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WP 120 Buckling behaviour of bars



  • Investigation of  all relevant buckling problems
  • Verification of the Euler Theory of buckling
  • Methods of force and deflection measurement
  • Supplementary set for experiments with eccentric application of force and transverse loading
  • Comprehensive instructional material


Technical Description

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, cross-sections
  * various materials
- verification of the Euler Theory: buckling on elastic bars
- 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, GRP
- cross-sections: 10x4mm, 25x6mm, 25x10mm
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 loads for transverse load: max. 20N
- 3x 5N, 1x 5N (hanger) 

Dimensions and Weight

LxWxH: 620x450x1150mm
Weight: approx. 63kg
LxWxH: 1170x480x178mm (storage system)
Weight: approx. 12kg (storage system)

Scope of Delivery
1 experimental unit
11 test bars
1 dial gauge with bracket
1 storage system with foam inlay 
1 set of instructional material

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