Hydrostatic Analyses for Rotational Tanks

How does the shell respond when the tank is full or in motion? We verify deflection, stress, and long-term (creep) effects by simulation.

Von Mises map at full fill level

1) Vertical Tanks

During fill/empty cycles, we validate deflection/stress at the base perimeter, manhole/neck regions and across the shell; long-term creep is included.

5000 L vertical tank — hydrostatic displacement + results table

Example Long-Term (Creep) Curve — 12 Months

ulong(t, T) ≈ u0(T) × kc(t, T)  —  base (instant) values: u0(23 °C)=4.8 mm; u0(40 °C)=6.4 mm

Time kc (23 °C) u (23 °C) kc (40 °C) u (40 °C)
1 month 1.20 5.8 mm 1.40 9.0 mm
3 months 1.35 6.5 mm 1.70 10.9 mm
6 months 1.50 7.2 mm 1.95 12.5 mm
12 months 1.60 7.7 mm 2.20 14.1 mm
Long-term creep: δ(t) — 12 months

2) Horizontal Tanks

Under fill, the shell bends along the major axis; local crushing and shape change can occur at the foot supports. Loss of roundness at the neck (ovalization) is critical for the cap. These areas are checked, with targeted redesign recommendations. Example below focuses on these regions. The long-term (creep) approach/assumptions are the same as for vertical tanks.

Horizontal polyethylene tank — hydrostatic displacement + results table

3) Agricultural Sprayer Tanks

Design and analysis must proceed in sync: at partial fill, braking/cornering/bumps cause sloshing and raise lateral loads, especially at attachment points. Analysis accounts for temperature-dependent E(T) of LLDPE, long-term behavior via k₍c₎(t, T), and thermal expansion (α). Realistic boundary conditions include chassis/foot contacts, clamps and fasteners with adequate contact and stiffness representations.

Sprayer tank — hydrostatic displacement + results table

Equivalent Static Acceleration — Quick Envelope

Lateral acceleration: a = √(aₓ² + aᵧ²)  —  slope: φ = arctan(a/g)  —  effective gravity: geff = √(g² + a²)

Vehicle axes: x = longitudinal (brake/accel), y = lateral (cornering), z = vertical.

Scenario a/g φ (°) geff/g
Nominal brake/turn 0.20 11.3 1.02
Aggressive brake/turn 0.30 16.7 1.04
Conservative worst-case 0.40 21.8 1.08
Validation — high 0.50 26.6 1.12
Equivalent static acceleration: φ and geff/g — design envelope 0.2–0.4g (optional check at 0.5g).

Scope & Deliverables

What We Test

  • Behavior under fill: p = ρ·g·h, level scenarios
  • Support effects: flat base · foot spacing/placement
  • Critical areas: manhole, neck/boss, corners and rib roots
  • On-vehicle tanks: equivalent static approach for accelerations
  • Long-term creep (optional scenarios)

Our Deliverables

  • Color maps: deflection (mm), von Mises (MPa)
  • Close-ups on critical details and comparisons
  • Tables: H–pmax–δmax–σvM,max–SF
  • 1-page executive summary + marked notes on CAD
  • Design recommendations: wall thickness, ribs, local geometry; and, when required, metal frame/support proposals

Frequently Asked Questions

It shows—backed by hard data—where the tank is weak when full, how much it deflects, and which details need reinforcement. You approach the right design early and cut needless prototyping/revisions.

We run design and engineering in one stream: turn your requirement set into a 3D model (CAD), validate with simulations and optimize for production. We apply the same analysis/improvement framework to existing designs.

For analysis-only requests, the minimum information is:

  • CAD: STEP/Parasolid + nominal wall thickness and critical details.
  • Capacity & fill: liters + min/max level.
  • Liquid: type/mix, specific gravity (SG/ρ), temperature range; any chemical notes.
  • Material specs: we derive the parameter set for your loading/conditions and send a short request list.
  • Support & restraints: flat base / saddle-feet (spacing) / strap locations; stationary or on-vehicle?
  • Targets/Limits: safety factor, weight/cost priorities, and any standards/specs.

Color maps of deflection and stress, close-ups of critical regions, a brief executive summary, and concrete design/reinforcement items:
  • Design improvements: corner/edge transitions, holes and attachment regions, local geometry optimizations (w.r.t. stress/deflection).
  • Wall thickness: global distribution + local thickening where needed.
  • Ribs: location, spacing and sizing (with corner radii/flow considerations).
  • Metal frame/supports: when needed, feasible frame/plate suggestions and compatible attachment points.
  • Manufacturing impact: weight/cost, demolding, venting and process notes.
If requested, we can apply the revisions directly to the CAD data.

We assess it via an application-specific equivalent static acceleration framework (fill ratio, acceleration directions and transport conditions). Outputs include deflection/stress maps plus the influence of foot spacing and attachment locations. Design suggestions on sections and mass distribution are added where relevant. For special cases, limited transient analysis can be performed.

Creep is the slow, time-dependent deformation common in polyethylene. We can include long-duration scenarios to estimate sagging tendency over months, supporting safer decisions on thickness and ribs.

Pressurized/vacuum service requires a separate assessment.

They depend on model complexity, number of scenarios (e.g., fill levels, support types), and requested extras. We clarify scope in a short call and send a timeline & quote.

Preferably STEP or Parasolid; IGES if needed. If CAD is not available, we can build a quick model from a dimensioned sketch and photos.

Yes. We mark revisions on CAD and, if needed, deliver practical proposals on mold/rib/support layout.

The following standards/docs help frame the scope and provide benchmarks. This page is not a verbatim application guide for them.

Note: Standards are copyrighted; access/purchase through their organizations.

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