Interfacial debonding behavior of composite beam/plates with PZT patch

This paper studies interfacial debonding behavior of composite beams which include piezoelectric materials, adhesive and host beam. The focus is put on crack initiation and growth of the piezoelectric adhesive interface. Closed-form solutions of interface stresses and energy release rates are obtained for adhesive layer in the piezoelectric composite beams. Finite element analyses have been carried out to study the initiation and growth of interfaces crack for piezoelectric beams with interface element by ANSYS, in which the interface element of FE model is based on the cohesive zone models to characterize the fracture behavior of the interfacial debonding. The results have been compared with analystical solution, and the influence of different geometry and material parameters on the interfacial behavior of piezoelectric composite beams have been discussed.

Strength improvement methods for back to back Litesteel beams

LiteSteel Beam (LSB) is a new cold-formed steel beam produced by OneSteel Australian Tube Mills (OATM). The new beam is effectively a channel section with two rectangular hollow flanges and a slender web, and is manufactured using patented dual electric resistance welding and automated roll-forming technologies. OATM is promoting the use of LSBs as flexural members in residential construction. When LSBs are used as back to back built-up sections, they are likely to improve their moment capacity. However, the research project conducted on the flexural behaviour of back to back built-up LSBs showed that the detrimental effects of lateral distortional buckling in single LSB members appear to remain with back to back built-up LSB members. The ultimate moment capacity of back to back LSB member is also affected by lateral distortional buckling failure. Therefore an investigation was conducted with an aim to develop suitable strength improvement methods, which are likely to mitigate lateral distortional buckling effects and hence improve the flexural strengths of back to back LSB members. This paper presents the details of this investigation, the results and recommendations for the most suitable and cost-effective method, which significantly improves the moment capacities of back to back LSB members.

Shear strength of LiteSteel beams with web openings

This paper presents the details of numerical studies on the shear strength of a recently devel-oped, cold-formed steel channel beam known as LiteSteel Beam (LSB) with web openings. The LSB sections are commonly used as floor joists and bearers in residential, industrial and commercial buildings. In these ap-plications they often include web openings for the purpose of locating services. This has raised concerns over the shear capacity of LSB floor joists and bearers. Therefore experimental and numerical studies were under-taken to investigate the shear behavior and strength of LSBs with web openings. In this research, finite ele-ment models of LSBs with web openings in shear were developed to simulate the shear behavior of LSBs. It was found that currently available design equations are conservative or unconservative for the shear design of LSBs with web openings. Improved design equations have been proposed for the shear capacity of LSBs with web openings based on both experimental and numerical study results.

Shear strength and design of LiteSteel beams

This paper presents the details of a parametric study based on finite element analyses (FEA) and development of design rules for the shear strength of a recently developed, cold-formed steel channel beam known as LiteSteel Beam (LSB). The LSB sections are commonly used as flexural members in residential, in-dustrial and commercial buildings. In order to ensure safe and efficient designs of LSBs, many research stu-dies have been undertaken on the flexural behaviour of LSBs. However, no research has been undertaken on the shear behaviour of LSBs. Therefore a detailed investigation including both numerical and experimental studies was undertaken to investigate the shear behaviour of LSBs. Both the experimental and FEA parametric study results showed that the current design rules in cold-formed steel design codes are very conservative for the shear design of LSBs. New shear strength equations for LSBs were proposed based on the experimental and FEA parametric study results.

Three-dimensional printing of hierarchical and tough mesoporous bioactive glass scaffolds with a controllable pore architecture, excellent mechanical strength and mineralization ability

New-generation biomaterials for bone regenerations should be highly bioactive, resorbable and mechanically strong. Mesoporous bioactive glass (MBG), as a novel bioactive material, has been used for the study of bone regeneration due to its excellent bioactivity, degradation and drug-delivery ability; however, how to construct a 3D MBG scaffold (including other bioactive inorganic scaffolds) for bone regeneration still maintains a significant challenge due to its/their inherit brittleness and low strength. In this brief communication, we reported a new facile method to prepare hierarchical and multifunctional MBG scaffolds with controllable pore architecture, excellent mechanical strength and mineralization ability for bone regeneration application by a modified 3D-printing technique using polyvinylalcohol (PVA), as a binder. The method provides a new way to solve the commonly existing issues for inorganic scaffold materials, for example, uncontrollable pore architecture, low strength, high brittleness and the requirement for the second sintering at high temperature. The obtained 3D-printing MBG scaffolds possess a high mechanical strength which is about 200 times for that of traditional polyurethane foam template-resulted MBG scaffolds. They have highly controllable pore architecture, excellent apatite-mineralization ability and sustained drug-delivery property. Our study indicates that the 3D-printed MBG scaffolds may be an excellent candidate for bone regeneration.

Inspiration and strength

Thoughts on Aborignal women's leadership.

Wind uplift strength of trapezoidal steel cladding with closely spaced ribs

When crest-fixed thin trapezoidal steel cladding with closely spaced ribs is subjected to wind uplift/suction forces, local dimpling or pull-through failures occur prematurely at their screw connections because of the large stress concentrations in the cladding under the screw heads. Currently, the design of crest-fixed profiled steel cladding is mainly based on time consuming and expensive laboratory tests due to the lack of adequate design rules. In this research, a shell finite element model of crest-fixed trapezoidal steel cladding with closely spaced ribs was developed and validated using experimental results. The finite element model included a recently developed splitting criterion and other advanced features including geometric imperfections, buckling effects, contact modelling and hyperelastic behaviour of neoprene washers, and was used in a detailed parametric study to develop suitable design formulae for local failures. This paper presents the details of the finite element analyses, large scale experiments and their results including the new wind uplift design strength formulae for trapezoidal steel cladding with closely spaced ribs. The new design formulae can be used to achieve both safe and optimised solutions.

Halogen bonding between an isoindoline nitroxide and 1,4-diiodotetrafluorobenzene: new tools and tectons for self-assembling organic spin systems

Halogen bonding has been observed for the first time between an isoindoline nitroxide and an iodoperfluorocarbon (see figure), which cocrystallize to form a discrete 2:1 supramolecular compound in which NO.⋅⋅⋅I halogen bonding is the dominant intermolecular interaction. This illustrates the potential use of halogen bonding and isoindoline nitroxide tectons for the assembly of organic spin systems...

Testing the vision: Preschool settings as places for meeting, bonding and bridging

The OECD (2006 Starting Strong II: Early Childhood Education and Care. OECD Publishing: Paris) envisions early childhood education and care settings as meeting places for diverse social groups; places that build social capital. This vision was assessed in a comparison of three preschools types: full-fee paying, subsidised-fee and publicly funded. The social composition within each was examined and the connectedness of the children (n = 472) who attended compared. Publicly funded preschools had more socially diverse populations. The quantity of social connectedness did not differ but children in publicly funded preschools described higher quality social relationships. Not all preschool settings are socially diverse but, where they are, the quality of relationships is highest.

Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis

Summary This systematic review demonstrates that vitamin D supplementation does not have a significant effect on muscle strength in vitamin D replete adults. However, a limited number of studies demonstrate an increase in proximal muscle strength in adults with vitamin D deficiency. Introduction The purpose of this study is to systematically review the evidence on the effect of vitamin D supplementation on muscle strength in adults. Methods A comprehensive systematic database search was performed. Inclusion criteria included randomised controlled trials (RCTs) involving adult human participants. All forms and doses of vitamin D supplementation with or without calcium supplementation were included compared with placebo or standard care. Outcome measures included evaluation of strength. Outcomes were compared by calculating standardised mean difference (SMD) and 95% confidence intervals. Results Of 52 identified studies, 17 RCTs involving 5,072 participants met the inclusion criteria. Meta-analysis showed no significant effect of vitamin D supplementation on grip strength (SMD −0.02, 95%CI −0.15,0.11) or proximal lower limb strength (SMD 0.1, 95%CI −0.01,0.22) in adults with 25(OH)D levels >25 nmol/L. Pooled data from two studies in vitamin D deficient participants (25(OH)D <25 nmol/L) demonstrated a large effect of vitamin D supplementation on hip muscle strength (SMD 3.52, 95%CI 2.18, 4.85). Conclusion Based on studies included in this systematic review, vitamin D supplementation does not have a significant effect on muscle strength in adults with baseline 25(OH)D >25 nmol/L. However, a limited number of studies demonstrate an increase in proximal muscle strength in adults with vitamin D deficiency. Keywords Muscle – Muscle fibre – Strength – Vitamin D