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9
The complexity of damages in composites is closely related to
anisotropy and includes various mechanisms, such as interfacial
debonding, matrix cracking, ply cracking, fibre breakage, and so on.
It is critical to understand the evaluation of damage accurately in
order to assess and predict the life of polymeric composites. From
the discussion, in the preceding sections, it is understood that the
composite consists of laminae, and the laminae consist of fibres and
a matrix. In order to understand and assess the behaviour of polymeric composites, it is important to understand the performance of
these materials under different loading conditions and operational
environments. The performance of polymeric composites is dependent on factors like loading conditions (such as cyclic or static),
temperature, humidity, volume fractions, exposure to radiation,
and the chemical environment. The assessment of the mechanical
behaviour may be carried out based on the loading conditions and
service environment [1, 2].
The characterization and testing of any material are used to
establish a complete understanding of it. Inherent defects in materials and process-driven discrepancies are common in polymeric
composites. The characterization and testing help in identifying any
flaw in the composites and, in turn, ensure their quality. It is also
important to characterize and test polymeric composites to generate the experimental data used to design the product and also to
predict its performance.
The characterization and testing methods must be easy to apply
and provide accurate results. New instrumentation techniques and
automation have made the results of characterization and testing
very accurate and easy to interpret. This had led to an easier correlation of the results. Because the characterization and testing equipment produced today are microprocessor controlled, they are very
versatile and accurate and have excellent capabilities. This chapter
delves in detail on the characterization and testing of composites.
? Example 9.1 Cite two examples of processing-driven defects in
polymeric composites.
v Answer
In a hand layup process, the orientation of reinforcement
cannot be repetitive (product-to-product), and this leads to
some variations in the properties obtained. Similarly, the
composites processed using autoclave moulding technology,
ineffective suctionning or vacuuming, or oversaturation of the
bleeder cloth lead to defective composite parts.
9.1 Sample Preparation
Sample preparation is the most important and critical activity
because it will enable decisions to be made on the acceptance and
qualifications of the product, design values, and process design.
Sample preparation is not limited to its physical dimension of standard. It is also important in terms of raw materials, processing techChapter 9 · Characterization and Testing of Polymeric Composites
9
The complexity of damages in composites is closely related to
anisotropy and includes various mechanisms, such as interfacial
debonding, matrix cracking, ply cracking, fibre breakage, and so on.
It is critical to understand the evaluation of damage accurately in
order to assess and predict the life of polymeric composites. From
the discussion, in the preceding sections, it is understood that the
composite consists of laminae, and the laminae consist of fibres and
a matrix. In order to understand and assess the behaviour of polymeric composites, it is important to understand the performance of
these materials under different loading conditions and operational
environments. The performance of polymeric composites is dependent on factors like loading conditions (such as cyclic or static),
temperature, humidity, volume fractions, exposure to radiation,
and the chemical environment. The assessment of the mechanical
behaviour may be carried out based on the loading conditions and
service environment [1, 2].
The characterization and testing of any material are used to
establish a complete understanding of it. Inherent defects in materials and process-driven discrepancies are common in polymeric
composites. The characterization and testing help in identifying any
flaw in the composites and, in turn, ensure their quality. It is also
important to characterize and test polymeric composites to generate the experimental data used to design the product and also to
predict its performance.
The characterization and testing methods must be easy to apply
and provide accurate results. New instrumentation techniques and
automation have made the results of characterization and testing
very accurate and easy to interpret. This had led to an easier correlation of the results. Because the characterization and testing equipment produced today are microprocessor controlled, they are very
versatile and accurate and have excellent capabilities. This chapter
delves in detail on the characterization and testing of composites.
? Example 9.1 Cite two examples of processing-driven defects in
polymeric composites.
v Answer
In a hand layup process, the orientation of reinforcement
cannot be repetitive (product-to-product), and this leads to
some variations in the properties obtained. Similarly, the
composites processed using autoclave moulding technology,
ineffective suctionning or vacuuming, or oversaturation of the
bleeder cloth lead to defective composite parts.
9.1 Sample Preparation
Sample preparation is the most important and critical activity
because it will enable decisions to be made on the acceptance and
qualifications of the product, design values, and process design.
Sample preparation is not limited to its physical dimension of standard. It is also important in terms of raw materials, processing techChapter 9 · Characterization and Testing of Polymeric Composites