Research simulation, not a helmet safety rating. These are unfiltered responses of an assumed headform and material model. The head has no neck or brain; the assembly has no facemask, retention, shell damage or debonding. Friction and foam unloading are assumptions.
Inspect the shell geometry and material directions
Actual screening mesh, shown at a common scale. Marks show the local ply material axis; they are not continuous manufactured fiber paths. Gold marks identify elements using the alternate coordinate chart. The face opening is visible; a facemask and chinstrap are not modeled.
The actual shapes tested
Composite shellUniform B foamSoft A inner foamFirm C outer foam
Sagittal sections at the same scale; front is to the right. Liner thickness varies with shape. Layer interfaces and shell thickness come from the computational inputs.
Comparison across all five impacts
Each entry reports its worst response across crown, front, side, rear and oblique impacts. The score is the largest of three ratios to the baseline oval with conventional fiber order. Lower is better for this chosen numerical objective; it is not an injury score.
| Shape / structure | Worst linear
m/s² | Worst angular
rad/s² | Worst spin
rad/s | Relative score | Cases |
|---|
Inspect the measured response histories
Blue: selected designBrown: oval / conventional fibers / uniform B baseline
Polished concept presentation
The oval A/C concept shown here illustrates the layer architecture. Its hardware, vents and cosmetic surfaces are not part of the simulation; choosing it for the rendering does not identify a winning design.
What the checks establish
Layer definitions and controlled comparisons
QI_B: mirrored [0,45,-45,90,0,45,-45,90] half-stack; uniform B foam. BAL_B: mirrored [-45,45,0,90,90,45,0,-45] half-stack; uniform B foam. This pair isolates ply order. BAL_AC: the same selected shell with A foam inside and C outside; the interface is placed to match the uniform B foam mass.
The outer shapes share the head-contact surface and covered head region. Foam volume is matched; shell ply thickness is adjusted to match shell mass. This does not keep local contact curvature or local cushioning stroke constant: those are the geometric variables being tested.
Numerical and physical limits
Normal velocity is 3 m/s. The oblique case adds 3 m/s tangential velocity. The assumed wall friction is 0.2. Impacts run for 6 ms initially; unfinished contact cases are withheld or extended. Head motion is reconstructed from eight rigid-cap node histories, sampled every 25 microseconds. The head reference is the nominal rigid cap's center of mass, fixed in that body.
Energy, hourglass energy, added mass, rigid-motion fit and end-of-contact checks are applied. Foam compression is checked at eight Gauss locations per element on every 0.25 ms frame. This does not bound every intervening solver step or validate multiaxial material behavior. Constitutive data, unloading and failure must be calibrated against experiments before making protection claims.
Download all-case CSV · Full comparison JSON · Models, inputs and evidence package