City University London

School of Engineering and Mathematical Sciences

Engineering Drawing and Design, EM 1105

   Printer ready Assignment

Additional reading:

1   2    3    4    5    6    7

                                               

Exercise code:          DE-2

 

Exercise type:           Individual – Design Exercise

Exercise title:                        Design Process - Satellite hinge

 

 

Exercise Assignment:

 

Task:  

Conduct the preliminary design process to select an optimal hinge for a small satellite panel deployment.

 

Specification:

  • Satellite has 8 solar panels (Fig.1). Inner panels (PI) are held by 90o hinge (A) to the satellite body. Outer panels (PO) are held to the inner panels by 180o hinge (B).
  • The solar panels are stowed during launch.
  • The solar panels are deployed when the satellite is stable in orbit.
  • The movement of the panels has to be strictly controlled. No damage to the panels should be made. Panels should be brought to rest and locked when fully deployed.
  • Reliability is very important. If the hinge fails, the whole satellite is unusable.Weight and strength are also important.
    • Max. panel acceleration/deceleration                  200     deg/sec/sec
    • Max. angular velocity                                              40        deg/sec
    • Max. weight of individual                                       200 g
    • Max. cost per hinge                                                 £400

 

The examples of possible solutions are given in Fig. 3:

  1. Constant torque hinge with mechanical spring
  2. Hinge with electric motor, micro switches and batteries
  3. Hinge driven by a cylinder containing compressed gas.

 

WHAT and HOW to do:

Use as many A3 paper with border and title block as necessary. Submitting them stapled together.

Assume that the problem is identified as explained in the assignment above.

  1. Define the problem in one sentence
  2. Define objectives for the product half page
  3. List all functions which hinge must perform
  4. Using above design specification, define design constraints.
  5. Make graphs angle-time, velocity-time, acceleration-time, torque-time for both hinges (A) & (B) (Fig.2)
  6. Based on available information specify 4 design criteria which will later be used to make decision.
  7. Make morphological chart for each identified function
  8. Draw three alternative solutions and make accurate sketches with the most important functional dimensions. You should use Fig 3. ONLY as a guide, not as the solution. YOU ARE NOT ALOWED TO COPY any part of Fig. 3 in your drawing.
  9. Make an analysis of all three solutions: weight, size, approximate cost of material.
  10. Make the decision matrix for 3 alternatives based on earlier specified criteria and state which solution you select as the best according to your criteria.

 

Exercise tips:

Always read exercise assignment carefully and act accordingly. Use lecture notes for reference (Lectures 11 & 13)

Scales, compass and other drawing tools should be used for this exercise. Arrange drawings neatly and ensure that all letters and lines are made according to BS308.

This is two-week exercise (week 14 and week 15). It is worth 20 marks.

Hand in finished report on as many A3 drawing as necessary during tutorials in week 16.
Ensure to your name, group and other relevant data are filled in the title block.

 Figure 1 Solar panel deployment

Fig1-Model

Figure 2 Graphs

image001   image002

                                    Hinge A                                                                              Hinge B

 

Figure 3 Alternative solutions:

Mech-AMech-B  Elec Pneum

A) Mechanical coil spring                   B) Electric motor                     C) Cylinder with
                                                                                                               compressed gas