Guest Lecture PE part2

Question 1

Case Study 2 - Load Path Validation for Cross Beam Fatigue Test

Physical fatigue test required to ……… some fatigue prediction software on a notch of a vehicle cross member

Used to develop and refine fatigue software code. FEA wrongly predicted the optimum loading direction so PE was used to obtain the ……… stress distributions

Answer 1

validate

correct

Question 2

Case Study 2

PE can be used to determine ……………… …………. between the interface of different components under clamping loads

This is difficult to do using FEA

Answer 2

Assembly stresses

Question 3

Case Study 2

In addition to assembly stresses, ………… ………… can be determined. Designs can be optimised and …….. paths can be corrected and ………. concentration can be optimised

Answer 3

load stresses,

load,

stress,

Question 4

_Case Study 2 - Dynamic PSA _

What is the advantage capturing an actual stress movie?

Answer 4

• can be used to determine correct load path
• Fast response time. Work completed much quicker than waiting for several hours for a specimen to crack on a fatigue test rig. Therefore, it saves time and money.

Question 5

Case Study 3 - Sluice gates

This is another example of companies ………… their FEA designs with PSA.

…………… stresses were also observed by looking at interactions with bolts and the material.

………. stresses were also simulated.

Without this …. …….. view of the stresses, an optimised design would have been hard to envisage.

The manufacturers used this techniques as a ……… ……… and gained an advantage over thier competitors

Answer 5

validating,

assembly,

full field,

selling point,

Question 6

Case Study 4 - Tractor gearbox and Linkage

the linkage and the gearbox were coated with PE coating (THIS TOOK QUITE A LOT OF TIME)

The components were then tested under operational loads

This highlighted high stress areas that the . . . had missed.

With PSA tests, it is important to avoid …. …….. washing out the images as it is unpolarised

Answer 6

FEA

sun light

Question 7

Case study 4

Why is the PE coating pink ?

Answer 7

Using RGB (red green blue) (pink colour) polarised light, the relative retardation of each of the colours through the coating can be calculated.

This is used to measure thickness changes in the coating and the software then allows thickness compensation pixel by pixel across the full field image.

The raw image on the left, although it picks up the max stress area is wrongly calibrated because the thickness is not uniform as the component is curved and the resin has flowed to the lowest bits during curing.

The RGB calculation rectifies this and gives a true stress plot as shown on the right.