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  • Strains in a thin cylinder under internal pressure
  • Cylinder with strain gauge application as vessel
  • Uniaxial or biaxial stress state represented in the experiment
  • Determination of axial and circumferential stress from measured strains


Technical Description

The findings obtained from the experiments using FL 130 demonstrate the calculation and design methods for pipes and pressure vessels commonly applied in practice. The principal stresses are key variables in calculating and designing steam tanks, pressure vessels and pipes.

The stresses and strains occurring in a vessel are not measured directly, but are determined by measuring the strains on the surface using strain gauges.

The FL 130 experimental unit is used to investigate stresses and strains in a thin-walled cylinder subjected to internal pressure. The oil-filled cylinder is closed at one end and a movable piston at the other end. This conveniently permits the unit to be either open or closed ended. A handwheel with a threaded spindle is used to move the piston. Two load cases are represented: biaxial stress state of a closed cylinder, such as a boiler tank, and uniaxial stress state of an open vessel, such as a pipe.

Internal pressure is generated inside the cylinder by a hydraulic cylinder and a hydraulic pump. A pressure gauge indicates the internal pressure. Strain gauges are attached to the surface of the cylinder to record the strains. The measuring amplifier FL 151 gives a direct readout of the measured strains. To assist and visualise evaluation of the experiment, the measurement data can be imported into the application software.

Mohr’s Circle for stress and strain analysis is used to represent the conversion of the strain graphically and determine the principal strains.

The principal stresses are calculated from the principal strains by applying the appropriate equations of elasticity.

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments

- measurement of strain using strain gauges
- application of Mohr’s Circle for stress and strain analysis, determination of the principal strains
- determination of the principal stresses: Axial and circumferential stresses in magnitude and direction
  * on an open vessel (pipe)
  * on a closed vessel (boiler tank)
- comparison of open / closed vessels
- determination of the Poissons ratio
- investigation of correlations between strain, pressure and stress in the plane biaxial stress state


[1] investigation of the stresses and strains in a thin-walled cylinder under internal pressure
[2] cylinder usable as open pipe or as closed tank
[3] strain gauge application on cylinder surface at various angles
[4] hydraulic cylinder with hydraulic pump to generate pressure
[5] hermetically sealed hydraulic system, maintenance-free 
[6] multi-pin connector for measuring amplifier FL 151 provided 

Technical Data
Aluminium cylinder
- length: 400mm
- diameter: d=75mm
- wall thickness: 2,8mm
- internal pressure: max. 3,5N/mm² (35bar)
Strain gauge application
- 5 strain gauges: half-bridges, 350 Ohm
- angle to vessel axis: 0°, 30°, 45°, 60°, 90°
- gauge factor: 2,00 +/-1%
- supply voltage: 10V
Pressure gauge
- 0...40bar, accuracy: class 1,0

Dimensions and Weight
LxWxH: 700x350x350mm
Weight: approx. 21kg

Scope of Delivery
1 experimental unit
1 set of instructional material

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