WWI helmet is tops for blast protection

Although helmet technology has evolved considerably in the intervening century since World War I, it is primarily ballistics and blunt force that today’s helmets are designed to withstand. On those metrics, they are far superior to their WWI counterparts, but when it comes to the blast waves from explosives, protection has not improved. 

Microlattice padding makes for safer helmets

Striker II fighter pilot helmet: Transforming aerial combat

A study conducted by bioengineers at Duke University compared the effectiveness of World War I helmets from the United Kingdom/United States (Brodie), France (Adrian), Germany (Stahlhelm) and a current United States combat variant (Advanced Combat Helmet). They used a shock tube which was pressurised with helium until a membrane wall burst, releasing the gas in a shock wave. A dummy with pressure sensors was placed underneath, and the helmets were tested in turn at varying distances from the blast to simulate different types of German artillery. The work is published in PLOS ONE.