UEMF-2API- EEMGC year: 2024/2025
Practical work of structural mechanics RDM
Experience 1: Simple bending test
Objective: This analysis aims to investigate stresses and deformations, as well as their distribution
among different materials, including steel and wood, to improve the design of beams that experience
bending.
Materials and methods:
The bending device is composed of:
A universal beam bending bench, positioned horizontally.
-A beam supported by two load cells (simple supports);
Weights suspended using weight hooks.
A sliding digital device comparator, utilized for measuring the displacements.
Note: The measurements are obtained from the digital load cell comparator (1 mm = 10 N).
Fig.1 Bending test device
1. Select an undeformed beam.
2. Position the load cell (support) and confirm that they are securely locked in place.
3. Install the beam into the supports.
4. Verify the alignment by using the dial gauge to ensure the beam is completely straight and level. Begin
by placing the dial gauge on the left support and resetting it to zero. Then, transfer it to the second support
1
and check that the reading remains at zero. If it does not, adjust the height of the load cell blade edges
until it reads zero.
5. Suspend the weight hook at choosing positions.
6. . Unlock the edges of the load cell blade.
7. Reset the load cell indicators to zero.
8. Place the loads onto the weight hooks.
9. Lightly tap the device and observe the values shown on the display.
Questions:
1. Fill in the following table for each position (take 3 positions):
2. Comment on the results
3. For each position of the load, determine the maximum bending moment in the beam
4. .At what position of the load is the bending moment maximum? Justify.
Fig.2 Practical diagram of the beam
With:
b a
RA = F and RB = F
L L
Table 1. Positions 1: a=…., and b=……
Load F (N) experimental theoretical
RA RB RA RB ∆ RA ∆ RB
Load 1=
Load 2=
Load 3=
Load 4=
2
Beam modeling using RDM 6 software:
Objectives: To illustrate the internal forces, including bending moments, shear forces, and deformations.
Additionally, this software compares the numerical results collected from RDM6 with those obtained
from the analytical calculations based on theoretical principles.
Step-by-Step Tasks for using RDM6:
1. Create the beam model :
Total length L (the same as in the experimental setup).
Supports: simple support on left and right.
2. Apply the load at different positions
3. Display results:
Reaction forces at supports RA and RB.
Bending moment diagram
Bending deflection (deformed shape)
Questions:
1. Compare the numerical results to your theoretical values.
2. Write a short conclusion on the consistency between theoretical and numerical approaches
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UEMF- EEMGC
Niveau: 1ACI GC Travaux pratiques RDM II Année: 2024-2025
Experience 2: Tensile test
Objectif: The tensile test involves applying a gradually increasing normal force to a standardized specimen, which
is either cylindrical or prismatic in shape and made from the material under examination, until the fracture occurs.
Materials and methods:
The test is conducted using a tensile testing machine, which gradually applies a tensile force that
increases from 0 to F on a specimen securely positioned between the hydraulic machine's ribs. The
vertical hydraulic testing machine is made up of several components (see Fig.3):
A frame that includes a base with a structure formed by two or four columns and an upper
crosspiece that supports a low-friction hydraulic cylinder.
A movable frame that operates without friction within the fixed frame, driven by the piston of the
hydraulic cylinder. The upward motion of this frame generates the tensile force.
A pressure generation unit that features a positive displacement pump.
A force measurement device associated with the cylinder, which generally consists of a measuring
line that is distinct from the supply line to account for pressure loss due to fluid flow, as well as a
manometric mechanism.
A device for measuring the axial deformation of a tensile specimen, consisting of an extensometer,
is utilized to directly measure the displacement on the effective portion of the specimen.
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Fig.3 Tensile test device
The test consists of loading a specimen of a given material with a tensile force, measuring the elongation of the
specimen for each force value.
1. Measure the dimensions of the specimen.
2. Mount the specimen between the lower and upper yoke of the bench using the two fixing pins.
3. Place the two strain measurement comparators in contact with the two yokes and reset them to zero.
4. Load the specimen and record the longitudinal strains.
Questions:
1. On the traction machine, measure the displacements in relation to the F(ΔL).
2. Calculate stress and strain ε for each point on the curve.
3. Plot the curves F(ΔL) and σ(ε).
4. Verify Hooke's law (To what extent is Hooke's Law no longer valid)?
5. determine the yield point, and the ultimate stress from the curve.
6. Calculate Young's modulus E, 0.2% yield strength, resilience modulus.
7. compare the obtained value with those in the literature.
8. Analyze the σ(ε) curve and identify the various regions of the curve.
points 1 2 3 4 5 6
F(N)
ΔL (mm)
σ (MPa)
ε
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Modeling in RDM6 :
Objectives:
Model a uniaxial tensile test in RDM6
Visualize stress distribution and deformation.
Compare simulation results with theoretical calculations.
Step-by-Step Tasks for using RDM6:
1. Create a straight bar with: Length L (the same used in the experimental setup), Cross-section: e.g., circular
or rectangular.
2. Boundary conditions:
Left end: Fixed (encasement)
Right end: Apply an axial force (F=1000N for example)
3. Observe simulation results :
Display and analyze: Stress distribution (σ), displacement or elongation ΔL, deformed shape of the bar (Optionally:
reaction forces, diagrams).
Questions:
1. What is the elongation ΔL displayed by RDM6?
F.L
2. Calculate the theoretical elongation using the formula: ΔL = and compare this value with
E.S
the one obtained from RDM6.
3. What is the maximum stress value? Is it uniform across the bar ?
4. Does the simulation confirm Hooke’s law (linear relationship between stress and strain)?
With: F the applied force, L initial length, E Young’s modulus, and S cross-sectional area.
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Experience 3: Torsion test
