods suffice for the flat-bottomed punch. In both models the crack dimensions are such that the load on the punch is minimized. For both geometries of punch tip, the predicted penetration pressure increases with diminishing punch radius, and with increasing toughness and strain-hardening capacity of solid. The penetration pressure for a flat-bottomed punch is two to three times greater than that for a sharp-tipped punch (assuming that the mode-I and mode-II toughnesses are equal), in agreement with experimental observations reported in a companion paper

Who needs what from a national health research system: Lessons from reforms to the English Department of Health's R&D system

This article has been made available through the Brunel Open Access Publishing Fund.Health research systems consist of diverse groups who have some role in health research, but the boundaries around such a system are not clear-cut. To explore what various stakeholders need we reviewed the literature including that on the history of English health R&D reforms, and we also applied some relevant conceptual frameworks. We first describe the needs and capabilities of the main groups of stakeholders in health research systems, and explain key features of policymaking systems within which these stakeholders operate in the UK. The five groups are policymakers (and health care managers), health professionals, patients and the general public, industry, and researchers. As individuals and as organisations they have a range of needs from the health research system, but should also develop specific capabilities in order to contribute effectively to the system and benefit from it. Second, we discuss key phases of reform in the development of the English health research system over four decades - especially that of the English Department of Health's R&D system - and identify how far legitimate demands of key stakeholder interests were addressed. Third, in drawing lessons we highlight points emerging from contemporary reports, but also attempt to identify issues through application of relevant conceptual frameworks. The main lessons are: the importance of comprehensively addressing the diverse needs of various interacting institutions and stakeholders; the desirability of developing facilitating mechanisms at interfaces between the health research system and its various stakeholders; and the importance of additional money in being able to expand the scope of the health research system whilst maintaining support for basic science. We conclude that the latest health R&D strategy in England builds on recent progress and tackles acknowledged weaknesses. The strategy goes a considerable way to identifying and more effectively meeting the needs of key groups such as medical academics, patients and industry, and has been remarkably successful in increasing the funding for health research. There are still areas that might benefit from further recognition and resourcing, but the lessons identified, and progress made by the reforms are relevant for the design and coordination of national health research systems beyond England.This article is available through the Brunel Open Access Publishing Fund

Soft network composite materials with deterministic and bio-inspired designs

Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices. © 2015 Macmillan Publishers Limited. All rights reservedopen7

Setting and meeting priorities in Indigenous health research in Australia and its application in the Cooperative Research Centre for Aboriginal Health

Priority setting is about making decisions. Key issues faced during priority setting processes include identifying who makes these decisions, who sets the criteria, and who benefits. The paper reviews the literature and history around priority setting in research, particularly in Aboriginal health research. We explore these issues through a case study of the Cooperative Research Centre for Aboriginal Health (CRCAH)'s experience in setting and meeting priorities

Ministries of Health and the Stewardship of Health Evidence

This chapter describes how Ministries of Health have been mandated to act as stewards of populations’ health according to the World Health Organization. We argue that this mandate extends to them having (at least partial) responsibility for ensuring relevant evidence informs policy decisions. Yet this requires consideration of the evidence advisory systems serving Ministry needs, particularly whether or how such systems work to provide relevant information in a timely manner to key decision points in the policy process. Insights from our six cases are presented to illustrate the structural and practical differences which exist between evidence advisory systems and how, at certain times, key health decisions may in fact lie outside ministerial authority. These divergent experiences highlight a range of analytical challenges when considering the provision of evidence to inform health decisions from an institutional perspective

Freedom and need: The evolution of public strategy for biomedical and health research in England

The optimal support of health-related research and development with public money is a complex challenge. Over the last century, policy makers in England have conceived and implemented a variety of models, ranging from independent, curiosity driven research to needs-based state commissions, and promoting different bodies to oversee scientific work. This paper traces these approaches, identifies the principles that drove them, and discusses their role in shaping policy for publicly funded health research, up to the recent launch of a new research strategy by the Department of Health

Innovative solutions to enhance safe and green environments for ageing well using co-design through Patient and Public Involvement.

Background: There is a need to develop innovative solutions to enhance safe and green physical environments, which optimise health, wellbeing and community participation among older adults. In order to develop solutions that meet the needs of a diverse ageing population, an interdisciplinary approach is needed. Our aim was to identify the needs of older people in relation to ageing well in the environment by bringing together knowledge from different perspectives using Patient and Public Involvement. Methods: An international consortium (Retrofit living For ageing well through Understanding and Redesign of Built environments consortium: ReFURB) was established in April 2018, including ten core members, to (i) explore cutting-edge solutions to safe living for ageing populations and (ii) develop innovative approaches to everyday physical environments, which bring about health benefits. We used a co-design, interdisciplinary framework involving older adults, carers, physiotherapists, geriatricians, engineers, human movement experts, geographers and psychologists from the UK and Australia. This engaged people in a one day workshop that comprised a series of presentations from international speakers on urban design, social connectedness, hazards and injury prevention, and the physical environment. Small group discussions (facilitated by consortium members) followed presentations to consider the opportunities, challenges and barriers encountered with ageing, which included the use of creative engagement activities (LEGO® Serious Play, mind maps, poster gallery walk), to help participants share personal stories and reflect on the issues raised. Thematic coding was used to synthesise the outputs of the small group work. Results: Five themes were identified across the workshops, comprising: access and transport; involvement of the whole community; restoration rather than redesign; assistive and digital technology; and intergenerational approaches. These dimensions related to the physical, social and nature-based qualities of everyday environments, as they pertain to ageing well. Conclusions: Co-design was a valuable tool that helped understand the perceptions of participants and essential to develop effective interventions and solutions. Participants highlighted several issues affecting people as they age and key environmental considerations to promote wellbeing, activity, and participation. The consortium identified gaps in the existing evidence base and are now planning activities to further develop research ideas in collaboration with our co-design participants