ST141 · Thin-Walled Cylinder

Experimental apparatus for stress and strain analysis on a thin-walled cylinder under internal pressure

An oil-filled aluminium cylinder fitted with surface strain gauges at five angular positions is pressurised by a hand-operated hydraulic pump while the student switches, with a single hand-wheel, between open-end (uniaxial) and closed-end (biaxial) boundary conditions. The apparatus makes the classical vessel equations

\sigma_t = \tfrac{pD}{2t}

and

\sigma_a = \tfrac{pD}{4t}

directly measurable and lets the student build Mohr's circle from experimental data.

Experiments

Measurement of surface strains with electrical-resistance strain gauges
Application of Mohr's circle to determine the principal strains
Determination of the principal stresses — axial and circumferential — in an open vessel (pipe) and in a closed vessel (boiler)
Comparison of open vs. closed vessels — uniaxial vs. biaxial stress state
Determination of Poisson's ratio
Determination of Young's modulus from the pressure–strain slope
Investigation of the relations between strains, pressure and stresses in a plane biaxial stress state

Cylinder

Material aluminium alloy

Length 400 mm

Outer diameter Ø 75 mm

Wall thickness 2.8 mm

End conditions open (pipe) and closed (boiler), selectable with hand-wheel

Strain gauge array

Gauges 5 × half-bridge, 350 Ω

Angular positions 0°, 30°, 45°, 60°, 90° to the cylinder axis

Gauge factor 2.00 ± 1 %

Excitation 10 V bridge supply

Pressurisation

Hydraulic pump hand-operated, sealed oil circuit (maintenance-free)

Max pressure 35 bar (3.5 N/mm²)

Manometer 0…40 bar, class 1.0

Delivery

Experimental unit on baseplate with hand-wheel and hand-pump
Instrumented cylinder with five strain gauges
Manometer, connecting leads, instruction manual

21 kg