ENGT5257 Structural Integrity: Design against Failure

Assignment: Critical Failure Analysis Assignment

Learning outcome 1: Interference between the applied stress and strength of the materials in the design stages.
Learning outcome 2: Describe the response of the engineering components - within the microstructural scale - to the external factors such as stress, humidity, light, temperature, and radiation.

Scope
Designing machines, vehicles and structures that are safe, reliable, and economical requires both efficient use materials and assurance that structural failure will not occur. Therefore, this module is appropriate for postgraduate students to study the mechanical behaviour of materials, specifically for topics such as fracture, fatigue, creep and corrosion. Structural Integrity: Design against Failure module covers topics such as types of materials and their properties and types of failure in materials. It also focuses on stress-based fatigue analysis, relatively new methods of fracture mechanics, creep, and corrosion resistance.

Structural Integrity: Design against Failure

Part 1 - Lab Report Maximum 500 Words

The following data of load (kN) vs. the gauge length (mm) is given for a tensile test sample, dimeter 12 mm and length 50 mm. Calculate, plot the engineering stress vs. engineering strain curve and extract, at least, five mechanical properties of the material under consideration.

Part 2 - Presentation
Preparing 7-10 minutes presentation to investigate a case study failure (of your choice), showing the reasons behind the failure and the precautions that had to be done to avoid the failure, in terms of materials selection, design, service conditions and environment.

Part 3 - Exercises

Exercise 1 - Crack Initiation
Highlight the main reasons behind developing microcracks near a base of steel shaft radiator fan blades, with listing ways that may help to stop growing the cracks.

Exercise 2 - Thermal Stresses
FR4 is a class of glass fiber epoxy laminate used in manufacturing printed circuit boards. Discuss the role of the coefficient of thermal expansion between the substrate and silicon, e.g. flip chips, within the electronics packaging point of view.

Exercise 3 - Mechanical Metallurgy Effects

In a lab, the available resources are: different metallic alloys, electrical oven reaches 2000oC, different cooling solutions, testing machines of tensile, hardness, fatigue and corrosion. Prepare an appropriate material, after applying heat treatments, to make a cutting tool for a vibrating hammer used to crush mine rocks. Give reasons for each suggested steps and heat treatments.

Exercise 4 - Low-Temperature Applications
You are an engineer designing a pressure vessel to hold liquid nitrogen. What general characteristics should the material have to be used for this application? Out of the various types of mechanical tests described in this module, describe the test(s) that aid in selecting an appropriate material? Showing the reasons for each chosen test/material.

Exercise 5 - Fatigue Life
A simply supported rotating shaft, loaded by a force 9 kN, made by machining from a low alloys steel with σu = 700 MPa, and σy = 500 MPa. Analyse the shaft and conclude some useful results. Estimate and comment on the life of the shaft.

Exercise 6 - Design based on Materials Properties
A cantilever beam with a length 100 mm is exposed to a bending force of 200 N at the free end.
Perform the selection of the material for minimum mass and minimum weight design of stiff ties; based on the properties given in the table below.
Calculate the beam radius r that is required for each material. Assume factor of safety = 2.
Compare and rank the materials based on relative criteria you think need to be considered.

Attachment:- Design against Failure.rar