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Embed code for: Structural Mechanics - Lab 3
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Faculty of Science, Engineering and Technology
MEE20004 - STRUCTURAL MECHANICS
LAB. 3 - BEAM BENDING - 2015 Sem. 2
By writing my name below, I declare this is an individual assignment and no part of this submission has been copied from any other student's work or from any other source except where due acknowledgment is explicitly made in the text, nor has any part been written for me by another person. Refer to Unit of Study Outline for Plagiarism guidelines.
STUDENT NAME & No. : Musty Alash / 9987282
Lab. Date & Time:. 14.10.2016 8:30am
Demonstrator : Dr. Yaman AL-KAMAKI
The aim of this laboratory is to compare experimental and theoretical deflections of a solid steel beam subjected to three point bending. Load is applied using a GUNT bending device.
Measure the dimensions of test beam cross-section and distance between two roller supports. Calculate the central applied Load required to produce a max. bending normal stress of 190 MPa in the beam. (Note: use Eqs. 1a, 1b and 1c shown on the next page.)
Measured Width (mm)
*Average Width (b) (mm)
Measured Height (mm)
*Average Height (h) (mm)
NOTE : Measure & record b and h at three locations and use Average values in calculations.
Distance between the roller supports (L) = 300 mm
Calculated Load (P) = 3.48 kN
Ensure force and deflection are initially zeroed. Apply the Load calculated in step 1 and record the resulting beam deflection under the indenter. (Note : Is “y” reading +’ve Or –‘ve ?)
Actual measured load (P) = 2.461 kN
Final measured /experimental deflection (y) = -1.221 mm (show sign and units)
Determine Theoretical value for EI by multiplying the I determined in step 1 with E= 200 GPa.
EI THEORY = +1289.4 Nm2 (show sign and units)
Calculate the theoretical deflection by using Eq. 1(a) - (d) shown overleaf.
Theoretical deflection (y) = -1.08 mm (show sign and units)
LL/2Roller supportIndenterTest beamForce Pyxx
For Central Load:
Eq. (1a) Eq. (1b)
Eq. (1c) Eq. (1d)
Unload beam and change the position of one roller support so that the beam is now non-symmetrically loaded as shown below. Apply the same calculated load as in Step (1) (which should not exceed 2.7 kN) and record final deflection.
Actual measured load (kN)
Final experimental deflection (mm)
Calculate the theoretical value of deflection by using Eq. (2).
Theoretical deflection = -0.577 mm (show sign and units)
Lv=150mmRoller supportIndenterTest beamForce Pyxu=100mmx
For Non-symmetric Load:
, Eq. (2)
Type and edit your report using Microsoft Word (hand-written is not acceptable except for the sample calculation). Email your individual Lab. Report to your demonstrator by due Date – 1 week after conducting Lab. Please scan your report and save whole report as one PDF file with a name of Surname_Initial_Student ID_Lab3.pdf. Please see the Study Guide or Blackboard for your demonstrator’s email address. Please refer to Unit of Study Outline for penalties etc.
The Report must include (in order) :
This handout as cover sheet /results for your report (1 mark).
Discussion and Conclusion, compare the experimental and theoretical deflections for both central and non-symmetrical loadings. Discuss errors and possible reasons. The expected length of the Discussion is between half and one full page using 12 font size with 1.5 line space (200-400 words). (2 marks).
Sample Calculations should be included in an Appendix, attached to the end. Only this part can be hand-written neatly (2 marks).
Procedure to operate the GUNT machine:
Turn on the computer and login by using your Swinburne student ID and password.
Click “Start” → “Programs” → “G.U.N.T” → “WP 3×0”.
Please select your language: English.
On the WP 300 Universal Material Tester interface, choose “Bending Test” (middle bottom icon).
Turn the handle (on the machine) clockwise to move the test bar up till it almost touches the indenter.
Apply a preload 0.1 kN. Then on the computer, click “Tare” to zero the force and deflection.
Click “File” → “New Series”, in the popup window, please type in the name of your file, then click“OK”.
Click the Spanner icon , on the menu, type in the parameters of your bars.
Click for continuous record.
Turn the handle clockwise to apply a load up to the value calculated (P on Page 1).
Click to stop recording.
Turn the handle anticlockwise to unload and move the test bar down.
Click “View” → “Table”, then read and write down the final force and deflection values (the second last row in the file).
Click “View” → “Force Bending Diagram”.
Change one of the mobile support to 200 mm, repeat Steps 5-13 to apply an non-symmetrical load to the test bar. In this case, the distance between the two supports or the effective length of the bar is 200/2+300/2=250 mm.
Remove the load and switch off the computer.
For this laboratory experiment the values for the experimental and theoretical deflections where almost identical, with an error percentage of only 0.67%.
Error in such an experiment is expected as there are a number of external factors that may influence both the experimental and the theoretical values. Human error can occur when manual measurements of the test piece are recorded. If the person is not careful when using the Vernier, values can be slightly inaccurate and therefor throw off the calculations. If the operator takes the force readings from the mechanical gauge on the bending devise and not the value indicated by the software, then the results may also become inaccurate.
The sample specimen used in this experiment could also lead to errors if it has gone through some plastic deformation through its time of use. This could have been cause by non-careful handling or exerting too much force on it in the bending machine.
The machine itself could also be a cause of error. If the machine has been misused or has not been calibrated through its time of use, then the results may end up becoming skewed.
The experimental and theoretical deflections of the solid steel beam subjected to three-point bending have been successfully extracted. This experiment was very effective in enhancing the operators’ understanding of how defection changes when the location of the force along the vertical axis being exerted on the test piece is changed.
6 of 6708
Turn the h