讲解 UFMFP9-15-3 MECHANICS OF MATERIALS 2024/25辅导 留学生Matlab程序

MODULAR PROGRAMME

COURSEWORK ASSESSMENT SPECIFICATION

Module Details

Mechanics of Materials Coursework:

You are asked to design a door handle in an aircraft, as shown in Figure 1.  The loads and major dimensions are provided in Table 1. You, as a designer, are free to choose the other geometric parameters freely considering that design  requirements for safety factors are satisfied. The bracket is mounted on the locking mechanism by the help of a flange. There is a fillet of radius r at the transition from the hollow shaft to the flange.

Figure 1 Door handle geometry

Parameterised geometric data choices are given in Table 1.

Question 1 (10 marks)

By doing a literature survey and/or consulting materials databases, choose a type of aircraft grade aluminium alloy for the material to be used in the design.

Question 2 (20 marks)

The bracket is expected to withstand a force of F without  yielding. Size your design to provide a reasonable Factor of Safety for static yielding.

Please refer to the techniques taught in the year 2 modules: “Structural Mechanics” . You should find the stresses at the most critical location with respect to the coordinate system shown. Then find the Principal Stresses, Maximum Shear Stress, von Mises Stress and the planes on which Principle Stresses and Maximum Shear Stress are acting. Show these planes by drawing a schematic at the critical location. Use a suitable static failure criterion!

Question 3 (10 marks)

Find the vertical and horizontal deflection of the end of the handle under the applied load using an energy method of your choice. Size your handle so that the static deflection in y- direction should not exceed 2 mm.

Question 4 (30 marks)

The service  load  consists of the  locking and  unlocking force  applied to the end of the handle. So for fatigue life calculations, the bracket can be considered to be subjected to a sinusoidal force with Fmax   = F and Fmin   = -F . Resize your design so that you can provide a reasonable factor of safety for infinite life in fatigue. (By doing a literature survey and/or consulting materials databases, try to find the actual S-N diagram of the aluminium alloy you have chosen. If you cannot, it is also fine to use approximated values derived from the UTS, as done in the lectorials)

If the bracket is subjected to a sinusoidal force function with Fmax   = 2F and Fmin   = 0  what will be the safety factor for infinite life in fatigue?

Question 5 (10 marks)

Given the fact that the alloy used is a ductile material, find the orientation of the plane at which crack initiates and progresses with respect to the coordinate system shown. Find the dimensions of the crack that will lead to a catastrophic failure.

Question 6 (10 marks)

Considering that the data retrieved from literature or provided by the manufacturer may not be reliable, you decided to test the specimen in the laboratory yourself. Find the relevant standards for obtaining the relevant material data for your design, provide a brief description of the specimens and procedures in your report.       [15 marks]

Miscellaneous (10 marks)

●   Conduct of presentation (including clarity of slides, time, delivery…)

●   Extent of individual effort

●   Evidence of teamwork

Table 1. Parametric data for design problem.

Your  submission  should   contain  two  files:   a  written “report”   in  .pdf  format  and  a spreadsheet in .xlsx format.

The report should contain a maximum of 10 pages and should contain the formulae used, calculations, relevant graphs  and  charts.  It  should  also  include  a  summary  table  in  a specified format for geometric dimensions, loads, stresses, stress concentration factors, stress intensity factors,  and safety factors at each of the stages of the design.

10 pages is quite short, and you do not need to obey all the rules of technical writing. Feel free to use bullet points instead of full sentences for instance. This being said, it is always a good idea to number headings, and number and caption figures and tables. In doubt, check with the module leader. The preferred channel of communication for this is the Forum on blackboard.

A template  Excel  Sheet  is  provided  with this  brief,  please fill  it  with  required  data  and formulae and submit it in addition to your report.

Remember  that  you  are  iterating  your  design.  Therefore  your  dimensions  and  the corresponding factors of safety will vary. It is recommended that you create different worksheets (within the same file) for the different stages and make your chosen data very clear.

You  can  use  Matlab  instead  if  you   prefer,  but  make  sure  your  code  is  very  well documented. You might want to complement your Matlab code with a table anyway, as a synthetic way to display your chosen parameters, and the resulting FOSs.

The most convenient way to submit is to zip your .pdf and your .xlsx files, and to submit this zip file.