A study on bending behaviours of aluminium foam-filled tubes

In the study, the strengthening effect of aluminium foam in thin-walled aluminium tubes subject to bending load in investigated experimentally and numerically. Bending tests are conducted on foam filler, hollow tube and foam-filled tube. The finite element method is used as well to get deeper insight into the crush failure modes via focusing on the influence from wall thickness of the tube. The obtained information is useful to optimally design foam-filled tubes as energy absorbing devices in automotive engineering. The optimisation results can be implemented to find an optimum foam-filled tube that absorbs the same energy as the optimal hollow tube but with much less weight. © (2014) Trans Tech Publications, Switzerland.

Best practice in stabilisation of oral endotracheal tubes : a systematic review

Mechanical ventilation of patients in intensive care units is common practice. Artificial airways are utilised to facilitate ventilation and the endotracheal tube (ETT) is most commonly used for this purpose. The ETT must be stabilised to optimise ventilation and avoid displacement or unplanned extubation. Tube movement is a major factor in causing airway trauma. A destabilised tube can cause fatal complications. A systematic review was conducted to identify and analyse the best available evidence on ETT stabilisation to determine which stabilisation method resulted in reduced tube displacement and the least amount of unplanned or accidental extubations. The types of stabilisations included one or a combination of the following methods: twill or cotton tape, adhesive tape, gauze, or a manufactured device. All relevant randomised controlled and quasi-experimental studies of ETT stabilisation practices, identified through electronic and hand searching, were assessed for inclusion in the study. One published randomised controlled trial and six published quasi-experimental studies met the inclusion and exclusion criteria and were retrieved. Data were extracted independently by two reviewers. Results of the systematic review showed that no single method of ETT stabilisation could be identified as superior for minimising tube displacement and unplanned or accidental extubations. Rigorous randomised controlled trials with clearly identified and described ETT stabilisation methods are required to establish best practice. In addition, comparative research to evaluate cost effectiveness and nursing time requirements would also be of significant benefit to critical care nursing practice.

Crushing simulation of foam-filled aluminium tubes

A numerical study is presented in this paper to investigate the energy absorption of foam-filled aluminium tubes during crushing. The post-buckling mode of the foam-tube structures has been successfully simulated. The predicted compressive load-displacement is in a good agreement with experimental results. The energy absorption ability of the composite structure due to plastic deformation in a crushing process is evaluated by comparison with the tube structure without foam. The results indicate that the energy absorption of a foam-filled tube structure is superior to the tube without foam. The influences of the friction and the geometric parameters of the structure on the energy absorption have also been investigated. Results from this study will assist automotive industry to design crashworthy components based on foam-filled tubes.

Crushing modes of aluminium tubes under axial compression

A numerical study of the crushing of circular aluminium tubes with and without aluminium foam fillers has been carried out to investigate their buckling behaviours under axial compression. A crushing mode classification chart has been established for empty tubes. The influence of boundary conditions on crushing mode has also been investigated. The effect of foam filler on the crushing mode of tubes filled with foam was then examined. The predicted results would assist the design of crashworthy tube components with the preferred crushing mode with the maximum energy absorption.

Strain rate effects on the energy absorption of rapidly manufactured composite tubes

As a result of recent increases in fuel prices and the growing number of accident fatalities, the two major concerns of the automotive industry and their customers are now occupant safety and fuel economy {1, 2]. Increasing the amount of energy and optimizing the manner in which energy is absorbed within vehicle crush zones can improve occupant survivability in the event of a crash, while fuel economy is improved through a reduction in weight.  Axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). This paper presents results from the tests conducted at quasi-static rates at Deakin Unniversity, Victoria Australia, and intermediate rate tests performed at the Oak Ridge National Laboratory, Tennessee  USA.   The quasi-static tests were conducted at 10mm/min (1.67x10-4m/s) using 5 different forms of initiation. Tests at intermediate rates were performed at speeds of 0.25m/s, 0.5m/s, 0.75m/s 1m/s, 2m/s and 4m/s. Quasi-static tests of tubular specimens showed high specific energy absorption (SEA) values with 86 kJ/kg for Carbon/Epoxy specimens. The SEA of the Glass/Polypropylene specimens was measured to be 29 kJ/kg. Results from the intermediate test rates showed that SEA values did not fall below 55kJ/kg for carbon specimens or 35kJ/kg for the Glass/Polypropylene specimens. When compared with typical steel and aluminium, SEA values of 15 kJ/kg and 30kJ/kg respectively, the benefits of using composite materials in crash structures is apparent.                                                                     

Modelling factors of square tubes in high speed bending situations

Accurate finite element crash simulations of side impact depend upon a thorough understanding of dynamic tube bending. There is a need to understand the dynamic bending mode of square sections (equivalent of automotive structural parts) to obtain a greater confidence in CAE. This work varied strain rate and material definitions, such as Cowper-Symonds vs Zerilli-Armstrong, as well as initial velocity and yield strength. The results show that most of the plastic work is done between strains rates of 30 ¿ 300/s and strains up to 0.3. Peak strain rates were marginally above 1000/s with maximum strain greater than 1. When the strain rate definition and material model were modified, it was shown that a higher yield stress produced a higher reaction force. These results would suggest that the strain rate sensitivity needs to be carefully identified for accurate crash simulations.

Energy absorption and crushing behaviour of foam-filled aluminium tubes

The crushing behaviour and energy absorption of foam filled aluminium tubular structures were investigated using the quasi-static compressive tests. The crushing behaviour of the tubular structures changed due to foam filling. The energy absorption of the foam filled tubular structures was improved significantly. Foam filling caused an interaction effect between the tube and the foam during progressive crushing, leading to an increase in the mean crushing load compared to that of the foam or tube itself. This interaction effect might be affected by several parameters such as the density of the foam, the properties of both the foam material and tube material, and the thickness and outer diameter of the tube. In particular, the interaction effect essentially depended on the ratio of the mean crushing force of the foam to that of the tube.

Inadvertent intracranial insertion of nasogastric tubes : An overview and nursing implications

Nasogastric tubes are a commonly used medical device. There are numerous complications associated with their use, one of the most significant is when they are inadvertently inserted into the cranium. Clinicians need to be aware of this complication and the type of patient who is most susceptible.

Nursing administration of medication via enteral tubes in adults : a systematic review

Background Enteral tubes are frequently inserted as part of medical treatment in a wide range of patient situations. Patients with an enteral tube are cared for by nurses in a variety of settings, including general and specialised acute care areas, aged care facilities and at home. Regardless of the setting, nurses have the primary responsibility for administering medication through enteral tubes. Medication administration via an enteral tube is a reasonably common nursing intervention that entails a number of skills, including preparing the medication, verifying the tube position, flushing the tube and assessing for potential complications. If medications are not given effectively through an enteral tube, harmful consequences may result leading to increased morbidity, for example, tube occlusion, diarrhoea and aspiration pneumonia. There are resultant costs for the health-care system related to possible increased length of stay and increased use of equipment. Presently what is considered to be best practice to give medications through enteral tubes is unknown.

Objectives The objective of this systematic review was to determine the best available evidence on which nursing interventions are effective in minimising the complications associated with the administration of medications via enteral tubes in adults. Nursing interventions and considerations related to medication administration included form of medication, verifying tube placement before administration, methods used to give medication, methods used to flush tubes, maintenance of tube patency and specific practices to prevent possible complications related to the administration of enteral medications.

Search strategy The following databases were searched for literature reported in English only: CINAHL, MEDLINE, The Cochrane Library, Current Contents/All Editions, EMBASE, Australasian Medical Index and PsychINFO. There was no date restriction applied. In addition, the reference lists of all included studies were scrutinised for other potentially relevant studies.

Selection criteria Systematic reviews of randomised controlled trials (RCTs) and RCTs that compared the effectiveness of nursing interventions and considerations used in the administration of medications via enteral tubes. Other research methods, such as non-randomised controlled trials, longitudinal studies, cohort and case control studies, were also included. Exclusion criteria included studies investigating drug–nutrient interactions or the bioavailability of specific medications.

Data collection and analysis Initial consideration of potential relevance to the review was carried out by the primary author (NP). Two reviewers independently assessed study eligibility for inclusion. A meta-analysis could not be undertaken, as there were no comparable RCTs identified. All data were presented in a narrative summary.

Results There is very limited evidence regarding the effectiveness of nursing interventions in minimising the complications associated with enteral tube medication administration in adults. The review highlights a lack of high quality research on many important nursing issues relating to enteral medication administration. There is huge scope for further research. Some of the evidence that was identified included that nurses should consider the use of liquid form medications as there may be fewer tube occlusions than with solid forms in nasoenteral tubes and silicone percutaneous endoscopic gastronomy tubes. Nurses may need to consider the sorbitol content of some liquid medications, for example, elixirs, as diarrhoea has been attributed to the sorbitol content of the elixir, not the drug itself. In addition, the use of 30 mL of water for irrigation when administering medications or flushing small-diameter nasoenteral tubes may reduce the number of tube occlusions.