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WP 120 Buckling Behaviour of Bars
Education / GUNT Hamburg / Engineering Mechanics and Machine Elements / Strength of Materials /

In technical mechanics, loss of stability is known as buckling. Under the effects of compressive forces, and under increasing load, the axis of the bar deflects laterally until it suddenly and violently fails (collapses), even before the fracture point is reached. The stresses in the bar often remain within the elastic range during this process.

  WP 120 investigates the buckling behaviour of bars under various influences. All relevant buckling problems are demonstrated by way of experimentation.

  For the purpose, one end of a bar is fixed or pinned, depending on the buckling case. A height-adjustable load-carrying cross-arm and a hand-operated spindle are used to apply compressive force to the bar. An axial bearing between the spindle and the bar support prevents torsional loading of the test bar. A hydraulic load cell measures the applied force and indicates it on a pressure gauge. The lateral deflection of the bar is indicated on a dial gauge.

  Experiments demonstrate various influences, such as bar lengths, materials and methods of support. A transverse load application device can be used to generate additional shear forces on the test bar.

  The experimental unit can be operated vertically or horizontally. The load gauge can be rotated 90° to adjust to the chosen option. A supplementary set extends the scope of experimentation offered by WP 120.

  The various elements of the experiment are clearly laid-out and housed securely in a storage system.


Learning Objectives / Experiments

- Investigation of buckling behaviour under the 
  influence of
  * various methods of support
  * various bar lengths
  * various materials
- Verification of the Euler Theory: Buckling on elastic 
- Determination of the modulus of elasticity for an 
  unknown material (GRP)
- Measurement of force and deflection 
- Calculation of the expected buckling force by the 
  Euler formula
- Graphical evaluation of deflection and force

With supplementary set WP 120.01
- Investigation of buckling behaviour under the 
  influence of
  * various cross-sectional shapes
  * eccentric application of force
  * additional transverse loading


[1] Investigation and testing of all relevant buckling cases
[2] Verification of the Euler Theory of buckling
[3] Experiments in horizontal or vertical orientation
[4] Test bars in various lengths and materials
[5] Test bar ends pinned or fixed
[6] Spindle to apply forces
[7] Transverse load application device generates shear forces
[8] Force measurement using a hydraulic load cell
[9] Measurement of lateral deflection by dial gauge
[10] Additional experiments with supplementary set WP 120.01

[11] Storage system to house the components

Technical Data
Test bars
- quantity: 11
- bar length: 350...700mm (max.)
- materials: aluminium, copper, brass, steel
Load application spindle
- force: max. 2000N
- stroke: max. 10mm
Lateral deflection: max. 20mm
Specimen holder bore: d=20mm
Measuring ranges
- force: 0...2500N, graduations: 50N
- deflection: 0...20mm, graduations: 0.01mm
Set of weights for transverse load: max. 20N
- 3x 5N, 1x 5N (hanger) 
Dimensions and Weight
l x w x h: 620 x 450 x 1,150 mm
Weight: approx. 63 kg
Scope of Delivery
1 experimental unit
11 test bars
1 dial gauge with bracket
1 storage system
1 set of instructional material
Order Details
020.12000  WP 120  Buckling Behaviour of Bars