Investigation of Simple Stability Problem :
Investigation of Simple Stability Problem
Buckling is a stability problem which
occurs in practice when slim components are subjected to compressive
loading. Following a “disturbance” to its equilibrium, such as caused by
compressive loading, a stable system returns to equilibrium when the
loading is removed. If the compressive load increases excessively,
instability of the system results. The component buckles and fails. The
critical compressive load at which the system becomes unstable is termed
the buckling force. A simple model for representing stability problems
is a twopart bar with an elastic joint which remains stable up to a
certain load level. If the buckling force is exceeded, the bar suddenly
buckles and so becomes unstable. This is
used to investigate simple stability problems on a buckling bar under
different conditions. The buckling bar is in two parts, with a central
articulated joint. A compressive load is applied to the bar by a lever
and weights. The infinitely variable loading is determined precisely
with the aid of a scale on the load application lever. Experiments
can depict a variety of conditions, such as an elastic joint or an
elastic clamp fixing. Two tension springs serve as the elastic joint.
For the elastic clamp fixing option, a steel leaf spring is mounted in
the bottom joint. The variable length of the leaf spring means various
degrees of clamping are possible. The two cases can be combined. Another
experiment demonstrates the influence of additional shear forces. It
involves applying a shear force to the joint in the buckling bar with a
cable and a weight. In all experiments the buckling bar is placed under
load until it reaches an unstable situation. The length of the lever arm
at which the buckling bar buckles is read from the scale and the
buckling force is then determined. The various elements of the
experiment are clearly laidout and housed securely in a storage system.
The complete experimental setup is arranged in the frame.The
wellstructured instructional material sets out the fundamentals and
provides a stepbystep guide through the experiments.
Specification:
1. Investigation of the buckling load under different conditions (elastic joint, elastic fixed end)
2. Twopart buckling bar with central joint
3. Loading infinitely variable with lever and set of weights
4. Determination of loading via scale on load application lever
5. Various degrees of clamping via leaf spring with variable length on bottom support
6. Thrust pad guided frictionfree inside spherical shell
7. Lowfriction joints with roller bearings
8. Device to generate shear forces
9. Storage system to house the components
10 Experimental setup in frame.
Technical Data:
Twopart buckling bar with central joint
 WxH: 20x20mm
 length: 2x250mm
 support: pinnedpinned (articulatedarticulated)
Elastic joint
 2 tension springs, rigidity: 2N/mm
 lever arm: 50mm
Elastic clamp fixing with steel leaf spring
 length: 500mm
 crosssection: 10x2mm
 2^{nd} moment of area: 6,66mm^{4}
 modulus of elasticity: 205000N/mm^{2}
Compressive force range: 25…120N
Shear force: 0…20N
Load application lever, lever ratio: 1:2 – 1:5
Set of weights
 8x 1N
 6x 5N
 2x 1N (hangers)
