Composites Knowledge Competition

Single choice questions

1) Which of the following statements is correct? ( )

(A) The tensile strength and elastic modulus of the fibers are very high in the

composite structure

(B) In composite structures, the tensile strength of the matrix (e.g., resin) is

higher than the tensile strength of the fiber

(C) The specific strength of composite is lower than that of aluminum alloy

(D) The specific modulus of composite is lower than that of aluminum alloy

2) Which of the following four statements is correct? ( )

(A) The designability of composite materials is poor

(B) The composite material has good vibration damping performance

(C) Composite material has bad fail-safe performance

(D) Composite is a kind of ductile material

3) According to the matrix material, which of the following statements is not the

classification of composite materials. ( )

(A) Metal matrix composite

(B) Resin matrix composite

(C) Ceramic matrix composite

(D) Boron fiber composite

4) Refering to the instrument detection method to detect the damage of composite

materials. Which of the following statements does not belong to that. ( )

(A) Ultrasonic testing

(B) Thermography technology testing

(C) X light detection

(D) Raman detection

5) Which of the following four statements about the function of the interfaces in

composite materials is correct. ( )

(A) It just bonds the matrix with the reinforcement together

(B) It can transfer overall load from the matrix to the reinforcement

(C) The performance of the composite is always improved

(D) The performance of the composite is always reduced

6) Which of the two experiments are used to evaluate the sensitivity of composite

laminates to structural defects / damage (except impact damage). ( )

(A) Open hole tension and open hole compression

(B) Inter-laminar shear and open hole compression

(C) Tensile test and compression test

(D) Open hole tension and bending test

7) What is the most critical performance index when composite materials are

designed to build the aircraft wing skin? ( )

(A)Tensile performance (B) Compression performance and shear strength

(C) Vibration Damping performance (D) Inter-laminar shear strength

8) Using the materials with higher specific modulus and specific strength to product

the components, which means ( )

(A) the smaller the weight and the greater the stiffness

(B) the higher the weight and the greater the stiffness

(C) the smaller the weight and the smaller the stiffness

(D) the smaller the weight and the smaller the stiffness

9) Compared with ordinary particle reinforced composite materials, in the condition

of same volume content of the particles, the nano particle reinforced materials

show ( )

(A) Lower cost (B) Better tensile performance

(C) More widely available raw materials (D) Better processability

10) Which of the following statement is correct about the epoxy resins? ( )

(A) Containing a large number of double bonds

(B) Using initiator during curing process

(C) Using amine curing agent during curing process

(D) Belong to the thermoset material

11) Which of the following statement about the electric conductivity of carbon fiber

is correct.( )

(A) Conductivity is much lower than metal

(B) Conductivity is much higher than metal

(C) No conductivity

(D) Just like metal

12) What does the young's modulus of the material mean? ( )

(A) The stress required to produce a unit elastic strain of the material

(B) Elastic strain induced by unit stress in material

(C) The ability of materials to resist plastic deformation

(D) The resistance of materials to deformation. the smaller the elastic modulus ,

the greater the stiffness of the material

13) In the curing process of composite structural repair, which of the following

statements about the curing temperature is correct. ( )

(A) The temperature is measured by the temperature gauge

(B) The temperature must be measured by thermocouples

(C) The temperature is the feeling by the hand

(D) The temperature is measured by a thermometer

14) Which of the following statements is correct? ( )

(A) When the composite structure is repaired, the prepreg can be got from the

refrigerator and opening the wrapping paper. It can be used immediately

(B) In the repair of composite structures, glass fiber prepreg can be used to repair

KEVLAR fiber plies

(C) The prepreg can be used as the wet layer repair in composite structure

(D) In the structural repair of composite materials, the prepreg exceeded the

storage period can be used

15) Which of the following statements is correct? ( )

(A) Civil aircraft fuselage skin uses honeycomb structure widely

(B) Glass fiber composites can be used to make radar enclosures or radio

Radome

(C) Glass fiber composites have a strong shielding effect on radar wave

(D) At present, the main load-bearing structure of large civil aircraft adopts

composite materials widely.

16) In the field of composite laminate repair, at least how many additional layers are

required in repair area? ( )

(A)4 (B)3 (C)2 (D)1

17) Which of the following statements is correct? ( )

(A) Adhesive aging would not cause debonding between panel and filling in

honeycomb sandwich structure

(B) Being in acoustic vibration environment for a long time, honeycomb

sandwich structure may initiates debonding damage between the panels and

the filling

(C) When subjected to bending, honeycomb sandwich will not collapse

(D) The panels of honeycomb structures do not produce fatigue damage under

cyclic load

18) Which of the following statements about the polymer matrix composites is

wrong. ( )

(A) Polymer matrix composites are also called resin matrix composites

(B) The commonly used matrices are thermoset and thermoplastic resins

(C) In thermosetting resins, the adhesive strength of the resins is weak and the

curing process is complex

(D) In thermoplastic resin, the resin has good processability.

19) Which of the following statements is not the advantage of adhesive repair process

in composite. ( )

(A) The stress concentration is small

(B) Less weight

(C) Poor aerodynamic performance

(D) High repair efficiency

20) According to the requirements of composite structural repair, which of the

following statements is wrong. ( )

(A) Satisfy the structural strength requirements, but can be unstable under

compression and shear load

(B) Satisfy the structural stiffness requirements

(C) Satisfy the durability requirements

(D) Added weight is small, the parts should meet the mass balance requirements.

21) According to the autoclave molding, which of the following statements is wrong.(

)

(A) It is a kind of special equipment that can be heated and pressed

simultaneously

(B) The mould can be wiped with hard materials

(C) Must check for any leakage of the vacuum bag

(D) Large size and complex shapes can be produced with this method

22) refering to the moulding pressing technology, which of the following statements

is correct. ( )

(A) It is a kind of molding method suitable for thermosetting resins only

(B) It is a kind of molding method suitable for thermoplastic resins only

(C) Molding material does not require pretreatment

(D) The production efficiency is low

23) Which of the following statement are not the factors that affect the strength of

glass fiber under normal temperature. ( )

(A)Storage time (B) Glass chemical composition (C) fiber diameter

(D) High temperature resistance

24) If moisture exists in sandwich structure , which statement is correct? ( )

(A) No debonding between sandwich core and panels

(B) Small holes could be placed on the panel and the moisture can be removed by

vacuum method

(C) Could not remove

(D) The panel of the corresponding part should be removed to reveal the

honeycomb core and the moisture could be removed by vacuum pumping

25) At present, the service temperature of most polymer matrix composites is ( )

(A) Less than 100 degrees

(B) Less than 200 degrees

(C) Less than 300 degrees

(D) Less than 400 degrees

26) Which of the following statements does not belong to the components of the

epoxy resin? ( )

(A)Fiber (B) Epoxy resin (C) Other Auxiliaries (D) Curing agent

27) Which statement is the correct description of the carbon steel? ( )

(A) Glass fiber reinforced Al matrix composites

(B) Glass fiber reinforced plastics

(C) Carbon fiber reinforced plastics

(D) Alumina fiber reinforced plastics

28) Which of the following statements about Kevlar fiber is correct. ( )

(A) Made by the method of dry-jet wet-spinning

(B) The axial strength is lower than the radial strength

(C) Strength performance can be maintained to over 1000 degrees

(D) Made by the chemical deposition method

29) Which of the following statements about carbon fiber is correct. ( )

(A) Made by the chemical deposition method

(B) Strength performance can be maintained to over 3000℃

(C) The axial strength is lower than the radial strength

(D) Made by spinning and carbonization process

30) The general service temperature of reinforced polypropylene plastics is ( )

(A)Less than 120 degrees (B) Less than 180 degrees

(C)Less than 250 degrees (D) More than 120 degrees

31) The mechanical properties of carbon fiber reinforced epoxy composites are

affected by moisture absorption, which statement is correct. ( )

(A) Epoxy resin becomes brittle after moisture absorption

(B) Water acts as plasticizer and reduces the glass transition temperature of resin

(C) Crosslinking reaction occurs in epoxy resin

(D) The hydrolysis occurs in epoxy resin

32) Which of the following statements about glass fiber is correct. ( )

(A) It is made of SiO2 glass

(B) It shows the highest specific modulus in all fibers

(C) The strength is worse than that of the whole glass

(D) The price is expensive and less applied

33) At present, the largest amount of reinforcement material used in composites is ( )

(A) Carbon fiber (B) Alumina fiber (C) Glass fiber (D) SiC fiber

34) At present, the largest amount of thermoset resins in composites for civil use is ( )

(A)Epoxy resin (B) Unsaturated polyester resin (C) Phenolic resin (D) Nylon

35) The general preparation process of polymer matrix composites does not include( )

(A) Prepreg manufacturing

(B) Layers of component

(C) Curing and post-treatment

(D) Dry process

36) The general service temperature of polyimide is ( )

(A)Less than 120 degrees (B) Less than 180 degrees

(C)Less than 250 degrees (D) More than 250 degrees

37) Which of the following statements is correct? ( )

(A) The radome for civil aircraft is made of aluminum alloy

(B) Kevlar fiber composites cannot be used in radar enclosures

(C) Glass fiber composites can be used to make radar enclosures

(D) Carbon fiber composites can be used to make radar enclosures

38) In aircraft structures, the external damage caused by lightning strikes is mainly on

( )

(A) All areas of the wing

(B) Fuselage and wing

(C) All areas of the airframe

(D) Radome / engine / wingtip

39) As to the riveting repair method in aviation field, which of the following

statements is correct. ( )

(A) A large number of fasteners will make the structure much heavier, so the use

of this method should be careful

(B) The riveting repair method is applicable to thin integral panels

(C) Riveted repairs can only be carried out externally

(D) The load delivered by riveted repair is small

40) The highest volume of fiber in composite products manufactured by RTM (resin

transfer molding) process can be ( )

(A) 30% (B) 40% (C) 50% (D) 60%

Multiple-choice question

1) Which of the following statements about metal matrix composite is correct? ( )

(A) High melting point and heavy metal are used as matrix

(B) Compared to the base metal or alloy, it shows worse plasticity and toughness.

(C) Higher working temperature than base metal or alloy

(D) The modulus of elasticity is lower than that of base metal or alloy

2) Which statements about longitudinal tensile modulus of unidirectional fiber

reinforced MMC are correct? ( )

(A) The tensile modulus increases with the increase of fiber volume content

(B) It has nothing to do with the volume content of fiber, but is related to the

modulus of fiber and matrix

(C) It is similar to the transverse tensile modulus

(D) It is related with the modulus of the matrix

3) Which statements about pultrusion are correct? ( )

(A) It is a low labor intensity and high efficiency FRP production method

(B) It is suitable for large products with complex shape

(C) It is suitable for products with constant cross-section profile

(D) Less equipment investment

4) The mechanical properties of glass fiber reinforced epoxy composites are affected

by moisture absorption, the reason are ( )

(A) Epoxy resin become brittle after moisture absorption

(B) Water acts as plasticizer and reduces the glass transition temperature of resin

(C) Fiber strength will decrease after moisture absorption

(D) It would destroy the interface between fiber and matrix

5) The main raw materials for producing carbon fiber are ( )

(A) Pitch (B) Polyacrylonitrile (C) polyethylene (D) Rayon

True or false questions

1) Glass fiber reinforced thermosetting resin composite is easy cutting material ( )

2) Carbon fiber has better heat resistance and corrosion resistance, and has high

mechanical properties, also is easy to manufacture. It has become an increasingly

important material in the field of civil aviation ( )

3) Thermoplastic resin matrix composites have high elastic modulus and good heat

resistance ( )

4) From the perspective of technology, the methods of repairing composite materials

mainly include adhesively bonding and mechanical connection. ( )

5) Autoclave molding is one of the earliest technologies used in aerospace

composite material manufacturing. ( )

6) The cost of vacuum bag/autoclave molding process is higher. It is the main

forming method of high quality composite components in aircraft structures

( )

7) Autoclave can monitor the temperature and pressure during curing, but can't

monitor the degree of vacuum ( )

8) The resin matrix composite has good chemical stability for atmosphere and water,

as well as ordinary concentration of acid, alkali, salt and so on ( )

9) A chemical reaction takes place between the matrix and the reinforcing material,

and compounds are formed at the interface so that the two can be combined. ( )

10) On Boeing 787 "dreamliner" aircraft, composite material consumption is about

fifty percent. ( )

11) Bismaleimide resin has a high cost and is mainly used on high temperature

resistant components in military aircraft ( )

12) For aircraft structural composites, the maximum service temperature depends

mainly on the heat resistance of the resin matrix ( )

13) Fiber surface treatment is to make the fiber surface more smooth ( )

14) One of the biggest drawbacks of composites is that they are prone to causing

defects during fabrication ( )

15) Thermosetting polyimide carbon fiber reinforced composites have poor heat

resistance and oxidation stability ( )

16) The elastic modulus of carbon fibers varies greatly along the axial and transverse

directions ( )

17) According to the geometry of reinforcing materials in composite materials,

composites can be divided into two categories: particle reinforced composites and

fiber reinforced composites. ( )

18) Nowadays, more and more fiber reinforced composites are used in military and

civil aircraft instead of aluminum alloy or even some titanium alloy. ( )

19) High specific strength and specific modulus show that, in the case of same

weight, the material has large load capacity, large stiffness and large deformation.

( )

20) For polymer matrix composites, the biggest threat to structural safety is impact

damage ( )

21) For the wing structure with large height, the honeycomb panel is used to replace

the stiffened plate in the skin panels (especially the upper wing panel), which can

reduce weight obviously. ( )

22) Carbon-carbon composites can be used as brake pads for aircraft ( )

23) Before the tensile test is started, it just needs one time preload. ( )

24) The compressive strength of the composite is usually lower than the tensile

strength ( )

25) Moisture has little effect on the interfacial properties of materials ( )

26) The cost of boron fiber is expensive ( )

27) Bamboo, hemp, wood, bone and skin are natural composite materials ( )

28) RTM (Resin Transfer Molding) technology can be used for the production of

complex composite components and is suitable for mass production ( )

29) When the RTM (Resin Transfer Molding) molding process is used to make

composite products, the position of the glue injection port and the glue outlet

must be set reasonably to avoid the defects such as enhanced body infiltration,

incomplete or bubble ( )

30) RTM (Resin Transfer Molding) molding technology is one of the main

development directions of cost effective manufacture technology of composite in

the aerospace field. ( )

31) RTM (Resin Transfer Molding) molding process has bad environmental

protection performance. ( )

32) The fibre metal laminates used in A380 civil aircraft is called ARALL (aramid

aluminum alloy laminate). ( )

Completion

1. The matrixes commonly used in composite materials include ， ， .2. The expression of maximum normal stress criterion is .

3. Delamination failure modes of composite laminates include ， .

4. The commonly used theoretical models for predicting fatigue life of composite

laminates are ， ， .

5. The composite materials exhibit apparent viscoelasticity at normal temperature.

This phenomenon is known as .

6. The main connection types of composite material includes ， ， .7. The heat resistance, aging resistance and flame retardancy performance of the

composites mainly depend on the properties of the material.

8. The commonly used composite molding processes include ， ， .

9. Nondestructive testing methods for composite structures mainly include ，

， .10. The expression of Tsai Hill failure criterion is .

11. The process of curing and bonding between different composites during once

curing is called .

12. By the action of heat, light, radiation, or chemical additives, the process of

crosslinking of thermosetting resins by irreversible chemical reactions is called

.

13. Due to moisture absorption and temperature changes, structural dimensions and

material properties of composite could change. This phenomenon is .