Thesis (MScEng)--Stellenbosch University, 2013. / AFRIKAANSE OPSOMMING: Saamgestelde materiale het baie gewilde materiale in die lugvaart- en motor
industrië geword as gevolg van die gewigsbesparende voordele wat dit inhou.
Kostes en ander verwerkingsprobleme het tradisioneel die wydverspreide gebruik
van spesifiek termoplasties-versterkte vesels in hierdie areas verhinder. Baie van
die vervaardigingsprobleme (spesifiek lang siklusse) is aangespreek met die
aanvang van termoplastiese matriks materiaal soos Polyphenolien Sulfied (PPS).
Hierdie materiaal voldoen ook aan die lugvaart-industrie se brand-, rook- en
giftigheidstandaarde.
Termoplastiese saamgestelde materiale kan byvoorbeeld gevind word op
komponente in vliegtuie se binneruimtes en ook die voorste rand van die vlerke.
Hierdie komponente is hoogs vatbaar vir impakskade. Die hoë sterkte en styfheid
tot gewig verhoudings van saamgestelde materiale laat toe vir dun materiaal
dwarssnitte. Komponente is dus kwesbaar vir uit-vlakkige impak beladings.
Saamgestelde materiale kan ook intern deur hierdie beladings beskadig word en
kan nie met die blote oog waargeneem kan word nie. Dit is dus nodig om die
skade weens hierdie beladings tydens normale gebruik akkuraat te voorspel.
Verder sal dit nuttig wees om die struktuur se gedrag te bepaal in toepassings
waar byvoorbeeld passasier veiligheid krities is, soos op vliegtuig ruglenings
tydens noodlandings.
In hierdie studie is die potensiële vervaardigingsvoordele van termoplastiese
saamgestelde materiale gedemonstreer. Daarbenewens is 'n uit-vlakkige impak
deur 'n sagte liggaam herbou in 'n laboratorium omgewing. Die primêre doelwit
van hierdie studie was om die impak numeries te modelleer.
Vervaardigingsvoordele van `n vesel versterkte termoplastiese laminaat is
gedemonstreer deur die vervaardiging van 'n konkawe, agt laag laminaat uit 'n
vooraf gekonsolideerde geweefde doek. Die totale verwerkingstyd van die plat
laminaat na 'n konkawe laminaat was minder as vyf minute. 'n Eenvoudige plat
laminaat en 'n konkawe laminaat is onderwerp aan 'n lae snelheid impak deur 'n
sagte projektiel. Die impak is gemodelleer deur die evaluering van drie
modelleringsmetodes vir die saamgestelde paneel. Die evalueringskriteria het o.a.
ingesluit of laminaat se volle gedrag suksesvol gemodelleer kon word met behulp
van slegs 2D dop elemente.
Die reaksie van die saamgestelde paneel en gepaardgaande faling is met
wisselende vlakke van sukses deur die drie geëvalueerde modelle voorspel. Die
faling van tussen-laminêre bindings (verwys na as delaminasie) kon nie deur
enige van die modelle voorspel word nie. Twee van die modelle het egter in-vlak
faling met redelike akkuraatheid voorspel. / ENGLISH ABSTRACT: Due to weight saving advantages composite materials have become a highly
popular material in the aerospace and automotive industries. Traditionally
processing difficulties and costs have been a barrier to widespread composite
material use in these industries. With the advent of thermoplastic matrix materials
such as Polyphenoline Sulphide (PPS) the processing difficulties (especially long
cycle times) experienced with traditional thermosetting resins can be addressed
while maintaining aerospace Fire-Smoke and Toxicity (FST) approval.
Thermoplastic composites can for example be found on aircraft interior
components and leading edges of the wings. These areas are highly susceptible to
impact damage. The high strength- and stiffness to weight ratios of composites
allows for thin material cross sections. This leaves the components vulnerable to
out-of-plane impact loads. Composite materials may also be damaged internally
by these loads, leaving the damage undetectable through visual inspections. It
may therefore be necessary to predict the amount of damage a component would
sustain during normal operation. Additionally, it would be useful to predict
structural response of these materials in applications where passenger safety is
crucial, such as aircraft seat backrests during emergency landings.
In this study the potential processing benefits of thermoplastic composite
materials were demonstrated. Additionally an out-of-plane impact from a soft
bodied projectile was reconstructed in a laboratory environment. The primary
objective was to numerically model the impact event.
Processing benefits of thermoplastics were demonstrated by producing a single
curvature eight layered laminate from a pre-consolidated woven sheet. The total
processing time from flat panel to a single curvature panel was below five
minutes. A simple flat laminate and a single curvature laminate were subjected to
a low velocity drop weight impact load from a soft bodied projectile. These
impact events were modelled by evaluating three modelling methods for the
composite panel structural response and damage evolution. Part of the evaluation
criteria included whether laminate failure could be modelled successfully using
only 2D shell elements.
The response of the composite panel and accompanying failure were predicted
with varying levels of success by the three evaluated models. The failure of interlaminar
bonds (referred to as delamination) could not be predicted by either
model. However two of the models predicted in-plane failure with reasonable
accuracy.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/80095 |
| Date | 03 1900 |
| Creators | Van der Westhuizen, Artho Otto |
| Contributors | Venter, Gerhard, Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 97 p. : ill. |
| Rights | Stellenbosch University |
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