mechanical engendering

ME 495 – Homework 8

Summer 2019

Submission Deadline: 19th July (Friday) midnight

Note: Write your name at the top right-hand corner of the first page of your homework.

Question 1: Read the following:

https://en.wikipedia.org/wiki/Constantan

What makes constantan an ideal material for stain gauges. Be brief and to the point.

Question 2: Explain what a balanced Wheatstone bridge means? How would you balance a

Wheatstone bridge with strain gauges?

Question 3: What is the voltage output (Vout) from the resistance networks shown below? Show

and explain your working steps clearly.

(a)

(b)

Question 4: A scale uses four internal strain gauges to measure the displacement of its diaphragm

as a means for determining load. Four active gauges are used in a bridge circuit. The gauge

factor is 3, and gauge resistance is 150 Ω for each gauge. If an applied load to the diaphragm causes a compression strain on R1 and R4 of 40με, while gauges R2 and R3 experience a tensile

strain of 40με, estimate the bridge voltage. The supply voltage is 10 V.

Question 5: Show how to use a Wheatstone bridge with a single active strain gauge to

compensate for temperature.

Question 6: Make an approximate estimate of ‘rise time’ of the sensor from the figure below.

Show the location in the graph. Explain the reason for your answer.