Crush Stress & SEA Testing

Measuring Dynamic Properties of Composites for Crash Modelling

Composites offer huge advantages in crash safety applications through their high specific energy absorption (SEA). A composite crash structure can be a fraction of the weight of a metal one for equal performance and take up less internal space. However, their crash performance is dependent on many factors including impact velocity, fibre orientation and geometry.

​Engenuity is one of the world’s leading organisations in the characterisation and prediction of crash performance of composites. We can help you in choosing, testing and characterising the best materials for efficient safety systems for passengers, batteries, hydrogen storage and critical systems. 

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Material Cards for Crash Modelling

Engenuity has an experienced analysis team that works with our materials laboratory to generate accurate material cards for crash simulation in a number of explicit codes. We test for all the necessary physical parameters, then build analysis models of the physical tests to develop material cards that accurately reflect the empirical behaviour. We can create material cards for pretty much all crash prediction software programs including LS-DYNA (MAT54 and MAT262) and Radioss.

However, the backbone of our crash prediction work is CZone. This is the only purely predictive, composite crash simulation software, being validated over many years’ use by automotive OEMs and Formula 1, and eliminating the requirement for “non-physical parameters” such as SOFT. Learn more about CZone. 

Crush Screening

Even very similar composite materials can perform very differently in crush, this is unrelated to their static mechanical properties. Engenuity uses crush screening to select those that are ideal crushing materials, grading materials into 3 different types. Type 1 materials provide a consistently high crush stress, these are recommended for all crash applications including demanding locations under axial load. Type 2 gives an initial high crush stress, but this then reduces as the crushing continues, these materials can be used in crush applications but there are better alternatives. Type 3 materials do not absorb much energy as they fail and therefore do not contribute to the safety of the vehicle during a crash event. 

Geometry Effects of Energy Absorption in Crash

It has long been claimed that SEA (and therefore crush stress) is not a material property as it can vary with component geometry. Engenuity has overcome this using two different values in simulation, a delamination free crush typical of flat samples and delamination suppressed crush typical of curved profiles. This approach has been validated through both component and vehicle level physical testing.

​Engenuity has also developed a methodology to generate both values directly from flat plaques as shown in the video below. 

Contact us now and learn how we can help you improve the data for your crash modelling
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