Frequently asked questions

SP-8007 gives a single empirical design curve drawn under most of the test data from the 1930s to the 1960s. Depending on build quality, it can be conservative or optimistic for your shell. In Skalnav's MDC approach, the knockdown factors are fitted to FE Monte-Carlo campaigns across geometry and imperfection amplitude — and checked against the experimental record. For cylinders, the MDC result and the NASA SP-8007 value sit side by side, and you can switch the comparison to another implemented method.

MDC is Skalnav’s own method: knockdown factors fitted to FE Monte-Carlo campaigns and checked against curated collapse tests, read at your shell’s geometry and imperfection amplitude w/t. EN 1993-1-6 is a reference method beside it: Skalnav implements EN 1993-1-6:2007 and selected procedures of EN 1993-1-6:2025, and where a procedure is implemented for the geometry and load case, its result sits beside the MDC result for the same shell.

With Professional, a measured scan of a cylinder can be classified against the EN 1993-1-6 fabrication tolerance classes (A excellent, B high, C normal) and turned into the amplitude w/t, so you read the MDC knockdown at your actual tolerance level (see Imperfection sensitivity). Whether the MDC knockdown may serve as the primary basis of your proof is decided by your project’s verification plan and approval authority.

Skalnav computes and documents the MDC knockdown factor with full traceability of inputs, method, design basis and engine version, and shows a referenced design method beside it, for example NASA SP-8007 or EN 1993-1-6. 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 how conservative or optimistic code values are for the case, and cross-checking a primary method against the experimental record.

Statistical bases for the design curve, analogous in spirit to material allowables: alongside the mean (best-estimate) curve, the B-Basis is the empirical 10th percentile of the underlying Monte-Carlo ensemble (conservative) and the A-Basis the empirical 1st percentile (highly conservative). They are quantile-based conservative approximations — not strict MIL-HDBK-5 tolerance limits — as the validation page states under Design bases. You choose the basis to match your project's reliability requirements.

From more than a century of published collapse experiments (1909–2026): 1,500+ comparison-ready tests in the Validation Hub, each traceable to its source publication, measured values strictly separated from assumed bounds. Most are compared with the MDC knockdown; where MDC cannot be compared, the test is compared with the reference method stated for its campaign.

Every result and report carries the engine version (build and knockdown-schema reference). An archived report can be re-checked against today's engine, so you see whether a later version changes a result.

Geometries: cylinders, cones, spherical shells (shallow cap through complete sphere) and dished heads (torispherical, with ellipsoidal and tori-cone head modes).

Walls: homogeneous isotropic walls, stepped walls (EN 1993-1-6:2025 D.5), composite laminates for cylinders and spheres (Beta; the anisotropy correction of the knockdown is calibrated for cylinders under axial compression only) and ring-stiffened cylinders under external pressure.

Load cases: axial compression, bending, torsion, transverse shear (Beta), external pressure and combined cases (axial + bending, axial or bending + internal pressure, axial + external pressure, axial + torsion), plus silo and tank workflows.

Not every combination carries a native MDC curve yet; where it does not, a referenced design method covers the case if it is implemented for it. The authoritative view is the coverage matrix.

The coverage matrix shows each geometry and load case with a released MDC knockdown, the one Beta cell, and the cells without an MDC route, where a referenced design method covers the case if it is implemented for it. The app warns when a design lies outside the range of the tests MDC is checked against, and it flags extrapolated values. MDC is a pre-design and verification aid: it does not replace GMNIA where cutouts outside the calibrated range, concentrated loads, welded joints with residual stresses or strain-rate effects govern, and the responsibility for the verification stays with the engineer.

Yes. Skalnav is a public preview ahead of full release with Structured Chaos II (Proc. R. Soc. A, accepted for publication). Individual modules marked Beta or Preview in the product are exactly that. The coverage matrix marks the one Beta cell, and engine versions are stamped on every result. Questions: contact@skalnav.com.

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 excl. VAT) 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.

Working on one project? 30-Day Professional Project Access gives one engineer the full Professional core for 30 days; it does not renew.

Licences are arranged directly with us — there is no online checkout. Request a licence or a quotation by e-mail; you receive a written quotation or order confirmation with the term, the named users and the licence scope; we then activate your named accounts. See How to buy.

Skalnav GmbH, Bremen, Germany — commercial register Amtsgericht Bremen, HRB 43265 HB; company details in the Impressum.

Professional is €9,900 per year for one named user. Team is €29,900 per year for up to 5 named users. An Enterprise starts at €75,000 per year and is scoped individually. Licence prices are per year and exclude VAT.

For a group between Team and Enterprise, Team — 10 seats covers up to 10 named users at €49,900 per year — ask us for a quote.

No. Every commercial licence runs the same released engineering core: the same methods, the same design bases (mean, B-Basis, A-Basis), the same applicability warnings and the same safety factors. We do not sell a more accurate answer at a higher price.

The tiers differ in how many engineers use the tool, whether they share an organisation and projects, team features such as batch studies, the support each plan lists, and how much integration, qualification or custom engineering work is included.

FE load import has no plan-specific case cap in any commercial licence; common file-size and row limits apply. The thermal correction for metal cylinders is shown for the most limiting load case in Professional and Project Access, and for each load case in Team and above.

Yes. Every commercial licence — Professional included — permits commercial use, and the results of your own engineering work may be delivered to your clients. There is no separate client-deliverable licence.

What is not permitted: sharing an account, reselling or sublicensing access to Skalnav, letting your client operate the tool on your licence, and redistributing the underlying Skalnav databases, knockdown-factor tables or software.

Yes — 30-Day Professional Project Access at €1,699 (excl. VAT) gives you the full Professional engineering core for one named user for 30 days. It does not renew: there is no subscription to cancel, and the licence simply ends. You get the same released methods, design bases and export formats as the annual licence, with no analysis or report limits added just because the term is short.

It is a short-term alternative to the annual licence, not the standard way to buy Skalnav: from roughly six 30-day blocks onward the annual licence is cheaper, and continuous professional use is expected to run on an annual licence. Project Access is arranged directly with us: contact us.

Yes. Upgrade to Professional Annual during the active 30-day access period and the full €1,699 Project Access fee is credited toward your first annual licence — €9,900 less the €1,699 credit leaves €8,201 to pay. The list price of Professional stays €9,900 per year; this is an upgrade credit for what you already paid, not a discount.

Credit terms: the Project Access must still be active when you order the annual licence; the credit is applied once, for the same legal entity that holds the Project Access, and multiple Project Access purchases do not accumulate; the maximum credit is the €1,699 fee; it is applied against the first Professional annual licence and is not paid out in cash or combined with other credits. VAT follows the actual invoice.

Team or broader upgrades can be discussed with Skalnav directly — write to us.

Academic covers education, teaching and non-commercial research. It is granted automatically for recognised institutional e-mail domains; other addresses start on the registered Explorer tier and can request Academic via Feedback.

Any commercial, contract or client work — including funded industry projects carried out at an institution — needs a Professional licence. Academic accounts work on the mean design basis without the plasticity correction and export the mission profile as CSV and PDF reports marked “Academic – non-commercial”; the Validation Hub, Imperfection Hub and Imperfection Guide are Professional features.

Yes. The Skalnav Startup Program is temporary adoption support for qualifying independent early-stage companies: Professional at €4,900 in year one and €7,400 in year two, Team at €14,900 in year one and €22,400 in year two, then standard pricing from year three.

Startup licences carry the same engineering core and the same commercial rights as the corresponding standard tier — it is a lower price, not a smaller product. We generally look for an independent company that is not part of a larger corporate group, younger than five years and under 100 employees; Skalnav reviews each application and decides the level of support case by case.

Every commercial licence includes e-mail support (contact@skalnav.com), best effort — there is no response-time commitment and no SLA. Enterprises also get a named technical contact and an agreed onboarding package.

The platform is hosted by IONOS SE on a single server in Germany, under IONOS's data-processing agreement with us; all assets are served self-hosted — no third-party CDNs or trackers. A data-processing agreement for customers (Art. 28 GDPR) is in legal review. Details: Security, data handling and procurement, and the privacy policy.

On-premise and air-gapped installation is not currently available. Where a programme requires it, it can be negotiated as separately scoped development with its own feasibility review — see Enterprise.

Single sign-on (SAML or OpenID Connect) and SCIM provisioning are not currently available. Accounts use individual sign-in with TOTP multi-factor authentication, which an organisation can enforce for all its members.

No. Skalnav runs in the browser. Current desktop versions of Chrome, Edge and Firefox are tested; Safari is supported on a best-effort basis; phones and tablets are limited, because the application is built for desktop work.

Your account stays open on a free tier and your data is not deleted: projects and exports stay retrievable, within that tier's limits. Deleting your account data is a separate step you trigger yourself, and you can export it at any time.

Registration is not available from EU-sanctioned countries; access is screened by country at registration. The export-control classification of the software is under legal review. Please do not upload classified or export-controlled data without agreeing it with us first.

A licence is the answer when your own engineers do the work and it comes back project after project. Engineering Services are for a single problem that needs independent judgement: a verification you want reviewed from outside, two methods that disagree, a contested imperfection basis or KDF, a review board asking for a second opinion, or a case that goes beyond a standard workflow.

The two support each other: a single review can be the start, with a licence once the workflow is routine — or a licence holder calls on us when a difficult case appears. Engagements from Advanced Buckling Engineering upward include Team access for the project duration, and 25% of the engagement fee is creditable toward a first annual licence.

No. An Independent Buckling Review is an independent engineering opinion within an agreed technical scope, delivered as a written review memorandum. It is not an approval by an authority, and Skalnav does not act as an appointed checking engineer (Prüfingenieur) or issue regulatory certification.

The memorandum states clearly which of the following applies: 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. Whether that evidence is admissible in your verification process is decided by your project's approval authority.

Fixed scope at a fixed project price, agreed in writing before work starts — no hourly billing. The published figures are entry prices: an Independent Buckling Review from €4,500, an Independent Buckling Verification from €9,900, Advanced Buckling Engineering from €15,000, and Method Development & Qualification from €30,000, with full qualification programmes project-priced from €150,000. Training starts at €4,500 (design workshops are priced per day) and technical talks at €3,500; travel and accommodation are quoted separately. All excl. VAT.

What moves the price: the number of structures and load cases, how many methods are compared, whether an FE review is included, composite construction, documentation depth and the meetings you need. Send a short description of the case and you get a written scope, price and schedule back.

Please do not attach proprietary engineering data to a first e-mail. Describe the case in general terms; we then agree how data is exchanged — under an NDA where you need one — before anything technical is sent. NDA available for confidential engineering engagements.

If the data is export-controlled, say so in your first e-mail, without details; the exchange route is agreed before anything technical is sent.