JEC COMPOSITES MAGAZINE - Issue #98 - July/August 2015 - 46

Research & development

fractography

Failure investigation of polymeric composite components
- Failure investigation of
polymeric composite components ........................ p48
- Nonwovens for composites
- recycling carbon waste
in the form of long fibres
.................................... p50

Fractographic analysis, i.e. the examination and interpretation of
fracture surfaces, provides an insight into the causes and location of
failure. Previously considered as a "black art", specialists now relate
fracture morphologies to failure mechanisms with confidence and
provide information about the failure sequence and source of failure
initiation. This technique gives great feedback and can allow better
design for next-generation parts.

he use of fibre-reinforced composite materials is increasing at an
unprecedented rate in transportation and energy whilst these materials are
starting to be adopted in construction,
oil and gas and biomedical applications.
As the global market for composites is
expected to reach US$105.8 billion in
2020 [1], the number of in-service failures will inevitably rise as will the need
to identify causes of failure and mitigate
against them.

ing more confident in predicting their
in-service performance via analytical
and numerical methods. However, the
complex architecture and sensitivity to
defects of composites has made designers reticent about incorporating these
materials into primary structures. During
service, composites can fail not only due
to overload but also due to material and
manufacturing defects as well as damage
during assembly and use which cannot be predicted using numerical tools.
This has necessitated a "make and test"
approach for composite design. Such an
approach is complemented by in-service
failure investigation, which involves
the dissection of the failed composite
components and the meticulous examination of the fractured surfaces to glean
information about the failure modes and
critical design parameters. The examination and interpretation of the fracture
surfaces to provide an insight into the
causes and location of failure is the subject of fractographic analysis.

Over recent years, the drive in the aerospace and automotive industries to develop lightweight structures to improve
the efficiency and reduce emissions has
made composites attractive candidates
for primary structural components. The
maturation of knowledge into composite
behaviour means designers are becom-

This post-mortem method is a powerful
tool which can offer valuable information
about the material quality and manufacturing process, mechanical performance
and failure, effect of environmental and
time-dependent conditions as well as
bridge the results from numerical and
experimental analysis.

By
Dr. SpyroS A. TSAmpAS
reSeArch engineer, mATeriAl TechnologieS,
SwereA Sicomp
Dr. emile S. greenhAlgh
reADer in compoSiTe mATeriAlS,
DepArTmenT of AeronAuTicS,
imperiAl college lonDon

46 jec composites magazine / No98 July - August 2015

http://www.jeccomposites.com/events/jec-forums-boston-2015

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #98 - July/August 2015