Hydraulic Cylinder Rod Buckling Calculator

Inputs

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Use theoretical full-bore push force from pressure, or enter the compressive rod load directly.
Piston diameter used with pressure to estimate theoretical push force.
mm
Working pressure at the cylinder. The first-pass compression load is P times full bore area.
bar
Solid piston rod diameter. I = pi*d^4/64 and A = pi*d^2/4.
mm
Unbraced rod length in compression, often near the extended stroke plus exposed rod geometry.
mm
Idealized effective-length factor K for the rod mounting and guidance.
Rod material elastic modulus. Carbon steel is about 200 GPa.
GPa
Axial yield screen for stocky rods where material yield can control before Euler buckling.
MPa
Multiplier applied to the base compression load before capacity comparison.
Required capacity divided by design compression load. The utilization output includes this target.

Results

Default result
Edit inputs
Actual safety factor(SF_actual)
2.312
Pass

Meets the entered 2:1 target.

Governing load divided by design compression load.

Also computed

Target utilization(U_target)Pass0.865

At or below target utilization.

Design load times target SF divided by governing load.

Governing rod capacity(P_gov)Pass90,790N

90.79 kN · 20,410 lbf

Euler buckling controls.

Design compression load(P_design)39,270N

39.27 kN · 8,828 lbf

Base load times load factor 1.25.

Euler buckling load(Pcr)90,790N

90.79 kN · 20,410 lbf

Pinned - pinned / clevis ends (K = 1.0) gives K = 1.

Rod yield load(P_yield)133,000N

133 kN · 29,910 lbf

Rod yield strength times solid rod area.

Max unsupported length(L_max)537.6mm

Buckling length limit at 2:1 target safety factor.

Length that meets the entered target safety factor for buckling.

Method notes 4 notes
  • Euler rod buckling uses Pcr = pi^2*E*I/(K*L)^2 with a solid round rod I = pi*d^4/64.
  • Rod yield load is Sy*A. The governing capacity is the smaller of Euler buckling load and yield load.
  • Hydraulic-push mode uses theoretical full-bore push force before mechanical friction or load-control losses; enter a known compression load when the machine load is lower than theoretical cylinder force.
  • End fixity, side load, eccentricity, initial rod straightness, gland/bearing support, mounting geometry, shock loads, tube/rod ratings and manufacturer column charts still need separate review.

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