2016 HL section B question 2 (Testing)

Question 1

describe two critical properties to be considered in the selection of polyethylene as a bearing material in this prosthetic device

Answer 1

resistant to wear

needs to be able to withstand impact and shock

reduce friction between titanium supports

all implant materials must be bio-compatible

Question 2

what does bio compatible mean

Answer 2

not harmful or toxic to living tissue.

Question 3

Describe, with the aid of a diagram a mechanical test suitable for measuring the hardness of titanium

Answer 3

Vickers test for hardness

indenter is pressed against the surface of the test specimen

The softer the material is the deeper the indentation will be

Question 4

outline 2 reasons why non-destructive tests are used during the manufacture of an engine crankshaft

Answer 4

it doesnt destroy the piece

it costs less

Question 5

describe, with the aid of a diagram the principle of eddy current testing

Answer 5

Coil with high frequency alternating current is placed next to conductive material

Eddy current is induced in material

Currents produce magnetic field in test material

Search coil is connected to an electronic reading device

Any defect in material distorts magnetic field and is indicated on the recording device

Question 6

what is a suitable application of eddy current testing

Answer 6

the detection of surface or sub-surface flaws in non ferrous metals.