5 Written questions
5 Matching questions
- in most cases fracture occurs because of the _____ stress component.
- Three common methods for measurement of ductility:
- Plastic deformation occurs when the ______________ within the prosthesis is exceeded.
- As the interatomic spacing increases, the internal energy increases. As long as the stress is <b>not greater than the proportional limit</b>, this <u>energy</u> is known as__________.
- Why do prostheses sometimes fail under a very small force, even though the strength of the prosthetic material is relatively high?
- a Flaws (could be microscopic)
- b 1. the <i>percent elongation</i> <b>after</b> fracture.
2. the <i>reduction in area </i>of the tensile test specimen
3. the max # of bends performed in a cold bend test.
- c resilience
the term resilience is associated with 'springiness'
- d b. tensile
- e Plastic deformation occurs when the <b>elastic stress limit (proportional limit)</b> within the prosthesis is exceeded.
5 Multiple choice questions
- Because of the reduction in area, the force required to increase deformation actually decreases.
Maximum stress that a structure can withstand without sustaining a specific amount of plastic strain (yield strength) or stress at the point of fracture (ultimate strength).
- Ratio of applied force to the actual cross-sectional area; however, for convenience stress is often calculated as the ratio of applied force to the initial cross-sectional area.
Maximum stress at which stress is proportional to strain and above which plastic deformation occurs.
in this case: PL= 1020 MPa
5 True/False questions
Two important aspects of microscopic flaws in brittle materials: → 1. tensile stress
2. shear stress
3. compressive stress
Elastic modulus → Relative stiffness of a material; ratio of elastic stress to elastic strain
fatigue failure →
Repeated stresses resulting in fractures. the fracture due to fatigue occurs at stress levels well below tensile strength.
Name three properties that are related to heardness: → 1. Compressive strength
2. proportional limit
the stress above which stress is no longer proportional to strain. → Force per unit area of a material subjected to flexural loading.