added lab 2

README.md

@@ -17,13 +17,40 @@ 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
+# 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](https://ugmelab.uconn.edu) 
+# [ugmelab.uconn.edu](https://ugmelab.uconn.edu) 
 
-### Lab #1 - Measurements of machining precision and accuracy
+# ME 3263 Introduction to Sensors and Data Analysis (Fall 2018)
+
+# 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: $R=\rho L/A$, where $\rho$ is the material
+resistivity, $L$ is the total length of the wire, and $A$ is the cross sectional
+area of the wire.  Note that as $L$ increases, the cross sectional area changes
+as
+well due to the Poisson contraction; the resistivity also 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.](./figure_01.png)
+
+*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
 
 [Lab 1 github files](https://github.uconn.edu/rcc02007/ME3263_Lab-01.git)
 
@@ -47,7 +74,7 @@ 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
+# Lab #0 - Introduction to the Student t-test
 
 **Outline and figures due Wed 9/5 by 5pm**