How Do You Calculate Strain in a Faulty T-Delta Rosette Configuration?

In summary, a prototype was tested using strain gauge rosettes at critical locations and the measured strains in three gauges were given. Due to a fault in the measuring circuit, the strain response in gauge A could not be recorded. To find the strain recorded by gauge A, an equation was used which involved the values of gauges B, C, and D. It was determined that gauges B and D were perpendicular, and therefore the equation needed to be adjusted accordingly. The angle thetaYY was also noted to be 90 degrees, which provided further information about the value of eYY. However, the exact value of gauge A could not be determined without additional information.
  • #1
jcurtis
2
0

Homework Statement

For experimental validation of a design based on FEA, a prototype was tested using strain gauge rosettes at critical locations in a typical t-delta configurations, consisting of 3 gauges: A, B, C and fourth (extra) gauge D. D normally serves as a check on the strains recorded by the rosette arms. In this instance due to a fault in the measuring circuit, the strain response in gauge A could not be recorded the measured strains in the other three gauges were: eB = (-)135x10-6, eC=227x10-6 and eD= (-)63 x 10-6.
What would have been the strain recorded by gauge A?

Homework Equations


I found that J=eXX + eYY = eA + eC = eB + eD


The Attempt at a Solution

I've looked in my notes that my lecturers put online and I've been searching on google all day and I can't find anything. I know it has something to do with the fourth gauge, but there's no information on the web about it that I could find. The equation I found seemed too simple as the question is worth 8 marks. Or is it more simple than I'm making out? Can anyone help please?
 
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  • #2
jcurtis: As I currently see it, you have four equations and four unknowns. Your relevant equation is currently incorrect; eB and eD are not mutually perpendicular. Try it again. And, you need to list three more equations, for strain in a strain gauge leg. You must list relevant equations yourself. The angle from gauge A to gauge D is 90 deg; but I think you knew that, right? Hint: thetaA = 0 deg.
 
  • #3
Thanks for replying. So you're saying I should swap eB and eA around because a and d are perpendicular?
I can't find any other strain equations that aren't to do with resistance. other than principle strain equations which I need the value of A for, however I know it has to just do with the values of B, C and D as that's all they've given me.. Sorry I'm being a bit dense here, I'm just very confused.
 
  • #4
Yes, swap eB and eA, then omit eB + eC from your above equation, because gauges B and C are not mutually perpendicular.
 
  • #5
Hint 2: thetaYY = 90 deg. Do you have anything else at 90 deg? What does that tell you about the value of eYY?
 

Related to How Do You Calculate Strain in a Faulty T-Delta Rosette Configuration?

1. What is a T-delta rosette strain gauge?

A T-delta rosette strain gauge is a type of sensor used to measure the strain or deformation of an object. It consists of three strain gauges arranged in a T-shape, with one gauge oriented in the same direction as the applied force and two gauges at right angles to the applied force.

2. How does a T-delta rosette strain gauge work?

A T-delta rosette strain gauge works by detecting changes in electrical resistance when an object is subjected to strain or deformation. As the object deforms, the strain gauges in the T-delta rosette change in length and therefore change in resistance. This change in resistance is measured and converted into a strain value.

3. What are the advantages of using a T-delta rosette strain gauge?

One advantage of using a T-delta rosette strain gauge is its ability to measure strain in multiple directions, providing a more complete picture of the strain on an object. It is also more accurate than single-axis strain gauges and can be used in a variety of applications, including structural testing and materials research.

4. How is a T-delta rosette strain gauge installed?

The installation process for a T-delta rosette strain gauge involves cleaning the surface of the object, applying an adhesive to the gauge and then attaching it to the surface. The gauge is then connected to a data acquisition system for measurement.

5. What are some common uses for a T-delta rosette strain gauge?

T-delta rosette strain gauges are commonly used in engineering and scientific research to measure strain and deformation in various materials. They are also used in industries such as aerospace, automotive, and civil engineering to test the strength and durability of structures and components.

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