The use of X-ray computed tomography for design and process modeling of aerospace composites: A review

In this study, we employ a parametric approach coupled with surface analysis to identify the source(s) of surface porosity and to develop effective mitigation strategies. Results confirmed that surface porosity was primarily associated with air that was trapped at the tool–prepreg interface during layup. The magnitude and distribution of surface porosity was affected by multiple parameters, including vacuum hold time, freezer and out time, and material and process modifications that affect air evacuation. The results indicated that prepreg out time (and thus tack) and vacuum quality were the primary drivers of surface porosity; for example, surface porosity decreased by 83% after just four days of out time and by 99% after 14 days of out time. These factors were used to formulate guidelines to mitigate surface porosity by (a) increasing the driving force for air evacuation and/or (b) increasing the permeability of the tool–prepreg interface.

/pdf/surface-porosity-during-vacuum-bag-only-prepreg-processing-2ea080spof.pdf

Surface porosity during vacuum bag-only prepreg processing: Causes and mitigation strategies

Composite materials proved highly successful for aerospace applications in the last decades, but increased cost pressure forces the composite industry to become more efficient. This requires new ma...

https://tandfonline.com/doi/pdf/10.1080/00207543.2018.1554918

Production planning optimisation for composite aerospace manufacturing

An efficient macro-scale finite element approach is introduced to predict defects that arise from the consolidation of carbon fibre woven fabric prepregs. The model incorporates the through-thickness compaction and inter-ply shear behaviour of the plies in the form of a compliant penalty contact in an explicit finite element simulation. For describing the compressibility of uncured prepregs, a one-dimensional compaction model is implemented via a user-subroutine. The model parameters were identified from an experimental programme and validated against compaction and inter-ply shear experiments on a Carbon/Epoxy prepreg. Moreover, the in-plane and out-of-plane behaviour of the woven fabric is captured through a hybrid hypo-elastic membrane and shell modelling approach. The applicability of the model is further demonstrated through a number of industrially relevant case studies. The method is simple, efficient, and it can be applied to assess various scenarios for modelling textile forming and consolidation behaviour.

Consolidation-driven wrinkling in carbon/epoxy woven fabric prepregs: an experimental and numerical study

Out-of-autoclave prepreg processing requires evacuation of volatiles in the early stages of processing to achieve an acceptable final void content. In this study, single prepreg plies were laid-up ...

/pdf/an-experimental-technique-to-characterize-interply-void-29imtevfoe.pdf

An experimental technique to characterize interply void formation in unidirectional prepregs

Air entrapped during the material deposition stage of prepreg layup can contribute to voidage in the cured laminate, which is a major factor in determining the quality of the resulting laminates and components. Removal of this entrapped air is therefore a priority to achieve maximum part performance. To date, there does not appear to have been any consistent study of the processes by which voids can be entrapped. This paper seeks to address this by presenting direct observations of the contact between a glass tool surface and the first ply of carbon fiber prepreg laid down onto it. The entrapment of air between the tool and ply is investigated, in terms of its distribution and evolution during debulk under vacuum at room temperature. A counterintuitive inverse relationship between initial area of contact and the final level of entrapped air was observed, with higher levels of initial contact leading to higher final levels of entrapped air. An initial examination was also carried out to review the ...

https://www.tandfonline.com/doi/pdf/10.1179/2055035914Y.0000000005

On the evolution of the distribution of entrapped air at the tool/first ply interf‘ace during lay-up and debulk

This study considers the effect of pressure in the hand layup and vacuum bagging processes. Firstly, the layup method is considered. The use of rollers is common shop-floor practice, but the results presented suggest that rolling plies can lead to areas of trapped air in laminates, as visualised by laying up a ply on a glass plate. The bagging process, designed to remove air and aid consolidation is a further opportunity for introducing variability in manufacture. Using a pressure mapping system, common bagging defects such as bridging and wrinkling are examined in the context of their effect on part quality. It is shown that bag pressure is far from hydrostatic when these features are present.

A study of the pressure distribution in the hand layup and vacuum bagging processes

Background: Demand for publicly funded orthopaedic outpatient services is growing rapidly which affects a health service’s ability to provide timely care. The current study describes the implementation and preliminary evaluation of a novel physiotherapist-led paediatric fracture clinic, which was introduced to provide more timely care to children. The study evaluated 1) the length of time patients spent in the outpatient department per appointment, 2) did-not-attend rates and 3) unplanned re-presentations to the clinic for the same problem. Methods: The study was conducted at a large regional hospital in Victoria, Australia. A physiotherapist-led paediatric fracture clinic was introduced in 2013 to provide care to children with acute simple limb fractures. Descriptive data for all patients seen in the clinic between 1st January 2013 and 31st December 2018 were collected prospectively. The performance of the new service was evaluated by comparing it to the pre-existing orthopaedic surgeon-led fracture clinic for the six months prior to the introduction of the new service for 1) the total time patients spent in the outpatient department per appointment and 2) the number of patients that failed to attend an appointment. The pre-existing surgeon-led clinic was also compared to the surgeon-led clinic for the six months following the introduction of the physiotherapist-led clinic. Total time spent in the department per appointment was compared between groups using linear regression, controlling for age, diagnosis and appointment type (new or review). The proportion of patients who did not attend an appointment were compared between groups using the chi square test. The number of unplanned representations to either clinic was assessed between 01/01/2013 and 31/12/2018. Results: Between 2013 and 2018, there were 4337 attendances at the physiotherapist-led clinic. Total time in the department was significantly less (p<.05) for patients seen in the physiotherapist-led clinic when compared to the pre-existing surgeon-led clinic (median difference 82 minutes). Total time in the surgeon-led clinic also reduced following the introduction of the new service (median difference 21 minutes). Did-not-attend rates (10.3%) and unplanned re-presentations (0.6%) were similar (p>.05) between the groups. Conclusions: The physiotherapist-led clinic improved the timeliness of care for paediatric patients without evidence of compromised patient safety. KEYWORDS: Paediatrics, musculoskeletal health, service evaluation, service redesign, workforce reform, fractures, orthopaedics.

A Physiotherapist-Led Paediatric Fracture Clinic was a Safe and Efficient Alternative to Traditional Outpatient Orthopaedic Care: A Preliminary Evaluation

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

M. A. Napper

Author Tools

Chat about Author

Papers

On the evolution of the distribution of entrapped air at the tool/first ply interf‘ace during lay-up and debulk

A study of the pressure distribution in the hand layup and vacuum bagging processes

A Physiotherapist-Led Paediatric Fracture Clinic was a Safe and Efficient Alternative to Traditional Outpatient Orthopaedic Care: A Preliminary Evaluation