Convergence diagnostics for nonlinear FEA jobs

The moment an engineer submits a nonlinear job and it either diverges or grinds through thousands of costly iterations, they open the log file and stare at Newton-Raphson residuals they can barely interpret. There is no structured path from 'job failed' to 'here is what to change.' They post on forums, try random contact stiffness tweaks, or restart with cruder settings — losing hours or days on a single run.

This gap persists for a structural reason: the major CAE vendors sell solvers, not debugging services. Their incentive is to add more solver features, not to make the current ones more transparent. The engineers who suffer most from convergence failures — junior analysts, teams working outside their comfort zone on contact-heavy assemblies — are not the same people who negotiate enterprise licenses. The buyer (the CAD/CAE manager or IT procurement team) rarely sees convergence failures in demos. So nobody complains loudly enough at the decision-making level to force the vendor to fix it.

What's missing is not a better solver — it's a structured post-mortem on why a specific run failed. Users explicitly describe 'lack of control in assuring convergency' and wish for 'auto optimization for contact stiffness or other factors.' The log files exist. The residual history exists. The contact force outputs exist. But they're raw, solver-specific, and require deep expertise to read. An engineer at an automotive supplier running an assembly simulation with separating contacts has no tool that ingests those logs, identifies which contact pair is the source of energy imbalance, and proposes a ranked list of parameter adjustments — tighter contact stiffness, smaller initial time step, penalty vs. augmented Lagrangian — with the reasoning made explicit.

This is a recurring business need, not a one-time fix. Every project with nonlinear contact generates new runs, new failures, new debugging cycles. Teams that do crash, NVH, or durability simulation hit this weekly. The cost is concrete: an engineer billing at $80–150/hr spending two days debugging a convergence issue before re-running an overnight job is a $2,000–4,000 event. If a team does this ten times a year, that's real money with a real paper trail — exactly the kind of cost a simulation manager can justify a subscription against.

What to build

Build a desktop-adjacent service that ingests solver log files and output databases from Ansys Mechanical and OptiStruct nonlinear runs, parses residual histories and contact status outputs, and produces a ranked diagnostic report naming the specific contact pair or element region driving divergence, with parameter adjustment recommendations tied to the failure mode detected.

Where to start

Start with Ansys Mechanical nonlinear contact failures only — the log format is well-documented, the user base is large, and the community around it (APDL scripting, Mechanical APDL logs) means you can validate recommendations against a large corpus of solved forum cases before you talk to a single paying customer.

The hard part

Each solver (Ansys, OptiStruct, Abaqus) writes log files in different formats and exposes different convergence metadata, so building a parser that works reliably across even two solvers requires significant reverse-engineering of undocumented output formats before you have a product worth showing anyone.

How it makes money

Per-analysis subscription: engineers or teams pay a monthly fee based on the number of diagnostic reports generated, starting around $200–400/month for a 5-seat team with unlimited runs, scaling by seat count.