Composites part 1 - c Flashcards
What is roving?
A bundle of continuous filaments. The bundle may be in the form of an untwisted strand or twisted yarn. The roving is available in a range of weights or ‘tex’; weighed in grams per kilometer.
What is chopped strand mat (CSM)?
This is a sheet of reinforcement material comprised of randomly dispersed chopped fibers (usually 25-50 mm in length) held together with a resinous binder. CSM is produced in a variety of widths, lengths and weights.
What is woven fabric? Explain weft and warp?
This is produced from yarns. Woven fabrics are described by the weave pattern; the number of yarns in warp and weft and the yarn count. In weaving the weft is the term for the yarn which is drawn through the warp to create cloth. Warp is the lengthwise or longitudinal thread in a roll, while weft is the transverse thread.
What is a plain weave?
The simplest form with warp and weft yarns alternatively passing under and over each other.
What is a balanced weave?
The number and count of warp and weft yarns are equal.
What is a satin weave?
Each warp and weft yarn goes over one yarn then under a number of yarns. Made by floating a yarn over 4+ yarns then under one yarn.
What are the advantages of satin weave?
Makes a very smooth, shiny and drapable fabric.
What are the disadvantages of satin weave?
Not durable, floats tend to break or snag.
What does a 5-harness satin weave have?
One warp yarn passing over 4 weft yarns before passing under the fifth yarn.
What is a twill weave?
One in which the warp and weft yarns which pass over each other are varied, recognizable by diagonal lines.
What does a 2x2 twill weave have?
2 over by 2 under.
Why are satin and twill weaves more suitable for moulding complex curvatures than plain weaves?
Because they have better drape characteristics.
What is woven roving?
Coarse heavy weight woven fabric produced from strand rovings. A range of filament diameter, no of strands and weave styles are available. Plain weave woven roving is the most common. Tapes are usually woven in a variety of weave styles and widths, normally less than 150mm.
How are knitted fabrics produced?
Produced using conventional textile knitting processes. Using modern computer controlled knitting machines the process is capable of producing a variety of patterns and shapes at high rates of production.
Why are knitted fabrics more pliable than woven?
Because they don’t have any crimped fibers.