DESCRIPTION

Technical Description

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 setup 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 measuring amplifier FL 151 (16 input channels). If there are more than 16 measuring points, the measuring amplifier can be extended by a measuring point add-on unit (FL 151.01) to 32 input channels. The software in FL 151 is used to manage the measurement data and provide graphical representation of the bar forces. The software features a comprehensive help function.

All the component elements of the experiment are clearly laid-out and housed securely in a storage system. The complete experimental setup  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 strain gauges