What is Skalnav?

Skalnav is the verification and decision platform for thin-walled structures — mechanistic buckling knockdown factors, curated experimental evidence, and audit-ready reports in one place.

The Problem

Shell buckling design still runs on 1960s assumptions.

Most structural teams face the same tradeoff: accept conservative empirical factors and carry unnecessary mass, or run expensive nonlinear FE campaigns for every design iteration. Neither approach gives you full visibility into the margin you're working with.

Empirical knockdown factors

NASA SP-8007 ties the knockdown factor to R/t alone — independent of length, imperfection amplitude and fabrication quality. It is a deliberately safe lower bound through 1960s test data; on a well-made modern shell, that safety margin is carried as structural mass.

Expensive nonlinear workflows

Running GNIA/GMNIA analyses for every candidate geometry is thorough but slow. Weeks per iteration, high FE expertise required, limited parameter exploration. The design space stays narrow because exploration is costly.

Opaque design margins

When different standards give different allowables for the same shell, which one is correct? Without a transparent, physics-based reference, teams default to the most conservative answer. The margin exists, but it's invisible.

The MDC Shift

From fixed empirical factors to mechanistic, imperfection-sensitive predictions.

Skalnav computes knockdown factors as a function of geometry (Batdorf Z) and imperfection amplitude (w/t). The result is a transparent, traceable design basis that works across standards — and recovers the structural margin that empirical methods leave behind.

Traditional approach

Single empirical KDF per geometry class
Imperfection sensitivity ignored or assumed
One standard at a time, manual comparison
Nonlinear FE required for margin visibility
Conservative by default, no transparency into how much
Days to weeks per design iteration

→

With Skalnav

KDF varies with geometry, imperfection, and fabrication class
Imperfection sensitivity is a parameter, not an assumption
9 standards computed simultaneously, side by side
Analytical pre-design narrows the FE campaign before it starts
Recoverable margin is quantified and traceable
Seconds per load case, full parameter exploration

H. N. R. Wagner, C. Hühne, R. Khakimova, S. Niemann, M. Wang, J. Zhang.
“Structured chaos: redefining the design of buckling-critical cylindrical shells.”
Proceedings of the Royal Society A, 481(2321), 2025.

How it works

From geometry to audit-ready proof — in four steps.

STEP 1

Define

Enter geometry, load case and material. Cylinder, cone, sphere or torispherical head.

STEP 2

Evaluate

Get the knockdown factor with its mechanistic basis: regime, imperfection sensitivity, Basis A/B — in seconds.

STEP 3

Compare

Check your result against nine design codes side by side, from NASA SP-8007 to EN 1993-1-6.

STEP 4

Document

Export a verification report with the full experimental evidence trail behind every number.

Method Comparison

MDC vs. NASA SP-8007 vs. GMNIA/FEM.

Three routes to a buckling proof — and what each one costs you in practice.

Criterion	MDC	NASA SP-8007	GMNIA/FEM
Time to result	Seconds	Minutes (hand calculation)	Days to weeks
Conservatism & KDF basis	Regime-dependent, mechanistically derived; conservatism quantified per curve (A/B basis selectable)	Single empirical lower-bound envelope from 1968 — safe, but blind to why	Exactly as conservative as the imperfection you assume — the result is an analyst choice
Imperfection provenance	Measured imperfection data, documented per curve	Implicit — the imperfections of the 1960s test articles, not those of your fabrication	Analyst-defined (eigenmode, dimple, scan); must be justified case by case
Validation basis	1,000+ curated experiments, cross-checked against full-scale launcher hardware where records are available	The historical test set it was fitted to; later large-scale tests (e.g. NASA SBKF) found it conservative	Per project — quality stands and falls with model and analyst
Required expertise	Design-engineer level: geometry, load case, material in — verified KDF out	Low — the cost is paid in structural mass instead	Nonlinear-FE specialist; days of modeling, meshing and imperfection studies per configuration

Demo

Skalnav in action.

70 seconds, no sound — why imperfections decide the buckling load, and what Skalnav does with them. Or open Skalnav in your browser.

Download the sample report for this barrel (PDF)

Physics Pillars

Three things the classical methods don’t tell you.

Empirical knockdown factors compress the physics into a single number. MDC keeps the three effects that actually govern shell stability visible, measurable, and traceable.

Imperfection Sensitivity

Small geometric deviations (weld distortion, out-of-roundness, dent) drive shells far below their classical buckling limit. MDC sweeps w/t continuously.

Compare amplitudes from Q=A workshop to Q=C field fabrication — see the recoverable margin at each level.

Learn more

Regime Analysis

Elastic, transition, plastic — every shell sits in one regime. MDC detects which one governs and surfaces the transition points.

No more accidentally applying an elastic formula to a plastic collapse. The governing regime is stated in every report.

Learn more

Plasticity Correction

Yielding changes the buckling response — and the interaction with the imperfection hook. MDC applies the physics-based correction, not an empirical knockdown.

Patte d’éléphant correction for combined axial + bending + internal pressure. Calibrated on the plasticity calibration subset — 400+ of the 1,000+ collapse tests.

Learn more

Industries

Built for shell buckling across industries.

Skalnav handles the structural stability problems that actually appear in real hardware — from rocket tanks to wind turbine towers.

Aerospace Wind Energy Civil Engineering Pressure Vessels

Aerospace

Launcher tanks and interstages under axial compression + bending
Imperfection-sensitive regimes handled without empirical knockdowns
Fairings, domes, and torispherical heads under combined loads

Explore aerospace →

Wind Energy

Tower-shell stability under wind + gravity
Monopile and transition-piece sizing with imperfection sensitivity
Can-to-can weld classification per EN 1993-1-6 fabrication tolerance
Fast sweep across diameter / thickness / height for offshore platforms

Explore wind energy →

Civil Engineering

Silos, chimneys, stacks, and water towers under wind + self-weight
Selected EN 1993-1-6:2025 procedures with method-specific production gates
Stability checks for tanks and containment shells
Legacy structure reassessment with modern imperfection data

Explore civil engineering →

Pressure Vessels

Cylindrical and spherical vessels under internal / external pressure
Torispherical and ellipsoidal heads with knuckle-region buckling
Ring-stiffened cylinders under external pressure
Combined pressure + axial + bending with plastic-collapse hook

Explore pressure vessels →

Validation & Trust

Every prediction is accountable to physical evidence.

MDC is not a black box. Every knockdown factor can be traced back to mechanistic models and compared against experimental collapse data. The methodology is published, the data is auditable, and the statistical basis is explicit.

1,000+

Experimental records

Curated buckling test data from 60+ years of published research. Blachut, Seaman, Kaplan-Fung, Wiggins, DNV-GL, and more. Filter by geometry, load case, author, and failure mode. Every MDC curve is overlaid against real collapse measurements — and every record is traceable to its source publication. The underlying MDC calibration programme draws on a curated database of 1,000+ independent, comparison-ready collapse tests — each backed by a deterministically reproducible FEM recomputation, with full per-campaign statistics (see the auto-generated validation report).

Peer-reviewed

Published methodology

The MDC framework is published in the Proceedings of the Royal Society A (2025). Full derivation, full author attribution. The scientific foundation is transparent and independently verifiable — not proprietary curve fitting.

A / B / Mean

Statistical basis

Results are available on A-Basis (p01: 99% survival, 95% confidence), B-Basis (p10: 90% survival), and Mean. Choose the basis that matches your certification requirement and regulatory context.

Scientific Foundation

Behind the methodology.

Skalnav is the engineering surface of more than a decade of research on shell stability. The methodology is peer-reviewed, the underlying data is traceable, and the scope is documented — built as a company, not only a research project.

Founder & Technical Lead

Dr.-Ing. Heinz Wagner

Structural engineer with 15+ years of shell-buckling research and regulated-industry validation. Doctorate awarded by TU Braunschweig (2018). Lead author of the MDC methodology paper published in Proceedings of the Royal Society A (2025). Based in Braunschweig, Germany.

Shell Buckling · Composite Manufacturing · Marketing

Dr.-Ing. Regina Wagner

Shell-buckling expertise and composite-manufacturing know-how. Technical support for product development, and social-media marketing strategy and execution.

Commercial & Operations

Sebastian Arnold

Business development, customer outreach, finance/control and operational setup.

→ Read the publication · DOI: 10.1098/rspa.2025.0196

Capabilities

Scope built for real engineering decisions.

Every feature exists because an engineer needed it to close a design trade or defend a result in a design review. Nothing is decorative.

Multi-Standard Comparison

NASA SP-8007, SP-8019, SP-8032, Eurocode 2007 & 2025, DNV RP-C202, ECSS, PD 5500, GOST 34233, and MDC — computed simultaneously on the same geometry and load case. Results side by side. No re-entry, no separate models.

Sizing & Back-Solve

Define a target load. Get the minimum compliant wall thickness across all applicable standards. Integrated with standard sheet thickness catalogues. Answers the question “how thin can I go?” in seconds.

Shell Optimizer

Minimum-mass design of tori-sphere heads under external pressure. Searches wall thickness, crown and knuckle radius against your target pressure — every candidate rated through the full MDC chain, imperfection knockdown and plasticity included.

Imperfection Sensitivity

Sweep w/t from 0 to 8 for cylinders and cones, and from 0 to 2 for spherical shells, to see how your design responds to manufacturing variability. Identify the threshold where safety margin erodes — before it becomes a test failure or a redesign.

Composite & Sandwich Shells

Classical Laminate Theory with full ABD matrix computation. Carbon, aramid, glass presets. Arbitrary stacking sequences. Smeared-thickness conversion for shell buckling. Anisotropy robustness assessment included.

Plasticity & Combined Loading

Automatic regime detection across elastic, transition, and plastic domains. Patte d’éléphant correction for combined stress states. 20+ load cases including axial, bending, torsion, external and internal pressure, and all relevant combinations.

Validation Hub

1,000+ curated experimental records. Every prediction can be compared against physical test data from published literature. Filter by campaign, geometry, material, failure mode. Discrepancies are visible, not hidden.

Audit-Ready Reports

PDF, CSV, and JSON export (HTML on the roadmap). Full traceability: inputs, intermediate values, charts, applicable standard, statistical basis, engine version, and design verdict. Structured for inclusion in design review and certification packages — formal review, acceptance, and approval remain with you and your certifying authority.

Feature Deep-Dive

The building blocks an engineer actually uses.

Each capability is exposed as an interactive workflow — not a checkbox. Click through the tabs to see what the tool does when you open it.

Validation HubPro Imperfection GuideAcademic Design Space ExplorerPro Method ComparisonAcademic

app.skalnav.com/validation

Heritage Check · 1,000+ Tests

See the shells in your neighbourhood that buckled below prediction.

For every MDC analysis, the Hub locates your design point within the 1,000+ curated collapse-test database and flags any nearby experiment that failed below the standards prediction. A non-conservative neighbour is information you cannot get anywhere else — a direct warning to revisit your margins before the design review, not after.

Read the other way, a design surrounded by well-characterised, conservative tests is a documented confidence argument for your review package: the physical record in your parameter neighbourhood, with similarity scores and measured buckling loads.

Whether that evidence supports any given approval remains the decision of the responsible authority — the Hub is supporting evidence, not a substitute for qualification testing. A single query still replaces days of literature search and gives your review package traceable, cited experimental references.

Spatial query: where your design sits in Z / R/t / K / w/t parameter space
Nearest-neighbour ranking with similarity scores and measured buckling loads
Flagging of non-conservative neighbours (experiments below standards predictions)
Direct citations to original test campaigns for inclusion in certification packages
Full CSV/JSON export of matching records or the complete database

app.skalnav.com/imperfection-guide

Imperfection Amplitude · Statistical Estimate

Know your imperfection before you measure it.

In early design, scan data for your shell does not yet exist — but Eurocode, ECSS, and DNV all require an imperfection amplitude. The Guide closes this gap: a statistically-backed w/t estimate from 172 measured shells covering lab-scale specimens through full-scale aerospace hardware (1970–2024).

Outputs include 90% B-Basis and 95% envelope, split by specimen class, with traceable citations to the original measurement campaigns. Use it to enter a defensible imperfection amplitude before the prototype is built. Provides the imperfection assumptions used in Level 1 analyses, where measured data is not yet available.

w/t estimate for your R/t and manufacturing class
90% B-Basis (regulated design) and 95% envelope (worst-case)
Power-law and linear fits with log R/t diagnostics
Split between lab-scale (149) and full-scale aerospace (23) subsets
Nearby-shell statistics within ±20% R/t
Traceable citations to original measurement campaigns

app.skalnav.com/explorer

Regime Map · Parameter Sweep · Measurement Decision

Decide what to measure — before you measure.

The Explorer shows where your shell sits in the regime map and how it moves as parameters change. R/t, L/R, imperfection amplitude, yield stress, and load combination — each slider updates the regime band and the knockdown curve in real time.

Step 1 — Imperfection sensitivity. A perfect shell (w/t = 0) sits in Regime 3 across nearly all geometries — local buckling and material yielding dominate. As imperfection amplitude grows, Regime 1 (imperfection-dominated) and Regime 2 (transition) emerge in the lower-Z range, while higher-Z geometries remain comparatively stable. The slider sweep tells you whether your design crosses into a sensitive regime as imperfections rise — and at what amplitude the crossing happens. This sets a practical threshold for fabrication tolerance.

Step 2 — Plasticity penalty. Plasticity does not affect all regimes equally. Regime 1 shells lose more capacity to yielding than Regime 3 shells. The Explorer makes this asymmetry visible in the same view, so the trade-off between regime and material strength is one decision, not several disconnected analyses.

Why this matters in design. A shell deep in Regime 3 with bounded imperfection amplitude is a Level 0 case — the analytical Skalnav result is sufficient. A shell crossing into Regime 1 or 2 is imperfection-driven; either physical measurement (Level 2) or worst-case envelope assumptions (Level 0) are needed. A shell in an unfavourable regime under any reasonable amplitude is a Level 3 candidate.

If your design lands in an unfavourable regime, the Explorer also shows the geometry levers that would shift it: a longer unsupported length raises Z, improving fabrication tolerance lowers w/t — both push toward Regime 3. Ring stiffeners go the opposite direction by lowering effective Z (shortening the unsupported field), which can be useful for local mode shaping or manufacturing constraints, but trades regime favourability for those gains. The Explorer quantifies the trade-off rather than guessing at it.

Current regime at a glance, across all active parameters
Live regime transitions as sliders move
Comparison against the perfect-shell limit
Geometry levers (length, fabrication quality, stiffeners) and their regime-shift effect
Whether the design is a Level 0, Level 1, Level 2, or Level 3 candidate

app.skalnav.com/compare

6 Standards · One Canvas · Same Axes

See which standard governs — and how much margin the others leave on the table.

Side-by-side allowable stress for NASA SP-8007, Eurocode 1993-1-6 (2007 and 2025), DNV RP-C202, ECSS-E-HB-32-24A, and MDC-B where each method supports the selected geometry and load case. Governing case is flagged. The delta between the most-conservative and the physics-based answer is the margin you can recover.

Report exports identify the selected method, edition, inputs, and calculated results.

MDC Coverage

What MDC delivers today — and what is still in development.

The MDC A-Basis and B-Basis are the statistical design allowables of the Pro tier. Released cells are validated against our test database; cells marked β are previews. Anything outside the matrix below runs through referenced third-party methods (Eurocode, NASA, DNV, ECSS, GOST) where implemented — free registration covers NASA SP-8007 and EN 1993-1-6:2007, the full set comes with the Professional plan.

Geometry	Axial Compression	Bending	Combined Bending + Compression	External Pressure
Cylinder	✓ MDC A & Bincl. plasticity & internal pressure	✓ MDC A & Bincl. plasticity & internal pressure	✓ MDC A & B	β MDC A & B — Betapreview in paid tiers · validation in progress
Cone	✓ MDC A & Bincl. plasticity & internal pressure	✓ MDC A & Bincl. plasticity & internal pressure	✓ MDC A & B	β MDC A & B — Betapreview in paid tiers · validation in progress
Sphere	—	—	—	✓ MDC A & Bincl. plasticity
Torisphere	—	—	—	✓ MDC A & Bincl. plasticity

Load cases marked β Beta are live in the paid tiers as a preview: the MDC engine runs the full calculation, but the statistical validation campaign is still being completed and individual sub-cases carry documented limitations — results are flagged accordingly in the app. Referenced third-party methods (NASA, Eurocode, DNV, ECSS, GOST) are available side by side only for their implemented geometry and load-case scopes. General availability follows with the SC2 release once the peer-reviewed methodology is published.

MDC Levels

Four levels of structural confidence.

The MDC framework defines a hierarchy of analysis depth. Each level trades effort for tighter design margin. Level 0 is delivered directly by Skalnav; Levels 1 to 3 are delivered as engineering services for programs requiring numerical analysis under MDC methodology.

0

Analytical worst-case

Direct MDC computation in the tool. No measurement, no FEM, no project setup. Returns a defensible knockdown factor on B-Basis or A-Basis statistical foundation. The right starting point for sizing trades, RFQ responses, and pre-design exploration.

Delivered by: Skalnav (Professional and above) — or as an Independent Buckling Review or Verification

1

FEM with database imperfections

Numerical analysis (your FE solver of choice) using imperfection amplitudes drawn from the MDC shell-imperfection database. Recovers margin compared to Level 0 by using realistic — rather than worst-case — fabrication assumptions. The right level for preliminary design once geometry is fixed.

Delivered by: Advanced Buckling Engineering — GMNIA scope

2

FEM with measured imperfections

Numerical analysis using physically measured imperfection data from the actual shell or a fabrication-equivalent specimen. Recovers further margin by removing statistical conservatism. The right level for verification before qualification testing or for shells already in production.

Delivered by: Advanced Buckling Engineering — measured-imperfection scope

3

FEM with regime-shifted geometry

Numerical analysis combined with geometry modification to push the shell into a more favourable regime — typically a longer unsupported length to raise Z, improving fabrication tolerance to lower w/t, or accepting Z-lowering ring stiffeners as a deliberate trade. MDC quantifies the regime shift and its KDF impact, replacing intuition with physics-based optimisation. The right level for mass-critical structures and unfavourable starting geometries.

Delivered by: Advanced Buckling Engineering — geometry-optimisation scope, with review support

Case Studies

What the margin looks like — two worked references.

Illustrative analyses prepared during the Skalnav beta program. Public case studies with named partners will follow general availability.

Two representative structures from energy and process engineering, each worked through in Skalnav — multi-standard, imperfection-aware, with the recoverable margin shown explicitly.

Wind Energy

Wind turbine tower — cylindrical section under combined loading

130 m steel tower, bending-dominated with axial from tower mass. Compared against Eurocode 1993-1-6 (2025), DNV RP-C202, and MDC A-basis. Fatigue excluded — focus on ultimate stability.

−17%steel mass vs Eurocode baseline

3methods side-by-side

illustrative

Illustrative analysis based on generic onshore wind-tower reference geometry. Not affiliated with or endorsed by any turbine or tower manufacturer.

Pressure Vessel

Torispherical head — internal & external pressure verification

ASME/PD 5500 torisphere for a 12 bar process vessel. Plastic buckling governed — not elastic. Compared against PD 5500, GOST 34233-2, Eurocode, and MDC A-basis. Crown-to-knuckle transition plastic-zone flagged automatically.

−15%wall thickness vs PD 5500

4standards side-by-side

illustrative

Illustrative analysis based on publicly-available process-vessel reference geometry. Not affiliated with or endorsed by any specific OEM.

Pricing

Priced for engineering value, not calculation count.

Every commercial licence runs the same released engineering core: the same methods, the same design bases, the same warnings. Tiers differ in how many engineers use them and how they work together — never in how the shell is analysed. Prices are per year, excl. VAT.

Software

Self-service access to Skalnav — from a no-login first look to organisation-wide licences.

Explorer

Free

No login. First look at Skalnav.

Cylinder geometry only
Axial + bending
EN 1993-1-6 (2007) + NASA SP-8007
Mean basis
Shell coverage map
No export, no saved cases

Try now

Academic

Free

Registered with an academic e-mail address. The full geometry range on mean basis — for research and teaching.

All 4 geometries
All load cases
NASA SP-8007 / 8019 / 8032, EN 1993-1-6 (2007) and the MDC method
Mean basis — no A-/B-Basis
Mission-profile envelope + implied-w/t theory
Watermarked CSV + PDF export
3 saved cases

Register free

Academic covers education, teaching and non-commercial research only. Any commercial, contract or client work — including funded industry projects — requires a Professional licence. Validation Hub, Imperfection Hub and the Imperfection Guide are Professional features. Academic accounts are granted automatically for recognised institutional e-mail domains — other addresses start on the registered Explorer tier and can request Academic via Feedback.

Professional

€9,900 / year

excl. VAT · 1 named user

For structural engineers and specialist consultants who use shell-buckling analysis as part of professional design work.

The complete released engineering core — every geometry, load case and design standard we ship, with no calculation held back from paying users
MDC A-Basis & B-Basis — probabilistic design allowables. Fully traceable: statistical basis, inputs, and engine version on every result.
Heritage Check — locate your design in the 1,000+ test database: nearest-neighbour ranking, similarity scores, non-conservative flagging
Imperfection Guide (full) — 90% B-Basis, 95% envelope, lab/full-scale subsets, source citations
Design Space Explorer and sizing workspace
Traceable references to the original test campaigns — supporting evidence for your design review, not a substitute for qualification testing
Commercial licence — results of your engineering work may be delivered to your clients. No separate client-deliverable licence.
CSV, PDF, DOCX and JSON export, no watermark
Unlimited audit-ready reports and saved cases
Worked Examples — our recalculation of the ECCS 125 reference cases
Product support by email

Evaluate Skalnav

Working on a single project?

30-Day Professional Project Access — €1,699 excl. VAT

The full Professional engineering core for one named user, for 30 days. Non-renewing — it ends by itself, with no subscription to cancel. No analysis or report limits just because the licence is short.

Upgrade without losing your project-access investment. Move to Professional Annual while your 30-day access is running and the full €1,699 is credited toward your first annual licence — €9,900 less €1,699, so €8,201 remains. Credit terms.

Request 30-Day Project Access

Team

€29,900 / year

excl. VAT · up to 5 named users

For engineering teams that want one shared basis for shell-buckling decisions.

Everything in Professional — identical engineering scope, for five engineers instead of one
Up to 5 named accounts of your organisation, including reviewers and admins
Shared organisation workspace with project sharing (read/write)
Organisation roles and audit trail
Organisation-wide MFA policy
Batch calculation (100 cases)
Full Validation Hub database export
Shell Optimizer for tori-sphere heads (full)
Priority support

Evaluate Skalnav for your team

Larger group? Business / Department — €49,900 / year (excl. VAT) covers up to ten named users on the same engineering scope. Ask for a quote.

Enterprise Design Partner

From €75,000 / year

excl. VAT · individually scoped

For departments and engineering programmes that need broader deployment, qualification or integration.

Everything in Team, across contractually agreed seats
Programme- or department-wide deployment, scoped per engagement
Limited v1 REST API — organisation token, ping and cylinder compute
Scoped custom-KDF engineering engagement
Named technical contact and an agreed onboarding package
Qualification, integration and custom engineering work under a separate statement of work

Discuss an Enterprise Design Partnership

Design Partner engagements are scoped individually, not sold as a self-service subscription. SSO/SCIM, on-premise and air-gapped deployment and a contractual uptime SLA are not currently available — where a programme requires them, they are subject to a separately scoped engagement and to feasibility review, not included in the licence.

Proof of Value

Evaluate Skalnav against a real engineering case before wider deployment.

Proof of Value

From €15,000

excl. VAT · scoped per engagement

Scope a Proof of Value

A paid, time-boxed engagement on an agreed representative shell case from your own programme — run and documented by us, so the evaluation produces a technical result your engineers can check rather than a demo.

An agreed representative shell case from your programme
Comparison against the method you use today
Method comparison across the applicable design standards
KDF and safety-margin analysis
Wall-thickness and sizing comparison
Sensitivity of the result to the governing assumptions
Engineering-workflow comparison
Documented assumptions, limitations and technical result

A Proof of Value quantifies what your current assumptions cost in margin on your case. It is an engineering investigation with a documented outcome — not a guarantee of any particular mass reduction. Extended scope from €25,000.

Skalnav Startup Program

For qualifying early-stage engineering and aerospace companies. Skalnav came out of the same ecosystem, so the programme lowers the entry cost for the first two years — it does not lower the product.

Startup Professional

€4,900 / year 1

excl. VAT · 1 named user

Year 1 — €4,900
Year 2 — €7,400
From year 3 — standard Professional pricing (€9,900)

Startup Team

€14,900 / year 1

excl. VAT · up to 5 named users

Year 1 — €14,900
Year 2 — €22,400
From year 3 — standard Team pricing (€29,900)

Eligibility

Approval required — startup pricing is granted on application, not selected at checkout.

Independent company, not a subsidiary of a larger corporate group
Generally younger than five years
Generally fewer than 100 employees
Eligibility and level of support reviewed by Skalnav

Apply for Startup Pricing

The Startup Program is temporary adoption support, not a reduced product: startup licences carry the same engineering scope, the same design bases and the same commercial rights as the corresponding standard tier. Skalnav reviews each application and decides the level of support case by case.

Engineering ServicesExpert-led

Some decisions need judgement rather than another licence: an independent review of a verification you already have, a counter-calculation, or a customer-specific method. Those are engineering engagements, priced per scope — see Engineering Services →

Licence scope: every commercial licence — Professional, Team, Business / Department and Enterprise Design Partner — permits commercial use, including delivering the results of your own engineering work to your clients. Not permitted: sharing an account, reselling or sublicensing access to Skalnav, redistributing the underlying Skalnav databases, knockdown-factor tables or software, and letting your client operate Skalnav on your licence. Licences are per named user; Team provides up to five individual accounts of your organisation, with shared projects.

Engineering Services

Specialist support for critical shell-buckling decisions.

When a design needs more than software alone, Skalnav provides independent technical review, independent verification, programme-level engineering support and knowledge transfer — led by Dr.-Ing. Heinz Wagner.

Skalnav software

Your engineers run the analysis themselves, repeatably, with the same released methods behind every result. The right answer for recurring shell-buckling work.

Engineering Services

Independent engineering judgement for one specific problem: method applicability is unclear, two methods disagree, the imperfection basis is contested, or a review board wants a second opinion from outside your organisation.

Independent Buckling Review

from €4,500

You already have a buckling verification. We review it and tell you what we find.

Scope

One clearly defined structure and its primary verification: applicability of the chosen method, geometry and boundary-condition assumptions, load definition, the elastic buckling basis, KDF selection, imperfection assumptions, plasticity treatment, interaction equations, safety and reserve factors, units and implementation — plus obvious conservatism or non-conservatism and whether the calculation actually supports the conclusion drawn from it.

You receive

Independent Technical Review Memorandum
Itemised observation and issue list
Limited comparison against an alternative method where it is informative
One review meeting with the reviewer

The memorandum states one of: no material technical objections within the agreed scope; observations and recommendations; points requiring clarification; or that the verification cannot be endorsed within the agreed scope. It is an independent engineering opinion — not an approval by an authority or an appointed checking engineer.

Request a Review

Independent Buckling Verification

from €9,900

You give us the design inputs. We calculate it ourselves, without starting from your result.

Scope

An independent counter-verification: analytical calculation with the applicable recognised methods and the MDC approach, comparison between those methods, an independent view of the knockdown factor, imperfection sensitivity, load interaction and sizing sensitivity where relevant — then a comparison against your own calculation and, where you supply it, your FE result.

You receive

Independent Buckling Verification Report
Method comparison with the governing case identified
Documented inputs, assumptions, limitations and exclusions
Technical review meeting

The €9,900 entry price covers one structure with a defined set of load cases. Several structures, many load cases, composite or stiffened walls, interaction studies or an FE review are scoped individually.

Scope a Verification

Advanced Buckling Engineering

from €15,000

Programme-level support where the difficulty is the engineering itself, not a single calculation.

Scope

Multiple structures and load cases, comparison across methods, FE comparison, sensitivity studies, an imperfection strategy for the programme, structural optimisation, review of supplier calculations, design-freeze support and technical decision support across repeated iterations and design reviews.

Named scopes

GMNIA buckling verification — nonlinear FEA to EN 1993-1-6 §9.8 with curated, documented database imperfections, including the k_GMNIA evidence package (§9.8.4(39) check cases). From €18,000.
Measured-imperfection allowables — you supply 3D or laser scan data (the measurement itself is not part of the service); we evaluate it to EN 1993-1-6 §9.4, run FEA with your measured imperfections in regime-correct form and derive a defensible A-/B-Basis allowable with representativeness documentation. From €30,000.
Design review & technical defence — preparation for PDR, CDR or QR: the buckling assumptions are challenged before your reviewers do it, supporting calculations are prepared, and we take part in the technical meetings to answer questions on the methodology and defend the assumptions alongside your team. Expert participation and technical support during your formal design reviews — Skalnav is not the approving authority. From €45,000.

Discuss your engineering case

Method Development & Qualification

from €30,000

Turn specialist knowledge into a method your organisation owns and can defend.

Scope

A customer-specific buckling methodology or knockdown factor: calibration against your structures, validation datasets, an FE benchmark programme, comparison with experimental data, statistical assessment, method documentation, and implementation into your engineering workflow — including into Skalnav where that is the right home for it.

You receive

Agreed methodology, documented
Validation evidence behind it
Implementation and documentation per the statement of work
Qualification support through your review process

A full programme — V&V dossier, benchmark suite, test correlation, independent replication and a review data package carried through qualification — is project-priced from €150,000. Skalnav supports your qualification; it does not itself issue regulatory certification.

Discuss a Method Programme

Training & Workshops

from €4,500

Put the expertise inside your own engineering team.

Shell-buckling engineering training

Classical elastic buckling, imperfection sensitivity, knockdown factors from the NASA SP-8007 philosophy through to modern approaches, axial, bending, torsion and external pressure, load interaction, plasticity, safety factors and sizing — with real engineering examples, the mistakes we see most often, and how analytical and FE results should be read against each other.

Half-day company trainingfrom €4,500
Full-day company workshopfrom €7,500
Two-day advanced masterclassfrom €12,000
Customer design workshop — your own structuresfrom €9,900 / day

Every format includes live training, presentation materials, worked examples and Q&A. The design workshop works on your real structures and your current methodology alongside the theory. Remote or on site; travel and accommodation are quoted separately. Teams on Team, Business or Enterprise can add Skalnav onboarding — method selection, workflows, sizing, reports — to any format.

Plan a Training

Technical Talks

from €3,500

A specialist lecture for your engineering organisation.

Topics

Why shell-buckling design stays conservative; from NASA SP-8007 to modern knockdown factors; imperfection sensitivity in thin-walled shells; what engineers get wrong about shell buckling; buckling under combined loading; lessons from six decades of collapse experiments; and designing closer to the real structural limit.

Corporate technical talk, 60–90 min + Q&Afrom €3,500
Specialist or executive briefing, prepared on your casefrom €5,000

Travel additional where required. Conference and academic speaking enquiries are welcome and handled case by case.

Invite a Speaker

Delivered and technically led by

Dr.-Ing. Heinz Wagner

Structural engineer specialising in buckling-critical thin-walled shell structures, with 15+ years of shell-buckling research and regulated-industry validation. Doctorate awarded by TU Braunschweig (2018). Lead author of the MDC methodology paper in Proceedings of the Royal Society A (2025) and developer of the MDC methodology behind Skalnav. Based in Braunschweig, Germany.

Engagements are delivered personally, which is also why capacity is limited: slots are agreed per quarter. Priority scheduling is available by agreement.

How an engagement runs

Every engagement is a fixed scope at a fixed project price, agreed in writing before work starts — no hourly billing. You send a short description of the structure and the question; we come back with a written scope, price and schedule. Reports identify the data you provided, the scope, the methods used, the assumptions, the limitations and the exclusions, so the result can be read and checked by a third party.

Documents and confidentiality

Please do not attach proprietary engineering data to a first e-mail. Tell us what the case is about, and we will agree how the data is exchanged — under an NDA where you need one — before anything technical is sent. NDA available for confidential engineering engagements.

Recurring shell-buckling work? Where the same analysis comes back project after project, your engineers can run the workflow directly in the software — see Skalnav Professional and Team. Engagements from Advanced Buckling Engineering upward include Team access for your team for the project duration, and 25% of the engagement fee is creditable toward your first annual licence.

For large organisations

What an Enterprise Design Partnership actually means.

Large aerospace, defence and energy organisations cannot procure a credit-card subscription, and a single-user licence is not built for their workflow. An Enterprise Design Partnership is an individually scoped engagement — deployment, qualification and integration agreed per programme, not a bigger plan on a price list.

The list below separates what is available today from what is not. Items shown as not currently available are exactly that: they are not shipped, not deployable on request, and cannot be ordered as part of a licence. Where a programme depends on one, it becomes a scoped development item with its own feasibility review and timeline — or the honest answer is that Skalnav is not yet the right tool for that constraint.

API & Automation · limited v1

REST API access

A limited v1 API is available today under a Design Partner engagement: an organisation token, a ping endpoint and cylinder compute, so your engineers can call Skalnav from Python or MATLAB instead of the browser. It is not a general API covering every calculation, and it carries no API availability commitment. Wider endpoint coverage is scoped per engagement.

Methodology Extension · scoped engagement

Custom KDF curves & norms

A scoped custom-KDF engineering engagement can embed your company’s internal knockdown factors, fabrication-quality classes or in-house reduction factors alongside referenced third-party methods. This is engineering work we agree and deliver per customer, not a self-service feature for arbitrary custom norms.

Identity & Access · built, not yet released

Company sign-in — OpenID Connect

OpenID Connect sign-in is implemented and tested against a reference identity provider, but it has not yet been run against a commercial directory or accepted by a customer, so we do not offer it as a released feature and will not tell your IT department that it is. SAML and SCIM are not implemented, and OIDC cannot deprovision an account the moment your directory disables it. What is in use today: individual accounts, organisation roles, an audit trail and an organisation-wide MFA policy. If your programme requires federated sign-in, it belongs in the engagement as a scoped item with its own acceptance against your own provider.

Data Sovereignty · built, not yet released

Customer-hosted installation

A customer-neutral deployment package, offline signed licensing and operator documentation exist and are tested — including an automated check that the running application opens no outbound connection. What has not happened: any installation in a real customer environment, and any run on a genuinely disconnected machine. So for ITAR, export-controlled, classified or IP-sensitive programmes we will discuss this as a scoped deployment with its own acceptance criteria; we will not sell it as something we can drop into your data centre today.

Support & Qualification · named contact today

Technical contact and qualification support

A Design Partner gets a named technical contact and an agreed onboarding package — direct email contact and scheduled review calls, rather than a ticket queue. Support for internal tool-qualification exercises (ECSS-E-ST-40, DO-330) and validation studies against your reference cases is delivered as scoped engineering work. A contractually dedicated support engineer requires a signed support agreement and confirmed staffing, and is not part of the licence.

Availability · not currently available

Uptime SLA

We do not offer a contractual uptime SLA, and we quote no availability percentage, because we have not yet measured and operated against one long enough to stand behind it. Maintenance windows and incident reporting can be agreed in writing; a service-credit-backed availability commitment cannot, until the operational evidence exists.

Compliance · on request

Procurement-ready paperwork

Formal quotation with VAT-ID, purchase-order workflow, annual framework agreement, NDA, Auftragsverarbeitungsvertrag (DPA under GDPR Art. 28), supplier-qualification questionnaires, export-control declarations. The things large buyers cannot close a deal without.

Commercial Flexibility · negotiated separately

Value-based agreements

A commercial model tied to a measured outcome rather than seats can be negotiated separately, but only once there is an agreed, measurable baseline and after legal review on both sides. We do not promise a mass reduction or any other guaranteed outcome as a condition of the licence.

When a standard licence is enough — and when it isn’t

Professional (€9,900 / year, excl. VAT) is the right choice for individual structural engineers, small consultancies, and early evaluation inside larger organisations. It covers the full analytical capability, all design bases, unlimited audit-ready reports and the complete standards set, and it permits commercial client work. Team (€29,900 / year) adds the shared organisation for up to five engineers, and Business / Department (€49,900 / year) extends the same scope to about ten. None of them computes differently.

An Enterprise Design Partnership is the right conversation as soon as any of the following apply:

deployment across a department or programme, beyond ten named users;
integration into a design-automation pipeline via the limited v1 API;
formal tool qualification for certification submissions;
custom KDFs, company-internal reduction factors, or tailored methods;
a requirement we do not yet meet — SSO/SCIM, on-premise or air-gapped hosting, or a contractual uptime SLA — which would have to be scoped as development work with its own timeline, not ordered as a feature.

→ Talk to us — we’ll scope the right setup honestly, including what we cannot deliver today, and prepare the paperwork your procurement team will ask for. If you would rather see evidence first, a Proof of Value runs Skalnav against one of your real design cases.

FAQ

Questions engineers ask before they commit.

SP-8007 gives a single empirical lower bound fitted to test data from the 1960s. Skalnav's MDC approach derives knockdown factors mechanistically from geometry, imperfection measures and buckling regime — and shows you the experimental evidence behind each curve. You can display both side by side in every analysis.

Skalnav computes and documents knockdown factors alongside nine established design codes, with full traceability of the underlying evidence. Whether a mechanistic KDF is admissible as the primary basis of a proof depends on your project's verification plan and approval authority — that decision always stays with them. Typical uses are justifying margins, quantifying the conservatism of code values, and cross-checking a primary method against the experimental record.

From six decades of published collapse experiments — 1,000+ curated records in the ValidationHub with documented provenance for every data point, measured values strictly separated from assumed bounds.

Yes — watch the demo, download the sample verification report, or open Skalnav directly in your browser: cylinder axial and bending work without a login.

Beyond that, a Proof of Value (from €15,000) runs Skalnav against an agreed real design case from your own programme and documents the result, and the Startup Program lowers the entry cost for qualifying early-stage companies.

All questions →

Shell buckling verification in minutes, not weeks.

What is Skalnav?

Skalnav

ValidationHub

Skalnav FEM

Shell buckling design still runs on 1960s assumptions.

Empirical knockdown factors

Expensive nonlinear workflows

Opaque design margins

From fixed empirical factors to mechanistic, imperfection-sensitive predictions.

Traditional approach

With Skalnav

From geometry to audit-ready proof — in four steps.

Define

Evaluate

Compare

Document

MDC vs. NASA SP-8007 vs. GMNIA/FEM.

Skalnav in action.

Three things the classical methods don’t tell you.

Imperfection Sensitivity

Regime Analysis

Plasticity Correction

Built for shell buckling across industries.

Aerospace

Wind Energy

Civil Engineering

Pressure Vessels

Every prediction is accountable to physical evidence.

Experimental records

Published methodology

Statistical basis

Behind the methodology.

Dr.-Ing. Heinz Wagner

Dr.-Ing. Regina Wagner

Sebastian Arnold

Scope built for real engineering decisions.

Multi-Standard Comparison

Sizing & Back-Solve

Shell Optimizer

Imperfection Sensitivity

Composite & Sandwich Shells

Plasticity & Combined Loading

Validation Hub

Audit-Ready Reports

The building blocks an engineer actually uses.

See the shells in your neighbourhood that buckled below prediction.

Know your imperfection before you measure it.

Decide what to measure — before you measure.

See which standard governs — and how much margin the others leave on the table.

What MDC delivers today — and what is still in development.

Four levels of structural confidence.

What the margin looks like — two worked references.

Wind turbine tower — cylindrical section under combined loading

Torispherical head — internal & external pressure verification

Priced for engineering value, not calculation count.

Specialist support for critical shell-buckling decisions.

Independent Buckling Review

Independent Buckling Verification

Advanced Buckling Engineering

Method Development & Qualification

Training & Workshops

Technical Talks

Dr.-Ing. Heinz Wagner

What an Enterprise Design Partnership actually means.

REST API access

Custom KDF curves & norms

Company sign-in — OpenID Connect

Customer-hosted installation

Technical contact and qualification support

Uptime SLA

Procurement-ready paperwork

Value-based agreements

Questions engineers ask before they commit.

Quantify the margin your structures are carrying.