School of Engineering/Aerospace Engineering and Aviation
March 2019
—
AERO2566 Aerospace Materials
Class test 1
Family Name: XXXXXXXXXXGiven Name(s):
Student #:
ALLOWABLE MATERIALS AND INSTRUCTIONS TO CANDIDATES
1. Write your full name and student number on the first page of this paper.
2. Answer each question within the provided space.
3. Attempt all questions.
4. Show all equations and workings. Marks will be deducted for missing, inco
ect
units or unlabeled sketches on final answers.
5. The maximum possible score is 15 marks and this assessment will contribute 15%
to the final course mark.
Page 2 of 6
Q1: Upon graduation, you are employed as an aerospace design engineer and you are tasked with building
a robotic arm to support astronauts during spacewalks at the International Space Station (ISS). A cable
attached to the robotic arm must be able to lift an astronaut of average weight 80 kg without fail. The
length of an unloaded cable is 5 m and under the extreme loading conditions, the cable must not
exceed 5.005 m in length. Under no circumstances should the cable be allowed to deform plastically.
(a) Given that the gravitational acceleration at the ISS is 10% lower than that on Earth, that the storage
space allows for a cable not larger than 5.3 mm in diameter and that a safety factor of 1.5 must be
applied, calculate the minimum modulus of elasticity of a material that can be used to manufacture
a cable satisfying the above requirements. (5 marks).
Page 3 of 6
(b) Available to you for the manufacturing of the cable are two materials as described below:
- A steel cable of ultimate tensile strength of 60 MPa, yield strength of 54.6 MPa, and density of
7.8 g/cm3;
- A ca
on fi
e-reinforced polymer composite cable of ultimate tensile strength 0.126 GPa and
density of 1800 kg/m3.
Considering that the ISS operates in an extreme thermal environment (e.g., -60 to 50ºC) and that
minimizing the satellite launch payload is a primary objective, which of these two materials would you
select for the cable? You must justify your selection against these two design requirements, showing all
workings that support your selection of the cable material (3 marks).
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Q2: Imagine that you are the principal engineer of a global helicopter rotor blade manufacturing company.
Your company wins a tender to design a new light-weight rotor blade.
The structural efficiency of aerospace materials is determined by the loading scenario (e.g., tensile,
compression or bending) and the design optimization objective. The structural efficiency equations
ased on the minimization of weight are given below for different loading scenarios.
For this task you have available two materials A and B, whose mechanical and physical properties are
given in the table below.
Considering that the rotor blade may experience more than one type of loading and using the structural
efficiency equations relating to potential loading conditions for the rotor blade, which one of these two
materials A or B, would you select if weight minimization was the objective? Justify your answer through
detailed workings (3 marks).
Material Density E - modulus Yield strength UTS Strain
[ kg/ m 3 ] [kN/mm 2 ] [ N/mm 2 ] [ N/mm 2 ] [%]
A 2 , XXXXXXXXXX XXXXXXXXXX
B 7 , XXXXXXXXXX,200 1, XXXXXXXXXX
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Q3: An airline approaches the aerospace design company that you work for with requirements to design
and build a mid-size aircraft (e.g., 200 – 300 passengers). The aircraft will be used primarily for short-
haul flights (e.g. 8 × 2 hour flights each day). The aircraft will be plying a route notorious for heavy
storms that usual involve hail stones.
(a) Considering these specific service/operational conditions, state two mechanical properties that will
e critical in your design process for continued airworthiness. Explain how you a
ived at these
critical properties (2 marks).
Page 6 of 6
(b) Can you suggest a material or a combination of materials that would be suitable for the design of
the upper fuselage section of this aircraft? Explain how the selected material or combination of
materials will help maintain airworthiness of this aircraft over its operational life (2 marks).
RMIT Classification: Trusted
RMIT Classification: Trusted
—
AERO2566 Aerospace Materials
Assignment 1
Family Name: Given Name(s):
Student #:
ALLOWABLE MATERIALS AND INSTRUCTIONS TO CANDIDATES
1. Write your full name and student number on the first page of this paper.
1. Answer all the questions within the provided space.
1. You have until Wednesday 1st of April 12.00 pm to attempt the questions and submit the assignment. Please submit a PDF copy of the assignment.
1. Show all equations and workings. Marks will be deducted for missing or inco
ect units.
1. The maximum possible score is 20 marks and this assessment will contribute 20% to the final course mark.
Q1: Explain and distinguish the following engineering terms:
(a) Stiffness versus modulus of elasticity [1 mark]
(b) Engineering stress versus true engineering stress [1 mark]
(c) Fracture toughness versus damage tolerance [1 mark]
(d) Fatigue life versus fatigue endurance limit [1 mark]
Q2: You are an aerospace design engineer building a robotic arm to support astronauts during spacewalks at the International Space Station (ISS). A 3 m-long cable attached to the robotic arm must be able to lift and support an astronaut weighing up to 60 kg without plastically deforming. The maximum allowable strain experienced by the cable must not exceed 0.1%. The gravitational acceleration at the ISS is 80% that on Earth and your design must consider a safety margin 50% greater than the maximum expected load. Two materials are at your disposal; steel and aluminium cables with respective Young’s moduli values of 210 and 70 GPa.
(a) If the cable will be strained to the allowable limit at least on one occasion, calculate the minimum diameter required of the steel and the aluminium cable that will be suitable for this application. Show all your workings step-by-step and report your answers in millimetres (mm). [4 marks]
(b) The yield strength of steel is twice that of the aluminium cable. If the densities of the steel and aluminium cables were 7.8 and 2.7 g/cm3, respectively, which of these two materials would you select for this application if your objective was to minimise the weight of the ISS. Show how you a
ived at your choice with the support of relevant calculations [2 marks]
Q3: Imagine that you are an engineer for an aircraft manufacturing company, and you have been asked to design a bulkhead for a mid-sized aircraft.
The structural efficiency of aerospace materials is determined by the loading scenario (e.g., tensile, compression or bending) and the design optimization objective. The structural efficiency equations based on the minimization of weight are given below for different loading scenarios.
For this task you have available two materials A and B, whose mechanical and physical properties are given in the table below.
Material
Density
Yield strain
Yield strength
UTS
Strain
[
kg
m
3
]
[%]
[
N/mm
2
]
[
N/mm
2
]
[%]
A
2
,
700
0.59
415
540
20
B
7
,
800
0.43
1,200
1,560
12
Considering the loading stresses experienced by the bulkhead