Journal of Materials Science and Engineering A 2 (1) (2012) 72-76
The U of Vacuum Assisted Resin Infusion Process on the Manufacturing of Wind Blade Composites
Lies A. Wisojodharmo and Seto Rono
Agency for the Asssment and Application of Technology (BPPT), Center for Materials Technology (PTM), Jl. MH Thamrin 8, BPPT II 22 Fl, Jakarta 10340
Received: April 28, 2011 / Accepted: May 29, 2011 / Published: January 10, 2012.
北京金色雨林
Abstract: There has been a growing interest to u composite materials in structural application ranging from aircraft to automotive applications. This is becau advanced composites exhibit desirable physical and chemical properties. Vacuum assisted resin infusion (VARI) technique has become popular in the manufacturing of composite materials. In this process, resin is drawn into preform through the u of a vacuum, rather than pumped under pressure. It has become a very attractive fabrication technology in recent years becau of low cost tooling scalability to very large structures. The fabrication technology of wind blades ud to be by hand lay-up techniques and without vacuum process. Wind blades produced by hand lay-up technique ud to experience cracks i
n leading edge part and also had short life-time. The rearch aims to get composite materials with better properties by means of VARI fabrication technique. In this paper, the composite materials were prepared by hand lay-up and VARI techniques. The composite specimens were made in 7 layers having 2 different fibre orientation angles namely 0/45/0/45/0/45/0 (asymmetric) and 45/0/45/0/45/0/45 (symmetric). The mechanical properties of composite materials made by VARI technique shown to have better properties than tho made by hand lay-up technique. The modulus elasticity of composite materials made by VARI were found to be higher by 40.36%; tensile strengths were higher by 42.54% and compressive strengths were higher by 106.87% than the composite materials made by hand lay-up technique. Furthermore, the weight of the resulting wind blade made by VARI was 2.491 kg, far lighter than the weight of the wind blade made by hand lay-up, which was 4.071 kg.
Key words: VARI, wind blade composites, mechanical properties.
1. Introduction
Composite is a combined material created by synthetic asmbly of two or more components, a lected filler, or reinforcing agent and a compatible matrix binder (resin) to obtain specific characteri
stics and properties. The components of composite do not dissolve or otherwi merge completely into each other, but do act in concert. The composites can be classified on the basis of the form of their structural components fibrous (compod of fibers in a matrix), laminar (compod of layers of materials) and particulate (compod of particles in a matrix). Typical resins include polyester, phenolics, epoxy, silicone, alkyd, melamine, polyimide, fluorocarbon, polycarbonate etc.
Corresponding author:Seto Rono, rearch field: compositematerial.E-mail:******************.At prent the u of thermotting resins (polyester, phenolic, polyimide, and epoxy) predominates. The u of reinforcing agents makes it possible for any thermot matrix property to improved or changed to meet varying requirements [1].
The composite industry employs many reinforcing agents and resins combination to achieve a diversity of performance and cost characteristics. The primary reinforcing agents ud in the production ud in the production of composites at prent time are glass, paper (cellulosic fiber), cotton, polyamide and other natural fiber, asbestos, sisal, and jute. The many forms
of fiberglass find wide u in the production of different commercial products (automobiles, appliances, etc.) as well as in the manufacture of parts
香取慎吾
for space craft, wind blade, and underwater vehicles.
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Fiberglass is principal reinforcing agent for strengthening resins, since it provides rather significant advantages on a cost-to-performance basis. Thermots (polyester, phenolic, polyimide, and epoxy) are resins ud most often in fiberglass composites.
Vacuum Assisted Resin Infusion Techniques have become popular in manufacturing of the composites [2-8]. The most popular term to describe vacuum infusion process are Vacuum Assiste
d Resin Transfer Moulding (VARTM), Vacuum Assisted Resin Infusion Moulding (VARIM) etc, basically the same technology, and describe methods bad on the impregnation of dry reinforcement by liquid thermot resin driven under vacuum, and this technique made to reduce the void content inside the moulded composites. With vacuum bag moulding, the bags are ud to evacuate the air from laminate and to generate the atmospheric pressure required for compaction over the mold [9-11]. The molding method include vacuum bag is shown in Fig. 1.
2. Experiment
2.1Materials
Materials employed in this experiment include Epoxy Resin EPR 174, Renlam M, Fiber Glass WR 200, WR 400, WR 600, Hardener V-140, relea agent, vacuum bag.
2.2 Specimen Materials
•The composite materials specimens in flat panel form were made from fiberglass and epoxy resin matrix, with the size 50 cm × 50 cm. The mold was made from flat glass which was covered with mirror glaze as relea agent. The composite materials were made by hand lay-up technique;
•The top of the mold is covered with “gelcoat”, then all surfaces were covered with mixture of epoxy resin and “hardener” with composition resin: hardener
= 2:1, then covered with fiberglass “woven roving”. The fiberglass was wetted by mixture of epoxy resin and hardener with hand lay-up techniques;
•Then all surfaces were covered by fiberglass, and the fiber was cut at 45 degree orientation angle, and continuously wetted with epoxy resins. The activities were repeated until 7 layers, and the fiber was cut and layered alternatingly at orientation angles: 0/45/0/45/0/45/0, and it is called asymmetric. •Another composite material specimens were also
Fig. 1 The vacuum bag molding method [1]. All Rights Rerved.
The U of Vacuum Assisted Resin Infusion Process on the Manufacturing贴纸英文
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Fig. 2 Design of wind blade with “Hub” and “Spar”.
made with orientation angles: 45/0/45/0/45/0/45/0/45, which is called symmetric;
•Then the composite materials were cured at room temperature. The composite materials were made by technique hand lay-up without vacuum process; •Another pair of composite material specimens were also made with the same method and same compositions, but then they were covered with plastic film (vacuum bag), and then vacuumed. The composites were made by technique hand lay-up with vacuum or it is called VARI techniques.
2.3 Characterization
The composite material specimens were characterized by mechanical properties which are tensile strength, modulus elasticity and compressive strength, in accordance to method designated in ASTM
D 790-80 (Compressive Strength), and ASTM D 638 (Tensile Strength and Modulus Elasticity).
2.4 Prototype Production
The wind blade was made from wood, and then all surfaces were covered with relea agent and continued with “gelcoat”, unsaturated polyester and fiberglass. The activities are repeated until a mold with thickness 3 mm is obtained.
The wind blade was made using this mold, and the process is the same method and the same composition with specimen materials. The design of wind blade is shown as pictured below: “Hub” is made from coconut wood, and “spar” is made from polyurethane.
3. Results and Discussion
cab
The influence of fiber orientation angle (asymmetric and symmetric) on the mechanical properties of
the composite materials is shown in Table 1. The compressive strength of composite material with fiber orientation angle asymmetric is higher than symmetric, but the tensile strength for symmetric is higher than asymmetric.
The influence of fiber glass type (WR 200, WR 400, WR 600) on the mechanical properties of the composite materials is shown in Table 2. The compressive strength of composite material which made from WR 200 is lower than WR 400 and tho of WR 600 are the least. The tensile strength of composite materials which is made from WR 200 is lower than WR 400 and tho of WR 600 are the least.
The influence of resin type (Epoxy Resin and Renlam M) on the mechanical properties of the composite materials is shown in Table 3. The compressive strength of composite material made from Epoxy resin are found to be higher than composite made from Renlam M, also the tensile strength of composite made from Epoxy resin are shown to be higher than from Renlam M, but modulus elasticity of composite with Renlam M is relatively higher.
specify是什么意思
The mechanical properties of the composite materials specimens with hand lay-up without vacuum and VARI techniques are shown in Table 4.
Table 1 The influence of fiber orientation.
The composite materials Compressive strength (MPa) Tensile strength (MPa) Mod. elasticity (GPa)
WR 200 Symmetric Epoxy resin 72.5 167.1 10.437
WR 200 Asymmetric Epoxy resin 47.4 131.5 7.937
WR 400 Symmetric Renlam M 66.2 187.2 13.665
WR 400 Asymmetric Renlam M 78.6 184.2 15.578
WR 600 Symmetric Renlam M 21.6
WR 600 Asymmetric Renlam M 26.5
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The U of Vacuum Assisted Resin Infusion Process on the Manufacturing
自考本科报名
of Wind Blade Composites
75dramatic irony
Table 2 The influence of fiberglass types.
The composite materials Compressive strength (MPa) Tensile strength (MPa) Mod. elasticity (GPa)
WR 200 Symmetric epoxy resin 72.5 167.1 10.437
WR 400 Symmetric epoxy resin 60.4 177.6 12.80
WR 600 Symmetric epoxy resin 27.7 124.3 8.902
WR 200 Asymetric epoxy resin 47.4 131.5 7.932
WR 400 Asymmetric epoxy resin 89.5 186.9 14.637
WR 600 Asymmetric epoxy resin 33.7
Table 3 The influence of resin type.
The composite materials Compressive strength (MPa) Tensile strength (MPa) Mod. elasticity (GPa)
WR 600 Asymmetric renlam M 26.5
WR 600 Asymmetric epoxy resin 33.7
WR 200 Symmetric epoxy resin 72.5 167.1 10.437
WR 200 Symmetric renlam M 71.5 162.6 10.349
WR 400 Asymmetric epoxy resin 89.5 186.9 14.900
WR 400 Asymmetric renlam M 78.6 184.2 15.578
WR 400 Symmetric epoxy resin 60.4 177.6 12.800
WR 400 Symmetric renlam M 66.2 187.2 13.665
Table 4 The influence of fabrication techniques.
Properties Hand lay-up technique without vacuum VARI technique % Increa Modulus elasticity (GPa) 7.37 10.35 40.36 Tensile strength (MPa) 114.13 162.68 42.54 Compressive strength (MPa) 34.5 71.37 106.87
The specimens made by VARI technique have mechanical properties higher than tho made by hand lay-up technique.
Moreover, the weight of wind blade made by hand lay-up without vacuum process is 4.071 kg, clearly heavier than the wind blade produced by VARI technique which weighs 2.491 kg. Therefore the weight of the VARI wind blade is lighter than the one made by hand lay-up technique without vacuum process. This is the conquence of significant reduction in the amount of voids trapped in the composite laminates, and thus creating a more compact material.
4. Conclusions
It is shown from the experimental data that wind blade is produced with composite material having the best optimum mechanical properties namely the one with asymmetric, WR 400 and matrix epoxy resin. Composite materials produced by VARI technique have better mechanical properties than tho made by hand lay-up technique without vacuum process. This is due to significant reduction in the number of voids created in the laminate, and thus creating more compact material.
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