The object of the experiment is to measure the bar forces in a single plane truss subjected to a single external force. The SE 110.21 experimental set-up features bars with special snap-lock closures on their ends allowing them to be fixed easily into the node disc. The range of different bar lengths provided permits three forms of truss to be constructed. The bars are hinged, joined together by node discs, and are subjected only to compressive or tensile stress. No moments are transmitted in the nodes; they can be regarded as frictionless. Consequently, our trusses can be considered as ideal trusses. A load application device attached to a node disc generates an external force. All the forces on the truss bars are recorded by means of strain gauges.
Computerised evaluation is provided by measurement amplifier FL 151 (16 input channels). If there are more than 16 measuring points, the measurement amplifier can be extended by a measuring point add-on unit (FL 151.01) to 32 input channels. The software is used to manage the measurement data and provide graphical representation of the bar forces. The software features a comprehensive help function.
The various elements of the experiment are clearly laid-out and housed
securely in a storage system. The complete experimental set-up is arranged in the frame SE 112. The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.
Learning Objectives / Experiments
- Measurement of the bar forces in various single
plane trusses - Dependency on the external force * magnitude * direction * point of application - Comparison of measurement results with
mathematical methods * method of joints * Ritter’s method of sections
- Basic principle: measurement of forces using
* Measurement of the bar forces in a single plane
truss1 * Construction of various truss forms1 * Bars with strain gauge full bridges to measure
bar force1 * Computerised evaluation of experiments
 Investigation of bar forces in a statically determinate truss  Construction of various trusses possible  2 supports with node discs  Load application device with force gauge mountable on different node discs  Strain gauge to measure force on each bar  Measurement amplifier FL 151 required  Software to evaluate measurement data  Storage system to house the components  Experimental set-up in frame SE 112
Bars: 19 - 2 bars 150mm - 5 bars 259mm - 7 bars 300mm - 1 bar 397mm - 3 bars 424mm - 1 bar 520mm - angle between bars: 30°, 45°, 60°, 90° - maximum bar force: 500N - strain gauge on each bar - height of truss max. 450mm - length of truss max. 900mm Load application device
- graduations: 10N
Dimensions and Weight
Weight: approx. 14 kg
Scope of Delivery
1 set of bars 5 node discs 2 supports with node disc 1 load application device 1 set of cables 1 storage system 1 software CD 1 set of instructional material