Quiz: Section 3.4 Ultimate Strengths of a Unidirectional Lamina

1. It is possible that by adding fibers to the matrix, the composite will have lower ultimate longitudinal tensile strength than the matrix alone. What is the fiber volume fraction for which this is possible called?

2. How many plies are generally used when experimentally finding the longitudinal tensile strength of a unidirectional lamina?

3. Once the fibers have broken in a unidirectional lamina under a longitudinal tensile stress, sometimes a composite can take more load. What is the volume fraction of fibers called for which this is possible?

4. How many plies are generally used to experimentally find the longitudinal compressive strength of a unidirectional lamina?

5. True or False: In a ceramic matrix composites when loaded along the fibers by a uniaxial load, generally matrix breaks precede fiber breaks.

6. Generally, for polymer matrix composites, the maximum strain to failure is greater for

7. Unidirectional composites are tested because

8. Poor bonding between the fiber and matrix results in

9. The component in a polymeric matrix composite which carries the largest percentage of the applied uniaxial load along the fibers is

10. Adding more fibers to a matrix in a polymer matrix composite

11. If the stress intensity factor is greater than the critical stress intensity factor for a material, then

12. When a crack develops in an isotropic material, the stresses at the crack tip are

13. The theoretical longitudinal compressive strength does not estimate the experimentally found values well because of several factors.  Check all that apply.