Introduction to Sensors and Data Analysis
ME 3263 Fall 2018
Labs 0 and 1 have a 3-page limit and 2-figure limit. Labs 2-6 have a 5-page limit and 4-figure limit. You can add additional pages and figures in an Appendix. The Appendix will not be formally graded, but you can use it to refer to data, methods, or diagrams that are relevant.
The report is scored 0-100. Over 70 is passing. Late submissions receive 10 point penalty per day.
Part of your "writing assignments" grade is based upon the reports that you make the final edits and improve the flow. The first author listed will get credit for the writing assignment portions. Take turns as first author and co-author. The group shares the pass/fail grade for the "lab report" grade.
Repository for laboratory notebooks
To access notebooks and interactive lab material, sign into github.uconn.edu, then follow the link to the class server.
ugmelab.uconn.edu
ME 3263 Introduction to Sensors and Data Analysis (Fall 2018)
Lab #3 Measuring Natural Frequencies
What are natural frequencies
In free vibration (i.e., no external forcing), structural components oscillate at specified frequencies or combinations of frequencies. Since these vibrations are unforced, the associated frequencies are referred to as natural frequencies; it's how the system vibrates if left to behave on its own. In contrast, driven linear systems vibrate at the driving frequency. An amplification of the response (called resonance) occurs when the driving frequency coincides with one of the natural frequencies. In short, the system is driven at a frequency at which it likes to vibrate. Large amplitude oscillations are the result. So it is important to know what the natural frequencies are a priori so you can avoid driving the system into resonance.
Lab #2 - Static beam deflections with strain gage
What is a Strain Gage?
A strain gage consists of a looped wire that is embedded in a thin backing. Two
copper coated tabs serve as solder points for the leads. See Figure 1a. The
strain gage is mounted to the structure, whose deformation is to be measured. As
the structure deforms, the wire stretches (increasing its net length ) and its
electrical resistance changes:
Figure 1: a) A typical strain gage. b) One common setup: the gage is mounted to measure the x-direction strain on the top surface. It's engaged in a quarter bridge configuration of the Wheatstone bridge circuit.
Lab #1 - Measurements of machining precision and accuracy
Outline and figures due in week 4 at beginning of lab
Final report due day before lab by 11:59pm
How can you measure something?
All measurements have traceable standards. There are seven base units in SI - meter (length), second (time), Mole (amount of substance), Ampere (electric current), Kelvin (temperature), Candela (Luminous intensity), and kilogram (mass) 1. Any measurement you make should have some method to check against a reference. In this lab, we will use calipers that measure dimensions i.e. meter 1E-3 (length). Calipers can always be verified to work with gage blocks.
Sources of measurement variations
No measurement is exact. No surface is compeletely flat. Every measurement you make has two types of uncertainties, systematic and random. Systematic uncertainties come from faults in your assumptions or equipment.
Lab #0 - Introduction to the Student t-test
Outline and figures due Wed 9/5 by 5pm
Final report due Thu 9/13 by 5pm
Lab 0 interactive notebook in ipynb jupyter notebook
We use statistics to draw conclusions from limited data. No measurement is exact. Every measurement you make has two types of uncertainties, systematic and random. Systematic uncertainties come from faults in your assumptions or equipment. Random uncertainties are associated with unpredictable (or unforeseen at the time) experimental conditions. These can also be due to simplifications of your model. Here are some examples for caliper measurements:
In theory, all uncertainies could be accounted for by factoring in all physics in your readings. In reality, there is a diminishing return on investment for this practice. So we use some statistical insights to draw conclusions.