Stress and strain analysis on a membrane (FL 120)

Stress and strain analysis on a membrane (FL 120)

deflection and strain of a membrane under compressive load



  • In experimental stress and strain analysis, strain gauges are used to determine stresses and strains in components and structures.
  • The maximum stresses and strains are key variables in terms of its structure, and ultimately dictate the dimensions of a component.
  • Strain gauges provide the means required to evaluate mechanical stress and strains.
  • The FL 120experimental unit can be used to measure the deflection and strain of a disk under different compressive loads.
  • For this purpose, a thin disk, also called a membrane or diaphragm, is clamped into place and subjected to pressure.
  • A cylinder with a hand-operated piston generates pressure in a maintenance-free hydraulic system.
  • This pressure is indicated on a manometer.
  • Strains on the surface of the membrane are recorded by strain gauges.
  • The layout of the strain gauges at optimally selected points provides a comprehensive view of the stresses and strains over the entire disk.
  • The maximum stresses and strains are calculated by applying the law of elasticity.
  • The strain gauge measurements are recorded and displayed by means of the FL 152measuring amplifier.
  • The measured values can be imported into the application software for visualisation to evaluate the experiment.
  • At the same time, the deflection of the membrane is measured by a dial gauge.
  • The dial gauge can be moved along a cross-member, enabling measurements to be taken at any radius.

Technical Details:


  • investigate the deflection and strain of a thin disk under compressive load
  • strain gauges measure in the radial and tangential direction
  • strain gauge configured as half-bridge
  • possible to measure the deflection at any radius
  • measure the deflection via adjustable dial gauge, scale indicates position along the radius
  • hermetically sealed hydraulic system, maintenance-free, for generating the compressive load
  • hydraulic system with hydraulic pump and manometer
  • FL 152 measuring amplifier required
  • software for analysing measured values in FL 152

Technical Data:

  • Aluminium disk:
    • outer diameter: Ø 230mm
    • diameter used in the experiment: Ø 200mm
    • thickness: 3mm
  • Strain gauge application:
    • 8 strain gauges: half-bridges, 350 Ohm
    • gauge factor: 2,00 ±1%
    • power supply: 10V
  • Dial gauge:
    • 0…20mm
    • graduation: 0,01mm
  • Manometer:
    • 0…1bar
    • accuracy: class 1,0
  • System pressure:
    • 0,6bar

Dimensions & Weight:

  • L x W x H: 700x350x350mm
  • Weight: approx. 25kg

Learning Objections/Experiments:

  • measure radial and tangential strain using strain gauges
  • measure deflection using a dial gauge
  • calculate the stresses from the measured strains: radial stress, tangential stress
  • determine direction of principal stress
  • application of Mohr’s strain circle to determine the principal strains
  • fundamental principle: using strain gauge technology to measure strains

Scope of Delivery:

  • 1 experimental unit
  • 1 set of instructional material


  • membrane with strain gauge application
  • determine radial and tangential stress profiles from measured strains


  • Required: FL 152 multi-channel measuring amplifier
  • Optional: WP 300.09 Laboratory trolley


Due to the continuous development of our products, the goods supplied may vary in detail to that illustrated on this Website.