Mechanical Engineering homework help

AME3143.001 SOLID MECHANICS
Fall 2020
Project #2: Analysis and Design of a Tracked Vehicle Suspension Arm
(100 points)
Assigned: Monday, November 9, 2020
Due: 5:45PM, Sunday, December 6, 2020
Please submit ONE PDF REPORT to the Project#2 Dropbox on Canvas before 5:45PM, Sunday,
December 6, 2020
Please read the following statements VERY carefully:
1. No late submission will be graded, no email submission will be accepted.
2. All reports must place a complete academic integrity pledge form (per Page 3 of the course syllabus)
as a cover page. A report without a pledge form, or with an incorrect or incomplete pledge form will
not be graded. The form must be signed and dated, and state who you work with and the aids you
received or offered. No resubmission or amended form after the due date will be accepted. NO
PLEDGE NO CREDIT.
3. Please do not engage in activities that cross the line of committing academic misconduct. Those who
received inadequate aids from or offered inadequate aids to others receive zero credit and will be
reported to OU Office of Academic Integrity Programs.
4. Please do not hesitate to bring questions to Dr. Chang or Anirban for clarifications. Only
clarifications to the project assignment will be offered. Questions regarding how to approach the
problem or how to carry out calculations are part of the assignment; therefore, will not be answered.
Please do not suggest a different object or part in place of the suspension arm. Please do not suggest a
different project to work on.
Project Statement: Project#2 involves analysis and redesign of a tracked vehicle suspension arm, as
shown in Figure 1. The large end (upper left) of the arm is tightly fit to a torsion bar of the tracked vehicle
suspension, and the other end connects to the shaft of a roadwheel. A suspension arm carries major load
of the vehicle while maneuvering in a bumpy terrain. The load is transmitted from the roadwheel through
the suspension arm to the torsion bar of the vehicle suspension. The load acting on the arm is a vertical
force coming from the roadwheel at the load application point shown in Figure 2. Also shown in Figure 2
are sketches of the suspension arm in two views with major dimensions and geometric shape. The
distance between the centers of the holes at the large (left) and right ends is 20 in. The cross-sectional area
of the arm is composed of two circular arcs of radius R = 0.75 in. and four straight lines. The distance
between the two arc centers is 1.75 in. at Section AA’ and 1.5 in. at Section BB’. In between, the arm is
linearly tapered along the x2-direction, as seen on the x2-x3 plane. The width of the cross section is 2 in.
The distance along the x1-direction between the two hole centers is 4.5 in. as seen on the x1-x2 plane. The
distance between the center of the hole at the right end and roadwheel where the load is applied is 4.0 in.
The suspension arm is made of AISI 1030 HR steel.
Figure 1 Suspension arm of a tracked vehicle
Figure 2 Major dimensions and geometric shape of the suspension arm
As stated above, the hole at the left end of the suspension arm is tightly fit to a torsion bar, and the hole at
its right end connects to the roadwheel shaft. When the tracked vehicle is not moving, the suspension arm
rests at a clockwise 30-degree angle measured from a horizontal line, as shown in Figure 3. While
maneuvering, the arm swings to an angle no less than 15 degrees.
o
30
Figure 3 Suspension arm at a rest position
In this project, you are asked to conduct stress analysis and redesign for the suspension arm. The project
involves:
(1) Carrying out stress analysis to identify the arm swing angle (greater than 15 degrees) where the arm
experiences a maximum stress (must include all component stresses present; i.e., axial, bending, and
torsion).
(2) Based on the finding in (1), calculate the maximum allowable force acting on the arm coming from
the roadwheel for a safety factor of 2.
(3) If the maximum allowable force obtained in (2) is increased by 10%, redesign the suspension arm that
maintains a safety factor 2 without increasing its weight.
Project Report: A report of no more than three pages must be submitted for grading before the due date
stated above. Graphs, tables, and data can be arranged in appendices. Appendices are not counted for the
page limit. The format and style of the report must conform to the report template provided in Project#1
assignment (CADandA_Newtemplate.doc) and must include the following:
(1) A short abstract that provides an overview and key findings of the project;
(2) A short introduction to summarize the engineering assignment;
(3) Your overall step-by-step approach;
(4) Assumptions (if any) you made for your analysis;
(5) Your calculations;
(6) Outcome and justification. Why your outcome is useful and reliable?
(7) Summary and lessons learned;
(8) References (if any).
Grading Criteria: The following is how your report will be graded by Dr. Chang and Anirban. In each
category listed below, the best work receive full credits, and the worse work receive zero point. In
between, points are assigned roughly proportionally depending on the accuracy, clarity, quality, and level
of effort of the work presented.
(1) How well and realistic is your approach in addressing the engineering problem (5%)
(2) How realistic and logical are the assumptions you made (5%)
(3) Free-body diagram and stress calculations (15%)
(4) The arm swing angle at the maximum stress (10%)
(5) The maximum allowable force calculated (10%)
(6) Re-designed arm (15%)
(7) Outcome and justifications (15%)
(8) Lessons learned (5%)
(9) Overall quality of the report (20%)
Please note that the points awarded following this approach is somehow subjective. Therefore, please
offer as detailed and as complete information as possible in your report so as that you earn highest points
possible. Your calculations must be presented clearly with adequate illustrations and explanations.
Calculations that are not clear and difficult to follow will receive a minimum, or in some cases, zero
credit.
Please note that Project#2 is a typical engineering assignment you will be given as a journeyman
engineer. In your report, you must not only show accurate engineering calculations but also demonstrate
sound engineering proficiency in presenting your work at a near-professional level.
PRIZE FOR THE BEST PROJECT WINNER(S):
• A certification letter from Dr. Chang for the winner(s) to keep and to show off
• A textbook of your choice (~$60 each, see below):