辅导MEC - 311、讲解Design Analysis、C++编程语言调试、C++辅导
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TCNJ
Department of Mechanical Engineering
Mechanical Design Analysis - I
MEC - 311
FALL 2O20
Computer Program Assignment # 1
Determination of the Principal and the Maximum Shear Stresses
Prof. Bijan Sepahpour, DE, PE
I. Requirements:
This computer Program design challenge will require the student to demonstrate two engineering
competencies. Specifically,
1. Understanding of the concepts involved with the relationships between stress and strain and what
techniques or modes may be available to conduct a “First Order Analysis” for obtaining the Principal
and the Maximum Shear Stresses and
2. Ability to develop a robust and flexible computer program that calculates solutions for Machine
Components/Structural members subject to stresses at critical locations.
II. Assignment:
Design and write a computer program for conducting “Stress Analysis”. The program must have
the following specific characteristics and attributes. It must be:
1. “Generic”
2. Created using a “High Level Language” such as “C++
”
3. “User-Friendly”
4. Flexible enough to take input values in any of the two “System International (SI)” or “US Customary
System of Units (USCS)” and return results in “the same” units chosen for input.
The program needs to use the following recommended set of units:
SI USCS
KN MPa m lb Ksi / Psi in
2
5. Enable the user to choose between “Strains” or “Stresses” as Input.
6. If the Inputs are chosen to be “Strains”, “only” those strains obtained from a “Rectangular Rosette
(with a 0º-45º-90º pattern)” may be inputted. [See Appendix-A (in this Handout) for information on
the relevant equations for this type of Strain Gauge.] Recalling that: σ1 > σ2 > σ3 ;
A. If both σ1
and σ2
are larger than zero, the program needs to add σ3=0 to the set of the
Principal Stresses,
B. If σ1 > 0 and σ3< 0 , it would add σ2=0 to the set of the Principal Stresses.
C. If both σ3
and σ2
are smaller than zero, it would add σ1=0 to the set of the
Principal Stresses.
D. This Subroutine must display: σ1
, σ2
, σ3
, and |τMax|Absolute in its Output.
……………………………………………………………………Note that: |τMax| Absolute
= (σ1
- σ3
)/2
7. If the Inputs are chosen to be “Stresses”, all six (6) stresses in a “General 3-D” state of stress [using
the Cubic Stress Equation need to be inputted].
A. Refer to the text and the handout on the use of the Cubic Stress Equation … and I1, I2 ,and I3.
B. This Subroutine must also display: σ1
, σ2
, σ3
, and | τMax |Absolute in its Output.
III. Deliverables (elements required in the Project Report):
1. Cover with information about the project and the Designer → This is a “Single-Effort Project.”
2. Grading/Evaluation Sheet of the Project [which is included in this Handout]
3. Completion and inclusion of the Project Rating and Assessment sheet,
4. Abstract,
5. Table of Contents,
6. Introduction and description of the goals in this challenge (One Page – Max.),
7. The “Flowchart” of the program (using “Standard” symbols) on “One (independent) Page-only”,
8. The “Program Code” →→ in the Appendix (only),
9. Testing the reliability of the program using the cases shown on Table #1 (next page) and “Directly
Printing the Input VS Output Results. Directly Printing means: Not Typed!
This part needs to be conducted:
A. for “each and every case”,
B. in the order of the Case #s listed in the table, and
C. placed in that order in your report.
10. Summary, conclusions, and comments regarding:
A. The description of the “Findings” and
B. the “Challenges” involved,
11. Recommendations for “Additions / Changes” (for the next iteration),
12. Acknowledgement(s),
13. References / Bibliography,
14. Appendix for inclusion of any relevant material and “this Project Outline”.
3
Table 1. Cases for Testing the Reliability of the Program
# Input Output
1
E = 115 GPa
ν = 0.310
ε 1 = -140 μ
ε 2 = -280 μ
ε 3 = 35 μ
σ1 = 12.65 MPa
σ2 = 0.0000 MPa
σ3 = -30.15 MPa
τ Max. = 21.40 MPa
2
E = 10,300 ksi
ν = 0.334
ε 1 = 100 μ
ε 2 = 300 μ
ε 3 = 200 μ
σ1 = 3541 psi
σ2 = 1099 psi
σ3 = 0.0000 psi
τ Max. = 1770 psi
3
E = 190 GPa
ν = 0.305
ε 1 = 150 μ
ε 2 = 250 μ
ε 3 = 200 μ
σ1 = 59.35 MPa
σ2 = 36.33 MPa
σ3 = 0.0000 Mpa
τ Max. = 29.68 MPa
4
E = 10,300 ksi
ν = 0.245
ε 1 = -125 μ
ε 2 = -238 μ
ε 3 = -15 μ
σ1 = 507.5 psi
σ2 = 0.0000 psi
σ3 = -2417 psi
τ Max. = 1463 psi
5
x τxy τxz 30 0 6
τyx y τyz = 0 -20 3.5 MPa
τzx τzy z 6 3.5 12.5
σ1 = 31.88MPa
σ2 = 11.00 MPa
σ3 = -20.38 Mpa
τ Max. = 26.14 MPa
6
x τxy τxz 34 0 6
τyx y τyz = 0 -12 3.5 Ksi
τzx τzy z 6 3.5 22.5
σ1 = 36.60 Ksi
σ2 = 20.26 Ksi
σ3 = -12.36 Ksi
τ Max. = 24.48 Ksi
7
Input from Example (4.4) in the Text
Output of Example (4.4)
4
Appendix: A
Relevant Relationships in application of Strains for obtaining Principal Stresses
Using the strain readings obtained from a 0º-45º-90º rectangular rosette strain gage, it is possible to
obtain the principal stresses and the maximum shear stress the following information:
1 – Principal Stresses; σ1= σMax. , σ2 = σMin.
2 – Maximum Shear Stress; τMax.
Formulas:
= (for a 2-D State of Stress)
Where:
v = Poisson’s Ratio
= Normal strain
= Normal stress
E = Modulus of Elasticity
Intersection point
5
MECH 311 / Mechanical Design Analysis I
EVALUATION OF THE COMPUTER PROJECT
1. Organization: Possible - (10%)…………………..………………………………….…………….Assigned:______
Cover…………………………………………….……………………….…
This (Evaluation) sheet (placed after the Cover)….….…
Project Rating and Assessment sheet…….……………….…
Numbering of the Pages...………………………………..……….
Abstract …………………………..…………………………………….…
Table of Contents.……………………………………………………..
List of Tables.……………….………………………………..…..……..
List of Figures.………………………………..……….………………..
Introduction and Description of the Project Goals …….
Flow Chart….……………….……………………..……………….……..
Testing (for Reliability of) the Program..…….………….…..
Conclusions, Observations, and Recommendations.…..
Bibliography.………………………………………….…………………..
Appendices.…………………………………………………..……….…..
On Time Submission.…….…………………………………….….…..
2. Flow Chart: Possible - (15%)…..……………………..……………………………………………Assigned:______
Logic ….…………………………………. (10)
Neatness and Readability ……… (05)
3. Quality/Efficiency of the (Program) Code: Possible - (20%)…………..……..……. Assigned:______
Consistent with Flowchart ……. (10)
Annotated for readability …….. (10)
4. Testing and Reliability of the Program: Possible - (40%)………..………..………….Assigned:______
Program, returns correct calculations …………… (30)
Program returns calculations in correct format (10)
5. Quality of the Technical Writing: Possible - (15%)……..………….………......……….Assigned:______
Correct grammar, sentence structure and spelling (05)
Quality and Clarity of statements ……………………… (05)
Economy of wording; succinct and direct ………….. (05)
_________ % x 35 Points = TOTAL: ____________ Pts.
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