P17665: Rotating Dynamometer for Cutting Tools

Integrated System Build & Test with Customer Demo

Table of Contents

1 Team Vision
2 Test Results Summary
3 Simulation Setup
4 500N
5 50N
6 Risk and Problem Tracking
7 Plans Going Forward

Team Vision

The goal of this phase was to find a conclusive explanation of why the wheatstone bridge subsystem is not outputting a voltage as expected. Unfortunately, the team has still not found out the specific reason for the low voltage output. Since the last phase the team has done the following:

Performed a cantilever beam test to rule out a bad lot of strain gauges and verify that the strain gauges can pick up strain shown in design simulations.

Checked accessible gauges on an individual level, and saw that they are changing in voltage, thereby verifying that they are not placed improperly.

Rechecked simulations to verify that strain gauge orientation is correct with respect to the strain.

What is next? We believe we have exhausted all nondestructive testing options. During the following few days and next week we are planning to move forward with removing strain gauges and testing placement in an experimental environment.

Test Results Summary

Cantilever Gauge Validation

Cantilever Test

What We Did:

Determined max and min strain our structure would experience
Placed gauges in areas on a test piece so they would experience an equivalent strain
Both Omega gauges and gauges from Dr. Liu's lab were tested to ensure functionality

Takeaways:

Both our gauges and Dr. Liu's gauges performed extremely well for the max strain
Both our gauges and Dr. Liu's gauges were slightly off for the min strain, but this is easily explained by imprecise placement of the gauges, slight changes in load location, and other environmental factors
It appears that the gauges are able to measure both the maximum and minimum strain that the structure will experience although there may be a slight loss in accuracy when measuring the minimum strain

Individual Gauge Test

Individual Gauge Test.

What We Did:

Voltages were measured at strain gauges listed above with unloaded conditions, loaded conditions at 25lb, and approximately 75lb weight on the structure.
We observed the strain gauges react to the weight placed on the system and saw that the voltage was changing only in the microvolt range.

Takeaways:

For this reason the team concludes that strain gauge placement is not an issue.
We also double checked the unloaded voltage values of the accessible gauge’s and observed that their unloaded voltage values are close to the values measured previously which shows that the gauges aren’t shorting anywhere.
This is a capture of the 25lb load test.
This is a capture of the 75lb load test.