Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

52.2.11 PRACTICE PROBLEMS

 

1.

  1. a) List at least 5 advantages of composite materials.
  2. b) List at least 3 disadvantages of composite materials.

 

2. For thermoset polymers, what effects does cross-linking generally have on the material properties?

 

3. Which type of glass is good for applications that require,

 

  1. a) Low cost?
  2. b) Operate at high temperatures?
  3. c) Are resistant to corrosion?

 

4.

  1. a) List 6 different forms (other than single filaments) that composite fibres may be purchased in.
  2. b) What form of composite fibres are best used for pultrusion?

 

5. If you were making boat hulls with pre-preg composite fibre and large moulds, what steps would be followed?

 

6. Indicate if the following parts are best made with pultrusion/filament winding/resin transfer moulding.

 

rocket engine tanks

car body panels

airplane fuselage

a mast for a sail boat

 

 

7. A composite section has a honeycomb core 1" thick and can withstand a maximum bending moment of 10KN. How much thicker/thinner would the honeycomb have to be to withstand 1KN?

 

8. TRUE / FALSE - Multi-directional fibres can be used with stereolithography to increase part strength.

 

9. What are the major factors that weaken composites? Explain the effect of each.

 

10. Describe the difference between alloys and composites.

 

11. Describe the properties of the matrix and fiber materials, and then describe why their combinations is so desirable.

 

12. What properties does a honeycomb core contribute to a composite part?

 

13. List 10 products that you have purchased or used that are made of composite materials.

 

14. What are the advantages and disadvantages of composite materials. What design considerations can be used to overcome the disadvantages?

 

15. A composite has more than one type of fiber. Why would this be desirable?

 

16. A part is made of a composite material that is 40% fibers (by area) with a Young's modulus of 300 GPa, and a matrix of 60 Gpa. The UTS of the fibers is 2000 GPa and 100 MPa for the matrix. If the total cross sectional area of the part is 2cm by 0.2cm, what is the effective stiffness and failure load?

 

17. Calculate the percentage increase in strength of nylon when e-glass fibers are added.

 

18. List 5 parts that benefit from the anisotropic properties of composites. Explain why.

 

19. Corrugated cardboard and composite honeycomb have similar construction. What are the similarities and differences in behavior?

 

20. List 8 different types of composite manufacturing processes and give an example of a part they are well suited to.

 

21. Composite materials typically cost more than metals. why are they preferred?

 

22. List 10 factors determine the strength of a composite materials and parts?