Understand Material, Geometric and Contact non-linearities for Piping Design & Analysis

A: Beyond about 1–2% strain or when displacements rival member depth, second-order effects dominate. Faster thermal ramps don't change material properties but they do push geometry into a non-linear regime; ignoring that gives tidy numbers that miss buckling or snap-through.

A: The zero-to-contact transition is the hard boundary. Once uplift occurs, friction drops out entirely, so a slotted detail alters load paths far more than small μ shifts or clerical mismatches.

A: Once soil yields, stiffness drops sharply. Compression-only contact with nonlinear p–y behaviour captures the threshold where restraint mobilises and then softens, matching observed field response rather than theoretical maxima.

A: At a few kN of friction force, travel-dependent behaviour stops being linear. Capturing that nonlinearity is the only way to see whether nozzle loads breach limits once the spring stops behaving as ideal.

A: Axial restraint changes whether contact engages in one or multiple directions. The symbol defines when and how restraint activates, which directly feeds the non-linear boundary condition.

A: Eigenvalues ignore post-yield geometry. Including imperfections and load–displacement response is the only way to see snap-through once stresses sit close to yield under secondary loads.

A: Once strain passes yield, stress limits lose meaning. True stress–strain data tied to strain acceptance captures plastic deformation during fast transients where inertia and unloading interact.

A: A few millimetres of gap delay contact. Thermal movement has to consume that clearance before restraint engages, shifting hot stress and load paths rather than cold weight effects.

A: Load-path switching is the red line. Even with low stresses, changing contact status invalidates linear superposition and forces a non-linear solution to stay defensible under audit.