pressure_lecture.doc

8/12/2019 pressure_lecture.doc

1/7

Pressure Vessels

o Any container that holds a fluid under a positive or negative internal pressure

Pressure may be well above or below atmospheric pressure

Vessels holding fluids under static pressure are also pressure vessels

o Many are used in everyday life

LessonExamples Lab Procedure

o You will perform tests on two different pressure vessels

Thin-walled and thick-walled

o Thin-Walled Vessel Test

Pressure vessel is considered thin-walled if

!Insideradius

WallThickness>

We will use a " strain gage rosette to measure strain on the outside of thevessel wall as pressure is applied inside

#ote the orientation of the " strain gages in the rosette $hould be !% &'% and (!) Also make sure you properly label which gage is A% *% and + for

the data you collect

,raw on board

rient the ./ a.is along gage A and y/ a.es along gage + Measure the orientation angleusing a protractor

$hould be measured as the angle between the a.ial direction of thecylinder and the gage oriented the closest to the a.ial direction

0gage A1

2ero the amp

$et the gage factor

*alance the strain

+lose the pressure relief valve

3se the pump to increase the pressure in 4'! psi increments from ! psi to

4!!! psi

Take readings from the " strain gages at each 4'! psi increment nce you reach 4!!! psi and are finished taking readings% open the

pressure relief valve


2/7


3/7

o Thick-Walled Pressure Vessel Test

The two strain gages we will use are designated as 5 and 54 on your data

sheet

These gages are aligned in two of the principal directionso 5 is aligned in the hoop direction

o 54 is in the radial direction 2ero the amp% set the gage factor% and balance the strain for gage 5

3se the switch to change to gage 54

,o not balance the strain again Write down what the strain is at ! psi and subtract this value from

all your others for gage 54

+lose the pressure relief valve

3se the pump to increase the pressure in 4' psi increments from ! psi to

!!! psi

Take strain reading for the two gages at each 4' psi increment

pen the pressure relief valve when finished Calculations

o Thin-Wall Experiment

*egin by entering your data in 6.cel

+reate a plot of normal strain vs7 pressure with a line for each of your

strain gages

Put all the lines on the same graph

3se linear regression to calculate the slope

p

i

of the lines for each of

your strain gages

+alculate the strains along the ./ and y/ a.es along with theshearing strain

o

pp

xA 8 =

o

pp

yC 8

=

0 9 1in in

p (psi)

A

p

C

p

B

p


4/7


5/7

o Thick-Wall Experiment

Much simpler than the thin-walled vessel


6/7

Lab Report

o Memo completed by your group worth !! points

Attach your initialed data sheet

Also attach a set of hand calculations

o 6.perimental ?esults

Thin-walled vessel $how the graph you will create from your data =nclude a table or tables showing your calculated e.perimental

values for the following;

p

x 8

p

y 8

p

yx88

p

x 8

p

y 8

p

yx 88

p

p

4 p

Also include a table showing the reference values ofp

andp

4

for the thin-walled vessel using both the thin-wall and thick-wall

theoryo 3se a B error to compare your e.perimental values to the

reference values

Thick-Walled Vessel

$how the graph you will create from your data =nclude a table showing the following calculated e.perimental

values;

p

p

"

p

p

"

Also include a table showing the reference values forp

and

p

"

found using both the thin-wall and thick-wall theories

o 3se a B difference to compare the theoretical values to

your e.perimental values

o ,iscussion of ?esults

+ompare your e.perimental principal stresses to those found using the twotheories

You need to compare your e.perimental results from each vessel toboth of the theories

3se a percent error ,iscuss how well the theories work

o =n particular mention if the thin-walled theory is

appropriate for use on thick-walled vessels

+ompare the calculated principal direction for the thin-walled vessel to the

measured orientation angle

=n theory these should be the same Presentation


7/7

o 6ach group will come to the board and fill in their e.perimental values for the

following;

Vessel Type

p

4

p

"

p

Thin-Walled #9A

Thick-Walled #9A

Then two random groups will be asked :uestions7

Documents

pressure_lecture.doc