Обучение чтению литературы на английском языке по специальности «Композиционные материалы» (120

5. Complete each sentence with an appropriate part.

6. Translate from Russian into English.

1.Композиционные материалы широко используются как

впромышленности, так и в повседневной жизни. 2. Композиты образуются путем соединения двух или более материа-

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лов с абсолютно разными свойствами. 3. За последние десятилетия было разработано множество новых композиционных материалов, причем некоторые из них обладают очень ценными свойствами. 4. Используются саморастущие кристаллические структуры, склеенные в единую массу полимерным клеем, композиции из термопласта с короткими армиирующими волокнами.

7. Read the information in the Text IB and ask questions to get these answers:

1)in the 1920; 2) 2 %; 3) by 1981; 4) in the 1950s; 5) 25 %;

6)boeing 707.

Text IB

Composites In Airspace Design

For many years, aircraft designers could propose theoretical designs that they could not build because the materials needed to construct them did not exist. (The term “unobtainium” is sometimes used to identify materials that are desired but not yet available.) For instance, large spaceplanes like the Space Shuttle would have proven difficult, if not impossible, to build without heat-resistant ceramic tiles to protect them during reentry. And high-speed forward-swept-wing airplanes like Grumman’s experimental X-29 or Russian Sukhoi S-27 Berkut would not have been possible without the development of composite materials to keep their wings from bending out of shape. Composites are the most important materials to be adapted for aviation since the use of aluminum in the1920s.

Fiberglass is the most common composite material, and consists of glass fibers in a resin matrix. Fiberglass was first used widely in the 1950s for boats and automobiles, and today most cars have fiberglass bumpers covering a steel frame. Fiberglass was first used in the Boeing 707 passenger jet in the 1950s, where it comprised about two percent of the structure. By the1960s, other composite materials became available, in particular boron

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fiber and graphite, embedded in epoxy resins. The U.S. Air Force and U.S. Navy began research into using these materials for aircraft control surfaces like ailerons and rudders. The first military production use of boron fiber was for the horizontal stabilizers on the Navy’s F-14 Tomcat interceptor. By 1981, the British Aerospace-McDonnel Douglas AV-8B flew with over 25 percent of its structure made of composite materials.

9. Answer the following questions and make a brief report on the properties of composite materials.

1.Why are composite materials better from a technical standpoint?

2.What makes composite materials stand out from the competition?

You will find the following vocabulary useful:

lightweight, much stronger, water-resistant, corrosionresistant, tough, reliable, stiff, durable, capable for recycling, abrasion resistant, thermally stable; to possess, to withstand, to exceed.

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2. Read and translate Text IIA.

Text IIA

Introduction to Manufacturing techniques

Every material possesses unique physical, mechanical, and processing characteristics and therefore a suitable manufacturing technique must be utilized to transform material to the final shape. One transforming method may be best suited for one material and may be not effective choice for another material. For example, wood is very easy to machine and therefore machining is quite heavily utilized for transforming a wooden block to its final shape. Ceramic parts are difficult to machine and therefore are usually made from powder using hot press techniques. In metals, machining of the blank or sheet to the desired shape using a lathe or CNC machine is very common. In metals, standard sizes of blanks, rods, and sheets are machined and then welded, adhered or fastened to obtain the final part. In composites, machining of standard-sized sheets or blanks is not common and is avoided because it cuts the fiber and creates discontinuity in the fibers. Exposed and discontinuous fibers decrease the performance of the composites. Moreover, the ease of composites processing facilitates obtaining near-net-shape parts. Composites do not have high pressure and temperature requirements for part processing as compared to the processing of metal parts using extrusion, roll forming, or casting. Because of this, composite parts are easily transformed to near-net-shape parts using simple and low-cost tooling. In certain applications such as making boat hulls, composite parts are made at room temperature with little pressure. This lower-energy requirement in the processing of composites as compared to metals offers various new opportunities for transforming the raw material to near-net-shape parts.

Composite production techniques utilize various types of composite raw materials, including fibers, resins, mats, fabrics, prepregs, and molding compounds, for the fabrication of

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composite parts. Each manufacturing technique requires different types of material systems, different processing conditions, and different tools for part fabrication.

3. Answer the questions to the text.

1. Why do we use different manufacturing techniques to transform material to the final shape? 2. What is very common during machining of the blank or sheet of metal to the desired shape? 3. Why do composite parts are easily transformed to near- net-shape parts using simple and low-cost tooling? 4. What row materials do composite production techniques utilize?

4. Complete each sentence with an appropriate part.

5. Translate from Russian into English.

Композиты — это материалы, которые состоят из двух или более органических или неорганических (inorganic) компонентов. Один из материалов служит матрицей. Этот материал удерживает все составляющие вместе. Другой

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материал — в форме волокон, внедренных в матрицу, — служит армирующим веществом.

6. Read and translate text IIB with a dictionary.

Text IIB

Wet Lay-Up Process

In the early days, the wet lay-up process was the dominant fabrication method for the making of composite parts. It is still widely used in the marine industry as well as making prototype parts. This process is labor intensive and has concerns for styrene emission because of its open mold nature. In this process, liquid resin is applied to the mold and then reinforcement is placed on top. A roller is used to impregnate the fiber with resin. Another resin and reinforcement layer is applied until a suitable thickness builds up. It is a very flexible process that allows the user to optimize the part by placing different types of fabric and mat materials. Because the reinforcement is placed manually, it is also called the hand lay-up process. This process requires little capital investment and expertise and therefore easy to use.

This process is widely used for making boats, windmill blades, storage tanks, and swimming pools. Because of its process simplicity and little capital investment, this process is widely used for making prototype parts.

Woven fabric of glass, Kevlar, and carbon fibers are used as reinforcing material. Epoxy, polyester, vinylester resins are used during the wet lay-up process, depending on the requirements of the part.

The mold design for the wet lay-up process is very simple as compared to other manufacturing processes because the process requires mostly a room temperature cure environment with low pressures.

The wet lay-up process is normally done under roomtemperature conditions. The resin is normally left at room

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temperature for a day or for overnight curing, depending on the resin chemistry. The cure time can be shortened by blowing warm air on the laminate. Pressure is applied using rollers during lamination.

7. Read and translate text IIС.

Text IIC

Typical Manufacturing Challenges

Some of the challenges that manufacturing engineers face during the prepreg lay-up process are listed below.

Maintaining accurate fiber orientations in the part is difficult because prepregs are laid down by hand. Automated tape placement equipment can be used for precise fiber control. Obtaining void-free parts is a challenge during this process. Voids are caused by entrapped air between layers. Achieving warpage — or distortion-free parts during the prepreg lay-up process is challenging. Warpage is caused by built-in residual stresses during processing.

8. Describe any other manufacturing process of composites. Useful vocabulary:

process cycle time, room-temperature, quality control, mold, demolding process (процесс извлечения из матрицы), fabrication, advantages, manually, core material, sandwich panel, tooling, challenges.

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the modern development of polymeric materials and high modulus fibers (carbon, aramidic) introduced a new generation of composites. The most relevant benefit has been the possibility of energetically convenient manufacturing associated with the low weight features. Due to the possibility of designing properties, composite materials have been widely used in the recent past, when stiffness / weight, strength / weight, ability to tailor structural performances and thermal expansion, corrosion resistance and fatigue resistance are required. Polymeric composites were mainly developed for aerospace applications where the reduction of the weight was the principal objective, irrespective of the cost. The scientific efforts in this field were therefore focused to the comprehension and optimization of the structural performances of these materials. A continuous task has been making composite components economically attractive.

Nowadays, the need of exploring new markets in the field of polymeric composites has recently driven the research in Europe towards the development of new products and technologies.

Since the beginning of the 90’s years, U.S. and Japan have recognized the need of expending composite applications. In the field of materials, Japan put more emphasis than U.S. on thermoplastic and high temperature resins. Moreover, due to the large extent of the textile industry in Japan, textile performing is significantly more advanced than in U.S., and this could lead to the development of cost-efficient automated computer-controlled looms for complex textile shapes. In contrast to the U.S. approach of developing computational models to better understand manufacturing processes, Japanese manufacturing science appears to reside in experienced workers who develop understanding of the process over long period of time.

Biomedical is another important field where composites are applied. Materials, able to simulate the complex structural properties of the natural tissues, which are composite in nature, have been developed but there are still few applications. This is due to the delay in the technology transfer from different areas

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