A helmet protects you by being crushed - it dissipates the kinetic energy of your head in the process. They’re not very strong in tension at all - a cracked hel

A helmet protects you by being crushed - it dissipates the kinetic energy of your head in the process. They’re not very strong in tension at all - a cracked helmet is a helmet that failed to do its job properly. If it crushed first & then cracked then that’s different of course.