Deriving Ogden Constitutive Parameters from Biaxial Stretch Testing Data
Deriving Ogden constitutive parameters pairs non-linear biaxial stretch data with Drucker stability constraints to ensure reliable finite element simulations.
Thermoforming Simulation
Meaning
Finite element analysis models sheet heating, plug assist contact, and pressure-driven mold inflation to predict wall thickness variations across formed plastic parts. Running thermoforming simulation optimizes tooling geometries, plug assist materials, and pressure timing before cutting physical metal molds. The predictive digital engineering method applies to semi-rigid thermoplastic sheet forming under pressure or vacuum, but does not extend to liquid resin casting or high-pressure injection molding operations.
Numerical Mechanics
Non-linear solvers model contact friction between heated polymer sheets and plug tools using hyperelastic or viscoelastic constitutive models. Executing thermoforming simulation requires updating shell element geometries dynamically as sheet material stretches into complex mold cavities. Dynamic explicit finite element codes compute localized thinning, corner bridging, and temperature loss during high-speed contact events.
Inaccurate friction coefficients between plug assist surfaces and warm plastic sheets yield false wall thickness distribution predictions in deep-draw containers.
Mold Optimization
Predicting thin spots allows tooling engineers to alter corner radii and plug shapes prior to machining hard metal tooling. Digital redesign cycles eliminate expensive mold rework and shorten production commissioning timelines.
Material Accuracy
Temperature-dependent stress-strain curves and accurate hyperelastic strain energy potentials are essential for reliable simulation outputs. Relying on room-temperature datasheet values produces severe discrepancies between predicted and actual part wall thicknesses.