4.1 Examine ductile and brittle failure

4.1

Examine ductile and brittle failure

i) Fully describe the mechanisms behind brittle and ductile fracture.

ii) Explain the difference between an engineering stress strain curve and true stress strain curvre

4.2

Analyse the mechanism of creep in materials

i) Describe the 3 stages of creep

ii) Describe 3 mechanisms of creep and explain the conditions for when each mechanism is dominants

4.3

Analyse fatigue in engineering structures

i)

Label the stress range, stress amplitude and the mean, maximum and minimum stress.

ii) Explain how fatigue laboratory tests and S-N curves can be used to predict fatigue lives for materials.

Iii An 8mm diameter cylindrical rod fabricated from a 1045 Steel is subjected to reversed tension compression load cycling along its axis. If the maximum tensile and compressive loads are +19kN and −19kN, respectively, determine its fatigue life. Assume that the stress plotted in the figure below is stress amplitude 4.1 Examine ductile and brittle failure

4.4

Analyse corrosion and wear

One-half of an electrochemical cell consists of a pure nickel electrode in a solution of Ni2+ ions; the other half is an iron electrode immersed in a Fe2+ solution.

i) Describe and show the reactions taking place.

ii) Explain what is meant by galvanic corrosion and describe an instance where galvanic may be experienced.

iii) Describe ways in which materials can be protected from galvanic corrosion.

4.5

Analyse fracture and cracking

Describe in detail the process by which materials fail due to fatigue failue

4.6

Calculate and apply stress concentration factors

A filleted bar as depicted in the graph below has the following dimensions and loads applied:

F = 8000N, D = 60mm, d = 40mm, r = 2mm.

By considering the stress concentration factor at the fillet, find the maximum stress acting on this bar.

Examine causes and protection against material failure 4.1 Examine ductile and brittle failure

All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1000 words.

4.7

Investigate and analyse methods used in an industrial application  to protect against material failure

For an industrial application of your choosing you must produce an investigation and analysis into ways in which materials are protected against failure.

The short report should include a breakdown of techniques used to prevent material failure and an analysis of the cost and effectiveness of these methods.