Plastic product Impact resistance - what can you do with the geometry
Skilled boxers have good impact resistance. They can absorb the energy of impacts with their whole body, not just one part of it, nose for instance. The same principle applies not only to material toughness, but to mechanics as well:
1: Try to distribute the energy of impacts to the whole construction. Do not maximise the stiffness of the product without a good reason. Think of the component as a spring.
2: Impact resistant materials are able to absorb energy in their internal structure. That requires bulkiness to some degree from the construction. A helmet with 0,5 mm wall thickness is not very impact resistant. Robustness is good. Don’t make the shock-absorbing elements too thin or lacy.
3: Sharp corners and notches operate as stress raisers. This goes with static loads as well, but in the case of impacts, they are merciless.
4: A rib that is meant to strengthen the product might easily reverse the intended purpose by crack propagation. Ribs should preferably be under compression rather than tension.
5: If possible, try to avoid weld lines in the areas that are exposed to shocks. The same goes for gating, too.
Did I miss something? Please add your own design tips in the comments below!