MEE 323 – Computer Aided Engineering II
Module 1: Homework – Introduction
Instructions:
• You must use this Word file as a template for your homework report. Add screenshots/figures
of all required modeling/analysis steps and all required discussions below the appropriate
question. Convert the final document to PDF.
• All answers must show figures and provide discussions justifying the results of the
analysis that was carried out. Points will only be awarded for answers that are sufficiently
justified.
• Turn in the homework report PDF to the appropriate assignment before the deadline.
• Upload a copy of your archived ANSYS files to the appropriate assignment. The uploaded
ANSYS files may be used to check your work and ensure academic integrity.
• Students in this class must adhere to ASU’s academic integrity policy, which can be found at
https://provost.asu.edu/academic-integrity/policy). Students are responsible for reviewing this
policy and understanding each of the areas in which academic dishonesty can occur. All
engineering students are expected to adhere to the ASU Academic Integrity Honor Code.
• All work submitted for the course must be your own and cannot have been submitted for
any other course or any previous section of this same course. Student academic integrity
violations are reported to the Fulton Schools of Engineering Academic Integrity Office (AIO).
Homework Objectives:
Identify the role of finite element analysis in the design process and understand its advantages and
limitations.
Reading Assignment:
Chapter 1 (Introduction) from Finite Element Simulations with ANSYS Workbench 2021.
Chapter 1 (Guilty Until Proven Innocent) from Lying by Approximation.
Questions and ANSYS Exercises:
Question 1:
Explain in your own words where finite element analysis fits into the design process. What is it
not intended to replace? What would the analyst need to consider (i) before running a finite element
simulation, (ii) during the simulation, and (iii) after running a finite element simulation?
Finite element analysis is used in the calculation and optimization phase of design. When designing
a part or system, the goal is to solve a problem. Engineering is the process of finding solutions to
problems, verifying validity and optimizing those solutions. Finite element analysis allows for
more detailed calculations on verifying the validity of a solution by calculating approximations for
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how materials respond to the loads on the system. Not only does FEA allow for verification that a
solution should work based on mathematical models, but it also can allow a designer to adjust a
design to optimize for loading conditions such as increasing or reducing materials in areas to
reduce weight, manufacturing costs or optimize for other goals of the system. Before being able to
run a finite element analysis a designer has to determine the loads on a system, geometry, materials
and design constraints. Determining the loads requires the designer to specify assumptions for the
loads on the system based on the intended use and use conditions. The loads on a system then
inform the designer on what Geometries are likely to work based on the designers experience and
standard engineering practices. Combined with the decision of geometry, the materials that the
system will use give the designer constraints to work off of when working on the geometry.
Combined with other constraints such as manufacturing methods and best practices, the designer
is then able to find an initial solution. After designing an initial system, the engineer then has to
validate and optimize the design. This is where FEA can be used most effectively. In the preprocessing phase the engineer determines mathematical models to use and how to represent the
system mathematically and in terms of the FEA mesh, loads and constraints. This is then input into
the FEA software to prepare for the FEA simulation.
When running the simulation, the engineer analyses the system and evaluates the mesh and other
FEA parameters to best approximate the system and generate a solution that gives the engineer
critical information such as stresses or deformation at critical points in the structures.
After running the simulation, the solution needs to be evaluated and assessed. To assess the
solution, it is best to have a mathematically derived solution independently found by the engineer
to ensure that the FEA model and the mathematical model of the system are close to validate the
results. If there is a large difference between the FEA model and the mathematical model, then
further refinement of the analysis is required and the FEA process will need to be repeated. When
the models line up sufficiently to validate accuracy of the system, the details of the FEA solution
can be used to inform optimizations in the system. For example, if the overall deformation of the
system is used to validate the FEA results, the FEA will also be able to evaluate granular
deformation of the system at more points than would be practical to work by hand. The same is
true of stresses and stress concentrations. This helps the engineer to find parts of the system that
are critically stressed or deformed and adjust the design accordingly. The FEA solution can also
inform the engineer what parts of the system might be over-engineered and where material or
components could be reduced or removed. This allows the engineer to iterate on the design and
optimize solutions mathematically before finding a final solution and testing prototypes or final
products as a final verification of the design assumptions and FEA analysis.
Question 2:
Explain in your own words what you think the two most important advantages and the two most
important limitations of finite element analysis. Why do these resonate with you? Where have you
seen or would you see these advantages being effectively used and the limitations being carefully
avoided?
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The two most important advantages of FEA are the ability to evaluate designs virtually, reducing
costs of testing and the ability to iterate a design based on a virtual model of a system. FEA allows
an engineer to input design parameters and material properties and virtually test the system, seeing
how stresses are concentrated or how and how much the system deforms. Using physical
techniques to find the same information is often very expensive and time consuming. The second
advantage of FEA, being able to quickly iterate a design is closely linked to the first advantage.
FEA allows much more fine evaluation of a system, giving stresses and deformation values for a
large number of points on the model that allow an engineer to find more sections where the design
can be changed to increase strength or reduce deformation, weight etc. of a part. Because FEA is
much quicker than physical testing especially for complex systems, an engineer can change the
design and re-test, iterating on the design much more than would be practical using physical
testing. These two strengths of FEA allow high performance applications such as aerospace
companies or performance automotive teams to quickly and effectively validate designs and
improve performance of parts.
The two main disadvantages of FEA are that it requires the engineer to make assumptions about
the system and that because it is a discrete approximation, the results can be mis-leading if
something about the system is incorrect. The first disadvantage is the need for an engineer to make
assumptions about the system. In physical testing and analysis, the part or prototype can be put in
realistic situations. With minimal assumptions or simplification of the loading and use of the
system in physical testing, unexpected behaviors, loading conditions and other environmental
factors can reveal flaws in the design assumptions or critical errors in the design implementation
such as differences due to manufacturing limitations or errors. This also ties into the second
disadvantage of FEA, that the results can be mis-leading. If the system is not properly represented
in the FEA model, such as elements being too large to properly represent the system in critical
areas, or loads being applied different than in reality, the FEA model will output an analysis that
is based on the flawed representation of the system. This requires an engineer to evaluate the results
and question and evaluate the validity of FEA results. If an FEA system does not give accurate
results, an engineer may be mis-lead to optimize the system in a way that causes failure in realworld conditions. These disadvantages can be mitigated by collaboration with other engineers,
getting varied perspectives on problems and validating results using physical testing on prototypes.
Question 3:
Find an example (you may use books, the internet, etc.) of finite element analysis applied to a realworld problem and describe (in a paragraph or two) how it was used to improve the design of the
structure being considered. Be sure to include references and citations to your source.
Finite Element Analysis is used in the engineering of structures for crash safety in vehicles. Crash
testing vehicles is destructive and thus expensive, however with finite element analysis, engineers
can test crash conditions on the structure to estimate deformation, energy absorption and energy
transfer through the car frame. The results from the use of these engineering tools can be seen in
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the difference between very old cars and the current vehicle models. Old vehicles were designed
to be sturdy, however when they got into a crash, they would not absorb much energy and were
much less safe. However modern cars are designed to crumple and deform to dissipate as much
energy from a crash before it reaches the passenger, while still remaining usable for hundreds of
thousands of miles. The use of FEA has allowed engineers to design these crumple zone and to
have a trend of reduction of crash fatalities from 1970 to today.
Source: NHSJS Finite Element Method’s Application in Vehicle Safety Design.
https://nhsjs.com/2024/finite-element-methods-application-in-vehicle-safety-design/
Question 4:
Explore the cantilever beam model created in the example videos for Module 1. Pick any one of
the three models created and change the loads, boundary conditions, etc. until you create something
interesting. Describe the changes you made, which model you used, and what you think the results
of the simulation are telling you. Show figures of the changed geometry, boundary conditions,
loads, and final deformations & stresses as appropriate.
Did you apply your mechanics of materials knowledge to this modified system? If not, do so and
explain (i) what you expected to see before running your simulation, (ii) what you saw during the
simulation, and (iii) how you can verify your solution using your knowledge from mechanics of
materials/structural mechanics.
I changed the line body model to a distributed load of 10N/m. The results of the simulation show
that the stresses in the beam are reduced by having the load distributed instead of at the end of the
beam.
(i)
I expected to see that the stresses and deformation would reduce by distributing the
load over the beam instead of having a point load at the end of the beam.
(ii)
The simulation showed that there was a reduction in deformation and stresses on the
beam.
(iii)
𝑤𝐿4
I was able to use the formulas from Mechanics of materials 𝑦 = 8𝐸𝐼 to find that the
theoretical max deflection at the end of the beam should be 7.5mm which is what the
simulation shows. This is a good verification that the simulation is valid.
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