Composite materials pultrusion

Pultrusion is also used to make structural shapes from composite materials. The incoming material is generally unidirectional and must be pulled through the pultrusion die because the uncured composite material is entirely too flexible to push (as in extrusion processes). The incoming material can be preshaped by various guides and rollers as in Figure 1-18. 

Figure 7.87 Schematic diagram of a typical pultrusion process. Reprinted, by permission, from M. Schwartz, Composite Materials Handbook, 2nd ed., p. 4.46. Copyright 1992 McGraw-Hill.

Pultrusion [PHENOLIC RESINS] (Vol 18) [PLASTIC PROCESSING] (Vol 19) [REINFORCED PLASTICS] (Vol 21) [COMPOSITEMATERIALS - SURVEY] (Vol 7) resin properties required for [COMPOSITE MATERIALS - POLYMER-MATRIX - THERMOSETS] (Vol 7)... 

Resin-based composites are usually defined as either conventional or advanced. Conventional composites usually contain glass or mineral fiber reinforcement, and sometimes carbon fiber, either alone or in combination with others. Conventional composites are usually produced in stock shapes such as sheet, rod, and tube. There are many methods of processing composite materials. These include filament winding, layup, cut fiber spraying, resin transfer molding, and pultrusion. 

The properties of composite materials cannot be predicted adequately by considering the fibre and resin constituents one by one. An important mechanism of composite failure under stress is delamination caused by differences between the engineering properties of successive plies or layers. These differences arise from the fact that successive layers may have different fibre orientations [34] or, occasionally, different fibres. It is a feature of laminates made by stacking pre-impregnated layers of reinforcement and is not an issue with, for example, unidirectional pultrusions. The process of delamination has been reviewed by Davies [35]. The fabrication of three-dimensional composites is an important step towards reducing or eliminating unwanted delaminations. Such materials are at an advanced stage of development. 

Manufacturing methods for composites vary from manual to fully automated processes, whereby the latter have better quality control than the former. Wet layup, pultrusion, and filament winding are all discussed in some detail, while other techniques such as pull-winding, resin transfer moulding, vacuum bag moulding, and injection moulding are left to specialized composite materials texts. 

Give a brief description of the pultrusion technique for the preparation of composite materials. 

The surface treatment chemistry of glass fiber is normally tailored to match the product function. Reinforcement size chemistries must be compatible with a multitude of processes and with the composite material end-use performance criteria. Processes such as injection molding require chopped fibers with compatibility for thermoplastic compounds. Filament winding and pultrusion require continuous fibers with utihty in thermoset and thermoplastic compovmds. Typically three basic components cue used with glass size chemistries a film former, lubricant, and coupling agent. Readers are directed to the patent literature or [1] and [2] for more specific details. 

Astrom, B.T. and Pipes, R.B. (1991) Correlation between modelling and experiments for a thermoplastic pultrusion process. Proceedings of the Vlllth International Conference on Composite Materials, ICCM-VIll (eds S.W. Tsai and G.S. Springer), Honolulu, Hawaii, USA, July 15-19, Section 13-A-1-13-A-10. 

The pull-off unit, which pulls the composite material through the whole pul-trusion unit, is a mechanism located behind the pultrusion die. Because the constructive implementation is of least importance for a successful pultrusion process, it can be any mechanism that pulls the composite through the process. However, there are only two versions of pull-off units in practice -a continuous and a reciprocating unit. ... 

Kerbiriou, V. and Friedrich, K., Pultrusion of thermoplastic composites Process optimization and mathematical modeling . Journal of Composites Materials, 12,... 

Larock, J. A. and Hahn, H. T., Pultrusion processes for thermoplastic composites . Journal of Thermoplastic Composite Materials, 2, 216-228, 1989. 

Ahmed, R, Joshi, S. C. and Lam, Y. C. (2004), Three-dimensional FE/NCV modelling of thermoplastic composites pultrusion . Journal ofThermoplastic Composite Materials, 17, 447-462. 

Ben, G. and Shoji, A. (2005), Pultrusion techniques and evaluations of sandwich beam using phenohc foam composite , Ariva/iceri Composite Materials, 14, 277—288. 

Goichi, H. (Nihon University, Japan) (2003), Pultrusion Method for Glass Fiber-Reinforced Phenol Foam Composite Material, Patent abstracts of Japan 2003-145570. 20 May 2003. 

Gorthala, R., Roux, J. A. and Vaughan, J. G. (1994), Resin flow, cure and heat transfer analysis for pultrusion process, Journal of Composite Materials, 28, 486-506. 

Owens Coming Composite Materials LLC (2009), Pultrusion, March 2009, France. 

Srinivasagnpta, D., Kardos, J. L. and Joseph, B. (2003), Rigorous dynamic model-based economic design of the injected pultrusion process with controllability considerations , Journal of Composite Materials, 37, 1851-1880. 

Pultrusion. The pultrusion process makes structural profiles of any shape continuously from composite materials (6-9), just as they would be extruded in aluminum. It is a one-step process that converts raw stock into finished product at rates up to 4.5 m/min. 

CompositGS. There has been substantial progress in improving the processability of phenolics in composite materials (104-106) to the point where a variety of materials are available for pultrusion, filament winding, and resin-transfer molding (see Composites, Fabrication). More complicated composite systems are based on aramid and graphite fibers. 

As with other manufacturing processes, advanced composite materials produced by pultrusion are constituted by two phases ... 

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