Paper, Order, or Assignment Requirements

I need all the questions from 1 to 7 on mechanics.

Faculty of Science and Engineering, School of Engineering

ASSESSMENT BRIEF

Module Title:

Engineering Mechanics I

Module Code:

4ET003

Component Number:

1 of 2

Element Number:

1of 2

Weighting:

30%

This assessment covers LO1 and LO2 as specified in the module guide

Learning Outcomes to be assessed:

Knowledge and Understanding:

Underpinning science and mathematics of stresses in mechanical components, including bending stress, kinematics, dynamics and mechanisms of mechanical systems. Understanding of calculus to derive equations for second moment of area.

Subject Specific Skills:

Select and apply appropriate theorems and formulae to solve stresses in mechanical components and analyze the states of mechanical components under static and dynamic loading. To be able to use a spreadsheet or a dedicated software package to determine stresses in mechanical components.

Intellectual Skills

To demonstrate the ability to describe and explain the performance of mechanical components using analytical equations.

Marking Criteria:

Students are expected to produce an individual written report demonstrating reasonable knowledge and understanding of the issues involved.

In order to successfully complete this component, the student need to achieve a minimum of 40%.

Assignment handed out:

26th Nov 2014

Latest date for submission:

4th January 2015

Assignments submitted after the deadline and without an authorized extension of time will be marked F0.

Please mark your assignment for the attention of:

Arun Arjunan

You should make it very clear what sources of information have been used; where material/information from these sources is quoted it must be clearly referenced using the Harvard Referencing System. (Details can be obtained from Learning Centres).

The assignment must be digitally produced (scanned versions are unacceptable) and submitted as an electronic copy on to the designated location in wolf. You will receive an email confirmation on uploading the coursework. You are advised to keep your own electronic & ‘hard’ copy of any work submitted.

Note: For the following questions, letter groups ABC, AB or BC represent numbers derived from your student number. For example: If your student number is 0924514, this corresponds to OABCDEF.

Letters

O

A

B

C

D

E

F

Student Number

0

9

2

4

5

1

4

Then ABC = 924 AB = 92 BC = 24 DEF = 514

Question 1

A group of engineering students are venturing to build a human powered aircraft as shown in Fig .1. The aircraft is to be designed with a wing span of 30 meters to achieve sufficient lift. The main load bearing element on the wing is an aluminium spar that extends along the length of the wing. The cockpit and supporting structures (without the wing) is expected to weigh AB kg excluding a pilot of 70 kg, the propeller mass is BC kg. Accordingly, to aid with the design of the wing apply the principles of engineering mechanics to analyse the following cases.

Fig. 1a

If the wing is to be designed with 4 aerofoil ribs of mass ABC grams each attached to the aluminium spar as shown in Fig 1b. Calculate the necessary support reaction to keep the aircraft in vertical equilibrium with the pilot assuming that the aircraft is simply supported at the wing ends. (Note: we are analysing for this case as this is the worst case of bending for the aluminium spar.)

[10%]

Fig. 1b

Analyse the shear forces in the aluminium spar shown in Fig. 1b by drawing a shear force diagram.

[10%]

Analyse the bending moment distribution along the length of the aluminium spar shown in Fig. 1b using a bending moment diagram.

[20%]

If the maximum bending stress the aluminium spar can withstand before yielding is 40 MPa, predict the smallest possible diameter for a solid aluminium spar without any factor of safety. (Material performance of aluminium: Young’s modulus = 68.9 MPa, Shear Modulus = 26 MPa, Poisson’s ratio = 0.3).

[10%]

If the solid spar is to be replaced by a hollow spar of external diameter 2.5 times the internal diameter. Predict the internal and external diameter for the hollow spar and compare the compressive and tensile bending stresses along the thickness of the spar (take 4 points along the thickness of the spar) using an ‘Excel’ type graph.

[20%]

Using the dimensions for the hollow spar analyse the support reactions, shear force and bending moment diagram for the case shown in Fig. 1b including the self-weight of the spar. Take the density of aluminium.

[30%]

Question 2

A 12 mm diameter steel rod is connected to a 30 mm wide by 8 mm thick aluminium rectangular bar as shown in Fig. 2a. Determine the force P required to stretch the assembly by 10 mm. Take the Young’s modulus of aluminium as ABC MPa and Steel as AB GPa.

[15%]

Fig. 2a

Question 3

The joint shown in Fig. 3a is under tension along the major axis with a force of DEF kN. The safety factor (FS) of 4 will be applied to the rivets securing the joint. Assume the material has an ultimate shear stress of 190 MPa.

Fig. 3a

Calculate the design stress for the rivet.

[5%]

Calculate the number of 10 mm diameter rivets that will be required to secure the joint for the design stress evaluated above.

[10%]

Question 4

A heavy-duty punch is used to make perforations on sheet of thickness 7 mm. The total pressure on the punch was measured to be ABC N/m2 on an area of 50 mm2 applied along the axial direction. If the diameter of the punch is 35 mm. Determine the shearing stress induced in the material. (Material data for steel: Young’s modulus = 210 GPA and Shear Modulus = 74 MPa).

[15%]

Question 5

The steel machine part show in Fig. 5a is subjected to a compressive force of AB kN at an angle to the horizontal. Determine the average compressive stress along the areas of contact defined by XY and YZ. (Material data for steel: Young’s modulus = 210 GPA and Shear Modulus = 74 MPa).

[15%]

Fig. 5a

Question 6

The rotating shaft of a human powered drive train is suddenly coupled to a freewheeling drum of a propeller shaft via a friction clutch. The moment of inertia of the drive train shaft is equivalent to a mass of 40 kg acting with a radius gyration of ABC mm. The freewheeling drum has a mass of BC kg and a radius of gyration of BCD mm. The initial velocity of the drivetrain shaft before coupling is AB rev/s and the freewheeling drum is initially at rest. Find the velocity of drivetrain shaft and freewheeling drum immediately after coupling.

[15%]

Question 7

A golf ball is struck at an angle of 50 degree with respect to horizontal, at a velocity of AB m/sec. The golf course is perfectly level and the golf ball stops instantaneously when it hits the ground.

Determine the horizontal distance travelled by the golf ball

[10%]

Determine the maximum height attained by the golf ball

[5%]

If the golf ball is to travel a vertical distance of BC m, using the same initial trajectory, determine the required initial velocity.