Brands
Vishay Measurements Group
Educational Program
Experiments in Mechanics
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| Experiments in Mechanics - Strain Gage Series are
six complete experiments designed by C.C. Perry around
the simple cantilever beam. (They are intended to teach
mechanics, using experimental stress analysis
technology as the teaching medium.) Presented in a
logical, easy-to-follow format on 8-1/2 x 11 in (216 x
279 mm) pages, each experiment will yield consistently
accurate and meaningful results when the instructions
are carefully followed. Necessary supplemental
information such as wiring diagrams, work sheets,
graphs, and illustrations is included. Additionally, a
list of the learning opportunities embodied in the
experiment, as well as sources of errors and estimates
of time required to perform the experiment, are
contained in separate "Notes to the
Instructor" provided with each set of experiments.
Experiments in Mechanics are complete exercises requiring a minimum of preparation time for the instructor. The experiments employ conventional strain gage technology and are coordinated with the Cantilever Beams. Experiments in Mechanics are available separately or in complete sets. Additionally, they are included with the Pregaged Beams (B-101 through B-106). |
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Experiment E-101
With a single strain gage mounted along the axis and
near the fixed end of a cantilever beam, the student
determines modulus of elasticity of the beam material
by:
Modulus of Elasticity - Flexure Designed for use with Pregaged Beam B-101.
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Experiment E-102
In this experiment, two strain gages are used, one
along the axis on the upper surface of the beam, and
one transversely oriented at the same section on the
lower surface on the beam. After applying an arbitrary
displacement or load to the beam, the two strains are
measured, and the Poisson's ratio of the beam
material is calculated from these data.
Poisson's Ratio - Flexure Designed for use with Pregaged Beam B-102. |
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Experiment E-103
A three-element strain gage rosette is mounted on a
cantilever beam for this experiment. The rosette is
oriented so that none of the element axes coincide with
the axes of symmetry of the beam.
Principal Strains and Stresses - Flexure Designed for use with Pregaged Beam B-103. After applying a known load to the beam, the student measures the strains along the three rosette axes and calculates the principal strains from the strain transformation relationships. Using the biaxial Hooke's law, the student calculates the principal stresses from the principal strains. These results are compared with the stress calculated from the flexure equations for the known load and measured beam dimensions. |
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Experiment E-104
A cantilever beam with a hole through the thickness of
the beam, on the centerline, is used in this
experiment. Three very small strain gages are mounted
at varying distances from the edge of the hole to
permit measuring the local increase in strain due to
the presence of the hole. The student is shown how to
extrapolate the strain data to the edge of the hole,
and compare the result to the nominal strain at the
same section to obtain a measure of the strain (or
stress) concentration factor.
Stress and Strain Concentration Designed for use with Pregaged Beam B-104. |
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Experiment E-105
This experiment provides a practical demonstration of
the relationship between the vertical shear force and
bending moment distributions in a beam. It exploits the
fact that the derivative (slope) of the bending moment
distribution is equal to the vertical shear force.
Cantilever Flexure Designed for use with Pregaged Beam B-105. The student is shown how to measure the slope of the moment distribution with two strain gages mounted at different points along the beam axis and connected to the strain indicator in a half-bridge arrangement. The output of the strain indicator is then directly proportional to the vertical shear force. This technique can be used to make a load or force transducer for which the output is independent of the point of load application, as long as it is not between the two strain gages.
Experiment E-106
The constant stress beam is employed in this experiment
as a vehicle for teaching the relationships among
bending moment, section modulus, and stress or strain
in a beam while, at the same time, introducing the
student to the concept of efficient beam design.Constant Stress Beams Designed for use with Pregaged Beam B-106. |
