Kolej Linton School of Mechanical Engineering

Coursework cover sheet – be sure to keep a copy of all work submitted

Section A - To be completed by the student – PLEASE PRINT CLEARLY Family Name(s)

Module No.

305 MED Forename(s)

ID Number(s) (from your student card)

Time taken (hrs) (per student for group coursework)

Faculty Date Stamp (or signature and date)

Lecturer

Haris Wahyudi Lab group / Tutorial group / Tutor (if applicable)

Module Code and Title

305 MED – Computer Aided Engineering

Due date:

22 March 2012 Assignment No. / Title

CW2: ASSIGNMENT 2

Extensions & late submissions allowed:

No

Estimated Time (Weeks)

3 Weeks Assignment type:

INDIVIDUAL

% of Module

Mark 20%

Hand out date:

1 March 2012

Declaration: I/we the undersigned confirm that I/we have read and agree to abide by the University regulations on plagiarism and cheating and Faculty coursework policies and procedures. I/we confirm that this piece of work is my/our own. I/we consent to appropriate storage of our work for checking to ensure that there is no plagiarism/ academic cheating. Signature(s): -------------------------------------- -------------------------------------- -------------------------------------- --------------------------------------

Section B - To be completed by the assessor

1. Develop 3-D beam, shell and solid finite element models and perform static stress and modal frequency analyses. 2. Use curve, surface and solid modeling with CAD software to develop 3-D component geometry and carry out static

stress and modal frequency finite element analyses.

Marks breakdown Max Awarded

Task 1

a. Determine the fracture of component

b. Justification in FEA

c. Determine the maximum stress field around crack

d. Details of the FE model

5

10

15

10

Task 2

a. Justification of design

b. Design optimization in FEA

c. Result discussion

d. FE model and procedures

15

20

15

10

Assessor’s signature / initials:

Date:

Total

100 Total

Extension Agreed until: Programme Leader Signature:

Penalty Due: (Yes / No)

Penalty Final Mark

Signed internal moderator:

This work may have been moderated. You may find additional comments in the work.

Kolej Linton School of Mechanical Engineering

This section may be used for feedback or other information

Coursework Task Sheet Module Title

Computer Aided Engineering Module Code

305 MED Assignment No. / Title

CW2- ASSIGNMENT 2 Hand out date:

1 March 2012 Lecturer

Haris Wahyudi Due date:

22 March 2012 Estimated Time (weeks)

3 Weeks Assignment type:

INDIVIDUAL Extensions & late submissions allowed:

No % of Module Mark

20% Submission arrangements

Assessment Criteria

KOLEJ UNIVERSITI LINTON Coventry University

BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING

Module Title: Computer Aided Engineering Module Code: 305 MED Module Assessor: Haris Wahyudi Internal Verifier: Dr. Elango Natarajan

ASSESSMENT GRADING CRITERIA

100% 80% 70%

The student demonstrates a thorough knowledge and understanding of the facts and ideas involved. Coherent; good linking of ideas and paragraphs. An ability to sustain an argument and to use appropriate citation to substantiate points made.

69% –

60%

Well-written, completely relevant, with evidence of a sound knowledge and understanding of the issues involved. Some comments are not justified but overall shows an ability of apply material gleaned from independent reading. Grammar and spelling sound.

59% –

50%

The student demonstrates an ability to understand the issues involved and or having read around the subject. There is some evidence of application of the knowledge and ideas. Maximum of 50% if the work contains sweeping unjustified statements, or if there is no evidence at all or substantiation of points use of appropriate citation.

49% –

35%

The student demonstrates reasonable knowledge and understanding of the issues involved but does not utilise material to support his/her argument. There is evidence of reading and the student has correctly references his/her work and included an appropriate bibliography. The work, although relevant, is descriptive.

34% –

30%

Poor English, poor structure, some irrelevant material, evidence of reading, most of the material emanating from taught sessions only. Possibly lacking in bibliography.

29% –

1%

The work contains inaccurate, outdated and inadequate knowledge of the topic. The work lacks clear explanation and does not answer the specified question. The work has virtually no structure and its argument lacks logic. The work reveals confused thinking, is very descriptive in content, with little or no substantive evidence and illustration. The work is grammatically deficient and its presentation unacceptable.

0%

No work submitted by the student or work was submitted beyond the agreed submission deadline, without prior approval.

KOLEJ UNIVERSITI LINTON Coventry University

BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING

Module Title: Computer Aided Engineering Module Code: 305 MED Module Assessor: Haris Wahyudi Internal Verifier: Dr. Elango Natarajan

ASSIGNMENT 2

Module Name: Computer Aided Engineering Intended Module Learning Outcome Covered 1. Develop 3-D beam, shell and solid finite element models and perform static stress and

modal frequency analyses. 2. Use curve, surface and solid modeling with CAD software to develop 3-D component

geometry and carry out static stress and modal frequency finite element analyses. Duration 3 weeks Assessment Criteria There are 100 marks in total for this assignment and a breakdown of these marks is provided in the assignment details. Scenario 1 Toughness is the resistance of a material to the propagation of a crack and fracture toughness is an indication of the amount of stress required to propagate an existing flaw. Consideration of fracture mechanics during the design process can assist in the prevention of failures of structural and mechanical components subject to fluctuating loads in service. The goal of fracture mechanics analysis is to predict the critical loads that will cause catastrophic failure in a structure or component. Task 1 One of the aircraft component is fabricated from aluminum 7075-T6 alloy. The modulus of elasticity, yield strength and poison ratio of 7075-T6 alloy is 71.7 GPa, 495 MPa and 0.33, respectively. This material has plane strain fracture toughness of 27.5 MPa√ . It has been determined that fracture results at a stress of 208 MPa when the maximum internal crack length is 2.0 mm (case 1).

Figure T1. Through internal crack

The stress intensity for this type of flaw is given by:

√ , where Y is dimensionless constant and a is crack length.

KOLEJ UNIVERSITI LINTON Coventry University

BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING

Module Title: Computer Aided Engineering Module Code: 305 MED Module Assessor: Haris Wahyudi Internal Verifier: Dr. Elango Natarajan

Perform analytical and numerical stress analysis of the component and upon completion of the analysis design you are required to answer the following: a. Determine whether fracture will occur if the component receives a stress about 350

MPa and the internal crack present is 1.0 mm (case 2). (5 marks)

b. Justify your answer by doing finite element analysis, let b = 5 mm and. What is the stress intensity from this analysis? (10 marks)

c. Determine the maximum stress field around crack using FEA for both cases above.

Compare the result with the yield strength of materials and discuss your answer. (15 marks)

d. Details of the FE model: analysis type, boundary condition, modeling techniques, element type, meshing techniques. (10 marks)

KOLEJ UNIVERSITI LINTON Coventry University

BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING

Module Title: Computer Aided Engineering Module Code: 305 MED Module Assessor: Haris Wahyudi Internal Verifier: Dr. Elango Natarajan

Scenario 2 An office furniture company is designing a new low cost chair. The basic concept calls for two upholstered cushions over sturdy plywood boards that are supported by two Z-shaped frames. Your assignment is to come up with the lowest cost design for the frame while meeting the following requirements: To simulate the forces from a person sitting while leaning against the back, the frames

must be able to support a vertical load of 80 Kg from the seat and 20 Kg normal to the back support.

Any part of the frame should not deflect more than 3.2 mm. The factor of safety against stress failure should be at least 3. The height and width of the chair is fixed.

Figure T2. Z-Shaped Chair (all units in cm)

Task 2 a. If the frames must be able to support a vertical weight of 100 Kg from the seat and the

frame to be made of 50 mm diameter steel tube with wall thickness 6 mm, determine if the given design meets the stress and the deflection constraints. For simplicity, assume the loads exerted from the plywood boards are uniformly distributed (do not consider the weight of the plywood boards). (15 marks)

KOLEJ UNIVERSITI LINTON Coventry University

BACHELOR OF ENGINEERING IN MECHANICAL ENGINEERING

Module Title: Computer Aided Engineering Module Code: 305 MED Module Assessor: Haris Wahyudi Internal Verifier: Dr. Elango Natarajan

b. Use design optimization in FEA software to obtain a minimum thickness of frame. For ease in manufacturing the same diameter must be used for the entire frame. However, the wall-thickness can be different for various part of the frame. Model the frame with beam elements; create a finite element mesh that contains few tens of elements. (20 marks)

c. Summary, tabulated and discussion of the result. (15 marks)

d. FE model and procedures. (10 marks) Use the following material parameters: E = 206.84 GPa, failure stress (yield stress = 410 MPa) and weight density ρ = 7086 Kg/m3. Possible evidence for report: Methods used to present the assignment. 1. Evidences that may be taken to be reviewed by lecturers or other assessors, which

include: Report (feasibility, technical, scientific) Softcopy of FEA files

2. Clear steps and sequences in solving using FEA with proper illustrations. 3. Insert page number; write name and IC number at the bottom (footer) in every page.