Independent, applied, constituent, remain, stiffness, common, composed, level

1. Composite materials are made of two or more … materials.

2. Composite materials are becoming more … in surgery.

3. The constituent materials in a composite … separate on a macroscopic … within the finished structure.

4. The properties are called isotropic if they are … of the direction of applied force.

5. The structure of new Boeing 787 is … largely of composites.

6. If the direction of the … load changes, the physical properties become different.

7. Aluminum and steel typically have the same … regardless of the directional orientation of the applied forces and/or moments.

8. Translate the text in writing. Use a dictionary. Find answers to the following questions:

1. What kinds of resins can be used in composites?

2. Are different resins equally resistant to degradation over time?

3. What is the main advantage of shape memory polymer resins?

Resins

Typically, most common composite materials, including fiberglass, carbon fiber, and Kevlar, include at least two parts, the substrate and the resin.

Polyester resin, tends to have yellowish tint, and is suitable for most backyard projects. Its weaknesses are that it is UV sensitive and can tend to degrade over time, and thus generally is also coated to help preserve it. It is often used in the making of surfboards and for marine applications. Its hardener is a MEKP, which is composed of methyl ethyl ketone peroxide, a catalyst. When MEKP is mixed with the resin, the resulting chemical reaction causes heat to build up and cure or harden the resin.

Vinylester resin tends to have a purplish to bluish or greenish tint. This resin has lower viscosity than polyester resin and is more transparent. This resin tends to be more resistant over time to degradation than polyester resin, and is more flexible. It uses the same hardener as polyester resin (at the same mix ratio) and the cost is approximately the same.

Epoxy resin is almost totally transparent when cured. In the aerospace industry epoxy is used as a structural matrix material or as structural glue.

Shape memory polymer (SMP) resins have varying visual characteristics depending on their formulation. These resins may be epoxy-based, which can be used for auto body and outdoor equipment repairs; cyanate-ester-based, which are used in space applications; and acrylate-based, which can be used in very cold temperature applications, such as for sensors that indicate whether perishable goods have warmed above a certain maximum temperature. These resins are unique in that their shape can be repeatedly changed by heating above their glass transition temperature (T_g). When heated, they become flexible and elastic, allowing for easy configuration. Once they are cooled, they will maintain their new shape. The resins will return to their original shapes when they are reheated above their T_g. The advantage of shape memory polymer resins is that they can be shaped and reshaped repeatedly without losing their material properties, and these resins can be used in fabricating shape memory composites.

Work in pairs. Discuss what you know about composite materials. Use the expressions: I'd like to say a few words about..., Of special interest is the fact that...., I'd like to draw your attention to..., To sum up I can say that....

Література

1. Беляева М.А., Голова З.С. Сборник технических текстов на англиском языке. Учебное пособие для вузов. Издательство литературы на иностранных языках. Москва. 1956. 599с.

1. Kucher A. Technology of Metals. Mir Publishers. Moscow.1990. 224c.

3. Коваленко В.Е. Englih. Издание пятое, дополненное и переработанное. Издательское объединение «вища школа». Львов. 1974. 343с.