EMA 630

Project 1a: Viscoelasticity experiment

In this project, you will work with a group to design an experiment to measure creep compliance or relaxation
modulus of a viscoelastic material of your choosing.
Requirements
Measure the creep compliance or relaxation modulus of a material over at least two decades in time. You will
design and build a testing apparatus yourself. The device that you design may not use specialty equipment for
materials testing—you must use supplies, materials, and equipment that would be available in a convenience store
or hardware store. Present your data in an abbreviated report (described below).
Tips & Suggestions
Choice of material and loading. Choose a material that will exhibit creep or relaxation over a time range
that is feasible for you to measure. Consider materials you interact with on a daily basis—seat cushions, foam,
rubbery polymers, food, etc. Choose the magnitude of loading such that the creep or relaxation will be measurable
for at least two decades in time.
Use of a camera. For this project, students often use the cameras on their cell phones to capture images. Try
this out before beginning the experiment. How well can you measure tiny displacements with cell phone images?
(Hint: Probably not well.) Are there clear markers on your sample for tracking? Is the image of the markers
collected by your camera clear or blurry? (Hint: Edges will be blury.) How much error is caused by moving the
camera phone in between collecting images?
Amplification of displacements. At some time points, the displacements of your material will be small.
Consider clever use of small levers or other mechanical devices can amplify the displacements, thereby reducing
error in your measurements.
Looking ahead to the next project. Project 1b will repeat the measurements at different temperatures.
Abbreviated Report
You will present your results with a report having the following sections:
◦ Abstract
◦ Experimental Methods
◦ Estimate of Error
◦ Graph and Caption of Results
Details on the requirements for each section are given below. Typical reports would have additional sections for
the introduction and and discussion; here, you will skip these sections to save time. Additionally, the text in the
results section is abbreviated as described below.
Abstract. The abstract should be a paragraph in length. Begin with 1–2 sentences motivating the work. These
sentences answer the question of why the general topic is interesting. State a key unknown question in the field.
This focuses your abstract onto a specific topic. (Note: The unknown question is what your plot and explanation
will address.) Explain the methods you used to address this question. State results and conclusions. (Note: The
hardest part of writing the abstract will be identifying the key question. This is also the most important part
of the abstract, because it tells the reader what they will learn from reading your report. You may have to be
creative in proposing a question that will interest the reader.)
Experimental Methods. This section describes the experimental technique and how the work was performed.
Write this section as a narrative of what was done rather than a step-by-step list of instructions (why?). For
experimental work, a simple schematic diagram should should be included as well as other important data such as
the manufacturer and model number of any equipment used. This may be important for reproducibility of results
and in interpretation of errors. Be sure to report the temperature at which the experiment was conducted.
Estimate of Error. Estimate the error in your measurements. Based on the measurement error, estimate the
error in your reported data for creep compliance or relaxation modulus. Explain how you arrived at your estimate
with text and equations. This section must be complete, but if done concisely, it does not have to be long.
 Results. Make two graphs of your results, one with time on linear axes and the second with time on logarithmic
axes. Clearly identify on the graphs the individual data points measured. Attempt to fit the data to various
potential constitutive functions (see section 2.6 of the textbook) and show on your graph the best fit you can find
(only show the best fit; do not show all of the fits that you attempted). Follow all rules of a quality plot: label
axes, include units, choose appropriate axis limits, text must be legible (not pixelated; suitable font size). See
Prof. Lakes’ web page for more information on making quality graphs. Write a descriptive and concise caption
describing each graph. The caption must appear below the figure. Write brief text commenting on the results.
Describe the general trends and comment on any sources of error or unexpected results. What functions did you
attempt to fit to? What fit was best, and what was the result? Does your material fit well to a single exponential
function? For the purposes of this report, the text describing the graphs should be about a paragraph. (Typically
a Results section would contain more detail, but for this assignment, be brief to save yourselves time.)
General Notes. Since we write documents on computers, single spacing is encouraged (double spacing comes
from the time of typewriters). Equations should be numbered so that you can refer to them in the text and the
reader can find them. Mathematical variables must be written in italic font. Units should be in upright (not
italic) font. Put a space between a number and its units (with the exception of the degree symbol used for tem-
perature, e.g., 22◦ C). Diagrams should be professional in appearance. Draw them using computational software.
Photographs can be used, but include photographs only if needed; avoid an excessive number of photographs.
Diagrams or images taken from the web must be cited. Before submitting, review the report to check for errors
that should be obvious to anyone; check numerical results for physical reasonableness; check physical property
results to make sure they have the proper units. If you need to cite references, use numbered references in the
text and list the references by corresponding number in a References section at the end of the report. Follow a
standard formatting style used by engineers such as Vancouver. For the purposes of this class, if a topic is cov-
ered in a relatively common textbook, it does not have to be cited. Specialty information, such as from research
manuscripts, should be cited.
Each group will submit one report. See the grading rubric for a detailed list of requirements.
A Note about Integrity
It is easy to identify work that has been plagiarized. Each person writes with a different style; when the writing
style changes abruptly, plagiarism is suspected. It’s easy to check for plagiarism—simply type the suspected phrase
or sentence into Google. I have caught people plagiarizing in academic classwork, research proposals, and even
technical manuscripts intended for publication with large publication companies.
Sometimes plagiarism results from laziness: it’s easier to
use the language of someone else than to generate your own.
Other times plagiarism is due to an oversight; for exam-
ple, I often see people copy and past text into their own
manuscript with plans to modify the copied text later. For-
getting to make this change would be accidental plagiarism
rather than intentional, but it is nevertheless unacceptable.
Fortunately, it’s easy to avoid this problem: never copy text
that isn’t yours—even a single sentence or phrase—in your
own manuscript.
You are not allowed to use AI tools for this assignment.
The tasks in this assignment are brief and specific, so AI will
not be helpful. This assignment is intended to help you think
deeply—use of AI is counter to that goal. It’s often easy to
identify text that was written by AI—the style is distinct and
the writing is often shallow. I’ve even seen students submit
AI-written text that was wildly off topic.
Grading
Look at the grading rubric carefully. All items are required.
EMA 630 Project 1a Grading Rubric
Abstract [20%]
◦ Follows “formula” described in the assignment instructions.
◦ Identifies a key question or issue that this report will address.

Methods and Estimate of Error [25%]

◦ Material used is described.
◦ Temperature is reported.
◦ Explains methods with enough detail that they could be repeated by the reader.
◦ A quality diagram (not a photograph) of the experimental testing device is included.
◦ Method can be used to quantify creep compliance or relaxation modulus.
◦ Written as a narrative rather than a list of instructions.
◦ Estimate of error of measurement is included and described correctly.
◦ Estimate of error of creep compliance or relaxation modulus is described correctly.

Results [35%]
◦ The data are sensible. Creep compliance or relaxation modulus shown is sensible for the material selected.
◦ The data span at least two decades in time.
◦ A fit to a constitutive relationship is included and described.
◦ The standard rules for a good quality figure are followed.
◦ A few sentences are written describing observations in the plot (especially unexpected results) and commenting
on whether a single exponential function fits well to the data.
◦ Numerical values have a reasonable number of digits.
◦ Numerical values use units.

General [20%]
◦ Entire report (including text, equations, figures, tables) is formatted on a computer.
◦ References cited (if any) are numbered and are referred to in the text as is done for scholarly articles.
◦ All figures have captions that are numbered and appear below the figure.
◦ Report is concise, without extra “content” that was not requested in the project instructions.
◦ Writing is clear with no (or minimal) errors/typos/etc.
◦ Names of all group members are listed.